Database / SQLite Interview questions

What is a FOREIGN KEY in SQLite and how do you enable it?

A FOREIGN KEY constraint links a column in one table to a primary/unique key in another, ensuring referential integrity — you can't insert a row referencing a value that doesn't exist in the referenced table.

CREATE TABLE order_item (
    id INTEGER PRIMARY KEY,
    person_id INTEGER,
    FOREIGN KEY (person_id) REFERENCES person(id)
);

Notably, SQLite parses foreign key constraints but doesn't actually enforce them by default, for historical backward-compatibility reasons — you must explicitly turn enforcement on per connection with:

PRAGMA foreign_keys = ON;

This is a common surprise for developers coming from other databases where foreign keys are always enforced: forgetting this pragma means orphaned references can silently be inserted with no error at all.

Take quiz

Does SQLite enforce foreign key constraints by default? Yes, always, with no configuration needed

✗ Not quite. Try again.

No, you must explicitly enable enforcement per connection

✓ Correct! Well done.

Only on tables created after SQLite version 4

✗ Not quite. Try again.

What PRAGMA statement enables foreign key enforcement? PRAGMA foreign_keys = ON;

✓ Correct! Well done.

PRAGMA enforce_fk = TRUE;

✗ Not quite. Try again.

PRAGMA strict_mode = ON;

✗ Not quite. Try again.

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Database / SQLite Interview questions

What is a FOREIGN KEY in SQLite and how do you enable it?

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