use List::Util 'first';
use namespace::clean;
-# FIXME
-# This dialect has not been ported to the subquery-realiasing code
-# that all other subquerying dialects are using. It is very possible
-# that this dialect is entirely unnecessary - it is currently only
-# used by ::Storage::DBI::ODBC::DB2_400_SQL which *should* be able to
-# just subclass ::Storage::DBI::DB2 and use the already rewritten
-# RowNumberOver. However nobody has access to this specific database
-# engine, thus keeping legacy code as-is
-# IF someone ever manages to test DB2-AS/400 with RNO, all the code
-# in this block should go on to meet its maker
-{
- sub _FetchFirst {
- my ( $self, $sql, $order, $rows, $offset ) = @_;
-
- my $last = $rows + $offset;
-
- my ( $order_by_up, $order_by_down ) = $self->_order_directions( $order );
-
- $sql = "
- SELECT * FROM (
- SELECT * FROM (
- $sql
- $order_by_up
- FETCH FIRST $last ROWS ONLY
- ) foo
- $order_by_down
- FETCH FIRST $rows ROWS ONLY
- ) bar
- $order_by_up
- ";
-
- return $sql;
- }
-
- sub _order_directions {
- my ( $self, $order ) = @_;
-
- return unless $order;
-
- my $ref = ref $order;
-
- my @order;
-
- CASE: {
- @order = @$order, last CASE if $ref eq 'ARRAY';
- @order = ( $order ), last CASE unless $ref;
- @order = ( $$order ), last CASE if $ref eq 'SCALAR';
- $self->throw_exception(__PACKAGE__ . ": Unsupported data struct $ref for ORDER BY");
- }
-
- my ( $order_by_up, $order_by_down );
-
- foreach my $spec ( @order )
- {
- my @spec = split ' ', $spec;
- $self->throw_exception("bad column order spec: $spec") if @spec > 2;
- push( @spec, 'ASC' ) unless @spec == 2;
- my ( $col, $up ) = @spec; # or maybe down
- $up = uc( $up );
- $self->throw_exception("bad direction: $up") unless $up =~ /^(?:ASC|DESC)$/;
- $order_by_up .= ", $col $up";
- my $down = $up eq 'ASC' ? 'DESC' : 'ASC';
- $order_by_down .= ", $col $down";
- }
-
- s/^,/ORDER BY/ for ( $order_by_up, $order_by_down );
-
- return $order_by_up, $order_by_down;
- }
-}
-### end-of-FIXME
-
=head1 NAME
DBIx::Class::SQLMaker::LimitDialects - SQL::Abstract::Limit-like functionality for DBIx::Class::SQLMaker
return $sql;
}
-=head2 Top
-
- SELECT * FROM
-
- SELECT TOP $limit FROM (
- SELECT TOP $limit FROM (
- SELECT TOP ($limit+$offset) ...
- ) ORDER BY $reversed_original_order
- ) ORDER BY $original_order
-
-Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>.
-
-=head3 CAVEAT
-
-Due to its implementation, this limit dialect returns B<incorrect results>
-when $limit+$offset > total amount of rows in the resultset.
-
-=cut
-sub _Top {
- my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
+# used by _Top and _FetchFirst
+sub _prep_for_skimming_limit {
+ my ( $self, $sql, $rs_attrs ) = @_;
# mangle the input sql as we will be replacing the selector
$sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix
or $self->throw_exception("Unrecognizable SELECT: $sql");
+ my %r = ( inner_sql => $sql );
+
# get selectors
- my ($in_sel, $out_sel, $alias_map, $extra_order_sel)
+ my ($alias_map, $extra_order_sel);
+ ($r{in_sel}, $r{out_sel}, $alias_map, $extra_order_sel)
= $self->_subqueried_limit_attrs ($rs_attrs);
my $requested_order = delete $rs_attrs->{order_by};
-
- my $order_by_requested = $self->_order_by ($requested_order);
+ $r{order_by_requested} = $self->_order_by ($requested_order);
# make up an order unless supplied
- my $inner_order = ($order_by_requested
+ my $inner_order = ($r{order_by_requested}
? $requested_order
: [ map
{ "$rs_attrs->{alias}.$_" }
]
);
- my ($order_by_inner, $order_by_reversed);
-
# localise as we already have all the bind values we need
{
local $self->{order_bind};
- $order_by_inner = $self->_order_by ($inner_order);
+ $r{order_by_inner} = $self->_order_by ($inner_order);
my @out_chunks;
for my $ch ($self->_order_by_chunks ($inner_order)) {
push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' );
}
- $order_by_reversed = $self->_order_by (\@out_chunks);
+ $r{order_by_reversed} = $self->_order_by (\@out_chunks);
}
# this is the order supplement magic
- my $mid_sel = $out_sel;
+ $r{mid_sel} = $r{out_sel};
if ($extra_order_sel) {
for my $extra_col (sort
{ $extra_order_sel->{$a} cmp $extra_order_sel->{$b} }
keys %$extra_order_sel
) {
- $in_sel .= sprintf (', %s AS %s',
+ $r{in_sel} .= sprintf (', %s AS %s',
$extra_col,
$extra_order_sel->{$extra_col},
);
- $mid_sel .= ', ' . $extra_order_sel->{$extra_col};
+ $r{mid_sel} .= ', ' . $extra_order_sel->{$extra_col};
}
# since whatever order bindvals there are, they will be realiased
for my $col (keys %$map) {
my $re_col = quotemeta ($col);
$_ =~ s/$re_col/$map->{$col}/
- for ($order_by_reversed, $order_by_requested);
+ for ($r{order_by_reversed}, $r{order_by_requested});
}
}
# generate the rest of the sql
- my $grpby_having = $self->_parse_rs_attrs ($rs_attrs);
+ $r{grpby_having} = $self->_parse_rs_attrs ($rs_attrs);
- my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias});
+ $r{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias});
+
+ \%r;
+}
+
+=head2 Top
+
+ SELECT * FROM
+
+ SELECT TOP $limit FROM (
+ SELECT TOP $limit FROM (
+ SELECT TOP ($limit+$offset) ...
+ ) ORDER BY $reversed_original_order
+ ) ORDER BY $original_order
+
+Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>.
+
+=head3 CAVEAT
+
+Due to its implementation, this limit dialect returns B<incorrect results>
+when $limit+$offset > total amount of rows in the resultset.
+
+=cut
+
+sub _Top {
+ my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
+
+ my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) };
$sql = sprintf ('SELECT TOP %u %s %s %s %s',
$rows + ($offset||0),
- $in_sel,
- $sql,
- $grpby_having,
- $order_by_inner,
+ $l{in_sel},
+ $l{inner_sql},
+ $l{grpby_having},
+ $l{order_by_inner},
);
$sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s',
$rows,
- $mid_sel,
+ $l{mid_sel},
$sql,
- $quoted_rs_alias,
- $order_by_reversed,
+ $l{quoted_rs_alias},
+ $l{order_by_reversed},
) if $offset;
$sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s',
$rows,
- $out_sel,
+ $l{out_sel},
+ $sql,
+ $l{quoted_rs_alias},
+ $l{order_by_requested},
+ ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) );
+
+ return $sql;
+}
+
+=head2 FetchFirst
+
+ SELECT * FROM
+ (
+ SELECT * FROM (
+ SELECT * FROM (
+ SELECT * FROM ...
+ ) ORDER BY $reversed_original_order
+ FETCH FIRST $limit ROWS ONLY
+ ) ORDER BY $original_order
+ FETCH FIRST $limit ROWS ONLY
+ )
+
+Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>.
+
+=head3 CAVEAT
+
+Due to its implementation, this limit dialect returns B<incorrect results>
+when $limit+$offset > total amount of rows in the resultset.
+
+=cut
+
+sub _FetchFirst {
+ my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
+
+ my %l = %{ $self->_prep_for_skimming_limit($sql, $rs_attrs) };
+
+ $sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY',
+ $l{in_sel},
+ $l{inner_sql},
+ $l{grpby_having},
+ $l{order_by_inner},
+ $rows + ($offset||0),
+ );
+
+ $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY',
+ $l{mid_sel},
+ $sql,
+ $l{quoted_rs_alias},
+ $l{order_by_reversed},
+ $rows,
+ ) if $offset;
+
+ $sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY',
+ $l{out_sel},
$sql,
- $quoted_rs_alias,
- $order_by_requested,
- ) if ( ($offset && $order_by_requested) || ($mid_sel ne $out_sel) );
+ $l{quoted_rs_alias},
+ $l{order_by_requested},
+ $rows,
+ ) if ( ($offset && $l{order_by_requested}) || ($l{mid_sel} ne $l{out_sel}) );
return $sql;
}
Otherwise we fall back to L</GenericSubQ>
=cut
+
sub _RowCountOrGenericSubQ {
my $self = shift;
my ($sql, $rs_attrs, $rows, $offset) = @_;
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