Learn Standard SQL Functions | Interactive Course

4/37 Count all rows

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

Nice. Now that you know the tables, let's get down to work.

We'll start off with a function you already know: COUNT(*), which is used to count all the rows in the result set. Just like this:

SELECT COUNT(*)
FROM translator
WHERE start_date >= '2016-01-01';

The above query will provide the number of translators who started contracting with the translation agency on January 1, 2016 or later.

Now's your turn. Count the number of all the projects for the client with id 1. Name the column projects_no.

Use a WHERE clause to select the ID.

Instruction

Exercise

Stuck? Here's a hint!

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Standard SQL Functions

Instruction

Exercise

Stuck? Here's a hint!

Need assistance?