Accessing Databases with...

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© 1992-2007 Pearson Education, Inc. All rights reserved.

25Accessing

Databases withJDBC

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OBJECTIVESIn this chapter you will learn: Relational database concepts. To use Structured Query Language (SQL) to retrieve

data from and manipulate data in a database. To use the JDBC™ API of package java.sql to access

databases. To use the RowSet interface from package javax.sql to

manipulate databases. To use JDBC 4.0’s automatic JDBC driver discovery. To use PreparedStatements to create precompiled SQL

statements with parameters. How transaction processing makes database

applications more robust.

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25.1 Introduction25.2 Relational Databases25.3 Relational Database Overview: The books Database25.4 SQL

25.4.1 Basic SELECT Query25.4.2 WHERE Claus25.4.3 ORDER BY Claus25.4.4 Merging Data from Multiple Tables: INNER JOIN

25.4.5 INSERT Statement25.4.6 UPDATE Statement25.4.7 DELETE Statement

25.5 Instructions for installing MySQL and MySQLConnector/J

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25.6 Instructions for Setting Up a MySQL User Account25.7 Creating Database book in MySQL25.8 Manipulating Databases with JDBC

25.8.1 Connecting to and Querying a Database25.8.2 Querying the books Database

25.9 RowSet Interface25.10 Java DB/Apache Derby25.11 PreparedStatements

25.12 Stored Procedures25.13 Transaction Processing25.14 Wrap-Up25.15 Web Resources and Recommended Readings

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25.1 Introduction

Database– Collection of data

DBMS– Database management system– Storing and organizing data

SQL– Relational database– Structured Query Language

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25.1 Introduction (Cont.)

RDBMS– Relational database management system– MySQL

- Open source- Available for both Windows and Linux- dev.mysql.com/downloads/mysql/4.0.hml

JDBC– Java Database Connectivity– JDBC driver

- Enable Java applications to connect to database- Enable programmers to manipulate databases using JDBC

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Software Engineering Observation 25.1

Using the JDBC API enables developers tochange the underlying DBMS withoutmodifying the Java code that accesses thedatabase.

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© 2005 Pearson Education, Inc. All rights reserved.

25.2 Relational Databases

• Relational database– Table

• Rows, columns– Primary key

• Unique data

• SQL queries– Specify which data to select from a table

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Fig. 25.1 | Employee table sample data.

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Fig. 25.2 | Result of selecting distinct Department and Locationdata from table Employee.

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25.3 Relational Database Overview: Thebooks Database

• Sample books database– Four tables

• authors– authorID, firstName, lastName

• titles– isbn, title, editionNumber, copyright, publisherID,

imageFile, price• authorISBN

– authorID, isbn

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Column Description

authorID Author’s ID number in the database. In the books database, this integer

column is defined as autoincremented —for each row inserted in this table, the authorID value is increased by 1 automatically to ensure

that each row has a unique authorID . This column represents the

table’s primary key.

firstName Author’s first name (a string).

lastName Author’s last name (a string).

Fig. 25.3 | authors table from the books database.

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authorID firstName lastName

1 Harvey Deitel

2 Paul Deitel

3 Andrew Goldberg

4 David Choffnes

Fig. 25.4 | Sample data from the authors table.

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25.3 Relational Database Overview: Thebooks Database (Cont.)

• Foreign key– A column

• matches the primary key column in another table– Helps maintain the Rule of Referential Integrity

• Every foreign key value must appear as another table’sprimary key value

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Column Description

authorID The author’s ID number, a foreign key to the authors table.

isbn The ISBN for a book, a foreign key to the titles table.

Fig. 25.5 | authorISBN table from the books database.

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authorID isbn authorID isbn

1 0131869000 2 0131450913

2 0131869000 1 0131828274

1 0131483986 2 0131828274

2 0131483986 3 0131450913

1 0131450913 4 0131828274

Fig. 25.6 | Sample data from the authorISBN table of books.

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Column Description

isbn

ISBN of the book (a string). The table’s primary key. ISBN is an abbreviation for “International Standard Book Number” —a numbering scheme that publishers use to give every book a unique identification number.

title Title of the book (a string).

editionNumber Edition number of the book (an integer).

copyright Copyright year of the book (a string).

Fig. 25.7 | titles table from the books database.

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isbn title editionNumber copyright

0131869000 Visual Basic How to Program 3 2006

0131525239 Visual C# How to Program 2 2006

0132222205 Java How to Program 7 2007

0131857576 C++ How to Program 5 2005

0132404168 C How to Program 5 2007

0131450913 Internet & World Wide Web

How to Program

3 2004

Fig. 25.8 | Sample data from the titles table of the books database.

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25.3 Relational Database Overview: Thebooks Database (Cont.)

• Entity-relationship (ER) diagram– Tables in the database– Relationships among tables

• Rule of Entity Integrity– Primary key uniquely identifies each row– Every row must have a value for every column of the

primary key– Value of the primary key must be unique in the table

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Fig. 25.9 | Table relationships in the books database.

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Common Programming Error 25.1

Not providing a value for every columnin a primary key breaks the Rule ofEntity Integrity and causes the DBMS toreport an error.

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Providing the same value for the primarykey in multiple rows causes the DBMS toreport an error.

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Providing a foreign-key value that does notappear as a primary-key value in anothertable breaks the Rule of ReferentialIntegrity and causes the DBMS to reportan error.

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25.4 SQL

• SQL keywords– SQL queries and statements

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SQL keyword Description

SELECT Retrieves data from one or more tables.

FROM Tables involved in the query. Required in every SELECT.

WHERE Criteria for selection that determine the rows to be retrieved, deleted or updated. Optional in a SQL query or a SQL statement.

GROUP BY Criteria for grouping rows. Optional in a SELECT query.

ORDER BY Criteria for ordering rows. Optional in a SELECT query.

INNER JOIN Merge rows from multiple tables.

INSERT Insert rows into a specified table.

UPDATE Update rows in a specified table.

DELETE Delete rows from a specified table.

Fig. 25.10 | SQL query keywords.

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25.4.1 Basic SELECT Query

• Simplest format of a SELECT query– SELECT * FROM tableName

• SELECT * FROM authors

• Select specific fields from a table– SELECT authorID, lastName FROM authors

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authorID lastName

1 Deitel

2 Deitel

3 Goldberg

4 Choffnes

Fig. 25.11 | Sample authorID and lastName data from the authors table.

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For most queries, the asterisk (*) should not be used to specifycolumn names. In general, you process results by knowing inadvance the order of the columns in the result—for example,selecting authorID and lastName from table authors ensuresthat the columns will appear in the result with authorID as thefirst column and lastName as the second column. Programstypically process result columns by specifying the column numberin the result (starting from number 1 for the first column).Selecting columns by name also avoids returning unneededcolumns and protects against changes in the actual order of thecolumns in the table(s).

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If you assume that the columns are alwaysreturned in the same order from a query thatuses the asterisk (*), the program mayprocess the results incorrectly. If the columnorder in the table(s) changes or if additionalcolumns are added at a later time, the orderof the columns in the result would changeaccordingly.

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25.4.2 WHERE Clause

• specify the selection criteria– SELECT columnName1, columnName2, … FROM

tableName WHERE criteria• SELECT title, editionNumber, copyright

FROM titlesWHERE copyright > 2002

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Portability Tip 25.1

See the documentation for your databasesystem to determine whether SQL is casesensitive on your system and to determinethe syntax for SQL keywords (i.e., shouldthey be all uppercase letters, all lowercaseletters or some combination of the two?).

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title editionNumber copyright

Visual C# How to Program 2 2006

Visual Basic 2005 How to Program 3 2006

Java How to Program 7 2007

C How to Program 5 2007

Fig. 25.12 | Sampling of titles with copyrights after 2005 from table titles.

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25.4.2 WHERE Clause (Cont.)

• WHERE clause condition operators– <, >, <=, >=, =, <>– LIKE

• wildcard characters % and _• SELECT authorID, firstName, lastName

FROM authorsWHERE lastName LIKE ‘D%’

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1 Harvey Deitel

2 Paul Deitel

Fig. 25.13 | Authors whose last name starts with D from the authors table.

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Read your database system’s documentationcarefully to determine whether your systemsupports the LIKE operator. The SQL wediscuss is supported by most RDBMSs, but itis always a good idea to check the features ofSQL that are supported by your RDBMS.

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25.4.2 WHERE Clause (Cont.)

• SELECT authorID, firstName, lastNameFROM authorsWHERE lastName LIKE ‘_i%’

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3 Andrew Goldberg

Fig. 25.14 | The only author from the authors table whose last namecontains o as the second letter.

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25.4.3 ORDER BY Clause

• Optional ORDER BY clause– SELECT columnName1, columnName2, … FROM

tableName ORDER BY column ASC• SELECT authorID, firstName, lastName

FROM authorsORDER BY lastName ASC

– SELECT columnName1, columnName2, … FROMtableName ORDER BY column DESC

• SELECT authorID, firstName, lastNameFROM authorsORDER BY lastName DESC

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4 David Choffnes

1 Harvey Deitel

2 Paul Deitel

3 Andrew Goldberg

Fig. 25.15 | Sample data from table authors in ascending order by lastName.

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3 Andrew Goldberg

1 Harvey Deitel

2 Paul Deitel

4 David Choffnes

Fig. 25.16 | Sample data from table authors in descending order by lastName.

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25.4.3 ORDER BY Clause (Cont.)

• ORDER BY multiple fields– ORDER BY column1 sortingOrder, column2 sortingOrder, …

• SELECT authorID, firstName, lastNameFROM authorsORDER BY lastName, firstName

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4 David Choffnes

1 Harvey Deitel

2 Paul Deitel

4 Andrew Goldberg

Fig. 25.17 | Sample data from authors in ascending orderby lastName and firstName.

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25.4.3 ORDER BY Clause (Cont.)

• Combine the WHERE and ORDER BY clauses• SELECT isbn, title, editionNumber, copyright, price

FROM titles WHERE title LIKE ‘%How to Program’ORDER BY title ASC

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isbn title edition - Number copyright

0132404168 C How to Program 5 2007

0131857576 C++ How to Program 5 2005

0131450913 Internet and World Wide Web How to Program 3 2004

0132222205 Java How to Program 7 2007

0131869000 Visual Basic 2005 How to Program 3 2006

013152539 Visual C# How to Program 2 2006

Fig. 25.18 | Sampling of books from table titles whose titles end withHow to Program in ascending order by title.

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25.4.4 Merging Data from Multiple Tables:INNER JOIN

• Split related data into separate tables• Join the tables

– Merge data from multiple tables into a single view– INNER JOIN

• SELECT columnName1, columnName2, … FROM table1

INNER JOIN table2 ON table1.columnName = table2.column2Name• SELECT firstName, lastName, isbn

FROM authors, authorISBN INNER JOIN authorISBN

ON authors.authorID = authorISBN.authorID ORDER BY lastName, firstName

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firstName lastName isbn firstName lastName isbn

David Choffnes 0131828274 Paul Deitel 0131525239

Harvey Deitel 0131525239 Paul Deitel 0132404168







Harvey Deitel 0131828274 Andrew Goldberg 0131450 913

Fig. 25.19 | Sampling of authors and ISBNs for the books they have written inascending order by lastName and firstName.

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If a SQL statement includes columns with thesame name from multiple tables, the statementmust precede those column names with their tablenames and a dot (e.g., authors.authorID).

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Failure to qualify names for columnsthat have the same name in two or moretables is an error.

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25.4.5 INSERT Statement

• Insert a row into a table– INSERT INTO tableName ( columnName1, … , columnNameN ) VALUES ( value1, … , valueN )

• INSERT INTO authors ( firstName, lastName ) VALUES ( ‘Sue’, ‘Smith’ )

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1 Harvey Deitel

2 Paul Deitel

3 Andrew Goldberg

4 David Choffnes

5 Sue Smith

Fig. 25.20 | Sample data from table Authors after an INSERT operation.

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It is normally an error to specify avalue for an autoincrement column.

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SQL uses the single-quote (') character as a delimiterfor strings. To specify a string containing a singlequote (e.g., O’Malley) in a SQL statement, the stringmust have two single quotes in the position where thesingle-quote character appears in the string (e.g.,'O''Malley'). The first of the two single-quotecharacters acts as an escape character for the second.Not escaping single-quote characters in a string that ispart of a SQL statement is a SQL syntax error.

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25.4.6 UPDATE Statement

• Modify data in a table– UPDATE tableName SET columnName1 = value1, … , columnNameN = valueN

WHERE criteria• UPDATE authors SET lastName = ‘Jones’ WHERE lastName = ‘Smith’ AND firstName = ‘Sue’

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1 Harvey Deitel

2 Paul Deitel

3 Andrew Goldberg

4 David Choffnes

5 Sue Jones

Fig. 25.21 | Sample data from table authors after an UPDATE operation.

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25.4.7 DELETE Statement

• Remove data from a table– DELETE FROM tableName WHERE criteria

• DELETE FROM authors WHERE lastName = ‘Jones’ AND firstName = ‘Sue’

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1 Harvey Deitel

2 Paul Deitel

3 Andrew Goldberg

4 David Choffnes

Fig. 25.22 | Sample data from table authors after a DELETE operation.

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25.5 Instructions to Install MySQL andMySQL Connector/J

• Install MySQL– Platform-specific installation requirements:

• dev.mysql.com/doc/refman/5.0/en/general-installation-issues.html

– Download your platform’s installer from:• dev.mysql.com/downloads/mysql/5.0.html• Need only the Windows Essentials package on Microsoft

Windows– Follow installation instructions for your platform:

• dev.mysql.com/doc/refman/5.0/en/installing.html

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• MySQL Server Instance Configuration Wizard– Click Next > then select Standard Configuration and

clickNext > again.

– Not necessary to install MySQL as a Windows service forour examples

• Uncheck Install as a Windows Service• Check Include Bin Directory in Windows PATH

– Click Next > then click Execute to perform the serverconfiguration.

– Click Finish to close the wizard.

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• Install MySQL Connector/J– Must install Connector/J JDBC driver from:

• dev.mysql.com/downloads/connector/j/5.0.html

– Download mysql-connector-java-5.0.4.zip– Extract mysql-connector-java-5.0.4.zip to your hard disk into

the folder mysql-connector-java-5.0.4– Documentation for MySQL Connector/J is in

connector-j.pdf in the docs subdirectory ofmysql-connector-java-5.0.4

– Docs also online at dev.mysql.com/doc/connector/j/en/connector-j.html

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25.6 Instructions on Setting MySQL UserAccount

• Set up a user account– Start database server

• mysqld-nt.exe on Windows– Start the MySQL monitor

• mysql –h localhost –u root– Select the built-in database mysql

• USE mysql;

– Add the user account jhtp7 and specify privileges• create user 'jhtp7'@'localhost' identified by 'jhtp7';• grant select, insert, update, delete, create, drop, references, execute

on *.* to 'jhtp7'@'localhost';– Exit the MySQL Monitor

• exit;

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25.7 Creating Database books in MySQL

• Create books database– Open Command Prompt and change to the directory

containing the SQL script books.sql– Start the MySQL monitor

• mysql –h localhost –u jhtp7 –p– Execute the script

• source books.sql;

– Exit the MySQL Monitor• exit;

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25.8 Manipulating Databases with JDBC

• Connect to a database• Query the database• Display the results of the query in JTable

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25.8.1 Connecting to and Querying aDatabase

• DisplayAuthors– Retrieves the entire authors table– Displays the data in the standard output stream– Example illustrates

• Connect to the database• Query the database• Process the result

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1 // Fig. 25.23: DisplayAuthors.java

2 // Displaying the contents of the authors table.

3 import java.sql.Connection;

4 import java.sql.Statement;

5 import java.sql.DriverManager;

6 import java.sql.ResultSet;

7 import java.sql.ResultSetMetaDat a ;

8 import java.sql.SQLException;

9

10 public c l ass DisplayAuthors

11 {

12 // JDBC driver name and database URL

13 static final String DR IVER = "com.mysql. jdbc.Driver" ;

14 stat ic final St ring DATABASE_URL = "jdbc:mysql://localhost/books" ;

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16 // launch the application

17 public stat ic vo id main( String args[] )

18 {

19 Connection connection = null ; // manages connection

20 Statement statement = null ; // query statement

21 ResultSet resultSet = null ; // manages results

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23 // connect to database books and query database

24 t r y

25 {

26 // load the driver class

27 Class.forName( DR IVER );

28

Outline

DisplayAuthors .java

(1 of 3 )

Imports for the JDBC classes andinterfaces from package java.sql

Declare a String constantthat specifies the JDBCdriver’s class name

Loads the class definitionfor the database driver.

Declare a Stringconstant that specifiesthe database URL

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29 // establish connection to database

30 connection =

31 DriverManager.getConnection( DATABASE_URL, "jhtp7" , "jhtp7" );

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33 // create Statement for querying database

34 statement = connection.createStatement();

35

36 // query database

37 resultSet = statement.executeQuery(

38 "SELECT authorID, firstName, lastName FROM authors" );

39

40 // process query results

41 ResultSetMetaData metaData = resultSet.getMetaData();

42 int numberOfColumns = metaData.getColumnCount();

43 System.out.println( "Authors Table of Books Database:\n" );

44

45 f o r ( int i = 1; i <= numberOfColumns; i++ )

46 System.out.printf( "%- 8 s\t" , metaData.getColumnName( i ) );

47 System. out.println();

48

49 while ( resultSet.next() )

50 {


52 System.out.printf( "%- 8 s\t" , resultSet.getObject( i ) ) ;

53 System.out.p rintln();

54 } // end while

55 } // end try

Outline


(2 of 3 )

Invokes Connection methodcreateStatement to obtain an objectthat implements interface Statement.Use the Statement object’s

executeQuery method toexecute a query that selectsall the author informationfrom table authors.

Obtains the metadatafor the ResultSet.Uses ResultSetMetaData

method getColumnCountto retrieve the number ofcolumns in the ResultSet.Obtain column

name using methodgetColumnNamePosition the ResultSet cursor to the first

row in the ResultSet with method next

Extract the contentsof one column in thecurrent row

Initialize aConnection referencecalled connection.

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56 catch ( SQLException sqlException ) 57 { 58 sqlException.printStackTrace(); 59 } // end catch 60 catch ( ClassNotFoundException classNotFound ) 61 { 62 classNotFound.printStackTrace(); 63 } // end catch 64 finally // ensure resultSet, statement and connection are closed 65 { 66 t r y 67 { 68 resultSet.close(); 69 statement.close(); 70 connection.close(); 71 } // end try 72 catch ( Exception exception ) 73 { 74 exception.printStackTrace(); 75 } // end catch 76 } // end finally 77 } // end main 78 } // end class DisplayAuthors Authors Table of Books Database: authorID firstName lastName 1 Harvey Deitel 2 Paul Deitel 3 Andrew Goldberg 4 David Choffnes

Outline


(3 of 3 )

Catch SQLException, which isthrown if the query execution orResultSet process fails

ClassNotFoundException isthrown if the class loadercannot locate the driver class

Close the Statement andthe database Connection.

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Most major database vendors provide theirown JDBC database drivers, and manythird-party vendors provide JDBC drivers aswell. For more information on JDBC drivers,visit the Sun Microsystems JDBC Web site,servlet.java.sun.com/products/jdbc/drivers.

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Most database management systems requirethe user to log in before accessing thedatabase contents. DriverManager methodgetConnection is overloaded with versionsthat enable the program to supply the username and password to gain access.

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RDBMS Database URL format

MySQL jdbc:mysql:// hostname : portNumber /databaseName

ORACLE jdbc:oracle:thin:@ hostname : portNumber : databaseName

DB2 jdbc:db2: hostname : portNumber /databaseName

Java DB/Apache Derby jdbc:derby: dataBaseName (embedded) !

jdbc:derb y:// hostname : portNumber /databaseName (network) !

Microsoft SQL Server jdbc:sqlserver:// hostname : portNumber ; databaseName=dataBaseName

Sybase jdbc:sybase:Tds: hostname : portNumber /databaseName

Fig. 25.24 | Popular JDBC database URL formats.

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Metadata enables programs to processResultSet contents dynamically whendetailed information about theResultSet is not known in advance.

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Initially, a ResultSet cursor is positionedbefore the first row. Attempting to access aResultSet’s contents before positioning theResultSet cursor to the first row withmethod next causes a SQLException.

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Performance Tip 25.1

If a query specifies the exact columns to selectfrom the database, the ResultSet contains thecolumns in the specified order. In this case, usingthe column number to obtain the column’s valueis more efficient than using the column name.The column number provides direct access to thespecified column. Using the column namerequires a search of the column names to locatethe appropriate column.

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Specifying column number 0 whenobtaining values from a ResultSetcauses a SQLException.

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Attempting to manipulate a ResultSet afterclosing the Statement that created theResultSet causes a SQLException. Theprogram discards the ResultSet when thecorresponding Statement is closed.

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Each Statement object can open only oneResultSet object at a time. When aStatement returns a new ResultSet, theStatement closes the prior ResultSet. Touse multiple ResultSets in parallel,separate Statement objects must return theResultSets.

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25.8.2 Querying the books Database

• Allow the user to enter any query into theprogram

• Display the results of a query in a JTable

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1 // Fig. 25.25: ResultSetTableModel.java

2 // A TableModel that supplies ResultSet data to a JTable.


4 import java.sql.Statement;



7 import java.sql.Re sultSetMetaData;


9 import javax.swing.table.AbstractTableModel;

10

11 // ResultSet rows and columns are counted from 1 and JTable

12 // rows and columns are counted from 0. When processing

13 // ResultSet rows or columns for use in a JTable, it is

14 // necessary to add 1 to the row or column number to manipulate

15 // the appropriate ResultSet column (i.e., JTable column 0 is

16 // ResultSet column 1 and JTable row 0 is ResultSet row 1).

17 public c l a s s ResultSetTableModel extends AbstractTableModel

18 {

19 pr ivate Connection connection;

20 pr ivate Statement statement;

21 pr ivate ResultSet resultSet;

22 pr ivate ResultSetMetaData metaData;

23 pr ivate int numberOfRows;

24

25 // keep track of database connection status

26 pr ivate boolean connectedToDatabase = fa lse ;

27

Outline

ResultSetTableModel.java

(1 of 7 )

Class ResultSetTableModel extendsclass AbstractTableModel, whichimplements interface TableModel.

Instance variable keeps trackof database connection status

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28 // constructor initializes resultSet and obtains its meta data object;

29 // determines number of rows

30 public ResultSetTableModel( String driver, String url, String username,

31 String password, String query )

32 th rows SQLException, ClassNotFoundException

33 {

34 Class.forName( driver );

35 // connect to database

36 connection = DriverManager.getConnection( url, username, password );

37

38 // create Statement to query database

39 statement = connection.createStatement(

40 ResultSet.TYPE_SCROLL_INSENSITIVE,

41 ResultSet.CONCUR_READ_ONLY );

42

43 // update database connection status

44 connectedToDatabase = t rue;

45

46 // set query and execute it

47 setQuery( query );

48 } // end constructor ResultSetTableModel

49

Outline


(2 of 7 )

Establishes a connectionto the database.

Invokes Connectionmethod createStatement tocreate a Statement object.

Constructor accepts five Stringarguments—the driver classname, the database URL, theusername, the password and thedefault query to perform

Indicate that connect todatabase is successful

Invokes ResultSetTableModelmethod setQuery to performthe default query.

79


50 // get class that represents column type

51 public Class getColumnClass( int column ) th rows IllegalStateException

52 {

53 // ensure database connection is available

54 i f ( !connectedToDatabase )

55 th row new IllegalStateException( "Not Connected to Database" );

56

57 // determine Java class of column

58 t r y

59 {

60 String className = metaData.getColumnClassName( column + 1 );

61

62 // return Class object that represents className

63 return Class.forName( className );

64 } // end try

65 catch ( Exception exception )

66 {

67 excepti on.pr intStackTrace();

68 } // end catch

69

70 return Object. c l ass ; // if problems occur above, assume type Object

71 } // end method getColumnClass

72

73 // get number of columns in ResultSet

74 public int getColu mnCount() th rows IllegalStateException

75 {



78 th row new IllegalStateException( "Not Connected to Database" ) ;

79

Outline


(3 of 7 )

Override method getColumnClass to obtain aClass object that represents the superclass ofall objects in a particular column

Verify databaseconnection status

Loads the class definition for the class andreturns the corresponding Class object.

Returns thedefault type.

Obtains the fully qualified classname for the specified column.

Override method getColumnCount toobtain the number of columns in themodel’s underlying ResultSet

80


80 // determine number of columns

81 t r y

82 {

83 return metaData.getColumnCount();

84 } // end try

85 catch ( SQLException sqlException )

86 {

87 sqlException.printStackTrace();

88 } // end catch

89

90 return 0; // if problems occur above, return 0 for number of columns

91 } // end method getColumnCount

92

93 // get name of a particular column in ResultSet

94 public String getColumnName( int co lumn ) th rows IllegalStateException

95 {




99

100 // determine col umn name

101 t r y

102 {

103 return metaData.getColumnName( column + 1 );

104 } // end try


106 {


108 } // end catch

109

Outline


(4 of 7 )

Obtains the number ofcolumns in the ResultSet.

Override method getColumnNameto obtain the name of the column inthe model’s underlying ResultSet

Obtains the column namefrom the ResultSet.

81


110 return "" ; // if problems, return empty string for column name

111 } // end method getColumnName

112

113 // return number of rows in ResultSet

114 public int getRowCount() th rows IllegalStateException

115 {



118 th row new IllegalStateException( "Not Connected to Database" ) ;

119

120 return numberOfRows;

121 } // end method getRowCount

122

123 // obtain value in particular row and column

124 public Object getValueAt( int row, int column )

125 th rows IllegalStateException

126 {




130

131 // obtain a value at specified ResultSet row and column

132 t r y

133 {

134 resultSet.absolute( row + 1 );

135 return resu ltSet.getObject( column + 1 );

136 } // end try

Outline


(5 of 7 )Override method getColumnCount toobtain the number of rows in themodel’s underlying ResultSet

Uses ResultSet method absolute to positionthe ResultSet cursor at a specific row.

Override method getValueAt to obtain theObject in a particular row and column of themodel’s underlying ResultSet

Uses ResultSet method getObjectto obtain the Object in a specificcolumn of the current row.

82



138 {


140 } // end catch

141

142 return "" ; // if problems, return empty string object

143 } // end method getValueAt

144

145 // set new database query string

146 public vo id setQuery( String query )

147 th rows SQLException, IllegalStateException

148 {




152

153 // specify query and execute it

154 resultSet = statement.executeQuery( query );

155

156 // obtain meta data for ResultSet

157 met aData = resultSet.getMetaData();

158

159 // determine number of rows in ResultSet

160 resultSet.last(); // move to last row

161 numberOfRows = resultSet.getRow(); // get row number

162

163 // notify JTable that model has changed

164 fireTableStructureChanged();

165 } // end method setQuery

166

Outline


(6 of 7 )

Executes the query toobtain a new ResultSet.

Uses ResultSet method last toposition the ResultSet cursor atthe last row in the ResultSet.

Uses ResultSet method getRowto obtain the row number for thecurrent row in the ResultSet.

Invokes method fireTableAStructureChangedto notify any JTable using thisResultSetTableModel object as its model thatthe structure of the model has changed.

83


167 // close Statement and Connection

168 public vo id disconnectFromDatabase()

169 {

170 i f ( connectedToDatabase )

171 {

172 // close Statement and Connection

173 t r y

174 {

175 resultS et.close();

176 statement.close();

177 connection.close();

178 } // end try

179 catch ( SQLException s qlException )

180 {


182 } // end catch

183 finally // update database connection status

184 {

185 connectedToDatabase = fa lse ;

186 } // end finally

187 } // end if

188 } // end method disconnectFromDatabase

189 } // end class ResultSetTableModel

Outline


(7 of 7 )

Method disconnectFromDatabaseimplement an appropriate termination methodfor class ResultSetTableModel

Verify whether the connectionis already terminated

Close the Statement and Connection if aResultSetTableModel object is garbage collected.

Set connectedToDatabase to false toensure that clients do not use an instance ofResultSetTableModel after that instancehas already been terminated

84


ResultSet static

type constant Description

TYPE_FORWARD_ONLY Specifies that a ResultSet ’s cursor can move only in the forward

direction (i.e., from the first row to the last row in the ResultSet ).

TYPE_SCROLL_INSENSITIVE Specifies that a ResultSet ’s cursor can scroll in either direction

and that the changes made to the ResultSet during ResultSet

processing are not reflected in the ResultSet unless the program

queries the database again.

TYPE_SCROLL_SENSITIVE Specifies that a ResultSet ’s cursor can scroll in either direction

and that the changes made to the ResultSet during ResultSet !

processing are reflected immediately in the ResultSet .!

Fig. 25.26 | ResultSet constants for specifying ResultSet type.

85



Some JDBC drivers do not supportscrollable ResultSets. In such cases, thedriver typically returns a ResultSet inwhich the cursor can move only forward.For more information, see your databasedriver documentation.

86



Some JDBC drivers do not support updatableResultSets. In such cases, the drivertypically returns a read-only ResultSet. Formore information, see your database driverdocumentation.

87



Attempting to update a ResultSet when thedatabase driver does not support updatableResultSets causesSQLFeatureNotSupportedExceptions.

88



Attempting to move the cursor backwardthrough a ResultSet when the databasedriver does not support backwardscrolling causes a SQLException.

89


ResultSet static concurrency constant

Description

CONCUR_READ_ONLY Specifies that a ResultSet cannot be updated (i.e., changes to the ResultSet

contents cannot be reflected in the database with ResultSet ’s update methods).

CONCUR_UPDATABLE Specifies that a !ResultSet can be updated (i.e., changes to the ! ResultSet !

contents can be reflected in the database with ! ResultSet ’s update methods). !

Fig. 25.27 | ResultSet constants for specifying result properties.

90


1 // Fig. 25.28: DisplayQueryResults.java

2 // Display the contents of the Authors table in the books database.

3 import java.awt.BorderLayout;

4 import java.awt.event.ActionListener;

5 import java.awt.event.ActionEvent;

6 import java.awt.event. WindowAdapter;

7 import java.awt.event.WindowEvent;


9 import java.util.regex.PatternSyntaxException;

10 import javax.swing.JFrame;

11 import javax.swing.JTextArea;

12 import javax.swing.JScrollPane;

13 import j avax.swing.Scrol lPaneConstants;

14 import javax.swing.JTable;

15 import javax.swing.JOptionPane;

16 import javax.swing.JButton;

17 import javax.swing.Box;

18 import javax.swing.JLabel;

19 import javax.swing.JTextField;

20 import javax.swing.R owFilter;

21 import javax.swing.table.TableRowSorter;

22 import javax.swing.table.TableModel;

23

24 public class DisplayQueryResults extends JFrame

25 {

26 // JDBC database URL, username and password

27 static final Str ing DR IVER = "com.mysql. jdbc.Driver" ;

28 static final String DATABASE_URL = "jdbc:mysql://localhost/books" ;

29 static final String USERNAME = "jhtp7" ;

30 static final String PASSWORD = "jhtp7" ;

Outline

DisplayQueryResults.java

(1 of 8 )

Declare the database driverclass name, database URL,username and password foraccessing the database

91


31

32 // default query retrieves all data from authors table

33 static final String DEFAULT_QUERY = "SELECT * FROM authors";

34

35 pr ivate ResultSetTableModel tableModel;

36 pr ivate JTextArea queryArea;

37

38 // cr eate ResultSetTableModel and GUI

39 public DisplayQueryResults()

40 {

41 super( "Displaying Query Results" ) ;

42

43 // create ResultSetTableModel and display database table

44 t r y

45 {

46 // create TableModel for results of query SELECT * FROM authors

47 tableModel = new ResultSetTableModel( DR IVER, DATABASE_URL,

48 USERNAME, PASSWORD, DEFAULT_QUERY );

49

50 // set up JText Area in which user types queries

51 queryArea = new JTextArea( DEFAULT_QUERY, 3, 100 );

52 queryArea.setWrapStyleWord( t rue );

53 queryArea.setLineWrap( t rue );

54

55 JScrollPane scrollPane = new JScr ollPane( queryArea,

56 Scrol lPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,

57 Scrol lPaneConstants.HORIZONTAL_SCROLLBAR_NEVER );

58

59 // set up JButton for submitting queries

60 JButton submitBut ton = new JButton( "Submit Query" ) ;

Outline


(2 of 8 )

Declare the default query

Declare tableModel to be a reference toResultSetTableModel

Create TableModelfor results of defaultquery “SELECT *FROM authors”

92


61

62 // create Box to manage placement of queryArea and

63 // submitButton in GUI

64 Box boxNorth = Box.createHorizontalBox();

65 boxNorth.add( scrollPane );

66 boxNorth.add( submitButton );

67

68 // create JTable delegate for tableModel

69 JTable resultTable = new JTable( tableModel );

70

71 JLabel filterLabel = new JLabel( "Filter:" ) ;

72 f inal JTextField filterText = new JTextField( ) ;

73 JButton filterButton = new JButton( "Apply Filter" );

74 Box boxSouth = boxNorth.createHorizontalBox();

75

76 boxSouth.add( filterLabel );

77 boxSouth.add( filterText );

78 boxSouth.a dd( filterButton );

79

80 // place GUI components on content pane

81 add( boxNorth, BorderLayout.NORTH );

82 add( new JScrollPane( resultTable ), BorderLayout.CENTER );

83 add( boxSouth, BorderLayout.SOUTH );

84

85 // create event listener for submitButton

86 submitButton.addActionListener(

87

Outline


(3 of 8 )Create JTable delegatefor tableModel

93


88 new ActionListener()

89 {

90 // pass query to table model

91 public void actionPerformed( ActionEvent event )

92 {

93 // perform a new query

94 t r y

95 {

96 tableModel.setQuery( queryArea.getText() );

97 } // end try


99 {

100 JOptionPane.showMessageDialog( null ,

101 sqlException.getMessage(), "Database error",

102 JOptionPane.ERROR_MESSAGE );

103

104 // try to recover from inv alid user query

105 // by executing default query

106 t r y

107 {

108 tableModel.setQuery( DEFAULT_QUERY );

109 queryArea.setText( DEFAULT_QUERY );

110 } // end try

111 catch ( SQLException sqlException2 )

112 {


114 sqlExcep tion2.getMessage(), "Database error",


116

Outline


(4 of 8 )

Register an event handler for thesubmitButton that the user clicksto submit a query to the database

Invoke ResultSetTableModelmethod setQuery to executethe new query

94


117 // ensure database connection is closed

118 tableModel.disconnectFromDatabase();

119

120 System.exit( 1 ); // terminate application

121 } // end inner catch

122 } // end outer catch

123 } // end actionPerformed

124 } // end ActionListener inner class

125 ); // end call to addActionListener

126

127 f inal TableRowSorter< TableModel > sorter =

128 new TableRowSorter< TableModel >( tableModel );

129 resultTable.setRowSorter( sorter );

130 setSize( 500, 250 ); // set window si z e

131 setVisible( t rue ); // display window

132

133 // create listener for filterButton

134 filterButton.addActionListener(


136 {

137 // pass filter text to listener

138 public void actionPerformed( ActionEvent e )

139 {

140 String text = filterText.getText();

141

142 i f ( text.length() == 0 )

143 sorter.setRowFilter( null );

144 else

145 {

146 t r y

Outline


(5 of 8 )

Ensure that the databaseconnection is closed

Set up TableRowSorter

No filter initially

95


147 {

148 sorter.setRowFilter(

149 RowFilter.regexFilter( text ) );

150 } // end try

151 catch ( PatternSyntaxExceptio n pse )

152 {


154 "Bad regex pattern" , "Bad regex pattern" ,


156 } // end catch

157 } // end else

158 } // end method actionPerfomed

159 } // end annonymous inner class

160 ); // end call to addActionLister

161 } // end try

162 c atch ( ClassNotFoundException classNotFound )

163 {


165 "Database Driver not found" , "Driver not found" ,


167


169 } // end catch

Outline


(6 of 8 )

Set filter using regularexpression

96



171 {

172 JOptionPane.showMessageDialog( null , sqlException.getMessage(),

173 "Database error", JOptionPane.ERROR_MESSAGE );

174

175 // ensure database connection is closed


177


179 } // end catch

180

181 // dispose of window when user quits applicatio n (this overrides

182 // the default of HIDE_ON_CLOSE)

183 setDefaultCloseOperation( DISPOSE_ON_CLOSE );

184

185 // ensure database connection is closed when user quits application

186 addWindowListener(

187

188 new WindowAdapter()

189 {

190 // disconnect from database and exit when window has closed

191 public void windowClosed( WindowEvent event )

192 {


194 System.exit( 0 );

195 } // end method windowClosed

196 } // en d WindowAdapter inner class

197 ); // end call to addWindowListener

198 } // end DisplayQueryResults constructor

199

Outline


(7 of 8 )

Ensure that the databaseconnection is closed

Ensure that the databaseconnection is closedwhen window is closed

97


200 // execute application

201 public static void main( String args[] )

202 {

203 new DisplayQueryResults();

204 } // end main

205 } // end class DisplayQueryResults

Outline


(8 of 8 )

98


25.10 RowSet Interface

• Interface RowSet– Configures the database connection automatically– Prepares query statements automatically– Provides set methods to specify the properties needed to establish

a connection– Part of the javax.sql package

• Two types of RowSet– Connected RowSet

• Connects to database once and remain connected– Disconnected RowSet

• Connects to database, executes a query and then closes connection

99


25.10 RowSet Interface (Cont.)

• Package javax.sql.rowset– JdbcRowSet

• Connected RowSet• Wrapper around a ResultSet• Scrollable and updatable by default

– CachedRowSet• Disconnected RowSet• Cache the data of ResultSet in memory• Scrollable and updatable by default• Serializable

– Can be passed between Java application• Limitation

– Amount of data that can be stored in memory is limited

100



A RowSet can provide scrollingcapability for drivers that do notsupport scrollable ResultSets.

101


1 // Fig. 25.29: JdbcRowSetTest.java

2 // Displaying the contents of the authors table using JdbcRowSet.

3 import java.sql.ResultSetMetaData;


5 import javax.sql.rowset.JdbcRowSet;

6 import com.sun.rowset.JdbcRowSetImpl; // Sun's JdbcRowSet implementation

7

8 public class JdbcRowSetTest

9 {

10 // JDBC driver name and database URL

11 static final String DR IVER = "com.mysql. jdbc.Driver" ;

12 static final String DATABASE_URL = "jdbc:mysql://localhost/books" ;

13 static final String USERNAME = "jhtp7" ;

14 static final String PASSWORD = "jhtp7" ;

15

16 // constructor connects to database, queries database, processes

17 // results and displays r esults in window

18 public JdbcRowSetTest()

19 {

20 // connect to database books and query database

21 t r y

22 {

23 Class.forName( DR IVER );

24

Outline

JdbcRowSetTest.java

(1 of 3 )

102


25 // specify properties of JdbcRowSet

26 JdbcRowSet rowSet = new JdbcRowSetImpl();

27 rowSet.setUrl( DATABASE_URL ); // set database URL

28 rowSet.setUsername( USERNAME ); // set username

29 rowSet.setPassword( PASSWORD ); // set password

30 rowSet.setCommand( "SELECT * FROM authors" ); // set query

31 rowSet.execute(); // execute query

32

33 // process query results

34 ResultSetMetaData metaData = rowSet.getMetaData();

35 int numberOfColumns = metaData.getColumnCount();

36 System.out.println( "Authors Table of Books Database:\n" );

37

38 // display rowset header


40 System.out.printf( "%- 8 s\t" , metaData.getColumnName( i ) );

41 System.out.println();

42

43 // display each row

44 while ( rowSet.next() )

45 {


47 System.out.printf( "%- 8 s\t" , rowSet.getObject( i ) );

48 System.out.println();

49 } // end whil e

50

51 // close the underlying ResultSet, Statement and Connection

52 rowSet.close();

53 } // end try

Outline

JdbcRowSetTest.java

(2 of 3 )

Use Sun’s referenceimplementation of JdbcRowSetinterface (JdbcRowSetImpl) tocreate a JdbcRowSet object

Invoke JdbcRowSet method setUrlto specify the database URLInvoke JdbcRowSet methodsetUsername to specify the usernameInvoke JdbcRowSet methodsetUsername to specify the passwordInvoke JdbcRowSet method

setCommand to specify the queryInvoke JdbcRowSet methodexecute to execute the query

103


54 catch ( SQLException sqlException ) 55 { 56 sqlException.printStackTrace(); 57 System.exit( 1 ); 58 } // end catch 59 catch ( ClassNotFoundException classNotFound ) 60 { 61 classN otFound.printStackTrace(); 62 System.exit( 1 ); 63 } // end catch 64 } // end DisplayAuthors constructor 65 66 // launch the application 67 public static void main( String args[] ) 68 { 69 JdbcRowSetTest application = new JdbcRowSetTest(); 70 } // end main 71 } // end class JdbcRowSetTest Authors Table of Books Database: authorID firstName lastName 1 Harvey Deitel 2 Paul Deitel 3 Andrew Goldberg 4 David Choffnes

Outline

JdbcRowSetTest.java

(3 of 3 )

104


25.11 Java DB/Apache Derby

• As of JDK 6, Sun Microsystems now bundles theopen-source, pure Java database Java DB (theSun branded version of Apache Derby) with theJDK

• We use the embedded version of Java DB• There is also a network version that executes

similarly to the MySQL DBMS introduced earlierin the chapter

105


25.11 Java DB/Apache Derby• Java DB comes with several batch files to configure and run it• First set the environment variable JAVA_HOME to refer to the JDK’s

C:\Program Files\Java\jdk1.6.0 installation directory• Open the batch file setEmbeddedCP.bat (located in C:\Program

Files\Java\jdk1.6.0\db\frameworks\embedded\bin) in a text editor suchas Notepad

• Locate the linerem set DERBY_INSTALL=

and change it toset DERBY_INSTALL=C:\Program Files\Java\jdk1.6.0\db

• Also, comment out the line@FOR %%X in ("%DERBY_HOME%") DO SET DERBY_HOME=%%~sX

by preceding it with REM• Save your changes and close this file

106



• Change directories to C:\Program Files\Java\jdk1.6.0\db\frameworks\embedded\bin\. Then, typesetEmbeddedCP.bat and press Enter to set theenvironment variables required by Java DB.

• Embedded Java DB database must reside in the samelocation as the application that manipulates the database

– Change to the directory that contains the code for Figs.25.30–25.32

• Execute the command"C:\Program Files\Java\jdk1.6.0\db\frameworks\embedded\bin\ij"

to start the command-line tool for interacting with JavaDB. The double quotes are necessary because the pathcontains a space.

107



• At the ij> prompt typeconnect 'jdbc:derby:AddressBook;create=true; user=jhtp7;password=jhtp7';

to create the AddressBook database in the currentdirectory. This command also creates the user jhtp7 withthe password jhtp7 for accessing the database.

• To create the database table and insert sample data in thedatabase type

run 'address.sql';• To terminate the Java DB command-line tool, type

exit;

108


25.12 PreparedStatements

• PreparedStatements execute more efficientlythan Statement objects

• PreparedStatements can specify parameters

109



• PreparedStatement to locate all book titles for anauthor with a specific last name and first name, and toexecute that query for several authors:

– PreparedStatement authorBooks = connection.prepareStatement( "SELECT lastName, firstName, title " + "FROM authors INNER JOIN authorISBN " + "ON authors.authorID=authorISBN.authorID " + "INNER JOIN titles " + "ON authorISBN.isbn=titles.isbn " + "WHERE lastName = ? AND firstName = ?" );

• Question marks (?) are placeholders for values that willbe passed as part of the query to the database

110



• Program must specify the parameter values by using thePreparedStatement interface’s set methods.

• For the preceding query, both parameters are strings thatcan be set with PreparedStatement method setStringas follows:

authorBooks.setString( 1, "Deitel" );authorBooks.setString( 2, "Paul" );

• setString automatically escapes String parameter valuesas necessary (e.g., the quote in the name O’Brien)

• More info at java.sun.com/javase/6/docs/api/java/sql/PreparedStatement.html

111


Performance Tip 25.2

PreparedStatements are more efficientthan Statements when executing SQLstatements multiple times and withdifferent parameter values.

112


Error-Prevention Tip 25.1

Use PreparedStatements withparameters for queries that receiveString values as arguments to ensurethat the Strings are quoted properly inthe SQL statement.

113


1 // Fig. 25.30: Person.java

2 // Person class that represents an entry in an address book.

3 public class Person

4 {

5 private int addressID;

6 pr ivate String firstName;

7 pr ivate String lastName;

8 pr ivate String email;

9 pr ivate String phoneNumber;

10

11 // no - argument constructor

12 public Person()

13 {

14 } // end no- argument Person constructor

15

16 // constructor

17 public Person( int id, String first, String last,

18 String emailAddress, String phone )

19 {

20 setAddressID( id );

21 setFirstName( first );

22 setLastName( last );

23 setEmail( emailAddress );

24 setPhoneNumber( phone );

25 } // end five - argument Person constructor

26

Outline

Person.java

(1 of 3 )

114


27 // sets the addressID

28 public void setAddressID( int id )

29 {

30 addressID = id;

31 } // end method setAddressID

32

33 // returns the addressID

34 public int getAddressID()

35 {

36 return addressID;

37 } // end method getAddressID

38

39 // sets the firstName

40 public void setFirstName( String first )

41 {

42 firstName = first;

43 } // end method setFirstName

44

45 // returns the first name

46 public String getFirstName()

47 {

48 return firstName;

49 } // end method getFirstName

50

51 // sets the lastName

52 public void setLastName( String last )

53 {

54 lastName = last;

55 } // end method setLastName

56

Outline

Person.java

(2 of 3 )

115


57 // returns the first name

58 public String getLastName()

59 {

60 return lastName;

61 } // end method getLastName

62

63 // sets the email address

64 public void setEmail( String emailAddress )

65 {

66 email = emailAddress;

67 } // end method setEmail

68

69 // returns the email address

70 public String getEmail()

71 {

72 return email;

73 } // end method getEmail

74

75 // sets the phone number

76 public void setPhoneNumber( String phone )

77 {

78 phoneNumber = phone;

79 } // end method setPhoneNumber

80

81 // returns the email address

82 public String getPhoneNumber()

83 {

84 return phoneNumber;

85 } // end method getPhoneNumber

86 } // end class Person

Outline

Person.java

(3 of 3 )

116


1 // Fig. 25.31: PersonQueries.java

2 // PreparedStatements used by the Address Book application



5 import java.sql.PreparedStatement;


7 import java.sql .SQLException;

8 import java.util.List;

9 import java.util.ArrayList;

10

11 public class PersonQueries

12 {

13 private static final String URL = " jdbc:derby:AddressBook";

14 private static final String USERNAME = "jhtp7" ;

15 p r iv ate static final String PASSWORD = "jhtp7" ;

16

17 pr ivate Connection connection = null ; // manages connection

18 pr ivate PreparedStatement selectAllPeople = null ;

19 pr ivate PreparedStatement selectPeopleByLastName = null ;

20 pr ivate PreparedStatement insertNewPerson = null ;

21

22 // constructor

23 public PersonQueries()

24 {

25 t r y

26 {

27 connection =

28 DriverManager.getConnection( URL, USERNAME, PASSWORD );

29

Outline

PersonQueries .java

(1 of 7 )

All program to usePreparedStatements

DeclarePreparedStatements

Note that we do not load theJava DB driver first. JDBC4’s automatic driverdiscovery is used here.

117


30 // create query that selects all entries in the AddressBook

31 selectAllPeople =

32 connection.prepareStatement( "SELECT * FROM Addresses" );

33

34 // create query that selects entries with a specific last name

35 selectPeopleByLastName = connection.prepareStatement(

36 "SELECT * FROM Addresses WHERE LastName = ?" );

37

38 // create ins ert that adds a new entry into the database

39 insertNewPerson = connection.prepareStatement(

40 "INSERT INTO Addresses " +

41 "( FirstName, LastName, Email, PhoneNumber ) " +

42 "VALUES ( ?, ?, ?, ? )" );

43 } // end try


45 {



48 } // end catch

49 } // end PersonQueries constructor

50

51 // select all of the addresses in the database

52 public List< Person > getAllPeople()

53 {

54 List< Person > results = null ;

55 ResultSet resultSet = null ;

56

Outline

PersonQueries .java

(2 of 7 )

Configure eachPreparedStatement. Each ?represents a parameter.

118


57 t r y

58 {

59 // executeQuery returns ResultSet containing matching entries

60 resultSet = selectAllPeople.executeQuery();

61 results = new ArrayList< Person >();

62


64 {

65 results.add( new Person(

66 resultSet.getInt( "address ID" ),

67 resultSet.getString( "firstName" ),

68 resultSet.getString( " lastName" ),

69 resultSet.getString( "email" ),

70 resultSet.getString( "phoneNumber" ) ) );

71 } // end while

72 } // end try


74 {

75 sqlException.print StackTrace();

76 } // end catch

77 finally

78 {

79 t r y

80 {

81 resultSet.close();

82 } // end try

Outline

PersonQueries .java

(3 of 7 )

Executes the query inPreparedStatementselectAllPeople.

Process the ResultSet.

119



84 {


86 close();

87 } // end catch

88 } // end finally

89

90 return results;

91 } // end method getAllPeople

92

93 // select person by last name

94

95 public List< Person > getPeopleByLastName( String name )

96 {

97 List< Person > results = null ;

98 ResultSet resultSet = null ;

99

100 t r y

101 {

102 selectPeopleByLastName.setString( 1, name ); // specify last name

103

104 // executeQuery returns ResultSet containing matching entries

105 resultSet = selectPeopleByLastName.executeQuery();

106

107 results = new ArrayList< Person >();

108

Outline

PersonQueries .java

(4 of 7 )

Specify the parameter toPreparedStatementselectPeopleByLastName.

Executes the query inPreparedStatementselectPeopleByLastName.

120



110 {

111 results.add( new Person(

112 resultSet.getInt( "address ID" ),

113 resultSet.getString( "firs tName" ),

114 resultSet.getString( " lastName" ),

115 resultSet.getString( "email" ) ,

116 resultSet.getString( "phoneNumber" ) ) );

117 } // end while

118 } // end try


120 {


122 } // end catch

123 finally

124 {

125 t r y

126 {

127 resultSet.close();

128 } // end try


130 {


132 close();

133 } // end catch

134 } // end finally

135

136 return results;

137 } // end method getPeopleByName

138

Outline

PersonQueries .java

(5 of 7 )

Process the ResultSet.

121


139 // add an entry

140 public int addPerson(

141 String fname, String lname, String email, String num )

142 {

143 int result = 0;

144

145 // set parameters, then execute insertNewPerson

146 t r y

147 {

148 insertNewPerson.setString( 1, fname );

149 insertNewPerson.setString( 2, lname );

150 insertNewPerson.setString( 3, email );

151 insertNewPerson.setString( 4, num );

152

153 // inser t the new entry; returns # of rows updated

154 result = insertNewPerson.executeUpdate();

155 } // end try


157 {


159 close();

160 } // end catch

Outline

PersonQueries .java

(6 of 7 )

Specify the parameters toPreparedStatementinsertNewPerson.

Executes the insert operation inPreparedStatementinsertNewPerson.

122


161

162 return result;

163 } // end method addPerson

164

165 // close the database connection

166 public void close()

167 {

168 t r y

169 {

170 connection.close();

171 } // end try


173 {


175 } // end catch

176 } // end method close

177 } // end interface PersonQueries

Outline

PersonQueries .java

(7 of 7 )

123


1 // Fig. 25.32: AddressBookDisplay.java

2 // A simple address book

3 import java.awt.event.ActionEvent;

4 import java.awt.event.ActionListener;

5 import java.awt.event.WindowAdapter;

6 import java.awt.event.WindowEvent;

7 import java.awt.Flow Layout;

8 import java.awt.GridLayout;

9 import java.util.List;

10 import javax.swing.JButton;

11 import javax.swing.Box;

12 import javax.swing.JFrame;

13 import javax.swing.JLabel;

14 import javax.swing.JPanel;

15 import javax.swing.JTextF ield;

16 import javax.swing.WindowConstants;

17 import javax.swing.BoxLayout;

18 import javax.swing.BorderFactory;

19 import javax.swing.JOptionPane;

20

21 public class AddressBookDisplay extends JFrame

22 {

23 pr ivate Person currentEnt ry ;

24 pr ivate PersonQueries personQueries;

25 pr ivate List< Person > results;

26 private int numberOfEntries = 0;

27 private int currentEntryIndex;

28

29 pr ivate JButton browseButton;

30 pr ivate JLabel emailLabel;

Outline

AddressBookDisplay.java

(1 of 14 )

124


31 pr ivate JTextField emailTextField;

32 pr ivate JLabel firstNameLabel;

33 pr ivate JTextField firstNameTextField;

34 pr ivate JLabel idLabel;

35 pr ivate JTextField idTextField;

36 pr ivate JTextField indexTextField;

37 p r i va t e JLabel lastNameLabel;

38 pr ivate JTextField lastNameTextField;

39 pr ivate JTextField maxTextField;

40 pr ivate JButton nextButton;

41 pr ivate JLabel ofLabel;

42 pr ivate JLabel phoneLabel;

43 pr ivate JTextField phoneTextField ;

44 pr ivate JButton previousButton;

45 pr ivate JButton queryButton;

46 pr ivate JLabel queryLabel;

47 pr ivate JPanel queryPanel;

48 pr ivate JPanel navigatePanel;

49 pr ivate JPanel displayPanel;

50 pr ivate JTextField query TextField;

51 pr ivate JButton insertButton;

52

53 // no - argument constructor

54 public AddressBookDisplay()

55 {

56 super( "Address Book" );

57

58 // establish database connection and set up PreparedState ments

59 personQueries = new PersonQueries();

60

Outline


(2 of 14 )

125


61 // create GUI

62 navigatePanel = new JPanel();

63 previousButton = new JButton();

64 indexTextField = new JTextField( 2 );

65 ofLabel = new JLabel();

66 maxTextField = new JTextField( 2 );

67 nextButton = new JButton();

68 displayPanel = new JPanel();

69 idLabel = new JLabel();

70 idTextField = new JTextField( 10 );

71 firstNameLabel = new JLabel();

72 firstNameTextField = new JTextField( 10 );

73 lastNameLabel = new JLabel();

74 lastNameTextField = new JTextField( 10 );

75 emailLabel = new JLabel();

76 emailTextField = new JTextField( 10 );

77 phoneLabel = new JLabel();

78 phoneTextField = new JTextField( 10 );

79 queryPanel = new JPan el();

80 queryLabel = new JLabel();

81 queryTextField = new JTextField( 10 );

82 queryButton = new JButton();

83 browseButton = new JButton();

84 insertButton = new JButton();

85

86 setLayout( new FlowLayout( FlowLayout.CENTER, 10, 10 ) );

87 setSize( 400, 300 );

88 setResizable( fa lse );

89

Outline


(3 of 14 )

126


90 navigatePanel.setLayout(

91 new BoxLayout( navigatePanel, BoxLayout.X_AXIS ) );

92

93 previousButton.setText( "Previous" );

94 previousButton.setEnabled( fa lse );

95 previousButton.addActionListener(


97 {

98 public void actionPerformed( ActionEvent evt )

99 {

100 previousButtonActionPerformed( evt );

101 } // end method actionPerformed

102 } // end anonymous inner class


104

105 navigatePanel.add( previousButton );

106 navigatePanel.add( Box.createHorizontalStrut( 10 ) );

107

108 indexTextField.setHorizontalAlignment(

109 JTextField.CENTER );

110 indexTextField.addActionListener(


112 {


114 {

115 indexTextFieldActionPerformed( evt );




119

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127


120 navigatePanel.add( indexTextField );


122

123 ofLabel.setText( "of" ) ;

124 navigatePanel.add( ofLabel );


126

127 maxTextField.setHorizontalAlignment(

128 JTextField.CENTER );

129 maxTextField.setEditable( fa lse );

130 nav igatePanel.add( maxTextField );


132

133 nextButton.setText( "Next" );

134 nextButton.setEnabled( fa lse );

135 nextButton.addActionListener(


137 {


139 {

140 nextButtonActionPerformed( evt );




144

145 navigatePanel.add( nextButton );

146 add( navigatePanel );

147

148 displayPanel.setLayout( new GridLayout( 5, 2, 4, 4 ) );

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128


149

150 idLabel.setText( "Address ID:" ) ;

151 displayPanel.add( idLabel );

152

153 idTextField.setEditable( fa lse );

154 displayPanel.add( idTextField );

155

156 firstNameLabel.setText( "First Name:" );

157 displayPanel.add( firstNameLabel );

158 displayPanel.add( firstNameTextField );

159

160 lastNameLabel.setText( "Last Name:" ) ;

161 displayPanel.add( lastNameLabel );

162 displayPanel.add( lastNameTextField );

163

164 emailLabel.setText( "Email:" );

165 displayPanel.add( emailLabel );

166 displayPanel.add( emailTextField );

167

168 phoneLabel.setText( "Phone Number:" );

169 displayPanel.add( phoneLabel );

170 displayPanel.add( phoneTextField );

171 add( displayPanel );

172

173 queryPanel.setLayout(

174 new BoxLayout( queryPanel, BoxLayout.X_AXIS) );

175

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129


176 queryPanel.setBorder( BorderFactory.createTitledBorder(

177 "Find an entry by last name" ) );

178 queryLabel.setText( "Last Name:" );

179 queryPanel.add( Box.createHorizontalStrut( 5 ) );

180 queryPanel.add( queryLabel );


182 queryPanel.add( queryTextField );


184

185 queryButton.setText( "Find" );

186 queryButton.addActionListener(


188 {


190 {

191 queryButtonActionPerformed( evt );




195

196 queryPanel.add( queryButton );


198 add( queryPanel );

199

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130


200 browseButton.setText( "Browse All Entries" ) ;

201 browseButton.addActionListener(


203 {


205 {

206 browseButtonActionPerformed( evt );




210

211 add( browseButton );

212

213 insertButton.setText( "Insert New Entry" );

214 insertButton.addActionListener(


216 {


218 {

219 insertButtonActionPerformed( evt );




223

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131


224 add( insertButton );

225

226 addWindowListener(

227 new WindowAdapter()

228 {

229 public void windowClosing( WindowEvent evt )

230 {

231 personQueries.close(); // close database connection


233 } // end method windowClosing


235 ); // end call to addWindowListener

236

237 setVisible( t rue );

238 } // end no- argument constructor

239

240 // handles call when previousButton is clicked

241 private void previousButtonActionPerformed( ActionEvent evt )

242 {

243 currentEntryIndex - - ;

244

245 i f ( currentEntryIndex < 0 )

246 currentEntryIndex = numberOfEntries - 1;

247

248 indexTextField.setText( "" + ( currentEntryIndex + 1 ) );


250 } // end method previousButtonActionPerformed

251

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132


252 // handles call when nextButton is clicked

253 private void nextButtonActionPerformed( ActionEvent evt )

254 {

255 currentEntryIndex++;

256

257 i f ( currentEntryIndex >= numberOfEntries )

258 currentEn tryIndex = 0;

259



262 } // end method nextButtonActionPerformed

263

264 // handles call when queryButton is clicke d

265 private void queryButtonActionPerformed( ActionEvent evt )

266 {

267 results =

268 personQueries.getPeopleByLastName( queryTextField.getText() );

269 numberO fEntries = results.size();

270

271 i f ( numberOfEntries != 0 )

272 {

273 currentEntryIndex = 0;

274 currentEntry = results.get( currentEntryIndex );

275 idTextField.setText( "" + currentEntry.getAdd ressID() );

276 firstNameTextField.setText( currentEntry.getFirstName() );

277 lastNameTextField.setText( currentEntry.getLastName() );

278 emailTextField.setText( currentEntry.getEmail() );

279 phoneTextField.se tText( currentEntry.getPhoneNumber() );

280 maxTextField.setText( "" + numberOfEntries );

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Executes the query inPreparedStatementselectPeopleByLastName fromclass PersonQueries.

133



282 nextButton.setEnabled( t rue );

283 previousButton.setEnabled( t rue );

284 } // end if

285 else


287 } // end method queryButtonActionPerformed

288

289 // handles call when a new value is entered in indextTextField

290 private void indexTextFiel dActionPerformed( ActionEvent evt )

291 {

292 currentEntryIndex =

293 ( Integer.parseInt( indexTextField.getText() ) - 1 );

294

295 i f ( numberOfEntries != 0 && currentEntryIndex < numberOfEntries )

296 {


298 idTextField.setText("" + currentEntry.getAddressID() );




302 phoneTextField.setText( currentEntry.getPhoneNumber() );



305 } // end if

306 } // end method indexTextFieldActionPerformed

307

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134


308 // handles call when browseButton is clicked

309 private void browseButtonActionPerformed( ActionEvent evt )

310 {

311 t r y

312 {

313 results = personQueries.getAllPeople();

314 numberOfEntries = resul ts.s ize();

315

316 i f ( numberOfEntries != 0 )

317 {

318 currentEntryIndex = 0;


320 idTextField.setText( "" + currentEntry.getAddr essID() );




324 phoneT extField.setText( currentEntry.getPhoneNumber() );



327 nextButton.setEnabled( t rue );

328 previousButton.setEnabled( t rue );

329 } // end if

330 } // end try

331 catch ( Exception e )

332 {

333 e.printStackTrace();

334 } // end catch

335 } // end method browseButtonActionPerformed

336

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Executes the query inPreparedStatementselectAllPeople from classPersonQueries.

135


337 // handles call when insertButton is clicked

338 private void insertButtonActionPerformed( ActionEvent evt )

339 {

340 int result = personQueries.addPerson( firstNameTextField.getText(),

341 lastNameTextField.getText() , emailTextField.getText(),

342 phoneTextField.getText() );

343

344 i f ( result == 1 )

345 JOptionPane.showMessageDialog( this , "Person added!" ,

346 "Person added", JOptionPane.PLAIN_MESSAGE );

347 else

348 JOptionPane.showMessageDialog( this , "Person not added!" ,

349 "Er ror" , JOptionPane.PLAIN_MESSAGE );

350


352 } // end method insertButtonActionPerformed

353

354 // main method

355 public static void main( String args[] )

356 {

357 new AddressBookDisplay();

358 } // end method main

359 } // end class AddressBookDisplay

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Executes the insert operation inPreparedStatementinsertNewPerson from classPersonQueries.

136


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137


25.12 Stored Procedures

• Stored procedures– Store SQL statements in a database– Invoke SQL statements by programs accessing the

database

• Interface CallableStatement– Receive arguments– Output parameters

138



Although the syntax for creating storedprocedures differs across databasemanagement systems, the interfaceCallableStatement provides a uniforminterface for specifying input and outputparameters for stored procedures and forinvoking stored procedures.

139



According to the Java API documentationfor interface CallableStatement, formaximum portability between databasesystems, programs should process the updatecounts or ResultSets returned from aCallableStatement before obtaining thevalues of any output parameters.

140


25.13 Transaction Processing

• Many applications require guarantees that aseries of database insertions, updates anddeletions executes properly before theapplications continue processing the nextdatabase operation

• Enables a program that interacts with a databaseto treat a database operation (or set ofoperations) as a single operation

– Known as an atomic operation or a transaction– At the end of a transaction, decide to commit or roll back

141



• Committing a transaction finalizes the databaseoperation(s); all insertions, updates and deletionsperformed as part of the transaction cannot bereversed without performing a new databaseoperation

• Rolling back a transaction leaves the database inits state prior to the database operation

142



• Methods of interface Connection– setAutoCommit specifies whether each SQL statement

commits after it completes (a true argument) or if severalSQL statements should be grouped as a transaction (afalse argument)

• If the argument to setAutoCommit is false, the programmust follow the last SQL statement in the transaction with acall to Connection method commit or rollback

– getAutoCommit determines the autocommit state for theConnection.

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