1: # The LearningOnline Network with CAPA
2: # MySQL utility functions
3: #
4: # $Id: lonmysql.pm,v 1.12 2003/03/21 16:04:42 matthew Exp $
5: #
6: # Copyright Michigan State University Board of Trustees
7: #
8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
9: #
10: # LON-CAPA is free software; you can redistribute it and/or modify
11: # it under the terms of the GNU General Public License as published by
12: # the Free Software Foundation; either version 2 of the License, or
13: # (at your option) any later version.
14: #
15: # LON-CAPA is distributed in the hope that it will be useful,
16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18: # GNU General Public License for more details.
19: #
20: # You should have received a copy of the GNU General Public License
21: # along with LON-CAPA; if not, write to the Free Software
22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23: #
24: # /home/httpd/html/adm/gpl.txt
25: #
26: # http://www.lon-capa.org/
27: #
28: ######################################################################
29:
30: package Apache::lonmysql;
31:
32: use strict;
33: use DBI;
34: use Apache::lonnet();
35:
36: ######################################################################
37: ######################################################################
38:
39: =pod
40:
41: =head1 Name
42:
43: lonmysql - LONCAPA MySQL utility functions
44:
45: =head1 Synopsis
46:
47: lonmysql contains utility functions to make accessing the mysql loncapa
48: database easier.
49:
50: =head1 Description
51:
52: lonmysql does its best to encapsulate all the database/table functions
53: and provide a common interface. The goal, however, is not to provide
54: a complete reimplementation of the DBI interface. Instead we try to
55: make using mysql as painless as possible.
56:
57: Each table has a numeric ID that is a parameter to most lonmysql functions.
58: The table id is returned by &create_table.
59: If you lose the table id, it is lost forever.
60: The table names in MySQL correspond to
61: $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.$table_id. If the table id
62: is non-numeric, it is assumed to be the full name of a table. If you pass
63: the table id in a form, you MUST ensure that what you send to lonmysql is
64: numeric, otherwise you are opening up all the tables in the MySQL database.
65:
66: =over 4
67:
68: =item Creating a table
69:
70: To create a table, you need a description of its structure. See the entry
71: for &create_table for a description of what is needed.
72:
73: $table_id = &create_table({
74: id => 'tableid', # usually you will use the returned id
75: columns => (
76: { name => 'id',
77: type => 'INT',
78: restrictions => 'NOT NULL',
79: primary_key => 'yes',
80: auto_inc => 'yes'
81: },
82: { name => 'verbage',
83: type => 'TEXT' },
84: ),
85: fulltext => [qw/verbage/],
86: });
87:
88: The above command will create a table with two columns, 'id' and 'verbage'.
89:
90: 'id' will be an integer which is autoincremented and non-null.
91:
92: 'verbage' will be of type 'TEXT', which (conceivably) allows any length
93: text string to be stored. Depending on your intentions for this database,
94: setting restrictions => 'NOT NULL' may help you avoid storing empty data.
95:
96: the fulltext element sets up the 'verbage' column for 'FULLTEXT' searching.
97:
98:
99:
100: =item Storing rows
101:
102: Storing a row in a table requires calling &store_row($table_id,$data)
103:
104: $data is either a hash reference or an array reference. If it is an array
105: reference, the data is passed as is (after being escaped) to the
106: "INSERT INTO <table> VALUES( ... )" SQL command. If $data is a hash reference,
107: the data will be placed into an array in the proper column order for the table
108: and then passed to the database.
109:
110: An example of inserting into the table created above is:
111:
112: &store_row($table_id,[undef,'I am not a crackpot!']);
113:
114: or equivalently,
115:
116: &store_row($table_id,{ verbage => 'I am not a crackpot!'});
117:
118: Since the above table was created with the first column ('id') as
119: autoincrement, providing a value is unnecessary even though the column was
120: marked as 'NOT NULL'.
121:
122:
123:
124: =item Retrieving rows
125:
126: Retrieving rows requires calling get_rows:
127:
128: @row = &Apache::lonmysql::get_rows($table_id,$condition)
129:
130: This results in the query "SELECT * FROM <table> HAVING $condition".
131:
132: @row = &Apache::lonmysql::get_rows($table_id,'id>20');
133:
134: returns all rows with column 'id' greater than 20.
135:
136: =back
137:
138: =cut
139:
140: ######################################################################
141: ######################################################################
142: =pod
143:
144: =head1 Package Variables
145:
146: =over 4
147:
148: =cut
149:
150: ##################################################
151: ##################################################
152:
153: =pod
154:
155: =item %Tables
156:
157: Holds information regarding the currently open connections. Each key
158: in the %Tables hash will be a unique table key. The value associated
159: with a key is a hash reference. Most values are initialized when the
160: table is created.
161:
162: The following entries are allowed in the hash reference:
163:
164: =over 4
165:
166: =item Name
167:
168: Table name.
169:
170: =item Type
171:
172: The type of table, typically MyISAM.
173:
174: =item Row_format
175:
176: Describes how rows should be stored in the table. DYNAMIC or STATIC.
177:
178: =item Create_time
179:
180: The date of the tables creation.
181:
182: =item Update_time
183:
184: The date of the last modification of the table.
185:
186: =item Check_time
187:
188: Usually NULL.
189:
190: =item Avg_row_length
191:
192: The average length of the rows.
193:
194: =item Data_length
195:
196: The length of the data stored in the table (bytes)
197:
198: =item Max_data_length
199:
200: The maximum possible size of the table (bytes).
201:
202: =item Index_length
203:
204: The length of the index for the table (bytes)
205:
206: =item Data_free
207:
208: I have no idea what this is.
209:
210: =item Comment
211:
212: The comment associated with the table.
213:
214: =item Rows
215:
216: The number of rows in the table.
217:
218: =item Auto_increment
219:
220: The value of the next auto_increment field.
221:
222: =item Create_options
223:
224: I have no idea.
225:
226: =item Col_order
227:
228: an array reference which holds the order of columns in the table.
229:
230: =item row_insert_sth
231:
232: The statement handler for row inserts.
233:
234: =item row_replace_sth
235:
236: The statement handler for row inserts.
237:
238: =back
239:
240: Col_order and row_insert_sth are kept internally by lonmysql and are not
241: part of the usual MySQL table information.
242:
243: =cut
244:
245: ##################################################
246: ##################################################
247: my %Tables;
248:
249: ##################################################
250: ##################################################
251: =pod
252:
253: =item $errorstring
254:
255: Holds the last error.
256:
257: =cut
258: ##################################################
259: ##################################################
260: my $errorstring;
261:
262: ##################################################
263: ##################################################
264: =pod
265:
266: =item $debugstring
267:
268: Describes current events within the package.
269:
270: =cut
271: ##################################################
272: ##################################################
273: my $debugstring;
274:
275: ##################################################
276: ##################################################
277:
278: =pod
279:
280: =item $dbh
281:
282: The database handler; The actual connection to MySQL via the perl DBI.
283:
284: =cut
285:
286: ##################################################
287: ##################################################
288: my $dbh;
289:
290: ##################################################
291: ##################################################
292:
293: # End of global variable declarations
294:
295: =pod
296:
297: =back
298:
299: =cut
300:
301: ######################################################################
302: ######################################################################
303:
304: =pod
305:
306: =head1 Internals
307:
308: =over 4
309:
310: =cut
311:
312: ######################################################################
313: ######################################################################
314:
315: =pod
316:
317: =item &connect_to_db()
318:
319: Inputs: none.
320:
321: Returns: undef on error, 1 on success.
322:
323: Checks to make sure the database has been connected to. If not, the
324: connection is established.
325:
326: =cut
327:
328: ###############################
329: sub connect_to_db {
330: return 1 if ($dbh);
331: if (! ($dbh = DBI->connect("DBI:mysql:loncapa","www",
332: $Apache::lonnet::perlvar{'lonSqlAccess'},
333: { RaiseError=>0,PrintError=>0}))) {
334: $debugstring = "Unable to connect to loncapa database.";
335: if (! defined($dbh)) {
336: $debugstring = "Unable to connect to loncapa database.";
337: $errorstring = "dbh was undefined.";
338: } elsif ($dbh->err) {
339: $errorstring = "Connection error: ".$dbh->errstr;
340: }
341: return undef;
342: }
343: $debugstring = "Successfully connected to loncapa database.";
344: return 1;
345: }
346:
347: ###############################
348:
349: =pod
350:
351: =item &disconnect_from_db()
352:
353: Inputs: none.
354:
355: Returns: Always returns 1.
356:
357: Severs the connection to the mysql database.
358:
359: =cut
360:
361: ###############################
362: sub disconnect_from_db {
363: foreach (keys(%Tables)) {
364: # Supposedly, having statement handlers running around after the
365: # database connection has been lost will cause trouble. So we
366: # kill them off just to be sure.
367: if (exists($Tables{$_}->{'row_insert_sth'})) {
368: delete($Tables{$_}->{'row_insert_sth'});
369: }
370: if (exists($Tables{$_}->{'row_replace_sth'})) {
371: delete($Tables{$_}->{'row_replace_sth'});
372: }
373: }
374: $dbh->disconnect if ($dbh);
375: $debugstring = "Disconnected from database.";
376: $dbh = undef;
377: return 1;
378: }
379:
380: ###############################
381:
382: =pod
383:
384: =item &number_of_rows()
385:
386: Input: table identifier
387:
388: Returns: the number of rows in the given table, undef on error.
389:
390: =cut
391:
392: ###############################
393: sub number_of_rows {
394: my ($table_id) = @_;
395: return undef if (! defined(&connect_to_db()));
396: return undef if (! defined(&update_table_info($table_id)));
397: return $Tables{&translate_id($table_id)}->{'Rows'};
398: }
399: ###############################
400:
401: =pod
402:
403: =item &get_dbh()
404:
405: Input: nothing
406:
407: Returns: the database handler, or undef on error.
408:
409: This routine allows the programmer to gain access to the database handler.
410: Be careful.
411:
412: =cut
413:
414: ###############################
415: sub get_dbh {
416: return undef if (! defined(&connect_to_db()));
417: return $dbh;
418: }
419:
420: ###############################
421:
422: =pod
423:
424: =item &get_error()
425:
426: Inputs: none.
427:
428: Returns: The last error reported.
429:
430: =cut
431:
432: ###############################
433: sub get_error {
434: return $errorstring;
435: }
436:
437: ###############################
438:
439: =pod
440:
441: =item &get_debug()
442:
443: Inputs: none.
444:
445: Returns: A string describing the internal state of the lonmysql package.
446:
447: =cut
448:
449: ###############################
450: sub get_debug {
451: return $debugstring;
452: }
453:
454: ###############################
455:
456: =pod
457:
458: =item &update_table_info()
459:
460: Inputs: table id
461:
462: Returns: undef on error, 1 on success.
463:
464: &update_table_info updates the %Tables hash with current information about
465: the given table.
466:
467: The default MySQL table status fields are:
468:
469: Name Type Row_format
470: Max_data_length Index_length Data_free
471: Create_time Update_time Check_time
472: Avg_row_length Data_length Comment
473: Rows Auto_increment Create_options
474:
475: Additionally, "Col_order" is updated as well.
476:
477: =cut
478:
479: ###############################
480: sub update_table_info {
481: my ($table_id) = @_;
482: return undef if (! defined(&connect_to_db()));
483: my $table_status = &check_table($table_id);
484: return undef if (! defined($table_status));
485: if (! $table_status) {
486: $errorstring = "table $table_id does not exist.";
487: return undef;
488: }
489: my $tablename = &translate_id($table_id);
490: #
491: # Get MySQLs table status information.
492: #
493: my @tabledesc = qw/
494: Name Type Row_format Rows Avg_row_length Data_length
495: Max_data_length Index_length Data_free Auto_increment
496: Create_time Update_time Check_time Create_options Comment /;
497: my $db_command = "SHOW TABLE STATUS FROM loncapa LIKE '$tablename'";
498: my $sth = $dbh->prepare($db_command);
499: $sth->execute();
500: if ($sth->err) {
501: $errorstring = "$dbh ATTEMPTED:\n".$db_command."\nRESULTING ERROR:\n".
502: $sth->errstr;
503: &disconnect_from_db();
504: return undef;
505: }
506: #
507: my @info=$sth->fetchrow_array;
508: for (my $i=0;$i<= $#info ; $i++) {
509: $Tables{$tablename}->{$tabledesc[$i]}= $info[$i];
510: }
511: #
512: # Determine the column order
513: #
514: $db_command = "DESCRIBE $tablename";
515: $sth = $dbh->prepare($db_command);
516: $sth->execute();
517: if ($sth->err) {
518: $errorstring = "$dbh ATTEMPTED:\n".$db_command."\nRESULTING ERROR:\n".
519: $sth->errstr;
520: &disconnect_from_db();
521: return undef;
522: }
523: my $aref=$sth->fetchall_arrayref;
524: $Tables{$tablename}->{'Col_order'}=[]; # Clear values.
525: # The values we want are the 'Field' entries, the first column.
526: for (my $i=0;$i< @$aref ; $i++) {
527: push @{$Tables{$tablename}->{'Col_order'}},$aref->[$i]->[0];
528: }
529: #
530: $debugstring = "Retrieved table info for $tablename";
531: return 1;
532: }
533:
534: ###############################
535:
536: =pod
537:
538: =item &create_table()
539:
540: Inputs:
541: table description
542:
543: Input formats:
544:
545: table description = {
546: permanent => 'yes' or 'no',
547: columns => [
548: { name => 'colA',
549: type => mysql type,
550: restrictions => 'NOT NULL' or empty,
551: primary_key => 'yes' or empty,
552: auto_inc => 'yes' or empty,
553: },
554: { name => 'colB',
555: ...
556: },
557: { name => 'colC',
558: ...
559: },
560: ],
561: 'PRIMARY KEY' => (index_col_name,...),
562: KEY => [{ name => 'idx_name',
563: columns => (col1,col2,..),},],
564: INDEX => [{ name => 'idx_name',
565: columns => (col1,col2,..),},],
566: UNIQUE => [{ index => 'yes',
567: name => 'idx_name',
568: columns => (col1,col2,..),},],
569: FULLTEXT => [{ index => 'yes',
570: name => 'idx_name',
571: columns => (col1,col2,..),},],
572:
573: }
574:
575: Returns:
576: undef on error, table id on success.
577:
578: =cut
579:
580: ###############################
581: sub create_table {
582: return undef if (!defined(&connect_to_db($dbh)));
583: my ($table_des)=@_;
584: #
585: # Build request to create table
586: ##################################
587: my @Columns;
588: my $col_des;
589: my $table_id;
590: if (exists($table_des->{'id'})) {
591: $table_id = $table_des->{'id'};
592: } else {
593: $table_id = &get_new_table_id();
594: }
595: my $tablename = &translate_id($table_id);
596: my $request = "CREATE TABLE IF NOT EXISTS ".$tablename." ";
597: foreach my $coldata (@{$table_des->{'columns'}}) {
598: my $column = $coldata->{'name'};
599: next if (! defined($column));
600: $col_des = '';
601: if (lc($coldata->{'type'}) =~ /(enum|set)/) { # 'enum' or 'set'
602: $col_des.=$column." ".$coldata->{'type'}."('".
603: join("', '",@{$coldata->{'values'}})."')";
604: } else {
605: $col_des.=$column." ".$coldata->{'type'};
606: if (exists($coldata->{'size'})) {
607: $col_des.="(".$coldata->{'size'}.")";
608: }
609: }
610: # Modifiers
611: if (exists($coldata->{'restrictions'})){
612: $col_des.=" ".$coldata->{'restrictions'};
613: }
614: if (exists($coldata->{'default'})) {
615: $col_des.=" DEFAULT '".$coldata->{'default'}."'";
616: }
617: $col_des.=' AUTO_INCREMENT' if (exists($coldata->{'auto_inc'}) &&
618: ($coldata->{'auto_inc'} eq 'yes'));
619: $col_des.=' PRIMARY KEY' if (exists($coldata->{'primary_key'}) &&
620: ($coldata->{'primary_key'} eq 'yes'));
621: } continue {
622: # skip blank items.
623: push (@Columns,$col_des) if ($col_des ne '');
624: }
625: if (exists($table_des->{'PRIMARY KEY'})) {
626: push (@Columns,'PRIMARY KEY ('.join(',',@{$table_des->{'PRIMARY KEY'}})
627: .')');
628: }
629: #
630: foreach my $indextype ('KEY','INDEX') {
631: next if (!exists($table_des->{$indextype}));
632: foreach my $indexdescription (@{$table_des->{$indextype}}) {
633: my $text = $indextype.' ';
634: if (exists($indexdescription->{'name'})) {
635: $text .=$indexdescription->{'name'};
636: }
637: $text .= ' ('.join(',',@{$indexdescription->{'columns'}}).')';
638: push (@Columns,$text);
639: }
640: }
641: #
642: foreach my $indextype ('UNIQUE','FULLTEXT') {
643: next if (! exists($table_des->{$indextype}));
644: foreach my $indexdescription (@{$table_des->{$indextype}}) {
645: my $text = $indextype.' ';
646: if (exists($indexdescription->{'index'}) &&
647: $indexdescription->{'index'} eq 'yes') {
648: $text .= 'INDEX ';
649: }
650: if (exists($indexdescription->{'name'})) {
651: $text .=$indexdescription->{'name'};
652: }
653: $text .= ' ('.join(',',@{$indexdescription->{'columns'}}).')';
654: push (@Columns,$text);
655: }
656: }
657: #
658: $request .= "(".join(", ",@Columns).") ";
659: unless($table_des->{'permanent'} eq 'yes') {
660: $request.="COMMENT = 'temporary' ";
661: }
662: $request .= "TYPE=MYISAM";
663: #
664: # Execute the request to create the table
665: #############################################
666: my $count = $dbh->do($request);
667: if (! defined($count)) {
668: $errorstring = "$dbh ATTEMPTED:\n".$request."\nRESULTING ERROR:\n";
669: return undef;
670: }
671: #
672: # Set up the internal bookkeeping
673: #############################################
674: delete($Tables{$tablename}) if (exists($Tables{$tablename}));
675: return undef if (! defined(&update_table_info($table_id)));
676: $debugstring = "Created table $tablename at time ".time.
677: " with request\n$request";
678: return $table_id;
679: }
680:
681: ###############################
682:
683: =pod
684:
685: =item &get_new_table_id()
686:
687: Used internally to prevent table name collisions.
688:
689: =cut
690:
691: ###############################
692: sub get_new_table_id {
693: my $newid = 0;
694: my @tables = &tables_in_db();
695: foreach (@tables) {
696: if (/^$ENV{'user.name'}_$ENV{'user.domain'}_(\d+)$/) {
697: $newid = $1 if ($1 > $newid);
698: }
699: }
700: return ++$newid;
701: }
702:
703: ###############################
704:
705: =pod
706:
707: =item &get_rows()
708:
709: Inputs: $table_id,$condition
710:
711: Returns: undef on error, an array ref to (array of) results on success.
712:
713: Internally, this function does a 'SELECT * FROM table WHERE $condition'.
714: $condition = 'id>0' will result in all rows where column 'id' has a value
715: greater than 0 being returned.
716:
717: =cut
718:
719: ###############################
720: sub get_rows {
721: my ($table_id,$condition) = @_;
722: return undef if (! defined(&connect_to_db()));
723: my $table_status = &check_table($table_id);
724: return undef if (! defined($table_status));
725: if (! $table_status) {
726: $errorstring = "table $table_id does not exist.";
727: return undef;
728: }
729: my $tablename = &translate_id($table_id);
730: my $request;
731: if (defined($condition) && $condition ne '') {
732: $request = 'SELECT * FROM '.$tablename.' WHERE '.$condition;
733: } else {
734: $request = 'SELECT * FROM '.$tablename;
735: $condition = 'no condition';
736: }
737: my $sth=$dbh->prepare($request);
738: $sth->execute();
739: if ($sth->err) {
740: $errorstring = "$dbh ATTEMPTED:\n".$request."\nRESULTING ERROR:\n".
741: $sth->errstr;
742: $debugstring = "Failed to get rows matching $condition";
743: return undef;
744: }
745: $debugstring = "Got rows matching $condition";
746: my @Results = @{$sth->fetchall_arrayref};
747: return @Results;
748: }
749:
750: ###############################
751:
752: =pod
753:
754: =item &store_row()
755:
756: Inputs: table id, row data
757:
758: returns undef on error, 1 on success.
759:
760: =cut
761:
762: ###############################
763: sub store_row {
764: my ($table_id,$rowdata) = @_;
765: #
766: return undef if (! defined(&connect_to_db()));
767: my $table_status = &check_table($table_id);
768: return undef if (! defined($table_status));
769: if (! $table_status) {
770: $errorstring = "table $table_id does not exist.";
771: return undef;
772: }
773: #
774: my $tablename = &translate_id($table_id);
775: #
776: my $sth;
777: if (exists($Tables{$tablename}->{'row_insert_sth'})) {
778: $sth = $Tables{$tablename}->{'row_insert_sth'};
779: } else {
780: # Build the insert statement handler
781: return undef if (! defined(&update_table_info($table_id)));
782: my $insert_request = 'INSERT INTO '.$tablename.' VALUES(';
783: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
784: $insert_request.="?,";
785: }
786: chop $insert_request;
787: $insert_request.=")";
788: $sth=$dbh->prepare($insert_request);
789: $Tables{$tablename}->{'row_insert_sth'}=$sth;
790: }
791: my @Parameters;
792: if (ref($rowdata) eq 'ARRAY') {
793: @Parameters = @$rowdata;
794: } elsif (ref($rowdata) eq 'HASH') {
795: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
796: push(@Parameters,$rowdata->{$_});
797: }
798: }
799: $sth->execute(@Parameters);
800: if ($sth->err) {
801: $errorstring = "$dbh ATTEMPTED insert @Parameters RESULTING ERROR:\n".
802: $sth->errstr;
803: return undef;
804: }
805: $debugstring = "Stored row.";
806: return 1;
807: }
808:
809: ###############################
810:
811: =pod
812:
813: =item &replace_row()
814:
815: Inputs: table id, row data
816:
817: returns undef on error, 1 on success.
818:
819: Acts like &store_row() but uses the 'REPLACE' command instead of 'INSERT'.
820:
821: =cut
822:
823: ###############################
824: sub replace_row {
825: my ($table_id,$rowdata) = @_;
826: #
827: return undef if (! defined(&connect_to_db()));
828: my $table_status = &check_table($table_id);
829: return undef if (! defined($table_status));
830: if (! $table_status) {
831: $errorstring = "table $table_id does not exist.";
832: return undef;
833: }
834: #
835: my $tablename = &translate_id($table_id);
836: #
837: my $sth;
838: if (exists($Tables{$tablename}->{'row_replace_sth'})) {
839: $sth = $Tables{$tablename}->{'row_replace_sth'};
840: } else {
841: # Build the insert statement handler
842: return undef if (! defined(&update_table_info($table_id)));
843: my $replace_request = 'REPLACE INTO '.$tablename.' VALUES(';
844: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
845: $replace_request.="?,";
846: }
847: chop $replace_request;
848: $replace_request.=")";
849: $sth=$dbh->prepare($replace_request);
850: $Tables{$tablename}->{'row_replace_sth'}=$sth;
851: }
852: my @Parameters;
853: if (ref($rowdata) eq 'ARRAY') {
854: @Parameters = @$rowdata;
855: } elsif (ref($rowdata) eq 'HASH') {
856: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
857: push(@Parameters,$rowdata->{$_});
858: }
859: }
860: $sth->execute(@Parameters);
861: if ($sth->err) {
862: $errorstring = "$dbh ATTEMPTED replace @Parameters RESULTING ERROR:\n".
863: $sth->errstr;
864: return undef;
865: }
866: $debugstring = "Stored row.";
867: return 1;
868: }
869:
870: ###########################################
871:
872: =pod
873:
874: =item &tables_in_db()
875:
876: Returns a list containing the names of all the tables in the database.
877: Returns undef on error.
878:
879: =cut
880:
881: ###########################################
882: sub tables_in_db {
883: return undef if (!defined(&connect_to_db()));
884: my $sth=$dbh->prepare('SHOW TABLES');
885: $sth->execute();
886: if ($sth->err) {
887: $errorstring = "$dbh ATTEMPTED:\n".'SHOW TABLES'.
888: "\nRESULTING ERROR:\n".$sth->errstr;
889: return undef;
890: }
891: my $aref = $sth->fetchall_arrayref;
892: my @table_list=();
893: foreach (@$aref) {
894: push @table_list,$_->[0];
895: }
896: $debugstring = "Got list of tables in DB: @table_list";
897: return @table_list;
898: }
899:
900: ###########################################
901:
902: =pod
903:
904: =item &translate_id()
905:
906: Used internally to translate a numeric table id into a MySQL table name.
907: If the input $id contains non-numeric characters it is assumed to have
908: already been translated.
909:
910: Checks are NOT performed to see if the table actually exists.
911:
912: =cut
913:
914: ###########################################
915: sub translate_id {
916: my $id = shift;
917: # id should be a digit. If it is not a digit we assume the given id
918: # is complete and does not need to be translated.
919: return $id if ($id =~ /\D/);
920: return $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.$id;
921: }
922:
923: ###########################################
924:
925: =pod
926:
927: =item &check_table()
928:
929: Input: table id
930:
931: Checks to see if the requested table exists. Returns 0 (no), 1 (yes), or
932: undef (error).
933:
934: =cut
935:
936: ###########################################
937: sub check_table {
938: my $table_id = shift;
939: return undef if (!defined(&connect_to_db()));
940: #
941: $table_id = &translate_id($table_id);
942: my @Table_list = &tables_in_db();
943: my $result = 0;
944: foreach (@Table_list) {
945: if ($_ eq $table_id) {
946: $result = 1;
947: last;
948: }
949: }
950: # If it does not exist, make sure we do not have it listed in %Tables
951: delete($Tables{$table_id}) if ((! $result) && exists($Tables{$table_id}));
952: $debugstring = "check_table returned $result for $table_id";
953: return $result;
954: }
955:
956: ###########################################
957:
958: =pod
959:
960: =item &remove_from_table()
961:
962: Input: $table_id, $column, $value
963:
964: Returns: the number of rows deleted. undef on error.
965:
966: Executes a "delete from $tableid where $column like binary '$value'".
967:
968: =cut
969:
970: ###########################################
971: sub remove_from_table {
972: my ($table_id,$column,$value) = @_;
973: return undef if (!defined(&connect_to_db()));
974: #
975: $table_id = &translate_id($table_id);
976: my $command = 'DELETE FROM '.$table_id.' WHERE '.$dbh->quote($column).
977: " LIKE BINARY ".$dbh->quote($value);
978: my $sth = $dbh->prepare($command);
979: $sth->execute();
980: if ($sth->err) {
981: $errorstring = "ERROR on execution of ".$command."\n".$sth->errstr;
982: return undef;
983: }
984: $debugstring = $command;
985: my $rows = $sth->rows;
986: return $rows;
987: }
988:
989:
990: 1;
991:
992: __END__;
993:
994: =pod
995:
996: =back
997:
998: =cut
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