SQL: COUNT Function

SQL COUNT is the aggregate arithmetic function. COUNT allows us to COUNT number of row that matches specified criteria. This function returns the number of rows in the query. The COUNT function will only count those records in which the field in the brackets is NOT NULL. The SQL COUNT function is easy to use.

SyntaxSELECT COUNT (column_name) FROM table_name WHERE conditions 
SQL COUNT Examples We want to know how many employees in the table: 
SQL > SELECT count (*) as "TOTAL ROW" from EMP; 

 Example of SELECT COUNT (DISTINCT Column Name)

COUNT and DISTINCT can be used together in a statement to fetch the number of distinct entries in a table. If we want to select the number of unique departments:

SELECT COUNT (DISTINCT JOB) AS Department FROM EMP; 

Example of using WHERE Clause

Select how many employees have salary over 1500:

SELECT COUNT (ename) AS Employee FROM Emp WHERE Sal > 1500 ; 

 Example of using GROUP BY

In some cases, you will be required to use a GROUP BY clause with the COUNT function. Sometime, we may want to know how many employees in each department:

SELECT deptno, COUNT (deptno) AS Employee FROM EMP GROUP BY Deptno;