Learn Standard SQL Functions | Interactive Course

18/37 AVG and GROUP BY

1. Introduction

2. Table translator

3. Table project

4. Count all rows

5. COUNT with column

6. COUNT(*) vs. COUNT(column) – practice

7. COUNT with expression

8. COUNT DISTINCT

9. COUNT DISTINCT with expression

10. COUNT and GROUP BY

11. COUNT and GROUP BY – additional practice

12. COUNT DISTINCT and GROUP BY

13. COUNT DISTINCT with expression and GROUP BY

14. Common mistake: COUNT(*) and LEFT JOIN

15. COUNT – additional exercise 1

16. COUNT – additional exercise 2

17. Function AVG

18. AVG and GROUP BY

19. AVG and NULLs

20. AVG and NULLs only

21. AVG with COALESCE

22. COALESCE with AVG

23. AVG and DISTINCT

24. ROUND and AVG

25. AVG – additional exercise

26. Function SUM

27. SUM with NULLs only

28. SUM and COALESCE

29. SUM and DISTINCT

30. MAX and MIN

31. SUM, MAX and MIN – exercise

Correct! Of course, we can use AVG with GROUP BY, just as we used COUNT:

SELECT
  client_id,
  AVG(price)
FROM project
GROUP BY client_id;

The above query will find the average price each customer paid for their projects.

Show each translator's ID together with the average number of words they had to translate in all their projects (as average). Exclude project with ID 6 – it was cancelled.

Use the inequality sign != to exclude project with ID 6.

Instruction

Exercise

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Standard SQL Functions

Instruction

Exercise

Stuck? Here's a hint!

Need assistance?