Lu Wei1 Outline Introduction Basic SQL Setting Up and Using PostgreSQL Advanced SQL Embeded SQL.

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Outline

• Introduction• Basic SQL• Setting Up and Using PostgreSQL• Advanced SQL• Embeded SQL

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Advanced SQL

• Index• View• Transaction• Integrity Constraints• Access control

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Advanced SQL


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Index

• An index is a structure that provides accelerated access to the rows of a table based on the values of one or more columns.

• We will discuss the index in detail in chapter11.

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Index

• Creating an Index (CREATE INDEX)

• Examples

CREATE [UNIQUE] INDEX IndexNameON TableName(columnName[ASC|DESC][,…])

CREATE UNIQUE INDEX StaffNoIndON Staff(staffNo);

CREATE INDEX RentIndON PropertyForRent(city,rent);

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Index

• Removeing an Index (DROP INDEX)

• Examples

DROP INDEX IndexName

DROP INDEX RentInd;

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Advanced SQL


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View

• The dynamic result of one or more relational operations on the base relations to produce another relation.

• A view is a virtual relation that does not necessarily exist in the in the database but can be produced upon request by a particular user, at the time of request.

• The DBMS stores the definition of the view in the database

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View

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View

• Creating a View (CREATE VIEW)

– If WITH CHECK OPTION is specified, SQL ensures that if a row fails to satisfy the WHERE clause of the defining query of a view, it is not added to the underlying base table of the view.

CREATE VIEW ViewName[(newColumnName[,…])]AS subselect [WITH [CASCADED|LOCAL] CHECK OPTION];

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View

• Examples – Horizontal views

CREATE VIEW IS_Student AS SELECT * FROM Student WHERE sDept='IS';

CREATE VIEW Manager3Staff AS SELECT * FROM Staff WHERE branchNo = ‘B003’;

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View

– Vertical views

CREATE VIEW Staff3 AS SELECT staffNo,fName,lName,position,sex

FROM Staff WHERE branchNo = ‘B003’;

CREATE VIEW Staff3 AS SELECT staffNo,fName,lName,position,sex

FROM Manager3Staff;

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View

– Grouped and joined views

Create a view of students who is in department ‘IS’ and elect the course ‘001’

CREATE VIEW IS_S1(sNo, sName, score) AS SELECT Student.sNo, sName, score FROM Student, SC WHERE sDept='IS' AND Student.sNo=SC.sNo AND SC.cNo='1';

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View

Create a view of staff who manage properties for rent, which includes the branch number they work at, their staff number, and the number of properties they manage.

CREATE VIEW StaffPropCnt(branchNo,staffNO,cnt)

AS SELECT s.branchNo,s.staffNo,COUNT(*) FROM Staff s,PropertyForRent p WHERE s.staffNo = p.staffNo GROUP BY s.branchNo,s.staffNo;

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View

• Removing a View (DROP VIEW)

– If CASCAE is specified, DROP VIEW deletes all related dependent objects, in other words, all objects that reference the view.

DROP VIEW ViewName [RESTRICT|CASCADE];

DROP VIEW Manager3Staff CASCADE;

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View

• View Resolution

SELECT *FROM empvu80;

iSQL*Plus

Oracle Server

USER_VIEWS EMPVU80

SELECT employee_id, last_name, salaryFROM employeesWHERE department_id=80;

EMPLOYEES

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View

SELECT staffNo,cnt FROM StaffPropCnt WHERE branchNo = ‘B003’ORDER BY staffNo;

SELECT s.staffNo AS staffNo,COUNT(*) AS cnt

FROM Staff s,PropertyForRent p WHERE s.staffNo = p.staffNo AND branchNo = ‘B003’GROUP BY s.branchNo,s.staffNoORDER BY staffNo;

Refer to page129

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View

• Restriction on Views– If a column in the view is based on an aggregate funct

ion, then the column may appear only in SELECT and ORDER BY clauses of queries that access the view. In particular, such a column may not be used in a WHERE clause and may not be an argument to an aggregate function in any query based on the view.

– A grouped view may never be joined with a base table or a view.

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View

SELECT COUNT(cnt) 　　　FROM StaffPropCnt;

SELECT * 　　　FROM StaffPropCnt

WHERE cnt > 2;

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View

• View Updatability– All updates to a base table are immediately reflected i

n all views that encompass that base table. – Similarly,we may except that if a view is updated then

the base table(s) will reflect that change. – Consider that if any view is updatable

INSERT INTO StaffPropCnt

VALUES(‘B003’,’SG5’,2);

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View

CREATE VIEW StaffPropList(branchNo,staffNo,propertyNo)

AS SELECT s.branchNo,s.staffNo,p.propertyNo

FROM Staff s,PropertyForRent p

WHERE s.staffNo = p.staffNo;

INSERT INTO StaffPropList

VALUES(‘B003’,’SG5’,’PG19’);

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View

For a view to be updatable, the DBMS must be able to trace any row or column back to its row or column in the source table.

Refere to page131 for upatable view definition given in the ISO standard.

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View

UPDATE IS_StudentSET sName='刘辰 'WHERE sNo=‘05002';UPDATE Student SET sName='刘辰 ' WHERE sNo=‘05002' AND sDept='IS';

INSERTINTO IS_StudentVALUES(‘05029’, ‘赵新’ , 20);

INSERT INTO Student(Sno,Sname,Sage,Sdept)VALUES(‘05029', '赵新 ', 20, 'IS');

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View

• WITH CHECK OPTION– The rows that enter or leave a view are called migrati

ng rows.– The WITH CHECK OPTION clause of the CREATE VI

EW statement prohibits a row migrating out of the view.

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View

CREATE VIEW Manager3Staff AS SELECT * FROM Staff WHERE branchNo = ‘B003’ WITH CHECK OPTION;

UPDATE Manager3StaffSET branchNo = ‘B005’WHERE staffNo = ‘SG37’;

INSERT INTO Manager3StaffVALUES(‘SL15’,’Mary’,’Black’,’Assistant’, ’F’,’1985-06-21’,8000,’B002’);

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View

CREATE VIEW LowSalaryAS SELECT * FROM Staff WHERE salary > 9000;

CREATE VIEW HighSalaryAS SELECT * FROM LowSalary WHERE salary > 10000WITH LOCAL CHECK OPTION;

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View

UPDATE Manager3StaffSET salary = 9500(8000?)WHERE staffNo = ‘SG37’;

CREATE VIEW Manager3StaffAS SELECT * FROM HighSalary WHERE branchNo = ‘B003’;

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View

• Advantages of using view– Data independence– Currently– Improved security– Reduced complexity– Convenience– Customization– Data integrity

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View

• Disadvantages of using view– Update restriction– Structure restriction– Performance

•

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Advanced SQL


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Transaction

• A transaction is a sequence of database statements that needs to execute atomically .

• A database transaction consists of one of the following:– DML statements which constitute one consistent change to the data.

– One DDL statement– One DCL statement

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Transaction

• Beginning and end of transaction– Implicitly declare– Explicitly declare (begin transaction, commit / rollbac

k)– Programmatic SQL aborts.

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Transaction

• Beginning and end of transaction in PostgreSQL through interactive terminal

SELECT * FROM librarian; INSERT INTO librarian VALUES('Mary');

BEGIN TRANSACTION (implicit) SELECT * FROM librarian; commit (implicit) BEGIN TRANSACTION (implicit) INSERT INTO librarian VALUES('Mary'); COMMIT(implicit)

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Transaction

BEGIN TRANSACTION; (explicit) SELECT * FROM librarian; INSERT INTO librarian VALUES('Mary'); COMMIT; (explicit)

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Advanced SQL


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Integrity Constraints

• Immediate and Deferred Integrity Constraints– In some situations, we do not want integrity constraint

s to be checked immediately, that is after every SQL statement has been executed, but instead at transaction commit

SET CONSTRAINTS{ALL|constraintName[,…]}{[NOT]DEFERRABLE}[INITIALLY IMMEDIATE|DEFEREED]

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Integrity Constraints

ALTER TABLEADD CONSTRAINT constraintNameFOREIGN KEY(columnName) REFERENCES tableName.columnNameDEFERRABLE INITIALLY DEFERRED/IMMEDIATE

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Advanced SQL


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Access control

• DBMS should provide a mechanism to ensure that only authorized users can access the database.

• SQL provide the GRANT and REVOKE statement to allow security to be set up.

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Username and passwordPrivileges

Access control

Databaseadministrator

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Access control

• Database security– System security– Data security

• System privileges: Gaining access to the database

• Object privileges: Manipulating the content of the database objects

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Access control

• System privileges– There are many system privileges available according

to different DBMSs.

• The database administrator has high-level system privileges for tasks such as:– Creating new users– Removing users– Removing tables

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Access control

• An application developer, for example, may have the following system privileges:– CREATE SESSION– CREATE TABLE– CREATE VIEW– CREATE PROCEDURE

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Access control

• Grant and revoke system privileges

GRANT {system_privilege|role}

[, {system_privilege|role} ]…

TO {user|role||PUBLIC}

[, {user|role||PUBLIC}][WITH ADMIN OPTION];

REVOKE {system_privilege|role}

[, {system_privilege|role} ]…

FROM {user|role||PUBLIC}

[, {user|role||PUBLIC}]...;

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Access control

• Examples

GRANT create session, create table, create sequence, create viewTO scott;Grant succeeded.Grant succeeded.

GRANT create session, create table, create sequence, create viewTO scott;Grant succeeded.Grant succeeded.

REVOKE create session, create table, create sequence, create viewFROM scott;Revoke succeeded.Revoke succeeded.

REVOKE create session, create table, create sequence, create viewFROM scott;Revoke succeeded.Revoke succeeded.

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Access control

• Object previliges– Object privileges vary from object to object.– An owner has all the privileges on the object.

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Access control

Object Privilege Table View Sequence Procedure

ALTER

DELETE

EXECUTE

INDEX

INSERT

REFERENCES

SELECT

UPDATE

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Access control

• Grant and revoke object privilegesGRANT {object_privilege[(column_list)]

[, object_privilege[(column_list)] …

|ALL [PRIVILEGES]}

ON [schema.]object

TO {user|role|PUBLIC}[,{user|role|PUBLIC}][WITH GRANT OPTION];

REVOKE {object_privilege

[, object_privilege ]…|ALL [PRIVILEGES]}

ON [schema.] object

FROM {user|role||PUBLIC}

[, {user|role||PUBLIC}]...

[CASCADE CONSTRAINTS];

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Access control

• Examples GRANT selectON employeesTO sue, rich;Grant succeeded.Grant succeeded.

GRANT selectON employeesTO sue, rich;Grant succeeded.Grant succeeded.

GRANT update (department_name, location_id)ON departmentsTO scott, manager;Grant succeeded.Grant succeeded.

GRANT update (department_name, location_id)ON departmentsTO scott, manager;Grant succeeded.Grant succeeded.

REVOKE select, insertON departmentsFROM scott;Revoke succeeded.Revoke succeeded.

REVOKE select, insertON departmentsFROM scott;Revoke succeeded.Revoke succeeded.

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Access control

• GRANT ALL PRIVILEGES

GRANT ALL PRIVILIGES

ON Staff

TO Manager

WITH GRANT OPTION;

GRANT ALL PRIVILIGES

ON Student, Course

TO U1;

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Access control

• GRANT specific privileges

GRANT SELECT, UPDATE (salary)

ON Staff

TO Personnel, Director;

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Access control

• GRANT specific privileges to PUBLIC

GRANT SELECT

ON Branch

TO PUBLIC;

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Access control

• REVOKE specific privileges from PUBLIC

REVOKE SELECT

ON Branch

FROM PUBLIC;

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Access control

• GRANT specific privileges from named user

REVOKE ALL PRIVILEGES

ON Staff

FROM Director;

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Access control

• About WITH ADMIN OPTION in system privilege DBA

GRANT

REVOKE

Jeff Emi

Jeff EmiDBA

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Access control

• About WITH GRANT OPTION in object privilege

GRANT

REVOKE

Bob Jeff Emi

EmiJeffBob

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Summary

• In this part you should have learned:– How to create and drop view and index– The concept of transaction– How to define integrity constraint– How to grant and revoke privileges

Lu Wei1 Outline Introduction Basic SQL Setting Up and Using PostgreSQL Advanced SQL Embeded SQL.

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