SQLite: sum Function

This SQLite post explains how to use the SQLite sum function with syntax and examples.

Description

The SQLite sum function returns the summed value of an expression.

Syntax

The syntax for the sum function in SQLite is:

SELECT sum(aggregate_expression)
FROM tables
[WHERE conditions];

OR the syntax for the sum function when grouping the results by one or more columns is:

SELECT expression1, expression2, ... expression_n,
       sum(aggregate_expression)
FROM tables
[WHERE conditions]
GROUP BY expression1, expression2, ... expression_n;

Parameters or Arguments

expression1, expression2, ... expression_n

Expressions that are not encapsulated within the sum function and must be included in the GROUP BY clause at the end of the SQL statement.

aggregate_expression

This is the column or expression that will be summed.

tables

The tables that you wish to retrieve records from. There must be at least one table listed in the FROM clause.

WHERE conditions

Optional. These are conditions that must be met for the records to be selected.

Applies To

The sum function can be used in the following versions of SQLite:

• SQLite 3.8.6, SQLite 3.8.x, SQLite 3.7.x, SQLite 3.6.x

Example - With Single Expression

Let's look at some SQLite sum function examples and explore how to use the sum function in SQLite.

For example, you might wish to know how the combined total salary of all employees whose employee_id is less than 45.

SELECT sum(salary) AS "Total Salary"
FROM employees
WHERE employee_id  45;

In this sum function example, we've aliased the sum(salary) expression as "Total Salary".

Example - Using DISTINCT

You can use the DISTINCT clause within the sum function. For example, the SQL statement below returns the combined total salary of unique salary values where the salary is above $25,000 / year.

SELECT sum(DISTINCT salary) AS "Total Salary"
FROM employees
WHERE salary > 25000;

If there were two salaries of $60,000/year, only one of these values would be used in the sum function.

Example - Using Formula

The expression contained within the sum function does not need to be a single field. You could also use a formula. For example, you might want to calculate the total commission.

SELECT sum(salary / 12) AS "Total monthly salary"
FROM employees;

Example - Using GROUP BY

In some cases, you will be required to use the GROUP BY clause with the sum function.

For example, you could also use the sum function to return the city and the total salaries (in the city) where the state is 'CA'.

SELECT city, sum(salary) AS "Total Salary"
FROM employees
WHERE state = 'CA'
GROUP BY city;

Because you have listed one column in your SELECT statement that is not encapsulated in the sum function, you must use a GROUP BY clause. The city field must, therefore, be listed in the GROUP BY section.