> [!tldr] > A **constraint** can be applied when creating a table. #### Constraint for primary key ``` CONSTRAINT constraint_name PRIMARY KEY (primary_key_column_name) ``` Example: ``` CONSTRAINT pk_people PRIMARY KEY (person_id) ``` #### Constraint for foreign key ``` CONSTRAINT constraint_name FOREIGN KEY (foreign_key_column_name) REFERENCES another_table (some_key_column) ``` Example: ``` CONSTRAINT fk_office_person_id FOREIGN KEY (person_id) REFERENCES office (office_id) ```