MAX [Aggregate]

Returns the greatest value of an expression over a group of rows. The return value has the same type as the expression data type.

The MAX analytic function function differs from the aggregate function, in that it returns the maximum value of an expression over a group of rows within a window.

Aggregate functions MIN and MAX can operate with Boolean values. MAX can act upon a Boolean data type or a value that can be implicitly converted to a Boolean. If at least one input value is true, MAX returns t (true). Otherwise, it returns f (false). In the same scenario, MIN returns t (true) if all input values are true. Otherwise it returns f.

Behavior Type

Immutable

Syntax

MAX ( expression )

Parameters

Examples

The following query returns the largest value in column sales_dollar_amount.

=> SELECT MAX(sales_dollar_amount) AS highest_sale FROM store.store_sales_fact;
 highest_sale 
--------------
          600
(1 row)

The following example shows you the difference between the MIN and MAX aggregate functions when you use them with a Boolean value. The sample creates a table, adds two rows of data, and shows sample output for MIN and MAX.

=> CREATE TABLE min_max_functions (torf BOOL);

=> INSERT INTO min_max_functions VALUES (1);
=> INSERT INTO min_max_functions VALUES (0);

=> SELECT * FROM min_max_functions;
  torf
------
 t
 f
(2 rows)

=> SELECT min(torf) FROM min_max_functions;
 min
-----
 f
(1 row)

=> SELECT max(torf) FROM min_max_functions;
 max
-----
 t
(1 row)