Tutorials › PostgreSQL Essentials › CREATE TABLE

CREATE TABLE

6 min read Quiz at the end

Create tables with column types and constraints like NOT NULL, UNIQUE, CHECK, and DEFAULT. Use GENERATED ALWAYS AS IDENTITY for auto-incrementing primary keys. Constraints enforce data rules at the database level.

Creating Tables

CREATE TABLE users (
  id        SERIAL PRIMARY KEY,
  name      VARCHAR(100) NOT NULL,
  email     TEXT UNIQUE NOT NULL,
  age       INTEGER CHECK (age >= 0),
  created   TIMESTAMP DEFAULT NOW()
);

Key constraints

PRIMARY KEY — unique identifier
NOT NULL — value required
UNIQUE — no duplicates
CHECK — custom validation
DEFAULT — auto value

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Topic Quiz · 5 questions

Test your understanding before moving on

1. Which constraint ensures no duplicate values?

💡 The UNIQUE constraint ensures all values in a column are distinct.

2. What does NOT NULL mean?

💡 NOT NULL means a value must be provided — NULL is not allowed.

3. Which constraint links two tables?

💡 A FOREIGN KEY references the primary key of another table.

4. What does CHECK do?

💡 CHECK enforces a custom validation condition on column values.

5. What does DEFAULT do?

💡 DEFAULT sets an automatic value when no value is inserted.

Quick Access

CREATE TABLE

Creating Tables

Key constraints

Test your understanding before moving on