SQL - COUNT() Function

The COUNT() function is an aggregate function that is used to find the number of values in the specified column excluding NULL values. It can be applied on numeric, character, or date values.

Syntax:

SELECT COUNT([ALL | DISTINCT] expression | column_name) FROM table_name [WHERE condition] [GROUP BY]    ;

For the demo purpose, we will use the following Employee table.

Specify the column name to count the total values in that column excluding NULL values. The following counts the total records in the FirstName column.

SELECT COUNT(FirstName) AS "Total" FROM Employee;

The COUNT() function excludes the NULL values.

SELECT COUNT(Email) AS "Total" FROM Employee;

The COUNT() function can contain other functions such as Distinct, as shown below.

SELECT COUNT(Distinct(LastName)) AS "Total" FROM Employee;

Use the COUNT(*) to count the total records in the table. The following query count the total records of the Employee table.

SELECT COUNT(*) AS "Total Records" FROM Employee;

The COUNT() is an aggregate function, so it can be used in Group By queries. The following query counts the number of employees in each department.

SELECT DeptId, COUNT(*) AS "Total Employees" FROM Employee GROUP BY DeptId;