[Solved] Given the table employees with a UNIQUE constraint on email, what happens if you run this query?INSERT INTO employees (id, email) VALUES (1, 'john@example.... | SQL

SQL - Table Constraints

Given the table employees with a UNIQUE constraint on email, what happens if you run this query?

INSERT INTO employees (id, email) VALUES (1, 'john@example.com');
INSERT INTO employees (id, email) VALUES (2, 'john@example.com');

AThe second insert fails due to UNIQUE constraint violation

BBoth inserts succeed, duplicates allowed

CThe first insert fails, second succeeds

DBoth inserts fail due to syntax error

Step-by-Step Solution

Solution:

Step 1: Understand UNIQUE constraint effect on inserts
The UNIQUE constraint prevents duplicate values in the constrained column.
Step 2: Analyze the inserts
The first insert adds 'john@example.com' successfully; the second insert tries to add the same email, causing a violation.
Final Answer:
The second insert fails due to UNIQUE constraint violation -> Option A
Quick Check:
UNIQUE constraint blocks duplicate inserts [OK]

Quick Trick: Duplicate values violate UNIQUE and cause insert failure [OK]

Common Mistakes:

MISTAKES

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