Lesson : 13 : SELECT with GROUP BY

SELECT with GROUP BY clause

GROUP BY Clause is used with the group functions to retrieve data grouped according to one or more columns.

 

Syntax :

 

SELECT col1, group function(col2), .. FROM <tablename> GROUP  BY column specified in select.

 

Examples :

 

1)      Total salary of the all employees

SQL> SELECT SUM(salary) from emp;

2)      Total salary  departmentwise

 

SQL> SELECT dept, SUM(salary) from emp GROUP BY dept;

 

3)      Number of employees in each location

SQL> SELECT location,count(*)  FROM emp GROUP  BY location;

4)      Average age of employess

SQL> SELECT Avg(age) from emp;

5)      Number of employess joined on each date

SQL>  SELECT  hiredate,count(*) FROM emp group by hiredate;