The Referential integrity constraint is specified between
two relations and is used to maintain the consistency among
tuples in the two relations
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– The referential integrity constraint states that a tuple(row) in
one relation that refers to another relation must refer to
an existing tuple(row) in that relation
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For Example , If we want to delete a mother tuple(row) before deleting
child tuple(row) which depend on mother current child primary key .
Then it will show the Referntial integrity constraint error.