SQL UNION Operator

Last Updated : 24 Aug, 2026

The SQL UNION operator is used to combine the result sets of two or more SELECT queries into a single output. It removes duplicate rows and returns only unique records from all combined queries.

  • UNION ALL includes all rows, even duplicates.
  • Queries must have matching columns and data types.
  • Helpful for combining data from different sources.

Example: First, we create a demo SQL database and tables, on which we will use the UNION Operator command.

A
Table1
B-new
Table2

Query:

SELECT city FROM Table1
UNION
SELECT city FROM Table2;

Output:

Berlin

Syntax

SELECT column_name FROM table1
UNION
SELECT column_name FROM table2;

Examples

Let's look at an example of UNION operator in SQL to understand it better. Let's create two tables "emp1" and "emp2";

1
emp1
2
emp2

Example: SQL UNION Operator

 In this example, we find the countries (only unique values) from both the "emp1" and the "emp2" tables: 

Query:

SELECT country FROM emp1
UNION
SELECT country FROM emp2
ORDER BY country;

Output:

3

Note: The UNION operator combines the results of two queries and removes duplicate rows, while UNION ALL includes all rows from both queries without eliminating duplicates.

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