Count ( ) In SQL Database this is a function which return no of rows from a table in Database . Generally this is used in SQL select statement and count the no. of records in a table .
Syntax ->

select count ( expression_name ) from table_name where clause ;

Example ->
Suppose i have a table , name is student

**Student_name**    **Student_Age**    **Student_Id**
   Mukesh               23                 1
   Ayush                24                 2

Suppose i want to count number of records in a table then we can do with the count ( ) function .

select count ( * ) from student ; // Output -> 2

To count distinct column_name

select count ( distinct Student_Age )  from student ; // Output -> 1