count() function in MYSQL by R4R Team

MYSQL COUNT() function:
-The count() function is used to return the count of an expression.
-When we want to count number of records in any column then we use count() function.

Syntax:
SELECT COUNT(expression)
FROM table_name
WHERE conditions;

Display all record of table:

SELECT * FROM employee;

emp_id	emp_name	department	emp_salary
1	Aman	D1	34000
2	Ram	D2	43000
3	Ramesh	D1	20000
4	John	D3	65000
5	Sita	D1	10000
6	Dinesh	D2	15000

Now we count all the employee:

SELECT COUNT(emp_id) from employee;

COUNT(emp_id)
6

Now we count the number of the employee which belong to department D1:

SELECT department,COUNT(emp_id) from employee WHERE department=D1;

department	COUNT(emp_id)
D1	3