1. Outline Introduction Basic SQL Setting Up and Using PostgreSQL
Advanced SQL
Embeded SQL
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2. Advanced SQL Index View Transaction Integrity Constraints
Access control
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3. Advanced SQL Index View Transaction Integrity Constraints
Access control
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4. 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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5. Index Creating an Index (CREATE INDEX) Examples
CREATE [UNIQUE] INDEX IndexName
ON TableName(columnName[ASC|DESC][,…])
CREATE UNIQUE INDEX StaffNoInd
ON Staff(staffNo);
CREATE INDEX RentInd
ON PropertyForRent(city,rent);
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6. Index Removeing an Index (DROP INDEX) Examples DROP INDEX IndexName
DROP INDEX RentInd;
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7. Advanced SQL Index View Transaction Integrity Constraints
Access control
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8. 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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9. View
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10. 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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11. 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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12. 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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13. 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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14. 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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15. 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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16. View View Resolution Oracle Server iSQL*Plus SELECT * FROM empvu80;
USER_VIEWS
EMPVU80
SELECT employee_id,
last_name,
salary
FROM employees
WHERE department_id=80;
iSQL*Plus
SELECT *
FROM empvu80;
EMPLOYEES
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17. View
Refer to page129
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.staffNo
ORDER BY staffNo;
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18. View Restriction on Views
If a column in the view is based on an aggregate function, 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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19. View SELECT COUNT(cnt) FROM StaffPropCnt; SELECT * FROM StaffPropCnt
WHERE cnt > 2;
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20. View View Updatability
All updates to a base table are immediately reflected in 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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21. 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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22. 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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23. View UPDATE IS_Student SET sName='刘辰' WHERE sNo=‘05002';
UPDATE Student SET sName='刘辰' WHERE sNo=‘05002' AND sDept='IS';
INSERT INTO IS_Student VALUES(‘05029’, ‘赵新’, 20);
INSERT INTO Student(Sno,Sname,Sage,Sdept) VALUES(‘05029', '赵新', 20, 'IS');
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24. View
WITH CHECK OPTION
The rows that enter or leave a view are called migrating rows.
The WITH CHECK OPTION clause of the CREATE VIEW statement prohibits a row migrating out of the view.
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25. View
CREATE VIEW Manager3Staff AS SELECT *    FROM Staff    WHERE branchNo = ‘B003’
WITH CHECK OPTION;
UPDATE Manager3Staff
SET branchNo = ‘B005’
WHERE staffNo = ‘SG37’;
INSERT INTO Manager3Staff
VALUES(‘SL15’,’Mary’,’Black’,’Assistant’, ’F’,’ ’,8000,’B002’);
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26. View
CREATE VIEW LowSalary AS SELECT *    FROM Staff    WHERE salary > 9000;
CREATE VIEW HighSalary AS SELECT *    FROM LowSalary    WHERE salary > 10000
WITH LOCAL CHECK OPTION;
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27. View
CREATE VIEW Manager3Staff AS SELECT *    FROM HighSalary    WHERE branchNo = ‘B003’;
UPDATE Manager3Staff
SET salary = 9500(8000?)
WHERE staffNo = ‘SG37’;
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28. View Advantages of using view Data independence Currently
Improved security
Reduced complexity
Convenience
Customization
Data integrity
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29. View Disadvantages of using view Update restriction
Structure restriction
Performance
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30. Advanced SQL Index View Transaction Integrity Constraints
Access control
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31. 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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32. Transaction Beginning and end of transaction Implicitly declare
Explicitly declare (begin transaction, commit / rollback)
Programmatic SQL aborts.
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33. 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)
INSERT INTO librarian VALUES('Mary');
COMMIT(implicit)
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34. Transaction BEGIN TRANSACTION; (explicit) SELECT * FROM librarian;
INSERT INTO librarian VALUES('Mary');
COMMIT; (explicit)
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35. Transaction Configure certain aspects of the transaction
SET TRANSACTION
[READ ONLY|READ WRITE]|
[ISOLATION LEVEL READ UNCOMMITTED|
READ COMMITTED|
REPEATABLE READ|
SERIALIZABLE]
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36. Advanced SQL Index View Transaction Integrity Constraints
Access control
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37. Integrity Constraints
Immediate and Deferred Integrity Constraints
In some situations, we do not want integrity constraints 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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38. Integrity Constraints
ALTER TABLE
ADD CONSTRAINT constraintName
FOREIGN KEY(columnName) REFERENCES tableName.columnName
DEFERRABLE INITIALLY DEFERRED/IMMEDIATE
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39. Advanced SQL Index View Transaction Integrity Constraints
Access control
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40. 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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41. Access control Username and password Privileges Database administrator
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42. 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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43. 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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44. 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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45. 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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46. Access control Examples GRANT create session, create table,
create sequence, create view
TO scott;
Grant succeeded.
REVOKE create session, create table,
create sequence, create view
FROM scott;
Revoke succeeded.
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47. Access control Object previliges
Object privileges vary from object to object.
An owner has all the privileges on the object.
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48. Access control Object Privilege Table View Sequence Procedure
ALTER Ö Ö
DELETE Ö Ö
EXECUTE Ö
INDEX Ö
INSERT Ö Ö
REFERENCES Ö Ö
SELECT Ö Ö Ö
UPDATE Ö Ö
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49. Access control Grant and revoke object privileges
GRANT {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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50. Access control Examples GRANT select ON employees TO sue, rich;
Grant succeeded.
GRANT update (department_name, location_id)
ON departments
TO scott, manager;
Grant succeeded.
REVOKE select, insert
ON departments
FROM scott;
Revoke succeeded.
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51. 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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52. Access control GRANT specific privileges GRANT SELECT, UPDATE (salary)
ON Staff
TO Personnel, Director;
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53. Access control GRANT specific privileges to PUBLIC GRANT SELECT
ON Branch
TO PUBLIC;
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54. Access control REVOKE specific privileges from PUBLIC REVOKE SELECT
ON Branch
FROM PUBLIC;
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55. Access control GRANT specific privileges from named user
REVOKE ALL PRIVILEGES
ON Staff
FROM Director;
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56. Access control About WITH ADMIN OPTION in system privilege DBA Jeff
Emi
GRANT
There are no cascading effects when a system privilege is revoked, regardless of whether it was given the ADMIN OPTION.
Read through the following steps that illustrate this.
Scenario
1. The DBA grants the CREATE TABLE system privilege to Jeff with the ADMIN OPTION.
2. Jeff creates a table.
3. Jeff grants the CREATE TABLE system privilege to Emi.
4. Emi creates a table.
5. The DBA revokes the CREATE TABLE system privilege from Jeff.
The result
Jeff’s table still exists, but no new tables can be created.
Emi’s table still exists and she still has the CREATE TABLE system privilege.
DBA
Jeff
Emi
REVOKE
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57. Access control About WITH GRANT OPTION in object privilege Bob Jeff
Emi
GRANT
REVOKE
Bob
Jeff
Emi
Revoking Object Privileges (continued)
Cascading effects can be observed when revoking a system privilege that is related to a DML operation. For example, if the SELECT ANY TABLE privilege is granted to a user, and that user has created procedures that use the table, all procedures that are contained in the user’s schema must be recompiled before they can be used again.
Revoking object privileges will also cascade when given WITH GRANT OPTION.
Read through the following steps that illustrate this.
Scenario
Jeff is granted the SELECT object privilege on EMPLOYEES with the GRANT OPTION.
Jeff grants the SELECT privilege on EMPLOYEES to Emi.
Later, the SELECT privilege is revoked from Jeff. This revoke is cascaded to Emi as well.
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58. 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
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