KwickClips Databases and SQL · 38 sec · free
Why did all marks become 80?
Short answer. The UPDATE had no WHERE.
What should WHERE use to hit one row?
The primary key.
Remember
| SET says what to change |
| WHERE says which rows |
You changed one student's marks. Why did everyone get eighty? You forgot where. Without it, update changes every row. Where roll equals two changes only Aman. Set says what changes. Where says which rows.
This clip is from the full lesson: SQL Data Manipulation: INSERT, UPDATE and DELETE — 5 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: CBSE Class 9 Computer Applications (165), CBSE Class 9 Computer Applications (165), CBSE Class 9 Computer Applications (165), CBSE Class 9 Information Technology (402)
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