1397
MySQLerrorddlhigh confidence
Incorrect foreign key definition for referenced table
Production Risk
Low — DDL fails; no data affected.
What this means
A FOREIGN KEY definition is syntactically incorrect, often due to SET DEFAULT reference action which InnoDB does not support.
Why it happens
- 1Using ON DELETE SET DEFAULT or ON UPDATE SET DEFAULT with InnoDB
- 2Incorrect number of columns in the FK vs the referenced index
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE t ADD CONSTRAINT fk FOREIGN KEY (col) REFERENCES ref(id) ON DELETE SET DEFAULT;
expected output
ERROR 1397 (HY000): Incorrect foreign key definition for 'fk': Key reference and table reference don't match
Fix
Use supported reference actions
Use supported reference actions
FOREIGN KEY (col) REFERENCES ref(id) ON DELETE SET NULL ON UPDATE CASCADE;
Why this works
InnoDB supports RESTRICT, CASCADE, SET NULL, and NO ACTION.
What not to do
✕
Sources
Official documentation ↗
MySQL 8.0 — 1397 ER_WRONG_FK_DEF
Content generated with AI assistance and reviewed for accuracy. Found an error? hello@errcodes.dev