SQL AVG

Write SQL to use of aggregate avg() function.

The AVG() function returns the average value of the selected column

Example

Table: Employee                             Table: Department
+----+-------+--------+--------------+      +----+----------+
| Id | Name  | Salary | DepartmentId |      | Id | Name     |
+----+-------+--------+--------------+      +----+----------+
| 1  | Ram   | 85000  | 1            |      | 1  | IT       |
| 2  | Henry | 80000  | 2            |      | 2  | Sales    |
| 3  | Sam   | 60000  | 2            |      +----+----------+
| 4  | Shyam | 60000  | 1            |
| 5  | Geeta | 90000  | 1            |
| 6  | Sheet | 90000  | 1            |
| 7  | Leela | 80000  | 1            |
| 8  | Geeta | 70000  | 1            |
+----+-------+--------+--------------+

Query: Calculate the average salary of each department

SELECT DP.NAME AS DEPARTMENTNAME,SALARY FROM (
SELECT AVG(EP.Salary) SALARY,EP.DepartmentID
FROM Employee EP 
GROUP BY EP.DepartmentID) JOIN Department DP
ON DepartmentID=DP.ID

Result: 

+--------------+---------+
|DEPARTMENTNAME| Salary  |
+--------------+---------+
|    IT        | 79166.66|
|    SALES     | 70000   |
+--------------+---------+