How to Use Subqueries in SQL: A Beginner's Guide

A subquery in SQL is a query nested inside another query.

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A subquery is used to retrieve data that will be used in the main query

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A subquery is enclosed in parentheses and placed inside another SQL statement

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Subqueries can return a single value, a single row or multiple rows of data, depending on the specific query.

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Subqueries can return a single value, a single row or multiple rows of data, depending on the specific query.

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Subqueries can be used with different operators such as IN, NOT IN, EXISTS, NOT EXISTS, ANY and ALL.

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Subqueries can be used to simplify complex queries and improve performance by reducing the amount of data that needs to be processed.

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Excessive use of subqueries can also lead to slow query performance and increased complexity in database design

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Demystifying SQL Primary Keys and foreign keys: What They Are?

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