Mapping Specialization/Generalization,”SUPERTYPE(CommonIdent, CommonAttr1, CommonAttr2)SUBTYPE1(CommonIdent, UniqueAttr1)SUBTYPE2(CommonIdent, UniqueAttr2, UniqueAttr3)As an alternative mapping for total specialization with disjoint relations, you can may consider dropping the supertype and creating tables for each subtype:SUBTYPE1(CommonIdent, CommonAttr1, CommonAttr2, UniqueAttr1)SUBTYPE2(CommonIdent, CommonAttr1, CommonAttr2, UniqueAttr2, UniqueAttr3)SUBTYPE3(CommonIdent, CommonAttr1, CommonAttr2
UniqueAttr4)note: commonattr1 is primary in all and same ID can appear in multiple tables”