Recuperar el valor de Returning

[Combat-F2D]

procedure insert_con_returning(query:TMDOQuery);

var tVardelTipodelField: tipo;

begin
with query do
begin
Close;
sql.Clear;
SQL.Add('Insert into familias (cod_familia, fecha_ingreso_familia, estado_familia) ');
sql.Add('Select gen_id(Select ibe$log, 1), current_timestamp, ');
sql.Add('''A'' From rdb$database ');
sql.Add('returning cod_familia ');
try
ExecSQL;

      tVardelTipodelField := FieldbyName('cod_familia').as....;

except
raise;
end;
end;
end;