SQL HAVING Clause: Main Tips
- The HAVING clause was added to SQL to add more functionality.
- WHERE keyword can not be used in union with other functions. That where HAVING clause come in handy.
- HAVING clause is often used with the COUNT function.
Syntax of SQL HAVING
SELECT name_of_column(s) FROM name_of_table WHERE condition GROUP BY name_of_column(s) HAVING condition ORDER BY name_of_column(s);
Theory is great, but we recommend digging deeper!
Let us say we have a database with information about pets.
Below is a "Pets" table:
SQL HAVING: Example
If we want to get the countries that have registered, for example, more than 2 pets, we would use HAVING clause.
The example below shows how to use it.
SELECT COUNT(ID), Country FROM Pets GROUP BY Country HAVING COUNT(ID) > 2;