COUNT Function [Aggregate]

Counts the number of rows in a group, depending on the specified parameters.

Syntax

COUNT ( * | expression | DISTINCT column-name )

Parameter	Description
*	Returns the number of rows in each group.
expression	Returns the number of rows in each group where expression is not the NULL value.
DISTINCT column-name	Returns the number of different values in column-name. Rows where the value is the NULL value are not included in the count.

Note:

When the query results are displayed, the * is not displayed in the column header, and appears as:

Count()

INT

Returns each unique city, and the number of rows with that city value:

SELECT city , Count(*)
FROM Employees
GROUP BY city