SQL Subqueries
6.Can subqueries be nested inside other subqueries?
-
A. No
-
B. Yes, up to one level
-
C. Yes, multiple levels
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D. Only in SELECT clause
Yes, multiple levels
Yes, multiple levels
7.What will be the output? - Assuming 'Sales' has department_id = 3
SELECT name
FROM employees
WHERE department_id = (
SELECT department_id
FROM departments
WHERE name = 'Sales'
);
-
A. All employees
-
B. Only employees from department 3
-
C. NULL
-
D. Error
Only employees from department 3
Only employees from department 3
8.What does this return?
SELECT name
FROM employees
WHERE salary > (
SELECT AVG(salary) FROM employees
);
-
A. Employees with below average salary
-
B. Employees with above average salary
-
C. All employees
-
D. NULL
Employees with above average salary
Employees with above average salary
9.What will happen?- If 3 customers are from the 'West' region
SELECT *
FROM orders
WHERE customer_id IN (
SELECT id FROM customers WHERE region = 'West'
);
-
A. 3 rows
-
B. All orders from those customers
-
C. Error
-
D. NULL
All orders from those customers
All orders from those customers
10.What’s the result?
SELECT name
FROM products
WHERE price = (
SELECT MAX(price) FROM products
);
-
A. Most expensive product(s)
-
B. Least expensive product
-
C. All products
-
D. NULL
Most expensive product(s)
Most expensive product(s)