What is a Subquery? A subquery is simply a select statement written inside another select statement. The inside query runs first and results is handed to outer query for use. Example: Explanation i)First it finds the Average Score ii)It finds all rows which are greater than the Average score. Types of Subqueries 1. Scalar Subquery It returns a single value It will output the single highest score recorded. 2. List Subquery It returns a column of values. e.g List of IDs. It is used with IN or NOT IN. It will output the names of members who scored above 80. 3. Subquery IN FROM You can place subquery in the from clause. SQL treats subquery as if it were a temporary table. When to use Subqueries When logic is simple and needs no re-use when you want to filter data based on aggregated values when you need a quick, one time calculation CTEs or Common Table Expressions It is a temporary result set defined at the start of a query using the WITH keyword. It acts like a named query you can reference later.…