SQL Server Aggregate Functions: MAX

What is the MAX Function?

The MAX function returns the maximum value from a set of values in a column or expression.

It can be used with numeric, date/time, and string data types to find the highest value.

MAX ignores NULL values when calculating the maximum.

• Syntax: MAX(column_name)
• Returns the largest value in the column.
• NULL values are excluded from the calculation.

Syntax and Basic Usage

The basic syntax for the MAX function is straightforward.

You specify the column or expression you want to evaluate inside the parentheses.

• SELECT MAX(column_name) FROM table_name;
• You can also use MAX with expressions, e.g., MAX(price * quantity).

Using MAX with GROUP BY

MAX is often used with the GROUP BY clause to find the maximum value per group.

This is useful for summarizing data by categories or other grouping criteria.

• GROUP BY groups rows sharing the same values in specified columns.
• MAX returns the highest value within each group.

Handling NULL Values

MAX automatically ignores NULL values in the column when determining the maximum.

If all values are NULL, MAX returns NULL.

• No need to filter out NULLs explicitly for MAX.
• Be aware of NULLs when interpreting results.