The SQL GROUP BY Clause is used along with the group functions to retrieve data grouped according to one or more columns.
For Example: If you want to know the total amount of salary spent on each department, the query would be:
SELECT dept, SUM (salary)
FROM employee
GROUP BY dept;
The output would be like:
NOTE: The group by clause should contain all the columns in the select list expect those used along with the group functions.
SELECT location, dept, SUM (salary)
FROM employee
GROUP BY location, dept;
