Add a unique constraint on the email column while creating the users table in PostgreSQL.

Question

Consider the SQL statement below for creating a table with a constraint in PostgreSQL. Which option correctly adds a unique constraint on the email column while creating the users table?
```
CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(255)
);
```

Accepted Answer

CREATE TABLE users (id SERIAL PRIMARY KEY, name VARCHAR(100), email VARCHAR(255), CONSTRAINT email_unique UNIQUE(email));

Answer

CREATE TABLE users (id SERIAL PRIMARY KEY, name VARCHAR(100), UNIQUE(email VARCHAR(255)));

Answer

CREATE TABLE users (id SERIAL PRIMARY KEY, name VARCHAR(100), email UNIQUE VARCHAR(255));

Answer

CREATE TABLE users (id SERIAL PRIMARY KEY, name VARCHAR(100), email VARCHAR(255) UNIQUE KEY);

Question from the PostgreSQL test

Add a unique constraint on the email column while creating the users table in PostgreSQL.