1229. Composite index for common filter — Hospital — implementation variant 29

DBMS Published 30 Sept 2026 Updated 30 Sept 2026 0 Views Verified

In a Hospital application, implement this production problem: Create an index for queries filtering by customer and date. The API/service receives user input and must return or modify data safely. Give the SQL solution, explain why it works, and show how the same operation is called from the selected stack.

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Answer & Explanation

4 Answers

Verified

Option A

UPDATE the_table SET status='active';

Additional Explanation

Incorrect: it does not implement the stated business rule and may modify/fetch the wrong rows.

Verified Correct Answer

Option B

CREATE INDEX idx_orders_customer_date ON orders(customer_id,order_date);

Additional Explanation

Column order should reflect the common access pattern. Verify with EXPLAIN and account for write/storage overhead.

Verified

Option C

DELETE FROM the_table;

Additional Explanation

Incorrect: it does not implement the stated business rule and may modify/fetch the wrong rows.

Verified

Option D

SELECT * FROM the_table;

Additional Explanation

Incorrect: it does not implement the stated business rule and may modify/fetch the wrong rows.