SQL COUNT()Function

The COUNT() function in SQL is used to return the number of rows that match a specified condition. It can be used with SELECT statements to count rows in a table, including duplicate values and NULLs.

Here’s a basic syntax of the COUNT() function:

SELECT COUNT(column_name)
FROM table_name
WHERE condition;

Examples:

1. Counting all rows in a table

Suppose we have a table called employees:

To count the total number of rows in the employees table, we can use:

SELECT COUNT(*) FROM employees;

Output:

2. Counting rows with a specific condition

To count the number of employees in the IT department:

SELECT COUNT(*) FROM employees WHERE department = 'IT';

Output:

3. Counting distinct values

To count the number of distinct departments:

SELECT COUNT(DISTINCT department) FROM employees;

Output:

4. Counting non-NULL values in a column

To count the number of non-NULL values in the department column:

SELECT COUNT(department) FROM employees;

Output:

This function is useful for generating reports and obtaining statistical data about the data in your database.