SQL MAX() function

Last update on September 07 2023 07:30:28 (UTC/GMT +8 hours)

MAX() function

The aggregate function SQL MAX() is used to find the maximum value or highest value of a certain column or expression. This function is useful to determine the largest of all selected values of a column.

Syntax:

MAX ([ALL | DISTINCT] expression )

DB2 and Oracle Syntax:

MAX ([ALL | DISTINCT] expression ) OVER (window_clause)

Parameters:

Name	Description
ALL	Applies to all values.
DISTINCT	Consider each unique value. DISTINCT is not meaningful with MAX function.
expression	Expression made up of a single constant, variable, scalar function, or column name or any combination of arithmetic, bitwise, and string operators. MAX can be used with numeric, character, and datetime columns, but not with bit columns. Aggregate functions and subqueries are not permitted.

DBMS Support: COUNT() function

DBMS	Command
MySQL	Supported
PostgreSQL	Supported
SQL Server	Supported
Oracle	Supported

Syntax diagram - MAX() function

Example:

To get maximum 'ord_amout' from the 'orders' table, the following SQL statement can be used :

Sample table: orders

SELECT MAX (ord_amount)
FROM orders;

Relational Algebra Expression:

Relational Algebra Tree:

Output:

MAX(ORD_AMOUNT)
---------------
           4500

Pictorial Presentation:

SQL MAX() with addition of two columns

To get the maximum value of (opening_amt+receive_amt) from the customer table, the following SQL statement can be used :

Sample table: customer

SELECT MAX (opening_amt+receive_amt) 
FROM customer;

Relational Algebra Expression:

Relational Algebra Tree:

Output:

MAX(OPENING_AMT+RECEIVE_AMT)
----------------------------
                       19000

Note: Outputs of the said SQL statement shown here is taken by using Oracle Database 10g Express Edition

Here is a slide presentation of all aggregate functions.

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