Foreign Key Violations

Missing corresponding rows in another table

1. Similar to finding rows that fall through a join
2. Master-detail deletion

Four commonly used methods:

1. ROWID IS NULL with outer join

    where b.xid(+) = a.xid and b.rowid is null

2. Correlated subquery predicate to NOT EXISTS

    where not exists
    (select 'x' from b where b.xid = a.xid)
   

3. Non-correlated subquery

    where a.xid not in (select b.xid from b)

4. MINUS with compound query

    select a.xid from a
    minus
    select b.xid from b