Subqueries

Updated on 2022-11-18 GMT+08:00

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EXISTS

The EXISTS predicate determines whether to return any row.

SELECT name FROM nation WHERE EXISTS (SELECT * FROM region WHERE region.regionkey = nation.regionkey)

IN

It determines whether any value generated by a subquery is equal to a given expression. The IN result complies with the standard null rule. Only one column must be generated for a subquery.

SELECT name FROM nation WHERE regionkey IN (SELECT regionkey FROM region)

Parent topic: DQL Syntax

Previous topic: JOINS

Next topic: SELECT VIEW CONTENT

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