SUBQUERIES SQL

-These are the SQL Statements which are embedded inside another SQL Statements.

Example:-
--1)To find the details of the person who earns the maximum salary or 3rd highest salary we have to use the subquery.

1. Subquery is always written in parentheses.
2.Subquery evaluates a particular data which can then be used as the input to the main query.
3.Subquery evaluates first.
4. Subqueries can be nested.

---Types of Subqueries:--

--1)Single row Subqueries

--2)Multiple row Subqueries.

---3)Subqueries using the exists operator:

---Single row Subqueries:--

---Only 1 row is returned by the subquery.

--Multiple row Subqueries:-

--More than 1 row is returned by the subquery.

--An error message will be generated which can then be resolved using the in operator.

--Exists operator subquery:-

---The subquery will just  return true or false

--values to the main query on the basis of which

--the main query will execute.