SQL · Joins and set operations

union all

Stacks result sets and keeps duplicates. Usually faster than UNION.

sqlRunnable example sql course

Syntax

select … union all select …

Example

Open in the lab

SELECT 'HTML' AS title UNION ALL SELECT 'CSS' UNION ALL SELECT 'HTML';

Reference pages are the quick answer. The course explains the why, shows the full example and ends with a challenge.