SQL UNION and UNION ALL Keywords
UNION
The UNION command combines the result set of two or more SELECT statements (only
distinct values)
The following SQL statement returns the cities (only distinct values) from both the "Customers" and the "Suppliers" table:
UNION ALL
The UNION ALL command combines the result set of two or more SELECT statements (allows
duplicate values).
The following SQL statement returns the cities (duplicate values also) from both the "Customers" and the "Suppliers" table:
Example
SELECT City FROM Customers
UNION ALL
SELECT City FROM Suppliers
ORDER BY City;
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