Another SQL set operation, UNION ALL, is almost the same as UNION, but will not eliminate duplicates.
As with the other topics we’ve covered in this series, there is a wealth of information available on the topic of sets, databases, and SQL.
Some good reads about Set Operations include:
Union and Union All:
See all of the SQL used in Querying Relational Databases in the Querying Relational Databases Cheat Sheet.
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