KwickClips Databases and SQL · 39 sec · free
Why can a name not be a key?
Short answer. Because names can repeat.
Can a key value be empty?
No.
Add a unique column
| AdmNo | Name |
|---|---|
| 1001 | Riya Shah |
| 1003 | Riya Shah |
Remember
| Every row needs a unique value |
| That column is a key |
Two students share one name. Which one paid the fees? Names can repeat. So give each row a unique number, the admission number. Now each Riya is different. Every row needs a unique value. That column is called a key.
This clip is from the full lesson: Keys in a Database: Primary, Candidate, Alternate and Foreign Key — 6 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: CBSE Class 9 Information Technology (402), CBSE Class 10 Information Technology (402), CBSE Class 10 Information Technology (402), CBSE Class 12 Computer Science (083)
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