[Solved] Given the table products with a unique index on s... Given the table products with a unique index on sku, what happens when you run this SQL?INSERT INTO products (sku, name) VALUES ('A123', 'Item1'); | SQL

SQL - Indexes and Query Performance

Given the table products with a unique index on sku, what happens when you run this SQL?

INSERT INTO products (sku, name) VALUES ('A123', 'Item1');
INSERT INTO products (sku, name) VALUES ('A123', 'Item2');

ASecond insert fails with a duplicate key error

BBoth inserts fail due to unique index

CFirst insert fails, second succeeds

DBoth rows insert successfully

Step-by-Step Solution

Solution:

Step 1: Understand unique index effect on inserts
The unique index on sku means no two rows can have the same sku value.
Step 2: Analyze the insert statements
The first insert adds 'A123' successfully. The second tries to insert 'A123' again, violating uniqueness, causing an error.
Final Answer:
Second insert fails with a duplicate key error -> Option A
Quick Check:
Duplicate insert = error [OK]

Quick Trick: Duplicate value in UNIQUE column causes insert error [OK]

Common Mistakes:

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