Group By Clause

Question

Why is it necessary to use group by with aggregate function or vice veraa

Answer 1

Suppose we need to categorise people according to their department in the data base .We can simply use group by clause instead of using seperate select statements and joining them. we have many advantages using group by clause like group by with having clause , here having is used to filter further. Similarly there are other benefits.
All these are used to make uour answer simple and easly understandable.