com.packageA.Class packageAClass = new com.packageA.Class();
com.packageB.Class packageBClass = new com.packageB.Class();

rule Class2Table
  transform c : OO!Class 
  to t : DB!Table, pk : DB!Column {
  
   if (c.`extends`.isDefined()){
   
    var childFkCol : new DB!Column;
    var parentFkCol : DB!Column;

  }

}

rule SingleValuedAttribute2Column
  transform a : OO!Attribute
  to c : DB!Column {
....
}