PostgreSQL GREATEST() Function

The PostgreSQL GREATEST() function returns the greatest value in a list of expressions. The expressions must all be convertible to a common data type, which will be the type of the result. NULL values in the list are ignored. The result will be NULL only if all the expressions evaluate to NULL.

Syntax

GREATEST(expr1, expr2, ... expr_n)

Parameters

Return Value

Returns the greatest value in a list of expressions.

Example 1:

The example below shows the usage of GREATEST() function.

SELECT GREATEST(20, 30, 60, 10);
Result: 60

SELECT GREATEST('20', '30', '60', '10');
Result: '60'

SELECT GREATEST('D', 'G', 'X', 'A');
Result: 'X'

SELECT GREATEST('Alpha', 'Beta', 'Delta', 'Gamma');
Result: 'Gamma'

SELECT GREATEST('Alpha1', 'Alpha2', 'Alpha3', 'Alpha4');
Result: 'Alpha4'

SELECT GREATEST(20, 30, 60, 10, NULL);
Result: 60

Example 2:

Consider a database table called Sample with the following records:

To get the greatest value, when values of column x, column y and column z are compared, the following query can be used:

SELECT *, GREATEST(x, y, z) AS GREATEST_Value FROM Sample;

This will produce the result as shown below: