WHERE Query in DBMS

Consider the sample table emp

Display the records of those employees whose designation is ‘MANAGER’

select * from emp
where job='MANAGER';

O/P

3 rows selected.

In our emp table, there are three managers that are why only three records are displayed, because the condition is true for only those three rows i.e when the job is a manager.

Display name, job, the salary of that employee whose salary is greater than 2900

select ename,job,sal 
from emp
where sal>2900;

O/P You can also display  only specified columns and filter the records

Operators that can be used in Where query in DBMS

Not only comparison(=) operator many operators shown below can be used with where clause

Display the records of all employees other than managers

select ename,sal,job,deptno from emp
where job != 'MANAGER';

O/P 4 rows selected

Display records of all employees whose salary is between 1000/- to 2500/-

select ename,sal,job,deptno from emp
where SAL between 1000 AND 2500;

• Here we can make use of between operator where the condition is applied for all the values within the specified range
• In the above example all the records of employees whose salary in between the range of 2000 and 2500 is displayed(inclusive of 2000 and 2500)

Deleting records based on the condition specified in where clause

Conditions can be specified by using where the where clause for deletion and updation of data

delete from emp
where empno=7934;

O/P

1 row deleted