[Solved] Which of the following statements correctly adds a UNIQUE constraint when creating a new table? — Ans: CREATE TABLE users (id INT, email VARCHAR(100) UNIQUE); | SQL

SQL - Table Constraints

Which of the following statements correctly adds a UNIQUE constraint when creating a new table?

ACREATE TABLE users (id INT, email VARCHAR(100) NOT NULL);

BCREATE TABLE users (id INT, email VARCHAR(100) PRIMARY KEY);

CCREATE TABLE users (id INT, email VARCHAR(100) UNIQUE);

DCREATE TABLE users (id INT, email VARCHAR(100) FOREIGN KEY);

Step-by-Step Solution

Solution:

Step 1: Review syntax for UNIQUE constraint in CREATE TABLE
Adding UNIQUE after the column type enforces uniqueness on that column.
Step 2: Eliminate other options
PRIMARY KEY also enforces uniqueness but is different; NOT NULL only disallows NULLs; FOREIGN KEY is unrelated.
Final Answer:
CREATE TABLE users (id INT, email VARCHAR(100) UNIQUE); -> Option C
Quick Check:
UNIQUE syntax in column definition = correct [OK]

Quick Trick: Add UNIQUE right after column type to enforce uniqueness [OK]

Common Mistakes:

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Which of the following statements correctly adds a UNIQUE constraint when creating a new table?