Hour 14. Using Subqueries to Define Unknown Data
What You’ll Learn in This Hour:
• What a subquery is
• The justifications of using subqueries
• Examples of subqueries in regular database queries
• Using subqueries with data manipulation commands
• Embedded subqueries
In this hour, you are introduced to the concept of subqueries. Using subqueries enables you to more easily preform complex queries.
What Is a Subquery?
A subquery, also known as a nested query, is a query embedded within the
WHERE clause of another query to further restrict data returned by the query. A subquery returns data that is used in the main query as a condition to further restrict the data to be retrieved. Subqueries are employed with the
UPDATE, and ...