UNION

Combine the results of two queries.

UNION

UNION combines two SELECT results and removes duplicate rows.

SELECT name FROM customers
UNION
SELECT name FROM suppliers;

This query makes one list of customer and supplier names.

name is selected from customers.

UNION — details

Each SELECT in a UNION must have the same number of columns with compatible types.

For example, to combine customer and supplier names into one list you join two SELECT name queries with UNION; column names come from the first query.

Exercise UNION

Combine customer and supplier names with UNION.

Show example solution

SELECT name FROM customers
UNION
SELECT name FROM suppliers;

Test yourself

What does UNION do with duplicates?
- Raises an error
- Removes them
- Keeps them
- Counts
Show answer

Removes them — UNION removes duplicate rows.

Add UNION

SELECT name FROM customers
____
SELECT name FROM suppliers;

Show answer

SELECT name FROM customers
UNION
SELECT name FROM suppliers;

UNION: match the terms

UNION

combine
INTERSECT

intersection
EXCEPT

difference
UNION ALL

with duplicates

Next lesson: UNION ALL

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