HAVING Clause in SQL Server GROUP BY

What is the HAVING Clause?

The HAVING clause is used to specify conditions on groups created by the GROUP BY clause.

It filters groups based on aggregate functions like COUNT, SUM, AVG, MAX, and MIN.

Without HAVING, you cannot filter groups by aggregated values.

• Filters grouped rows after aggregation.
• Works only with GROUP BY or aggregate queries.
• Cannot be used without GROUP BY unless aggregate functions are present.

Syntax of HAVING Clause

The basic syntax for using HAVING with GROUP BY is as follows:

• SELECT column1, aggregate_function(column2)
• FROM table_name
• GROUP BY column1
• HAVING aggregate_function(column2) condition;

Difference Between WHERE and HAVING

WHERE filters rows before grouping, while HAVING filters groups after aggregation.

You cannot use aggregate functions in WHERE, but HAVING allows conditions on aggregates.

• WHERE filters individual rows.
• HAVING filters grouped results.
• Use WHERE for row-level filtering, HAVING for group-level filtering.

Examples Using HAVING Clause

Let's explore practical examples to understand HAVING usage.