What are some examples of SQL subqueries?

What are some examples of SQL subqueries?

SQL subqueries are queries nested inside another query. They can be used in SELECT, INSERT, UPDATE, or DELETE statements. For example, to find employees who earn more than the average salary, you could use a subquery like this:

SELECT * FROM employees WHERE salary > (SELECT AVG(salary) FROM employees);

Can you give me another example?

Sure! Here's another example: if you want to find customers who have placed orders, you can use a subquery like this:

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

What about using subqueries in the FROM clause?

Great question! You can use subqueries in the FROM clause to create a temporary table. For instance:

SELECT avg_salary FROM (SELECT AVG(salary) as avg_salary FROM employees) as avg_table;