lib/Data/Query/Renderer/SQL/Slice/RowNum.pm

   1 package Data::Query::Renderer::SQL::Slice::RowNum;
   2
   3 use Data::Query::ExprHelpers;
   4 use Moo::Role;
   5
   6 with 'Data::Query::Renderer::SQL::Slice::SubqueryRemap';
   7
   8 sub _render_slice {
   9   my ($self, $dq) = @_;
  10   die "Slice's inner is not a Select"
  11     unless is_Select my $orig_select = $dq->{from};
  12   my %remapped = $self->_subquery_remap_select($orig_select);
  13   my $inside_select = Alias(
  14     $remapped{default_inside_alias},
  15     Select($remapped{inside_select_list}, $orig_select->{from}),
  16   );
  17   unless ($dq->{offset}) {
  18     return $self->render(
  19       Select(
  20         $remapped{outside_select_list},
  21         Where(
  22           Operator(
  23             { 'SQL.Naive' => '<=' },
  24             [
  25               Literal(SQL => 'ROWNUM'),
  26               $dq->{limit}
  27             ]
  28           ),
  29           $inside_select
  30         )
  31       )
  32     );
  33   }
  34   my ($limit_plus_offset, $offset_plus) = (
  35     { %{$dq->{limit}}, value => $dq->{limit}{value}+$dq->{offset}{value} },
  36     { %{$dq->{limit}}, value => $dq->{offset}{value}+1 }
  37   );
  38
  39   my $rownum_name = 'rownum__index';
  40
  41   if ($dq->{order_is_stable}) {
  42     return $self->render(
  43       Select(
  44         $remapped{outside_select_list},
  45         Where(
  46           Operator(
  47             { 'SQL.Naive' => '>=' },
  48             [ Identifier($rownum_name), $offset_plus ]
  49           ),
  50           Alias(
  51             $remapped{default_inside_alias},
  52             Select(
  53               [ @{$remapped{outside_select_list}},
  54                 Alias($rownum_name, Literal(SQL => 'ROWNUM')) ],
  55               Where(
  56                 Operator(
  57                   { 'SQL.Naive' => '<=' },
  58                   [ Literal(SQL => 'ROWNUM'), $limit_plus_offset ]
  59                 ),
  60                 $inside_select,
  61               )
  62             )
  63           )
  64         )
  65       )
  66     );
  67   } else {
  68     return $self->render(
  69       Select(
  70         $remapped{outside_select_list},
  71         Where(
  72           Operator(
  73             { 'SQL.Naive' => 'BETWEEN' },
  74             [ Identifier($rownum_name), $offset_plus, $limit_plus_offset ]
  75           ),
  76           Alias(
  77             $remapped{default_inside_alias},
  78             Select(
  79               [ @{$remapped{outside_select_list}},
  80                 Alias($rownum_name, Literal(SQL => 'ROWNUM')) ],
  81               $inside_select
  82             )
  83           )
  84         )
  85       )
  86     );
  87   }
  88 }
  89
  90 1;