Free SQL Subqueries Tutorial

Subqueries are extremely useful, particularly for web-based database applications where you need to take two queries and manually put them together to reach a desired result — subqueries allow SQL to do all of the heavy lifting! Subqueries can also be used in many cases to replace a self-join (or vice-versa). A SQL join is usually quicker but, as we’ve discussed many times before, there is usually more than one way to perform any given SQL task. A query in a query?The subquery is fa 
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