SQL COUNT

Write SQL COUNT queries.

The COUNT() the function returns the number of rows that match a specified criterion.

Example

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

Approach

Mysql:  Count all employee of department=1

SELECT COUNT(*) AS TOTALEMPLOYEE 
FROM EMPLOYEE WHERE DepartmentId=1;

Result: TOTAL EMPLOYEE=6

Mysql:  Department wise employee count

SELECT DepartmentId,COUNT(*) AS TOTALEMPLOYEE 
FROM EMPLOYEE 
GROUP BY DepartmentId;

Result:

+--------------+---------------+
| DepartmentId | TOTALEMPLOYEE |
+--------------+---------------+
| 1            |   6           | 
| 2            |   2           | 
+--------------+---------------+