Creating Tables in SQL | Online Course | Vertabelo Academy | Vertabelo Academy

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11/27 There can only be one...

1. Primary keys – Introduction

2. Primary keys – Syntax

3. Primary keys – Missing values

4. Primary keys – adding new values

5. Primary keys – duplicated values

6. Primary keys – NULL values

7. Primary keys – summary

8. Syntax revisited

9. Primary key data type

10. Primary keys in ERD

11. There can only be one...

12. ...but one there should be!

13. Multi-column primary keys – introduction

14. Uniqueness with multi-column primary keys

15. Uniqueness with multi-column primary keys – continued

16. Uniqueness with multi-column primary keys – summary

17. Multi-column primary keys in ERD

18. NOT NULL – Adding NULL values

19. NOT NULL – Creating tables

20. NULLable columns – default behavior

21. NULLable columns – default behavior continued

22. NULL columns

23. NULL or NOT NULL?

24. NULL in ERD diagrams

Great! Another important thing you should know about primary keys is that there can only be one primary key in a table. Let's delve into that.

Run the template query we created for you. As you might notice, we tried to set both the id and title columns as the primary keys. Do you think we will succeed?

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