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A subquery is a SELECT statement nested inside another statement such as SELECT, INSERT, UPDATE, or DELETE. Typically, you can use a subquery anywhere that you use an expression. Consider this following subquery example that uses the products table from the sample database.
This Oracle tutorial explains how to use Oracle subqueries with syntax and examples. A subquery is a query within a query. In Oracle, you can create subqueries within your SQL statements.
Using Subqueries. A subquery answers multiple-part questions. For example, to determine who works in Taylor's department, you can first use a subquery to determine the department in which Taylor works. You can then answer the original question with the parent SELECT statement.
Module 1. Introduction. This tutorial shows you how to write subqueries. It uses the bricks and colours table. Run the queries below to see their contents: select * from bricks; select * from colours; Note: This tutorial makes heavy use of group by. If you want a refresher on this, check out module 7 of Databases for Developers: Foundations.
This chapter contains these sections: About Queries and Subqueries. Creating Simple Queries. Hierarchical Queries. The Set Operators. Sorting Query Results. Joins. Using Subqueries. Unnesting of Nested Subqueries.
This chapter describes SQL queries and subqueries. This chapter contains these sections: About Queries and Subqueries. Creating Simple Queries. Hierarchical Queries. The UNION [ALL], INTERSECT, MINUS Operators. Sorting Query Results. Joins. Using Subqueries.
The WITH clause, or subquery factoring clause, is part of the SQL-99 standard and was added into the Oracle SQL syntax in Oracle 9.2. The WITH clause may be processed as an inline view or resolved as a temporary table.
