COUNT Aggregate Function

The function uses the following syntax:

COUNT([DISTINCT] <Expression>)

This function counts the number of values selected from the field indicated in the parameter. As opposed to other aggregate functions, you can use COUNT in three ways.

• First, this function allows you to count the number of field values, not equal to NULL.
• Secondly, this function allows you to count the number of different field values, not equal to NULL. To do so, you must use the DISTINCT keyword before the field specifications.
• Lastly, the functions can calculate the number of rows in the query result. To do so, you must use an asterisk ("*") as a function parameter.

You can indicate expressions containing values of any type as a function parameter. You cannot use this function with ValueStorage expressions and unlimited length strings.

Example:

SELECT
   COUNT (*) AS Total,
   COUNT (DISTINCT Invoice.Nomenclature) AS Different

FROM
   Document.ExpInvoice.Content AS Invoice

Query result:

Total	Different
24	8

See also: Aggregate Functions