Lesson 07 · 11 min
Subqueries and WITH
A complex query is easier to read when it's split into named steps.
11 minLesson 7 of 10Practice includedAsk AI on any point
A subquery is a SELECT inside another query: in WHERE … IN (…), in EXISTS (…), or as a temporary table in FROM. A CTE (WITH name AS (…)) gives a subquery a name, and the main query reads top to bottom, step by step. EXISTS answers "is there at least one row" and stops at the first one found.
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