PostgreSQL LEAST Function

Summary: in this tutorial, you’ll learn how to use the PostgreSQL LEAST function to select the lowest value from a list of values.

Getting Started with the PostgreSQL LEAST function #

The LEAST function accepts a list of values and returns the smallest value.

Here’s the syntax of the LEAST function:

LEAST (expression1, expression2, ....)Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql)

The LEAST function ignores NULL. It’ll return NULL if all expressions evaluate to NULL.

In SQL standard, the LEAST function returns NULL if any expression evaluates to NULL. Some database systems behave this way such as MySQL.

Basic PostgreSQL LEAST function examples #

The following example uses the LEAST function to return the lowest number in the list:

SELECT LEAST(1,2,3) lowest;Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql)

Try it

Output:

 lowest
---------
       1

The LEAST function returns 3 because it is the lowest number in the list.

The following example uses the LEAST function to return the smallest string in alphabetical order:

SELECT LEAST('A','B','C') smallest;Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql)

Try it

Output:

 smallest
---------
 A

The LEAST function returns the letter 'A' is the smallest value alphabetically among 'A', 'B', and 'C'.

The following example uses the LEAST function to compare two boolean values:

SELECT LEAST(true, false) smallest;Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql)

Try it

Output:

 smallest
---------
 f

When comparing true and false, true is greater than false so the LEAST function returns false.

The following example uses the LEAST function to find the earliest date in a list of date literals:

SELECT
  LEAST ('2025-01-01', '2025-02-01', '2025-03-01', NULL) earliest;Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql)

Try it

Output:

   earliest
------------
 2025-01-01

In this example, the LEAST function returns the January 1, 2025 because it the earliest dates among January 1, 2025, February 1 2025, and March 1, 2025

Notice that the LEAST function ignores NULL in the list.

Summary #

Use the LEAST function to return the smallest value in a list of values.
The LEAST function ignores NULL.

Quiz #

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