What are the properties and different Types of Sub-Queries?

Properties of Sub-Query

• A sub-query must be enclosed in the parenthesis.


• A sub-query must be put in the right hand of the comparison operator, and A sub-query cannot contain an ORDER-BY clause.


• A query can contain more than one sub-query.

Types of Sub-query

• Single-row sub-query, where the sub-query returns only one row.


• Multiple-row sub-query, where the sub-query returns multiple rows,, and


• Multiple column sub-query, where the sub-query returns multiple columns