Overview

UNION is used to combine the results of two or more SELECT statements. To work properly:

• Each select statement should return the same number of column
• Each column should have the same type
• Columns should be in the same order

Syntax

• UNION will return distinct results.
• UNION ALL will return all results including duplicates.

Examples

Let’s assume the following two tables listA

listB

liastA UNION listB

will return

liastA UNION ALL listB

will return