Question

When one SQL query is embedded in the WHERE clause of another SQL query, this is referred to as a __________.

a) subset
b) join
c) WHERE Query
d) subquery
e) set query

Answer 1

A subquery is when one SQL query is embedded in the WHERE clause of another SQL query. It allows you to use the result of one query as input for another query.

Step-by-step explanation:

When one SQL query is embedded in the WHERE clause of another SQL query, this is referred to as a subquery. A subquery allows you to use the result of one query as input for another query, providing a way to combine or filter data based on specific conditions.

For example, let's say you have a table of customers and a table of orders. You can use a subquery in the WHERE clause to retrieve all the customers who have placed orders:

SELECT * FROM customers WHERE customer_id IN (SELECT customer_id FROM orders);

This query will return all the customers whose customer IDs appear in the orders table.