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home / developersection / forums / what is the difference between the count() function and the sum() function in sql?
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What is the difference between the COUNT() function and the SUM() function in SQL?

Revati S Misra 708 30 Jun 2023

What is the difference between the COUNT() function and the SUM() function in SQL?

mssql server mssql serversql serversql
Updated 18 Nov 2023
Revati S Misra
Revati S Misra

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Skilled in SEO, content writing, and digital marketing. Completed several years of working in many organizations including multinational companies. I love to learn new things in life that keep me motivated.

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1 Answers

Aryan Kumar
Aryan Kumar 18 Nov 2023
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In SQL, the COUNT and SUM functions serve different purposes and are used for different types of calculations.

COUNT Function:

The COUNT function is used to count the number of rows in a result set or the number of occurrences of a particular value in a column. It is often used in combination with the GROUP BY clause to get counts for groups of data.

Syntax:

SELECT COUNT(column_name) FROM table_name WHERE condition;
  • If column_name is specified, it counts the number of non-NULL values in that column.
  • If * is used instead of column_name, it counts the total number of rows in the result set.

Example:

-- Count the number of employees in the 'HR' department
SELECT COUNT(employee_id) FROM employees WHERE department = 'HR';

SUM Function:

The SUM function, on the other hand, is used to calculate the sum of numerical values in a column. It adds up the numeric values in the specified column.

Syntax:

SELECT SUM(column_name) FROM table_name WHERE condition;
  • It is applicable only to numeric columns.

Example:

-- Calculate the total salary of all employees
SELECT SUM(salary) FROM employees;

Key Differences:

Purpose:

  • COUNT is used to count the number of rows or occurrences.
  • SUM is used to calculate the sum of numeric values.

Data Type:

  • COUNT can be used with any data type, including text and NULL values.
  • SUM is specifically used with numeric data types.

Usage:

  • COUNT can be used without specifying a column (COUNT(*)) to count all rows, or with a specific column to count non-NULL values in that column.
  • SUM is used with a specific numeric column to calculate the sum of its values.

NULL Handling:

  • COUNT counts the number of non-NULL values.
  • SUM includes NULL values in the calculation, treating them as 0.

Example:

-- Count the number of employees and calculate the total salary
SELECT COUNT(employee_id) AS total_employees, SUM(salary) AS total_salary FROM employees;

In this example, we are using both COUNT and SUM to get the count of employees and the total salary in a single query.

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