Recap of SQL Lab no 8 Advance Database Management System

Outline Revision of SQL Commands –Insert –Update –Delete

INSERT Statement There are two types of INSERT statements –One row at a time can be inserted in tables. Specify values for each column with the VALUES Clause –Multiple rows can be inserted in a single INSERT Statement.

INSERT INTO Customer ( CustID, Name, Address, Phone ) VALUES ( 101, ‘Ali Khan’, ’21 Sabzazar Karachi’, ’ ’ )

Example – One row at a time INSERT INTO Customer ( CustID, Name, Address, Phone ) VALUES ( 101, ‘Ali Khan’, ’21 Sabzazar Karachi’, ’ ’ )

Example – One row at a time INSERT INSERT INTO Customer VALUES ( 101, ‘Ali Khan’, ’21 Sabzazar Karachi’, ’ ’ )

Example – Multiple rows INSERT INSERT INTO DBMSStudent SELECT * FROM Student WHERE StdMajor = ‘DBMS’

UPDATE Statement There can be 2 types of UPDATE statements –Single column update –Multiple column update

Single Column UPDATE UPDATE Employee SET EmpSalary=EmpSalary*5 WHEREEmpDept=‘Finance’ Note: All Employees of Finance Dept got five times raise in salary

Multiple Columns UPDATE UPDATE Employee SET EmpLastName=‘Homer’, EmpPhone=’ ’, EmpDept=‘Accounts’ WHEREEmpDept=‘Finance’

Multiple Columns UPDATE UPDATE Student SET StdMajor=‘Computer Engineering’, StdSession= ‘2k3-CP’ Notice there is no WHERE condition

DELETE Statement There are 2 types of DELETE statements –Selected rows DELETE –All rows DELETE

Example - Selected Rows DELETE DELETE FROM Student WHERE StdMajor=‘IS’ AND StdSession=‘Fall04’

Example - Selected Rows DELETE DELETE statement Using Join Operator DELETE Offering.* FROM Offering INNER JOIN Faculty ON Offering.FacID=Faculty.FacID WHERE FacFisrtName=‘John’ ANDFacLastName=‘Barron’ Note: Used when rows of a table reference other tables

Example – All rows DELETE DELETE FROM DBMSStudent

DELETE and UPDATE actions for Referenced Rows Deleting a referenced row : What happens to related rows (in foreign key table) when referenced rows are deleted Updating the PK of a referenced row: What happens to related rows when the primary key of the referenced row is updated

Things to done … Some ACTIONS must be applied on referenced rows of the tables in CREATE TABLE statements Restrict (NO ACTION) Cascade (CASCADE) Nullify (SET NULL) Default (SET DEFAULT)

Example CREATE TABLE Enrollment ( EnrID INTEGER NOT NULL, Stdid CHAR(11) NOT NULL, Enrgrade DECIMAL(3,2) CONSTRAINT PKEnrID PRIMARY KEY(EnrID), CONSTRAINT FKStdid FOREIGN KEY(STDid) REFERENCES Student ON DELETE NO ACTION ON UPDATE CASCADE )