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

Correct Answer: 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