my @data = $c->model("t1")->search(
    {
      "t2.num" => $a,
      "t3.name" => "xyz"
    }, 
    {
      prefetch => [qw/t2 t3/],
      select => [qw/xyz rst/], #xyz feild is comman in t2 and t3
      distinct => [qw/xyz rst/],
      order_by => [qw/rst/]
    }
  )->all;