PostgreSQL MAX() Function

The PostgreSQL MAX() function returns the maximum value of an expression or specified column of a given table.

Syntax

The syntax for using MAX() function is given below:

SELECT MAX(column_name) 
FROM table_name
WHERE condition(s);

The PostgreSQL GROUP BY clause is used to arrange result table into identical groups when one or more columns are used. Please note that it is must to include those column names in a GROUP BY clause which are not encapsulated within the MAX() function. See the syntax below:

SELECT column1, column2, ...
       MAX(column_name) 
FROM table_name
WHERE condition(s)
GROUP BY column1, column2, ...;

Parameters

Return Value

Returns the maximum value of a given expression.

Example - With Single Column

Consider a database table called Employee with the following records:

To fetch maximum Salary of the employees present in the Employee table, the query will be:

SELECT MAX(Salary) AS MaxSalary 
FROM Employee;

This result of the above query will be:

Example - Using GROUP BY

Consider the above discussed database named Employee which contains the following records:

To fetch the maximum Salary of the employees group by their age, where age is greater than 27, the following query can be used:

SELECT Age, MAX(Salary) AS MaxSalary 
FROM Employee
WHERE Age > 27
GROUP BY Age;

This result of the above code will be: