SQLiteSQLite SQLITE_CONSTRAINT
SQLite: UNIQUE Constraint Failed
SQLite raises a UNIQUE constraint failed error when an INSERT or UPDATE attempts to write a duplicate value into a column or combination of columns with a UNIQUE or PRIMARY KEY constraint.
Example Query
INSERT INTO users (id, email) VALUES (1, 'a@example.com'); -- Fails if id=1 or email='a@example.com' already exists
Common Causes
- 1Inserting a row with a primary key that already exists
- 2Duplicate values in a UNIQUE column
- 3Re-running a seed script without clearing the table
How to Fix It
Use INSERT OR IGNORE to skip duplicates, or INSERT OR REPLACE to overwrite them. Check for existence before inserting. Use autoincrement primary keys to avoid manual ID management.
Need a reliable database?
Try Supabase — free PostgreSQL with a generous free tier. No credit card required.
Got a query causing this error?
Paste it into SQLbuddy and get an instant plain-English explanation with optimization tips.
Analyze My Query →