my$synonym_sth=$self->core->dbc->prepare('DELETE external_synonym FROM external_synonym, xref WHERE external_synonym.xref_id = xref.xref_id AND xref.external_db_id = ?');
my$go_sth=$self->core->dbc->prepare('DELETE FROM go_xref');
my$go_sth=$self->core->dbc->prepare('DELETE FROM ontology_xref');
my$identity_sth=$self->core->dbc->prepare('DELETE identity_xref FROM identity_xref, object_xref, xref WHERE identity_xref.object_xref_id = object_xref.object_xref_id AND object_xref.xref_id = xref.xref_id AND xref.external_db_id = ?');
my$object_sth=$self->core->dbc->prepare('DELETE object_xref FROM object_xref, xref WHERE object_xref.xref_id = xref.xref_id AND xref.external_db_id = ?');
my$dependent_sth=$self->core->dbc->prepare('DELETE d FROM dependent_xref d, xref x WHERE d.dependent_xref_id = x.xref_id and x.external_db_id = ?');