Which statement correctly contrasts a PRIMARY KEY with a UNIQUE constraint?

Problem Statement

Explanation

A primary key uniquely identifies each row and forbids NULL by definition. It is also the default target for foreign keys. UNIQUE enforces distinct values but often allows one or more NULLs depending on the DBMS. You can define multiple UNIQUE constraints per table.

Code Solution

SolutionRead Only

CREATE TABLE users (
  id BIGINT PRIMARY KEY,
  email TEXT UNIQUE
);

Practice Sets

This question appears in the following practice sets:

Constraints, Keys & Data Integrity

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Which statement correctly contrasts a PRIMARY KEY with a UNIQUE constraint?

Problem Statement

Explanation

Code Solution

Practice Sets

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Master Interviews Anywhere, Anytime

Which statement correctly contrasts a PRIMARY KEY with a UNIQUE constraint?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime