SQL COUNT() Function

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

SQL COUNT(column_name) Syntax

The COUNT(column_name) function returns the number of values (NULL values are not counted) in the specified column:

SQL COUNT(*) Syntax

The COUNT(*) function returns the number of records in the table:

SQL COUNT(DISTINCT column_name) Syntax

The COUNT(DISTINCT column_name) function returns the number of distinct values in the specified column:

Note: COUNT(DISTINCT) is applicable to Oracle and Microsoft SQL Server, but not to Microsoft Access.

Demonstration Database

In this tutorial, we will use the tutorialpro sample database.

Below is the data from the "access_log" table:

+-----+---------+-------+------------+
| aid | site_id | count | date       |
+-----+---------+-------+------------+
|   1 |       1 |    45 | 2016-05-10 |
|   2 |       3 |   100 | 2016-05-13 |
|   3 |       1 |   230 | 2016-05-14 |
|   4 |       2 |    10 | 2016-05-14 |
|   5 |       5 |   205 | 2016-05-14 |
|   6 |       4 |    13 | 2016-05-15 |
|   7 |       3 |   220 | 2016-05-15 |
|   8 |       5 |   545 | 2016-05-16 |
|   9 |       3 |   201 | 2016-05-17 |
+-----+---------+-------+------------+

SQL COUNT(column_name) Example

The following SQL statement calculates the total number of visits for "site_id"=3 in the "access_log" table:

Example

SQL COUNT(*) Example

The following SQL statement calculates the total number of records in the "access_log" table:

Example

SELECT COUNT(*) AS nums FROM access_log;

Executing the above SQL outputs the following result:

SQL COUNT(DISTINCT column_name) Example

The following SQL statement calculates the number of distinct "site_id" records in the "access_log" table:

Example

SELECT COUNT(DISTINCT site_id) AS nums FROM access_log;

Executing the above SQL outputs the following result: