GREATEST

Returns the largest value in a list of expressions of any data type. All data types in the list must be the same or compatible. A NULL value in any one of the expressions returns NULL. Results can vary, depending on the locale's collation setting.

Behavior type

Syntax

GREATEST ( { * | expression[,...] } )

Arguments

* | expression[,...]

The expressions to evaluate, one of the following:

• * (asterisk)

  Evaluates all columns in the queried table.

• expression

  An expression of any data type. Functions that are included in expression must be deterministic.

Examples

GREATEST returns 10 as the largest value in the list:

=> SELECT GREATEST(7,5,10);
 GREATEST
----------
       10
(1 row)

If you put quotes around the integer expressions, GREATEST compares the values as strings and returns '7' as the greatest value:

=> SELECT GREATEST('7', '5', '10');
 GREATEST
----------
 7
(1 row)

The next example returns FLOAT 1.5 as the greatest because the integer is implicitly cast to float:

=> SELECT GREATEST(1, 1.5);
 GREATEST
----------
      1.5
(1 row)

GREATEST queries all columns in a view based on the VMart table product_dimension, and returns the largest value in each row:

=> CREATE VIEW query1 AS SELECT shelf_width, shelf_height, shelf_depth FROM product_dimension;
CREATE VIEW
=> SELECT shelf_width, shelf_height, shelf_depth, greatest(*) FROM query1 WHERE shelf_width = 1;
 shelf_width | shelf_height | shelf_depth | greatest
-------------+--------------+-------------+----------
           1 |            3 |           1 |        3
           1 |            3 |           3 |        3
           1 |            5 |           4 |        5
           1 |            2 |           2 |        2
           1 |            1 |           3 |        3
           1 |            2 |           2 |        2
           1 |            2 |           3 |        3
           1 |            1 |           5 |        5
           1 |            1 |           4 |        4
           1 |            5 |           3 |        5
           1 |            4 |           2 |        4
           1 |            4 |           5 |        5
           1 |            5 |           3 |        5
           1 |            2 |           5 |        5
           1 |            4 |           2 |        4
           1 |            4 |           4 |        4
           1 |            1 |           2 |        2
           1 |            4 |           3 |        4
...

See also