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d5dedbd6 |
1 | package DBIx::Class::SQLMaker::LimitDialects; |
7fca91be |
2 | |
3 | use warnings; |
4 | use strict; |
5 | |
6 | use Carp::Clan qw/^DBIx::Class|^SQL::Abstract|^Try::Tiny/; |
7 | use List::Util 'first'; |
8 | use namespace::clean; |
9 | |
2149a4e9 |
10 | # FIXME |
11 | # This dialect has not been ported to the subquery-realiasing code |
12 | # that all other subquerying dialects are using. It is very possible |
13 | # that this dialect is entirely unnecessary - it is currently only |
14 | # used by ::Storage::DBI::ODBC::DB2_400_SQL which *should* be able to |
15 | # just subclass ::Storage::DBI::DB2 and use the already rewritten |
16 | # RowNumberOver. However nobody has access to this specific database |
17 | # engine, thus keeping legacy code as-is |
18 | # IF someone ever manages to test DB2-AS/400 with RNO, all the code |
19 | # in this block should go on to meet its maker |
20 | { |
21 | sub _FetchFirst { |
22 | my ( $self, $sql, $order, $rows, $offset ) = @_; |
23 | |
24 | my $last = $rows + $offset; |
25 | |
26 | my ( $order_by_up, $order_by_down ) = $self->_order_directions( $order ); |
27 | |
28 | $sql = " |
29 | SELECT * FROM ( |
30 | SELECT * FROM ( |
31 | $sql |
32 | $order_by_up |
33 | FETCH FIRST $last ROWS ONLY |
34 | ) foo |
35 | $order_by_down |
36 | FETCH FIRST $rows ROWS ONLY |
37 | ) bar |
38 | $order_by_up |
39 | "; |
40 | |
41 | return $sql; |
42 | } |
43 | |
44 | sub _order_directions { |
45 | my ( $self, $order ) = @_; |
46 | |
47 | return unless $order; |
48 | |
49 | my $ref = ref $order; |
50 | |
51 | my @order; |
52 | |
53 | CASE: { |
54 | @order = @$order, last CASE if $ref eq 'ARRAY'; |
55 | @order = ( $order ), last CASE unless $ref; |
56 | @order = ( $$order ), last CASE if $ref eq 'SCALAR'; |
57 | croak __PACKAGE__ . ": Unsupported data struct $ref for ORDER BY"; |
58 | } |
59 | |
60 | my ( $order_by_up, $order_by_down ); |
61 | |
62 | foreach my $spec ( @order ) |
63 | { |
64 | my @spec = split ' ', $spec; |
65 | croak( "bad column order spec: $spec" ) if @spec > 2; |
66 | push( @spec, 'ASC' ) unless @spec == 2; |
67 | my ( $col, $up ) = @spec; # or maybe down |
68 | $up = uc( $up ); |
69 | croak( "bad direction: $up" ) unless $up =~ /^(?:ASC|DESC)$/; |
70 | $order_by_up .= ", $col $up"; |
71 | my $down = $up eq 'ASC' ? 'DESC' : 'ASC'; |
72 | $order_by_down .= ", $col $down"; |
73 | } |
74 | |
75 | s/^,/ORDER BY/ for ( $order_by_up, $order_by_down ); |
76 | |
77 | return $order_by_up, $order_by_down; |
78 | } |
79 | } |
80 | ### end-of-FIXME |
81 | |
d5dedbd6 |
82 | =head1 NAME |
83 | |
84 | DBIx::Class::SQLMaker::LimitDialects - SQL::Abstract::Limit-like functionality for DBIx::Class::SQLMaker |
85 | |
86 | =head1 DESCRIPTION |
87 | |
88 | This module replicates a lot of the functionality originally found in |
89 | L<SQL::Abstract::Limit>. While simple limits would work as-is, the more |
90 | complex dialects that require e.g. subqueries could not be reliably |
91 | implemented without taking full advantage of the metadata locked within |
92 | L<DBIx::Class::ResultSource> classes. After reimplementation of close to |
93 | 80% of the L<SQL::Abstract::Limit> functionality it was deemed more |
94 | practical to simply make an independent DBIx::Class-specific limit-dialect |
95 | provider. |
96 | |
97 | =head1 SQL LIMIT DIALECTS |
98 | |
99 | Note that the actual implementations listed below never use C<*> literally. |
100 | Instead proper re-aliasing of selectors and order criteria is done, so that |
101 | the limit dialect are safe to use on joined resultsets with clashing column |
102 | names. |
103 | |
104 | Currently the provided dialects are: |
105 | |
106 | =cut |
107 | |
108 | =head2 LimitOffset |
109 | |
110 | SELECT ... LIMIT $limit OFFSET $offset |
111 | |
112 | Supported by B<PostgreSQL> and B<SQLite> |
113 | |
114 | =cut |
7fca91be |
115 | sub _LimitOffset { |
116 | my ( $self, $sql, $order, $rows, $offset ) = @_; |
117 | $sql .= $self->_order_by( $order ) . " LIMIT $rows"; |
118 | $sql .= " OFFSET $offset" if +$offset; |
119 | return $sql; |
120 | } |
121 | |
d5dedbd6 |
122 | =head2 LimitXY |
123 | |
124 | SELECT ... LIMIT $offset $limit |
125 | |
126 | Supported by B<MySQL> and any L<SQL::Statement> based DBD |
127 | |
128 | =cut |
7fca91be |
129 | sub _LimitXY { |
130 | my ( $self, $sql, $order, $rows, $offset ) = @_; |
131 | $sql .= $self->_order_by( $order ) . " LIMIT "; |
132 | $sql .= "$offset, " if +$offset; |
133 | $sql .= $rows; |
134 | return $sql; |
135 | } |
d5dedbd6 |
136 | |
137 | =head2 RowNumberOver |
138 | |
139 | SELECT * FROM ( |
140 | SELECT *, ROW_NUMBER() OVER( ORDER BY ... ) AS RNO__ROW__INDEX FROM ( |
141 | SELECT ... |
142 | ) |
143 | ) WHERE RNO__ROW__INDEX BETWEEN ($offset+1) AND ($limit+$offset) |
144 | |
145 | |
146 | ANSI standard Limit/Offset implementation. Supported by B<DB2> and |
147 | B<< MSSQL >= 2005 >>. |
148 | |
149 | =cut |
7fca91be |
150 | sub _RowNumberOver { |
151 | my ($self, $sql, $rs_attrs, $rows, $offset ) = @_; |
152 | |
153 | # mangle the input sql as we will be replacing the selector |
154 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
155 | or croak "Unrecognizable SELECT: $sql"; |
156 | |
157 | # get selectors, and scan the order_by (if any) |
158 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
159 | = $self->_subqueried_limit_attrs ( $rs_attrs ); |
160 | |
161 | # make up an order if none exists |
162 | my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order; |
163 | my $rno_ord = $self->_order_by ($requested_order); |
164 | |
165 | # this is the order supplement magic |
166 | my $mid_sel = $out_sel; |
167 | if ($extra_order_sel) { |
168 | for my $extra_col (sort |
169 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
170 | keys %$extra_order_sel |
171 | ) { |
172 | $in_sel .= sprintf (', %s AS %s', |
173 | $extra_col, |
174 | $extra_order_sel->{$extra_col}, |
175 | ); |
176 | |
177 | $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; |
178 | } |
179 | } |
180 | |
181 | # and this is order re-alias magic |
182 | for ($extra_order_sel, $alias_map) { |
183 | for my $col (keys %$_) { |
184 | my $re_col = quotemeta ($col); |
185 | $rno_ord =~ s/$re_col/$_->{$col}/; |
186 | } |
187 | } |
188 | |
189 | # whatever is left of the order_by (only where is processed at this point) |
190 | my $group_having = $self->_parse_rs_attrs($rs_attrs); |
191 | |
192 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
193 | my $idx_name = $self->_quote ('rno__row__index'); |
194 | |
195 | $sql = sprintf (<<EOS, $offset + 1, $offset + $rows, ); |
196 | |
197 | SELECT $out_sel FROM ( |
198 | SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM ( |
199 | SELECT $in_sel ${sql}${group_having} |
200 | ) $qalias |
201 | ) $qalias WHERE $idx_name BETWEEN %u AND %u |
202 | |
203 | EOS |
204 | |
205 | $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger |
206 | return $sql; |
207 | } |
208 | |
209 | # some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) ) |
210 | sub _rno_default_order { |
211 | return undef; |
212 | } |
213 | |
d5dedbd6 |
214 | =head2 SkipFirst |
215 | |
216 | SELECT SKIP $offset FIRST $limit * FROM ... |
217 | |
218 | Suported by B<Informix>, almost like LimitOffset. According to |
219 | L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported. |
220 | |
221 | =cut |
7fca91be |
222 | sub _SkipFirst { |
223 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
224 | |
225 | $sql =~ s/^ \s* SELECT \s+ //ix |
226 | or croak "Unrecognizable SELECT: $sql"; |
227 | |
228 | return sprintf ('SELECT %s%s%s%s', |
229 | $offset |
230 | ? sprintf ('SKIP %u ', $offset) |
231 | : '' |
232 | , |
233 | sprintf ('FIRST %u ', $rows), |
234 | $sql, |
235 | $self->_parse_rs_attrs ($rs_attrs), |
236 | ); |
237 | } |
238 | |
d5dedbd6 |
239 | =head2 FirstSkip |
240 | |
241 | SELECT FIRST $limit SKIP $offset * FROM ... |
242 | |
243 | Supported by B<Firebird/Interbase>, reverse of SkipFirst. According to |
244 | L<SQL::Abstract::Limit> C<... ROWS $limit TO $offset ...> is also supported. |
245 | |
246 | =cut |
7fca91be |
247 | sub _FirstSkip { |
248 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
249 | |
250 | $sql =~ s/^ \s* SELECT \s+ //ix |
251 | or croak "Unrecognizable SELECT: $sql"; |
252 | |
253 | return sprintf ('SELECT %s%s%s%s', |
254 | sprintf ('FIRST %u ', $rows), |
255 | $offset |
256 | ? sprintf ('SKIP %u ', $offset) |
257 | : '' |
258 | , |
259 | $sql, |
260 | $self->_parse_rs_attrs ($rs_attrs), |
261 | ); |
262 | } |
263 | |
d5dedbd6 |
264 | =head2 RowNum |
265 | |
266 | SELECT * FROM ( |
267 | SELECT *, ROWNUM rownum__index FROM ( |
268 | SELECT ... |
d9672fb9 |
269 | ) WHERE ROWNUM <= ($limit+$offset) |
270 | ) WHERE rownum__index >= ($offset+1) |
d5dedbd6 |
271 | |
272 | Supported by B<Oracle>. |
273 | |
274 | =cut |
7fca91be |
275 | sub _RowNum { |
276 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
277 | |
278 | # mangle the input sql as we will be replacing the selector |
279 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
280 | or croak "Unrecognizable SELECT: $sql"; |
281 | |
282 | my ($insel, $outsel) = $self->_subqueried_limit_attrs ($rs_attrs); |
283 | |
284 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
285 | my $idx_name = $self->_quote ('rownum__index'); |
286 | my $order_group_having = $self->_parse_rs_attrs($rs_attrs); |
287 | |
d9672fb9 |
288 | if ($offset) { |
289 | |
290 | $sql = sprintf (<<EOS, $offset + $rows, $offset + 1 ); |
7fca91be |
291 | |
292 | SELECT $outsel FROM ( |
293 | SELECT $outsel, ROWNUM $idx_name FROM ( |
294 | SELECT $insel ${sql}${order_group_having} |
d9672fb9 |
295 | ) $qalias WHERE ROWNUM <= %u |
296 | ) $qalias WHERE $idx_name >= %u |
7fca91be |
297 | |
298 | EOS |
d9672fb9 |
299 | } |
300 | else { |
301 | $sql = sprintf (<<EOS, $rows ); |
302 | |
303 | SELECT $outsel FROM ( |
304 | SELECT $insel ${sql}${order_group_having} |
305 | ) $qalias WHERE ROWNUM <= %u |
306 | |
307 | EOS |
308 | } |
7fca91be |
309 | |
310 | $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger |
311 | return $sql; |
312 | } |
313 | |
d5dedbd6 |
314 | =head2 Top |
315 | |
316 | SELECT * FROM |
317 | |
318 | SELECT TOP $limit FROM ( |
319 | SELECT TOP $limit FROM ( |
320 | SELECT TOP ($limit+$offset) ... |
321 | ) ORDER BY $reversed_original_order |
322 | ) ORDER BY $original_order |
323 | |
324 | Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>. |
325 | |
326 | =head3 CAVEAT |
327 | |
328 | Due to its implementation, this limit dialect returns B<incorrect results> |
329 | when $limit+$offset > total amount of rows in the resultset. |
330 | |
331 | =cut |
7fca91be |
332 | sub _Top { |
333 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
334 | |
335 | # mangle the input sql as we will be replacing the selector |
336 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
337 | or croak "Unrecognizable SELECT: $sql"; |
338 | |
339 | # get selectors |
340 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
341 | = $self->_subqueried_limit_attrs ($rs_attrs); |
342 | |
343 | my $requested_order = delete $rs_attrs->{order_by}; |
344 | |
345 | my $order_by_requested = $self->_order_by ($requested_order); |
346 | |
347 | # make up an order unless supplied |
348 | my $inner_order = ($order_by_requested |
349 | ? $requested_order |
350 | : [ map |
351 | { join ('', $rs_attrs->{alias}, $self->{name_sep}||'.', $_ ) } |
352 | ( $rs_attrs->{_rsroot_source_handle}->resolve->_pri_cols ) |
353 | ] |
354 | ); |
355 | |
356 | my ($order_by_inner, $order_by_reversed); |
357 | |
358 | # localise as we already have all the bind values we need |
359 | { |
360 | local $self->{order_bind}; |
361 | $order_by_inner = $self->_order_by ($inner_order); |
362 | |
363 | my @out_chunks; |
364 | for my $ch ($self->_order_by_chunks ($inner_order)) { |
365 | $ch = $ch->[0] if ref $ch eq 'ARRAY'; |
366 | |
367 | $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
368 | my $dir = uc ($1||'ASC'); |
369 | |
370 | push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); |
371 | } |
372 | |
373 | $order_by_reversed = $self->_order_by (\@out_chunks); |
374 | } |
375 | |
376 | # this is the order supplement magic |
377 | my $mid_sel = $out_sel; |
378 | if ($extra_order_sel) { |
379 | for my $extra_col (sort |
380 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
381 | keys %$extra_order_sel |
382 | ) { |
383 | $in_sel .= sprintf (', %s AS %s', |
384 | $extra_col, |
385 | $extra_order_sel->{$extra_col}, |
386 | ); |
387 | |
388 | $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; |
389 | } |
390 | |
391 | # since whatever order bindvals there are, they will be realiased |
392 | # and need to show up in front of the entire initial inner subquery |
393 | # Unshift *from_bind* to make this happen (horrible, horrible, but |
394 | # we don't have another mechanism yet) |
395 | unshift @{$self->{from_bind}}, @{$self->{order_bind}}; |
396 | } |
397 | |
398 | # and this is order re-alias magic |
399 | for my $map ($extra_order_sel, $alias_map) { |
400 | for my $col (keys %$map) { |
401 | my $re_col = quotemeta ($col); |
402 | $_ =~ s/$re_col/$map->{$col}/ |
403 | for ($order_by_reversed, $order_by_requested); |
404 | } |
405 | } |
406 | |
407 | # generate the rest of the sql |
408 | my $grpby_having = $self->_parse_rs_attrs ($rs_attrs); |
409 | |
410 | my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias}); |
411 | |
412 | $sql = sprintf ('SELECT TOP %u %s %s %s %s', |
413 | $rows + ($offset||0), |
414 | $in_sel, |
415 | $sql, |
416 | $grpby_having, |
417 | $order_by_inner, |
418 | ); |
419 | |
420 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
421 | $rows, |
422 | $mid_sel, |
423 | $sql, |
424 | $quoted_rs_alias, |
425 | $order_by_reversed, |
426 | ) if $offset; |
427 | |
428 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
429 | $rows, |
430 | $out_sel, |
431 | $sql, |
432 | $quoted_rs_alias, |
433 | $order_by_requested, |
434 | ) if ( ($offset && $order_by_requested) || ($mid_sel ne $out_sel) ); |
435 | |
436 | $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger |
437 | return $sql; |
438 | } |
439 | |
d5dedbd6 |
440 | =head2 RowCountOrGenericSubQ |
441 | |
442 | This is not exactly a limit dialect, but more of a proxy for B<Sybase ASE>. |
443 | If no $offset is supplied the limit is simply performed as: |
444 | |
445 | SET ROWCOUNT $limit |
446 | SELECT ... |
447 | SET ROWCOUNT 0 |
448 | |
449 | Otherwise we fall back to L</GenericSubQ> |
450 | |
451 | =cut |
7fca91be |
452 | sub _RowCountOrGenericSubQ { |
453 | my $self = shift; |
454 | my ($sql, $rs_attrs, $rows, $offset) = @_; |
455 | |
456 | return $self->_GenericSubQ(@_) if $offset; |
457 | |
458 | return sprintf <<"EOF", $rows, $sql; |
459 | SET ROWCOUNT %d |
460 | %s |
461 | SET ROWCOUNT 0 |
462 | EOF |
463 | } |
464 | |
d5dedbd6 |
465 | =head2 GenericSubQ |
466 | |
467 | SELECT * FROM ( |
468 | SELECT ... |
469 | ) |
470 | WHERE ( |
471 | SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id |
472 | ) BETWEEN $offset AND ($offset+$rows-1) |
473 | |
474 | This is the most evil limit "dialect" (more of a hack) for I<really> stupid |
475 | databases. It works by ordering the set by some unique column, and calculating |
476 | the amount of rows that have a less-er value (thus emulating a L</RowNum>-like |
477 | index). Of course this implies the set can only be ordered by a single unique |
478 | column. Also note that this technique can be and often is B<excruciatingly |
479 | slow>. |
480 | |
481 | Currently used by B<Sybase ASE>, due to lack of any other option. |
482 | |
483 | =cut |
7fca91be |
484 | sub _GenericSubQ { |
485 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
486 | |
487 | my $root_rsrc = $rs_attrs->{_rsroot_source_handle}->resolve; |
488 | my $root_tbl_name = $root_rsrc->name; |
489 | |
490 | # mangle the input sql as we will be replacing the selector |
491 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
492 | or croak "Unrecognizable SELECT: $sql"; |
493 | |
494 | my ($order_by, @rest) = do { |
495 | local $self->{quote_char}; |
496 | $self->_order_by_chunks ($rs_attrs->{order_by}) |
497 | }; |
498 | |
499 | unless ( |
500 | $order_by |
501 | && |
502 | ! @rest |
503 | && |
504 | ( ! ref $order_by |
505 | || |
506 | ( ref $order_by eq 'ARRAY' and @$order_by == 1 ) |
507 | ) |
508 | ) { |
509 | croak ( |
510 | 'Generic Subquery Limit does not work on resultsets without an order, or resultsets ' |
511 | . 'with complex order criteria (multicolumn and/or functions). Provide a single, ' |
512 | . 'unique-column order criteria.' |
513 | ); |
514 | } |
515 | |
516 | ($order_by) = @$order_by if ref $order_by; |
517 | |
518 | $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
519 | my $direction = lc ($1 || 'asc'); |
520 | |
521 | my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/; |
522 | |
523 | my $inf = $root_rsrc->storage->_resolve_column_info ( |
524 | $rs_attrs->{from}, [$order_by, $unq_sort_col] |
525 | ); |
526 | |
527 | my $ord_colinfo = $inf->{$order_by} || croak "Unable to determine source of order-criteria '$order_by'"; |
528 | |
529 | if ($ord_colinfo->{-result_source}->name ne $root_tbl_name) { |
530 | croak "Generic Subquery Limit order criteria can be only based on the root-source '" |
531 | . $root_rsrc->source_name . "' (aliased as '$rs_attrs->{alias}')"; |
532 | } |
533 | |
534 | # make sure order column is qualified |
535 | $order_by = "$rs_attrs->{alias}.$order_by" |
536 | unless $order_by =~ /^$rs_attrs->{alias}\./; |
537 | |
538 | my $is_u; |
539 | my $ucs = { $root_rsrc->unique_constraints }; |
540 | for (values %$ucs ) { |
541 | if (@$_ == 1 && "$rs_attrs->{alias}.$_->[0]" eq $order_by) { |
542 | $is_u++; |
543 | last; |
544 | } |
545 | } |
546 | croak "Generic Subquery Limit order criteria column '$order_by' must be unique (no unique constraint found)" |
547 | unless $is_u; |
548 | |
549 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
550 | = $self->_subqueried_limit_attrs ($rs_attrs); |
551 | |
552 | my $cmp_op = $direction eq 'desc' ? '>' : '<'; |
553 | my $count_tbl_alias = 'rownum__emulation'; |
554 | |
555 | my $order_sql = $self->_order_by (delete $rs_attrs->{order_by}); |
556 | my $group_having_sql = $self->_parse_rs_attrs($rs_attrs); |
557 | |
558 | # add the order supplement (if any) as this is what will be used for the outer WHERE |
559 | $in_sel .= ", $_" for keys %{$extra_order_sel||{}}; |
560 | |
561 | $sql = sprintf (<<EOS, |
562 | SELECT $out_sel |
563 | FROM ( |
564 | SELECT $in_sel ${sql}${group_having_sql} |
565 | ) %s |
566 | WHERE ( SELECT COUNT(*) FROM %s %s WHERE %s $cmp_op %s ) %s |
567 | $order_sql |
568 | EOS |
569 | ( map { $self->_quote ($_) } ( |
570 | $rs_attrs->{alias}, |
571 | $root_tbl_name, |
572 | $count_tbl_alias, |
573 | "$count_tbl_alias.$unq_sort_col", |
574 | $order_by, |
575 | )), |
576 | $offset |
577 | ? sprintf ('BETWEEN %u AND %u', $offset, $offset + $rows - 1) |
578 | : sprintf ('< %u', $rows ) |
579 | , |
580 | ); |
581 | |
582 | $sql =~ s/\s*\n\s*/ /g; # easier to read in the debugger |
583 | return $sql; |
584 | } |
585 | |
586 | |
587 | # !!! THIS IS ALSO HORRIFIC !!! /me ashamed |
588 | # |
589 | # Generates inner/outer select lists for various limit dialects |
590 | # which result in one or more subqueries (e.g. RNO, Top, RowNum) |
591 | # Any non-root-table columns need to have their table qualifier |
592 | # turned into a column alias (otherwise names in subqueries clash |
593 | # and/or lose their source table) |
594 | # |
595 | # Returns inner/outer strings of SQL QUOTED selectors with aliases |
596 | # (to be used in whatever select statement), and an alias index hashref |
597 | # of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst |
598 | # higher up). |
599 | # If an order_by is supplied, the inner select needs to bring out columns |
600 | # used in implicit (non-selected) orders, and the order condition itself |
601 | # needs to be realiased to the proper names in the outer query. Thus we |
602 | # also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL => |
603 | # QUOTED ALIAS pairs, which is a list of extra selectors that do *not* |
604 | # exist in the original select list |
7fca91be |
605 | sub _subqueried_limit_attrs { |
606 | my ($self, $rs_attrs) = @_; |
607 | |
608 | croak 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' |
609 | unless ref ($rs_attrs) eq 'HASH'; |
610 | |
611 | my ($re_sep, $re_alias) = map { quotemeta $_ } ( |
612 | $self->name_sep || '.', |
613 | $rs_attrs->{alias}, |
614 | ); |
615 | |
616 | # correlate select and as, build selection index |
617 | my (@sel, $in_sel_index); |
618 | for my $i (0 .. $#{$rs_attrs->{select}}) { |
619 | |
620 | my $s = $rs_attrs->{select}[$i]; |
621 | my $sql_sel = $self->_recurse_fields ($s); |
622 | my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef; |
623 | |
7fca91be |
624 | push @sel, { |
625 | sql => $sql_sel, |
626 | unquoted_sql => do { local $self->{quote_char}; $self->_recurse_fields ($s) }, |
627 | as => |
628 | $sql_alias |
629 | || |
630 | $rs_attrs->{as}[$i] |
631 | || |
632 | croak "Select argument $i ($s) without corresponding 'as'" |
633 | , |
634 | }; |
635 | |
636 | $in_sel_index->{$sql_sel}++; |
637 | $in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias; |
638 | |
639 | # record unqualified versions too, so we do not have |
640 | # to reselect the same column twice (in qualified and |
641 | # unqualified form) |
642 | if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) { |
643 | $in_sel_index->{$1}++; |
644 | } |
645 | } |
646 | |
647 | |
648 | # re-alias and remove any name separators from aliases, |
649 | # unless we are dealing with the current source alias |
650 | # (which will transcend the subqueries as it is necessary |
651 | # for possible further chaining) |
652 | my (@in_sel, @out_sel, %renamed); |
653 | for my $node (@sel) { |
654 | if (first { $_ =~ / (?<! ^ $re_alias ) $re_sep /x } ($node->{as}, $node->{unquoted_sql}) ) { |
655 | $node->{as} = $self->_unqualify_colname($node->{as}); |
656 | my $quoted_as = $self->_quote($node->{as}); |
657 | push @in_sel, sprintf '%s AS %s', $node->{sql}, $quoted_as; |
658 | push @out_sel, $quoted_as; |
659 | $renamed{$node->{sql}} = $quoted_as; |
660 | } |
661 | else { |
662 | push @in_sel, $node->{sql}; |
663 | push @out_sel, $self->_quote ($node->{as}); |
664 | } |
665 | } |
666 | |
667 | # see if the order gives us anything |
668 | my %extra_order_sel; |
669 | for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { |
670 | # order with bind |
671 | $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; |
672 | $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix; |
673 | |
674 | next if $in_sel_index->{$chunk}; |
675 | |
676 | $extra_order_sel{$chunk} ||= $self->_quote ( |
677 | 'ORDER__BY__' . scalar keys %extra_order_sel |
678 | ); |
679 | } |
680 | |
681 | return ( |
682 | (map { join (', ', @$_ ) } ( |
683 | \@in_sel, |
684 | \@out_sel) |
685 | ), |
686 | \%renamed, |
687 | keys %extra_order_sel ? \%extra_order_sel : (), |
688 | ); |
689 | } |
690 | |
691 | sub _unqualify_colname { |
692 | my ($self, $fqcn) = @_; |
693 | my $re_sep = quotemeta($self->name_sep || '.'); |
694 | $fqcn =~ s/ $re_sep /__/xg; |
695 | return $fqcn; |
696 | } |
697 | |
698 | 1; |
d5dedbd6 |
699 | |
700 | =head1 AUTHORS |
701 | |
702 | See L<DBIx::Class/CONTRIBUTORS>. |
703 | |
704 | =head1 LICENSE |
705 | |
706 | You may distribute this code under the same terms as Perl itself. |
707 | |
708 | =cut |