SQL - Table Constraints
Why might a database designer choose
ON UPDATE CASCADE over ON UPDATE RESTRICT for a foreign key?Why might a database designer choose ON UPDATE CASCADE over ON UPDATE RESTRICT for a foreign key?
hard📝 Conceptual Q10 of 15
Step-by-Step Solution
Solution:
Step 1: Understand ON UPDATE CASCADE purpose
ON UPDATE CASCADE automatically updates child foreign keys when parent keys change.Step 2: Compare with ON UPDATE RESTRICT
ON UPDATE RESTRICT blocks parent key changes if children exist, preventing automatic sync.Final Answer:
To automatically keep child foreign keys in sync when parent keys change. -> Option BQuick Check:
ON UPDATE CASCADE syncs keys automatically [OK]
Quick Trick: CASCADE keeps keys synced automatically [OK]
Common Mistakes:
MISTAKES- Confusing CASCADE with RESTRICT
- Thinking CASCADE sets keys to NULL
- Assuming CASCADE improves performance
Master "Table Constraints" in SQL
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