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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 | |
7fca91be |
205 | return $sql; |
206 | } |
207 | |
208 | # some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) ) |
209 | sub _rno_default_order { |
210 | return undef; |
211 | } |
212 | |
d5dedbd6 |
213 | =head2 SkipFirst |
214 | |
215 | SELECT SKIP $offset FIRST $limit * FROM ... |
216 | |
217 | Suported by B<Informix>, almost like LimitOffset. According to |
218 | L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported. |
219 | |
220 | =cut |
7fca91be |
221 | sub _SkipFirst { |
222 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
223 | |
224 | $sql =~ s/^ \s* SELECT \s+ //ix |
225 | or croak "Unrecognizable SELECT: $sql"; |
226 | |
227 | return sprintf ('SELECT %s%s%s%s', |
228 | $offset |
229 | ? sprintf ('SKIP %u ', $offset) |
230 | : '' |
231 | , |
232 | sprintf ('FIRST %u ', $rows), |
233 | $sql, |
234 | $self->_parse_rs_attrs ($rs_attrs), |
235 | ); |
236 | } |
237 | |
d5dedbd6 |
238 | =head2 FirstSkip |
239 | |
240 | SELECT FIRST $limit SKIP $offset * FROM ... |
241 | |
242 | Supported by B<Firebird/Interbase>, reverse of SkipFirst. According to |
243 | L<SQL::Abstract::Limit> C<... ROWS $limit TO $offset ...> is also supported. |
244 | |
245 | =cut |
7fca91be |
246 | sub _FirstSkip { |
247 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
248 | |
249 | $sql =~ s/^ \s* SELECT \s+ //ix |
250 | or croak "Unrecognizable SELECT: $sql"; |
251 | |
252 | return sprintf ('SELECT %s%s%s%s', |
253 | sprintf ('FIRST %u ', $rows), |
254 | $offset |
255 | ? sprintf ('SKIP %u ', $offset) |
256 | : '' |
257 | , |
258 | $sql, |
259 | $self->_parse_rs_attrs ($rs_attrs), |
260 | ); |
261 | } |
262 | |
d5dedbd6 |
263 | =head2 RowNum |
264 | |
265 | SELECT * FROM ( |
266 | SELECT *, ROWNUM rownum__index FROM ( |
267 | SELECT ... |
d9672fb9 |
268 | ) WHERE ROWNUM <= ($limit+$offset) |
269 | ) WHERE rownum__index >= ($offset+1) |
d5dedbd6 |
270 | |
271 | Supported by B<Oracle>. |
272 | |
273 | =cut |
7fca91be |
274 | sub _RowNum { |
275 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
276 | |
277 | # mangle the input sql as we will be replacing the selector |
278 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
279 | or croak "Unrecognizable SELECT: $sql"; |
280 | |
281 | my ($insel, $outsel) = $self->_subqueried_limit_attrs ($rs_attrs); |
282 | |
283 | my $qalias = $self->_quote ($rs_attrs->{alias}); |
284 | my $idx_name = $self->_quote ('rownum__index'); |
285 | my $order_group_having = $self->_parse_rs_attrs($rs_attrs); |
286 | |
d9672fb9 |
287 | if ($offset) { |
288 | |
289 | $sql = sprintf (<<EOS, $offset + $rows, $offset + 1 ); |
7fca91be |
290 | |
291 | SELECT $outsel FROM ( |
292 | SELECT $outsel, ROWNUM $idx_name FROM ( |
293 | SELECT $insel ${sql}${order_group_having} |
d9672fb9 |
294 | ) $qalias WHERE ROWNUM <= %u |
295 | ) $qalias WHERE $idx_name >= %u |
7fca91be |
296 | |
297 | EOS |
d9672fb9 |
298 | } |
299 | else { |
300 | $sql = sprintf (<<EOS, $rows ); |
301 | |
302 | SELECT $outsel FROM ( |
303 | SELECT $insel ${sql}${order_group_having} |
304 | ) $qalias WHERE ROWNUM <= %u |
305 | |
306 | EOS |
307 | } |
7fca91be |
308 | |
7fca91be |
309 | return $sql; |
310 | } |
311 | |
d5dedbd6 |
312 | =head2 Top |
313 | |
314 | SELECT * FROM |
315 | |
316 | SELECT TOP $limit FROM ( |
317 | SELECT TOP $limit FROM ( |
318 | SELECT TOP ($limit+$offset) ... |
319 | ) ORDER BY $reversed_original_order |
320 | ) ORDER BY $original_order |
321 | |
322 | Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>. |
323 | |
324 | =head3 CAVEAT |
325 | |
326 | Due to its implementation, this limit dialect returns B<incorrect results> |
327 | when $limit+$offset > total amount of rows in the resultset. |
328 | |
329 | =cut |
7fca91be |
330 | sub _Top { |
331 | my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_; |
332 | |
333 | # mangle the input sql as we will be replacing the selector |
334 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
335 | or croak "Unrecognizable SELECT: $sql"; |
336 | |
337 | # get selectors |
338 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
339 | = $self->_subqueried_limit_attrs ($rs_attrs); |
340 | |
341 | my $requested_order = delete $rs_attrs->{order_by}; |
342 | |
343 | my $order_by_requested = $self->_order_by ($requested_order); |
344 | |
345 | # make up an order unless supplied |
346 | my $inner_order = ($order_by_requested |
347 | ? $requested_order |
348 | : [ map |
3f5b99fe |
349 | { "$rs_attrs->{alias}.$_" } |
4376a157 |
350 | ( $rs_attrs->{_rsroot_rsrc}->_pri_cols ) |
7fca91be |
351 | ] |
352 | ); |
353 | |
354 | my ($order_by_inner, $order_by_reversed); |
355 | |
356 | # localise as we already have all the bind values we need |
357 | { |
358 | local $self->{order_bind}; |
359 | $order_by_inner = $self->_order_by ($inner_order); |
360 | |
361 | my @out_chunks; |
362 | for my $ch ($self->_order_by_chunks ($inner_order)) { |
363 | $ch = $ch->[0] if ref $ch eq 'ARRAY'; |
364 | |
365 | $ch =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
366 | my $dir = uc ($1||'ASC'); |
367 | |
368 | push @out_chunks, \join (' ', $ch, $dir eq 'ASC' ? 'DESC' : 'ASC' ); |
369 | } |
370 | |
371 | $order_by_reversed = $self->_order_by (\@out_chunks); |
372 | } |
373 | |
374 | # this is the order supplement magic |
375 | my $mid_sel = $out_sel; |
376 | if ($extra_order_sel) { |
377 | for my $extra_col (sort |
378 | { $extra_order_sel->{$a} cmp $extra_order_sel->{$b} } |
379 | keys %$extra_order_sel |
380 | ) { |
381 | $in_sel .= sprintf (', %s AS %s', |
382 | $extra_col, |
383 | $extra_order_sel->{$extra_col}, |
384 | ); |
385 | |
386 | $mid_sel .= ', ' . $extra_order_sel->{$extra_col}; |
387 | } |
388 | |
389 | # since whatever order bindvals there are, they will be realiased |
390 | # and need to show up in front of the entire initial inner subquery |
4c2b30d6 |
391 | # *unshift* the selector bind stack to make this happen (horrible, |
392 | # horrible, but we don't have another mechanism yet) |
393 | unshift @{$self->{select_bind}}, @{$self->{order_bind}}; |
7fca91be |
394 | } |
395 | |
396 | # and this is order re-alias magic |
397 | for my $map ($extra_order_sel, $alias_map) { |
398 | for my $col (keys %$map) { |
399 | my $re_col = quotemeta ($col); |
400 | $_ =~ s/$re_col/$map->{$col}/ |
401 | for ($order_by_reversed, $order_by_requested); |
402 | } |
403 | } |
404 | |
405 | # generate the rest of the sql |
406 | my $grpby_having = $self->_parse_rs_attrs ($rs_attrs); |
407 | |
408 | my $quoted_rs_alias = $self->_quote ($rs_attrs->{alias}); |
409 | |
410 | $sql = sprintf ('SELECT TOP %u %s %s %s %s', |
411 | $rows + ($offset||0), |
412 | $in_sel, |
413 | $sql, |
414 | $grpby_having, |
415 | $order_by_inner, |
416 | ); |
417 | |
418 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
419 | $rows, |
420 | $mid_sel, |
421 | $sql, |
422 | $quoted_rs_alias, |
423 | $order_by_reversed, |
424 | ) if $offset; |
425 | |
426 | $sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s', |
427 | $rows, |
428 | $out_sel, |
429 | $sql, |
430 | $quoted_rs_alias, |
431 | $order_by_requested, |
432 | ) if ( ($offset && $order_by_requested) || ($mid_sel ne $out_sel) ); |
433 | |
7fca91be |
434 | return $sql; |
435 | } |
436 | |
d5dedbd6 |
437 | =head2 RowCountOrGenericSubQ |
438 | |
439 | This is not exactly a limit dialect, but more of a proxy for B<Sybase ASE>. |
440 | If no $offset is supplied the limit is simply performed as: |
441 | |
442 | SET ROWCOUNT $limit |
443 | SELECT ... |
444 | SET ROWCOUNT 0 |
445 | |
446 | Otherwise we fall back to L</GenericSubQ> |
447 | |
448 | =cut |
7fca91be |
449 | sub _RowCountOrGenericSubQ { |
450 | my $self = shift; |
451 | my ($sql, $rs_attrs, $rows, $offset) = @_; |
452 | |
453 | return $self->_GenericSubQ(@_) if $offset; |
454 | |
455 | return sprintf <<"EOF", $rows, $sql; |
456 | SET ROWCOUNT %d |
457 | %s |
458 | SET ROWCOUNT 0 |
459 | EOF |
460 | } |
461 | |
d5dedbd6 |
462 | =head2 GenericSubQ |
463 | |
464 | SELECT * FROM ( |
465 | SELECT ... |
466 | ) |
467 | WHERE ( |
468 | SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id |
469 | ) BETWEEN $offset AND ($offset+$rows-1) |
470 | |
471 | This is the most evil limit "dialect" (more of a hack) for I<really> stupid |
472 | databases. It works by ordering the set by some unique column, and calculating |
473 | the amount of rows that have a less-er value (thus emulating a L</RowNum>-like |
474 | index). Of course this implies the set can only be ordered by a single unique |
475 | column. Also note that this technique can be and often is B<excruciatingly |
476 | slow>. |
477 | |
478 | Currently used by B<Sybase ASE>, due to lack of any other option. |
479 | |
480 | =cut |
7fca91be |
481 | sub _GenericSubQ { |
482 | my ($self, $sql, $rs_attrs, $rows, $offset) = @_; |
483 | |
4376a157 |
484 | my $root_rsrc = $rs_attrs->{_rsroot_rsrc}; |
7fca91be |
485 | my $root_tbl_name = $root_rsrc->name; |
486 | |
487 | # mangle the input sql as we will be replacing the selector |
488 | $sql =~ s/^ \s* SELECT \s+ .+? \s+ (?= \b FROM \b )//ix |
489 | or croak "Unrecognizable SELECT: $sql"; |
490 | |
491 | my ($order_by, @rest) = do { |
492 | local $self->{quote_char}; |
493 | $self->_order_by_chunks ($rs_attrs->{order_by}) |
494 | }; |
495 | |
496 | unless ( |
497 | $order_by |
498 | && |
499 | ! @rest |
500 | && |
501 | ( ! ref $order_by |
502 | || |
503 | ( ref $order_by eq 'ARRAY' and @$order_by == 1 ) |
504 | ) |
505 | ) { |
506 | croak ( |
507 | 'Generic Subquery Limit does not work on resultsets without an order, or resultsets ' |
508 | . 'with complex order criteria (multicolumn and/or functions). Provide a single, ' |
509 | . 'unique-column order criteria.' |
510 | ); |
511 | } |
512 | |
513 | ($order_by) = @$order_by if ref $order_by; |
514 | |
515 | $order_by =~ s/\s+ ( ASC|DESC ) \s* $//ix; |
516 | my $direction = lc ($1 || 'asc'); |
517 | |
518 | my ($unq_sort_col) = $order_by =~ /(?:^|\.)([^\.]+)$/; |
519 | |
520 | my $inf = $root_rsrc->storage->_resolve_column_info ( |
521 | $rs_attrs->{from}, [$order_by, $unq_sort_col] |
522 | ); |
523 | |
524 | my $ord_colinfo = $inf->{$order_by} || croak "Unable to determine source of order-criteria '$order_by'"; |
525 | |
526 | if ($ord_colinfo->{-result_source}->name ne $root_tbl_name) { |
527 | croak "Generic Subquery Limit order criteria can be only based on the root-source '" |
528 | . $root_rsrc->source_name . "' (aliased as '$rs_attrs->{alias}')"; |
529 | } |
530 | |
531 | # make sure order column is qualified |
532 | $order_by = "$rs_attrs->{alias}.$order_by" |
533 | unless $order_by =~ /^$rs_attrs->{alias}\./; |
534 | |
535 | my $is_u; |
536 | my $ucs = { $root_rsrc->unique_constraints }; |
537 | for (values %$ucs ) { |
538 | if (@$_ == 1 && "$rs_attrs->{alias}.$_->[0]" eq $order_by) { |
539 | $is_u++; |
540 | last; |
541 | } |
542 | } |
543 | croak "Generic Subquery Limit order criteria column '$order_by' must be unique (no unique constraint found)" |
544 | unless $is_u; |
545 | |
546 | my ($in_sel, $out_sel, $alias_map, $extra_order_sel) |
547 | = $self->_subqueried_limit_attrs ($rs_attrs); |
548 | |
549 | my $cmp_op = $direction eq 'desc' ? '>' : '<'; |
550 | my $count_tbl_alias = 'rownum__emulation'; |
551 | |
552 | my $order_sql = $self->_order_by (delete $rs_attrs->{order_by}); |
553 | my $group_having_sql = $self->_parse_rs_attrs($rs_attrs); |
554 | |
555 | # add the order supplement (if any) as this is what will be used for the outer WHERE |
556 | $in_sel .= ", $_" for keys %{$extra_order_sel||{}}; |
557 | |
558 | $sql = sprintf (<<EOS, |
559 | SELECT $out_sel |
560 | FROM ( |
561 | SELECT $in_sel ${sql}${group_having_sql} |
562 | ) %s |
563 | WHERE ( SELECT COUNT(*) FROM %s %s WHERE %s $cmp_op %s ) %s |
564 | $order_sql |
565 | EOS |
566 | ( map { $self->_quote ($_) } ( |
567 | $rs_attrs->{alias}, |
568 | $root_tbl_name, |
569 | $count_tbl_alias, |
570 | "$count_tbl_alias.$unq_sort_col", |
571 | $order_by, |
572 | )), |
573 | $offset |
574 | ? sprintf ('BETWEEN %u AND %u', $offset, $offset + $rows - 1) |
575 | : sprintf ('< %u', $rows ) |
576 | , |
577 | ); |
578 | |
7fca91be |
579 | return $sql; |
580 | } |
581 | |
582 | |
583 | # !!! THIS IS ALSO HORRIFIC !!! /me ashamed |
584 | # |
585 | # Generates inner/outer select lists for various limit dialects |
586 | # which result in one or more subqueries (e.g. RNO, Top, RowNum) |
587 | # Any non-root-table columns need to have their table qualifier |
588 | # turned into a column alias (otherwise names in subqueries clash |
589 | # and/or lose their source table) |
590 | # |
591 | # Returns inner/outer strings of SQL QUOTED selectors with aliases |
592 | # (to be used in whatever select statement), and an alias index hashref |
593 | # of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used for string-subst |
594 | # higher up). |
595 | # If an order_by is supplied, the inner select needs to bring out columns |
596 | # used in implicit (non-selected) orders, and the order condition itself |
597 | # needs to be realiased to the proper names in the outer query. Thus we |
598 | # also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL => |
599 | # QUOTED ALIAS pairs, which is a list of extra selectors that do *not* |
600 | # exist in the original select list |
7fca91be |
601 | sub _subqueried_limit_attrs { |
602 | my ($self, $rs_attrs) = @_; |
603 | |
604 | croak 'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)' |
605 | unless ref ($rs_attrs) eq 'HASH'; |
606 | |
3f5b99fe |
607 | my ($re_sep, $re_alias) = map { quotemeta $_ } ( $self->{name_sep}, $rs_attrs->{alias} ); |
7fca91be |
608 | |
609 | # correlate select and as, build selection index |
610 | my (@sel, $in_sel_index); |
611 | for my $i (0 .. $#{$rs_attrs->{select}}) { |
612 | |
613 | my $s = $rs_attrs->{select}[$i]; |
614 | my $sql_sel = $self->_recurse_fields ($s); |
615 | my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef; |
616 | |
7fca91be |
617 | push @sel, { |
618 | sql => $sql_sel, |
619 | unquoted_sql => do { local $self->{quote_char}; $self->_recurse_fields ($s) }, |
620 | as => |
621 | $sql_alias |
622 | || |
623 | $rs_attrs->{as}[$i] |
624 | || |
625 | croak "Select argument $i ($s) without corresponding 'as'" |
626 | , |
627 | }; |
628 | |
629 | $in_sel_index->{$sql_sel}++; |
630 | $in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias; |
631 | |
632 | # record unqualified versions too, so we do not have |
633 | # to reselect the same column twice (in qualified and |
634 | # unqualified form) |
635 | if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) { |
636 | $in_sel_index->{$1}++; |
637 | } |
638 | } |
639 | |
640 | |
641 | # re-alias and remove any name separators from aliases, |
642 | # unless we are dealing with the current source alias |
643 | # (which will transcend the subqueries as it is necessary |
644 | # for possible further chaining) |
645 | my (@in_sel, @out_sel, %renamed); |
646 | for my $node (@sel) { |
3f5b99fe |
647 | if ( |
648 | $node->{as} =~ / (?<! ^ $re_alias ) \. /x |
649 | or |
650 | $node->{unquoted_sql} =~ / (?<! ^ $re_alias ) $re_sep /x |
651 | ) { |
7fca91be |
652 | $node->{as} = $self->_unqualify_colname($node->{as}); |
653 | my $quoted_as = $self->_quote($node->{as}); |
654 | push @in_sel, sprintf '%s AS %s', $node->{sql}, $quoted_as; |
655 | push @out_sel, $quoted_as; |
656 | $renamed{$node->{sql}} = $quoted_as; |
657 | } |
658 | else { |
659 | push @in_sel, $node->{sql}; |
660 | push @out_sel, $self->_quote ($node->{as}); |
661 | } |
662 | } |
663 | |
664 | # see if the order gives us anything |
665 | my %extra_order_sel; |
666 | for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) { |
667 | # order with bind |
668 | $chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY'; |
669 | $chunk =~ s/\s+ (?: ASC|DESC ) \s* $//ix; |
670 | |
671 | next if $in_sel_index->{$chunk}; |
672 | |
673 | $extra_order_sel{$chunk} ||= $self->_quote ( |
674 | 'ORDER__BY__' . scalar keys %extra_order_sel |
675 | ); |
676 | } |
677 | |
678 | return ( |
679 | (map { join (', ', @$_ ) } ( |
680 | \@in_sel, |
681 | \@out_sel) |
682 | ), |
683 | \%renamed, |
684 | keys %extra_order_sel ? \%extra_order_sel : (), |
685 | ); |
686 | } |
687 | |
688 | sub _unqualify_colname { |
689 | my ($self, $fqcn) = @_; |
3f5b99fe |
690 | $fqcn =~ s/ \. /__/xg; |
7fca91be |
691 | return $fqcn; |
692 | } |
693 | |
694 | 1; |
d5dedbd6 |
695 | |
696 | =head1 AUTHORS |
697 | |
698 | See L<DBIx::Class/CONTRIBUTORS>. |
699 | |
700 | =head1 LICENSE |
701 | |
702 | You may distribute this code under the same terms as Perl itself. |
703 | |
704 | =cut |