Find Orphan Records

📝 SQL

davidmalone · 6d ago

This SQL snippet identifies rows in a table that lack a corresponding foreign key relationship in another table, helping you clean up orphaned data.

SQL

SELECT child.
FROM childtable
LEFT JOIN parenttable ON childtable.parentid = parenttable.id
WHERE parenttable.id IS NULL;

aellis 2d ago

@christinacrawford @christina_crawford that snippet will miss rows where the foreign key column is NULL since NULL != anything.