create table AA ( cAaID c(6) primary key, ...useful data about AA records.. ) create table VG ( cVgID c(6) primary key, cVgDsc c(40) ) create table AG ( cAgID c(6) primary key, cAgVgID c(6) references VG, cAgAaID c(6) references AA ) create table BB ( cBbID c(6) primary key ) create table BG ( cBgID c(6) primary key, cBgVgID c(6) references VG, cBgAaID c(6) references BB )