What is subquery in SQL?

• • A subquery is a SQL query within a query.
Nested queries that provide data to the enclosing query.
  • Can be used in SELECT, INSERT, UPDATE, and DELETE statements
  • Subqueries can be used to retrieve data from multiple tables and can be used as an alternative to a join
  • Subqueries can also be used inside the WHERE or HAVING clause of the SELECT, INSERT, UPDATE, and DELETE statements

Syntax

SELECT Column names  FROM Table1  
WHERE  ColumnName [Comparison Operator] 
(SELECT  ColumnName
FROM Table2  WHERE  [Condition]);

[Comparison Operator] could be equality operators such as =, >, <, >=, <=. I  or LIKE operator

Recommended Articles:

• • SQL-Independent Sub Queries
  • SQL-Correlated Sub Queries
  • SQL Views
  • SQL Index
  • SQL Aggregate Function