SQL Foreign Key
6.Which keyword is used to enforce foreign key relationship?
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A. FOREIGN JOIN
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B. REFERENCE
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C. REFERENCES
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D. RELATED TO
REFERENCES
REFERENCES
7.Which of these can occur if foreign key is violated?
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A. Row is inserted
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B. Silent success
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C. Error thrown
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D. NULL inserted
Error thrown
Error thrown
8.What does ON DELETE CASCADE do?
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A. Deletes child rows when parent is deleted
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B. Deletes parent rows when child is deleted
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C. Deletes all records
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D. Ignores delete
Deletes child rows when parent is deleted
Deletes child rows when parent is deleted
9.Can FOREIGN KEY column have NULL values?
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A. Yes
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B. No
Yes
Yes
10.What does this line mean?
FOREIGN KEY (dept_id) REFERENCES department(id)
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A. dept_id is a primary key
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B. dept_id links to id in department
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C. id is copied into dept_id
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D. It’s a default column
dept_id links to id in department
dept_id links to id in department