Page 7 - Simple Queries in SQL

NULL Values

 NULL values
select * from employee
where comm is NULL;

select * from employee
where comm is NOT NULL;

Simple calculations
 Display of simple calculations
Select ename, sal+comm
from employee
where comm is not NULL;

 Displaying Annual salary of dept 20
select ename, sal*12
from employee
where deptno=20;

COLUMN alias

Select ename NAME, sal*12 "ANNUAL SALARY"
from employee;
OR
Select ename NAME, sal*12 AS "ANNUAL SALARY"
from employee;

PATTERN Matching

 Pattern matching
% matches any substring (0 onwards)
_ matches exactly one character (no zero even)
 select * from emp
where ename like 'A%';
 select * from emp
where ename like '_ _ E%';