COUNT

Computes either the number of rows in a group of rows or the number of non‑NULL values in a group of values.

Syntax

COUNT ( {[ ALL ]expression}|{ DISTINCT column_ref}| * )

The keyword DISTINCT specifies that the duplicate values are to be eliminated before computing the count.

If the argument to COUNT function is ‘*', then the function computes the count of the number of rows in a group.

If the argument to COUNT function is not ‘*', then NULL values are eliminated before the number of rows is computed.

The argument column_ref or expression can be of any type.

The result of the function is of BIGINT data type. The result is never NULL.

This example illustrates the COUNT function:

SELECT COUNT (*)
FROM orders
WHERE order_date = SYSDATE ;