Why do we need GROUP BY with AGGREGATE FUNCTIONS?

Question

I saw an example where there was a list (table) of employees with their respective monthly salaries. I did a sum of the salaries and saw the exact same table in the ouptput

Answer 1

If you wanted to add up all the numbers you would not have a GROUP BY:

SELECT SUM(MonthlySalary) AS TotalSalary
FROM Employee

+-----------+
|TotalSalary|
+-----------+
|777400     |
+-----------+

The point of the GROUP BY is that you get a separate total for each employee.

+--------+------+
|Employee|Salary|
+--------+------+
|John    |123400|
+--------+------+
|Frank   |413000|
+--------+------+
|Bill    |241000|
+--------+------+