PostgreSQL – MAX() Function

PostgreSQL MAX() function is an aggregate function that returns the maximum value in a set of values.

Syntax: MAX(expression);

The MAX() function can be used with SELECT, WHERE and HAVING clause.

Now let’s look into some examples.For examples we will be using the sample database (ie, dvdrental).
Example 1:
The below query gets us the maximum amount paid by customers in the payment table:

SELECT MAX(amount)
FROM payment;

Output:

Example 2:
The following query gets the largest payment paid by each customer:

SELECT
    customer_id,
    MAX (amount)
FROM
    payment
GROUP BY
    customer_id;

Output: