My sql università di enna a.a. 2005-06
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Mysql
Basi di Dati
Università di Enna A.A. 2005/06
Intro
MySQL® and the MySQL logo are registered trademarks of MySQL AB (a Swedish company)
The MySQL® software delivers a very fast, multi-threaded, multi-user, and robust SQL (Structured Query Language) database server
The MySQL Web site (http://www.mysql.com/) provides the latest information about MySQL and MySQL AB
the “AB” part of the company name is the acronym for the Swedish “aktiebolag,” or “stock company”
License
The MySQL software is Dual Licensed
Users can choose to use the MySQL software as an Open
Source product under the terms of the GNU General Public
License
Users can purchase a standard commercial license from
MySQL AB
See http://www.mysql.com/company/legal/licensing/
for more information on our licensing policies.
Documentation
The MySQL Database Software is under constant
development, and the Reference Manual is updated
frequently as well. The most recent version of the
manual is available online in searchable form at
http://dev.mysql.com/doc/
Formats available:
HTML
CHM
Operating Systems Supported by MySQL
It is possible to port MySQL to all modern systems
that have a C++ compiler and a working
implementation of POSIX threads
Thread support is needed for the server. To compile
only the client code, the only requirement is a C++
compiler
“We use and develop the software ourselves primarily
on Linux (SuSE and Red Hat), FreeBSD, and Sun
Solaris (Versions 8 and 9)”
Operating Systems Supported by MySQL
MySQL has been reported to compile successfully on the following operating systems:
AIX 4.x, 5.x
Amiga
BSDI 2.x
Digital Unix 4.x
FreeBSD 2.x, 3.x, 4.x
Mac OS X
Windows 9x, Me, NT, 2000, XP, and 2003
Installing MySQL on Windows
A native Windows version of MySQL has been
available from MySQL AB since version 3.21 and
represents a sizable percentage of the daily
downloads of MySQL
The installer for the Windows version of MySQL 5.0,
combined with a GUI Configuration Wizard,
automatically installs MySQL, creates an option file,
starts the server, and secures the default user accounts
Installing MySQL on Windows
MySQL 5.0 for Windows is available in three distribution formats:
The binary distribution contains a setup program that installs everything you need so that you can start the server immediately
The source distribution contains all the code and support files for building the executables using the Visual Studio 2003 compiler system
Generally speaking, you should use the binary distribution. It is simpler to use than the others, and you need no additional tools to get MySQL up and running
Installing MySQL on Windows
A copy of the MySQL binary distribution for Windows, which can be downloaded from http://dev.mysql.com/downloads/
You may also have the following optional requirements:
If you plan to connect to the MySQL server via ODBC, you also need a Connector/ODBC driver
If you need tables with a size larger than 4GB, install
MySQL on an NTFS or newer filesystem
For MySQL 5.0, there are three installation packages to choose from when installing MySQL on Windows. The packages are as follows:
Essential package
Complete package
Noinstall archive
The Essentials package is recommended for most users
Installing MySQL on Windows
The following entries are created within the new Start menu section: MySQL Command Line Client : This is a shortcut to the
mysql command-line client and is configured to connect as the root user. The shortcut prompts for a root user password when connecting
MySQL Server Instance Config Wizard : This is a shortcut to the MySQL Configuration Wizard. Use this shortcut to configure a newly installed server, or to re-configure an existing server
MySQL Documentation : This is a link to the MySQL server documentation that is stored locally in the MySQL server installation directory. This option is not available when the MySQL server is installed using the Essentials installation package.
Installing MySQL on Windows
The Main Features of MySQL
Written in C and C++
Tested with a broad range of different compilers
Works on many different platforms
Uses GNU Automake, Autoconf, and Libtool for portability
APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl are available
…
Column Types
Many column types:
signed/unsigned integers 1, 2, 3, 4, and 8 bytes long
FLOAT, DOUBLE
CHAR, VARCHAR
TEXT
BLOB
DATE, TIME, DATETIME, TIMESTAMP, YEAR
SET, ENUM
Fixed-length and variable-length records
Statements and Functions
Full operator and function support in the SELECT and WHERE clauses of queries.
Full support for SQL GROUP BY and ORDER BY clauses. Support for group functions (COUNT(), COUNT(DISTINCT ...), AVG(), STD(), SUM(), MAX(), MIN()
Support for LEFT OUTER JOIN and RIGHT OUTER JOIN
Support for aliases on tables and columns as required by standard SQL
Statements and Functions (2)
DELETE, INSERT, REPLACE, and UPDATE return the
number of rows that were changed (affected)
The MySQL-specific SHOW command can be used to
retrieve information about databases, database engines, tables,
and indexes. The EXPLAIN command can be used to
determine how the optimizer resolves a query
Function names do not clash with table or column names. For
example, ABS is a valid column name. The only restriction is
that for a function call, no spaces are allowed between the
function name and the ‘(’ that follows it
You can mix tables from different databases in the same query
Limits
Handles large databases.
“We use MySQL Server with databases that
contain 50 million records …”
“… We also know of users who use MySQL
Server with 60,000 tables and about 5,000,000,000
rows …”
Connectivity
Clients can connect to the MySQL server using TCP/IP sockets on any platform
The Connector/ODBC (MyODBC) interface provides MySQL support for client programs that use ODBC (Open Database Connectivity) connections.
For example, you can use MS Access to connect to your MySQL server.
The Connector/J interface provides MySQL support for Java client programs that use JDBC connections
How Big MySQL Tables Can Be
MySQL 3.22 had a 4GB (4 gigabyte) limit on table
size.
With the MyISAM storage engine in MySQL 3.23,
the maximum table size was increased to 65536
terabytes (2567 – 1 bytes).
With this larger allowed table size, the maximum
effective table size for MySQL databases is usually
determined by operating system constraints on file
sizes, not by MySQL internal limits
The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive
Win32 (FAT/FAT32) 2GB/4GB
Win32 (NTFS) 2TB
Linux 2.2-Intel 2GB
Linux 2.4+ (ext3) 4TB
Windows users please note: FAT and VFAT (FAT32) are not considered suitable for production use with MySQL. Use NTFS instead
How Big MySQL Tables Can Be
Connecting to and Disconnecting from
the Server
To connect to the server, you will usually need to
provide a MySQL username when you invoke mysql
and, most likely, a password. If the server runs on a
machine other than the one where you log in, you will
also need to specify a hostname
shell> mysql -h host -u user –p
Enter password: ********
Connecting to and Disconnecting from
the Server
shell> mysql -h host -u user –p
Enter password: ********
host and user represent the hostname where your
MySQL server is running and the username of your
MySQL account
The ******** represents your password; enter it
when mysql displays the Enter password: prompt.
Connecting to and Disconnecting from
the Server
Connecting to and Disconnecting from
the Server
Some MySQL installations allow users to connect as the anonymous (unnamed) user to the server running on the local host.
If this is the case on your machine, you should be able to connect to that server by invoking mysql without any options:
shell> mysql
Connecting to and Disconnecting from
the Server
After you have connected successfully, you can
disconnect any time by typing QUIT (or EXIT) at
the mysql > prompt:
shell> QUIT
Bye
shell> EXIT
Bye
On Unix, you can also disconnect by pressing Control-D
Entering Queries
mysql> SELECT VERSION( ), CURRENT_DATE;
Notes • When you issue a command, mysql sends it to the
server for execution and displays the results, then prints another mysql> prompt to indicate that it is
ready for another command.
Notes (2)
mysql displays query output in tabular form (rows and columns). The first row contains labels for the columns. The rows following are the query results.
Notes (3)
mysql shows how many rows were returned and how
long the query took to execute, which gives you a
rough idea of server performance
Entering Queries
Keywords may be entered in any lettercase. The
following queries are equivalent:
mysql> SELECT VERSION(), CURRENT_DATE;
mysql> select version(), current_date;
mysql> SeLeCt vErSiOn(), current_DATE;
• Here's another query. It demonstrates that you can use
mysql as a simple calculator
Entering Queries
You can even enter multiple statements on a single line. Just end each one with a semicolon
Entering Queries
A command need not be given all on a single line, so
lengthy commands that require several lines are not a
problem
mysql determines where your statement ends by
looking for the terminating semicolon, not by looking
for the end of the input line
Entering Queries
Entering Queries
The following table shows each of the prompts you may
see and summarizes what they mean about the state that
mysql is in:
mysql> Ready for new command.
-> Waiting for next line of multiple-line command
‘> Waiting for next line, waiting for completion of
a string that began with a single quote (‘'’)
Entering Queries
"> Waiting for next line, waiting for completion of a
string that began with a double quote (‘"’)
`> Waiting for next line, waiting for completion of an
identifier that began with a backtick (‘`’)
/*> Waiting for next line, waiting for completion of a comment
that began with /*
Entering Queries
Entering Queries
Entering Queries
mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;
'>
Creating and Using a Database
This section shows you how to:
Create a database
Create a table
Load data into the table
Retrieve data from the table in various ways
Use multiple tables
Use the SHOW statement to find out what databases
currently exist on the server
Creating and Using a Database
If the test database exists, try to access it
Creating and Using a Database
USE
USE, like QUIT, does not require a semicolon
You can terminate such statements with a
semicolon if you like; it does no harm
It must be given on a single line
Creating and Using a Database
Creating and Selecting a Database If the administrator creates your database for you when setting
up your permissions, you can begin using it. Otherwise, you
need to create it yourself
Creating and Selecting a Database
Creating a Table
Creating the database is the easy part, but at this point it's empty, as SHOW TABLES tells you:
Creating a Table
Creating the database is the easy part, but at this point it's empty, as SHOW TABLES tells you:
Creating a Table
Create table slides (id integer, contents varchar(30), images char);
Creating a Table
mysql> show tables;
Creating a Table
mysql> describe slides;
Loading Data into a Table
After creating your table, you need to populate it. The
LOAD DATA statement is useful for this
Because you are beginning with an empty table, an
easy way to populate it is to create a text file
containing a row for each of your slide, then load the
contents of the file into the table with a single
statement
Loading Data into a Table
Loading Data into a Table
mysql> LOAD DATA LOCAL INFILE
- > 'C:\\Documents and Settings\\User\\Documenti\\Didattica\\ceri\\Mysql\\dati\\
‘ > slides.txt' INTO TABLE slides;
Loading Data into a Table
mysql> LOAD DATA LOCAL INFILE
- > 'C:\\Documents and Settings\\User\\Documenti\\Didattica\\ceri\\Mysql\\dati\\
‘ > slides.txt' INTO TABLE slides;
Retrieving Information from a Table
mysql> select * from slides;
mysql> select contents from slides;
Retrieving Information from a Table
mysql> delete from slides;
Retrieving Information from a Table
mysql> select * from slides;
Retrieving Information from a Table
Source
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