Wednesday, November 6, 2013

Do Subqueries Add Expressive Power to SQL Queries?

Patrick87 (via @CompSciFact):

Are there any known forms to which all SQL queries can be reduced? Do any of these eliminate subqueries? Or are there some instances where no equivalent, subquery-free query exists?

The answer is yes for SQL, but for NSPredicate subqueries do add expressiveness because the base queries are more limited.

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