Count() Function

Introduction:

The count function returns the number of rows which are currently in existence.It is used when number of rows in the collection are unknown. This Count function oftenly used when you have large tables, or you expect a large output means you want to count total number of rows with you search condition like in where clause. In such situations, it is desirable to determine the number of rows of output that you will be getting before actually displaying the output. In this section, we introduce the COUNT function and we also take another look at the concept of null values.

Syntax:

SELECT COUNT(column_name) FROM table_name;

Example:

SELECT COUNT(DISTINCT column_name) FROM table_name;