FREQUENTLY ASKED QUESTIONS

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151) My boss has changed his mind. Now he doesn't want to pay more than 10,000.so revoke that salary constraint.

SQL>alter table emp modify constraint chk_001 enable;

152) Add column called as mgr to your emp table;

SQL>alter table emp add(mgr number(5));

153) Oh! This column should be related to empno. Give a command to add this constraint.

SQL>ALTER TABLE EMP ADD CONSTRAINT MGR_DEPT FOREIGN KEY(MGR) REFERENCES EMP(EMPNO)

154) Add deptno column to your emp table

SQL>alter table emp add(deptno number(5));

155) This deptno column should be related to deptno column of dept table;

SQL>alter table emp add constraint dept_001 foreign key(deptno)
reference dept(deptno)
[deptno should be primary key]

156) Give the command to add the constraint.

SQL> alter table


157) Create table called as newemp. Using single command create this table as well as get data into this table(use create table as);

SQL>create table newemp as select * from emp;

SQL>Create table called as newemp. This table should contain only empno,ename,dname.

SQL>create table newemp as select empno,ename,dname from emp,dept where 1=2;

158) Delete the rows of employees who are working in the company for more than 2 years.

SQL>delete from emp where (sysdate-hiredate)/365>2;

159) Provide a commission(10% Comm Of Sal) to employees who are not earning any commission.

SQL>select sal*0.1 from emp where comm is null

160) If any employee has commission his commission should be incremented by 10% of his salary.

SQL>update emp set comm=sal*.1 where comm is not null;

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