UNION ALL

Keep duplicates when combining.

UNION ALL combines two SELECT results keeping duplicates. It is faster than UNION.

SELECT name FROM customers
UNION ALL
SELECT name FROM suppliers;

This query gives all names including duplicates.

name is selected from customers.

UNION ALL — details

UNION ALL is faster because it does not filter duplicates. Use it when duplicates matter.

For example, if the same person is both a customer and a supplier, UNION ALL shows them twice and UNION once.

Combine customer and supplier names with UNION ALL keeping duplicates.

Show example solution

SELECT name FROM customers
UNION ALL
SELECT name FROM suppliers;

Add ALL

SELECT name FROM customers
UNION ____
SELECT name FROM suppliers;

Show answer

SELECT name FROM customers
UNION ALL
SELECT name FROM suppliers;

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