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

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15/27 Uniqueness with multi-column primary keys – continued

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

Nice! We have successfully inserted the new row since the combination title + year was unique.

But what happens if the combination of values is not unique? Let's find out.

Run the template query, that tries to add a new movie where the combination title + year is the same as the combo in another row.

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