SQL Practice: Level 19

Hands-On SQL Training

I think it's high time to put everything you've learned in this level into practice - time for a real SQL battle! This time you get to be the captain in naval battles on an ancient land. We believe in you, young SQL Jedi. Build the right queries, and the secrets of ancient battles will be revealed to you.

This assignment works the same way: write queries for the tasks and send them to us through the form. You can see the correct output in the test terminal when you select the task number. Your mission is to get the same result using the power of SQL!

Database Schema "Computer Firm"

Cool schema! Besides the structure of the database, you can see the relationships and the key fields that link the tables

1. Computers. Find the model numbers and prices of all products (of any type) made by maker B (Latin letter).

2. Find the maker that produces PCs but not laptops.

3. Find the makers of PCs with a processor of at least 450 MHz. Output: Maker

4. Find the average speed of laptops priced above $1000

5. Find the average speed of PCs made by maker A

6. Find pairs of PC models that have the same speed and RAM. Each pair should appear in the result only once, i.e. (i,j) but not (j,i). Output order: the model with the higher number, the model with the lower number, speed, and RAM

7. Find the laptop models whose speed is lower than the speed of any of the PCs.

Output: type, model, speed

8. Find the makers of the cheapest color printers. Output: maker, price

9. For each maker that has models in the Laptop table, find the average screen size of the laptops it produces.

Output: maker, average screen size

10. Find the makers that produce both PCs

with a speed of at least 750 MHz and laptops with a speed of at least 750 MHz.

Output: Maker