makes search_related on extended rels without the optimized version work. involves...
[dbsrgits/DBIx-Class-Historic.git] / lib / DBIx / Class / Manual / FAQ.pod
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81791ac3 1=head1 NAME
2
3DBIx::Class::Manual::FAQ - Frequently Asked Questions (in theory)
4
5=head1 DESCRIPTION
6
7This document is intended as an anti-map of the documentation. If you
8know what you want to do, but not how to do it in L<DBIx::Class>, then
b5871402 9look here. It does B<not> contain much code or examples, it just gives
81791ac3 10explanations and pointers to the correct pieces of documentation to
11read.
12
13=head1 FAQs
14
15How Do I:
16
17=head2 Getting started
18
19=over 4
20
21=item .. create a database to use?
22
23First, choose a database. For testing/experimenting, we reccommend
e147365d 24L<DBD::SQLite>, which is a self-contained small database (i.e. all you
c0e1e949 25need to do is to install L<DBD::SQLite> from CPAN, and it works).
81791ac3 26
27Next, spend some time defining which data you need to store, and how
28it relates to the other data you have. For some help on normalisation,
30a3e744 29go to L<http://b62.tripod.com/doc/dbbase.htm>.
81791ac3 30
31Now, decide whether you want to have the database itself be the
32definitive source of information about the data layout, or your
33DBIx::Class schema. If it's the former, look up the documentation for
34your database, eg. L<http://sqlite.org/lang_createtable.html>, on how
35to create tables, and start creating them. For a nice universal
36interface to your database, you can try L<DBI::Shell>. If you decided
37on the latter choice, read the FAQ on setting up your classes
38manually, and the one on creating tables from your schema.
39
40=item .. use DBIx::Class with L<Catalyst>?
41
e147365d 42Install L<Catalyst::Model::DBIC::Schema> from CPAN. See its
81791ac3 43documentation, or below, for further details.
44
45=item .. set up my DBIx::Class classes automatically from my database?
46
e147365d 47Install L<DBIx::Class::Schema::Loader> from CPAN, and read its documentation.
81791ac3 48
49=item .. set up my DBIx::Class classes manually?
50
e147365d 51Look at the L<DBIx::Class::Manual::Example> and come back here if you get lost.
81791ac3 52
53=item .. create my database tables from my DBIx::Class schema?
54
55Create your classes manually, as above. Write a script that calls
56L<DBIx::Class::Schema/deploy>. See there for details, or the
57L<DBIx::Class::Manual::Cookbook>.
58
7c14c3cf 59=item .. store/retrieve Unicode data in my database?
60
61Make sure you database supports Unicode and set the connect
62attributes appropriately - see
63L<DBIx::Class::Manual::Cookbook/Using Unicode>
64
7f613f3a 65=item .. connect to my database?
66
67Once you have created all the appropriate table/source classes, and an
b5871402 68overall L<Schema|DBIx::Class::Schema> class, you can start using
7f613f3a 69them in an application. To do this, you need to create a central
70Schema object, which is used to access all the data in the various
71tables. See L<DBIx::Class::Schema/connect> for details. The actual
72connection does not happen until you actually request data, so don't
73be alarmed if the error from incorrect connection details happens a
74lot later.
75
63426052 76=item .. use DBIx::Class across multiple databases?
77
78If your database server allows you to run querys across multiple
79databases at once, then so can DBIx::Class. All you need to do is make
80sure you write the database name as part of the
81L<DBIx::Class::ResultSource/table> call. Eg:
82
83 __PACKAGE__->table('mydb.mytablename');
84
85And load all the Result classes for both / all databases using one
86L<DBIx::Class::Schema/load_namespaces> call.
87
88=item .. use DBIx::Class across PostgreSQL/DB2/Oracle schemas?
89
90Add the name of the schema to the L<DBIx::Class::ResultSource/table>
91as part of the name, and make sure you give the one user you are going
c0e1e949 92to connect with has permissions to read/write all the schemas/tables as
63426052 93necessary.
7f613f3a 94
40f2550b 95=back
81791ac3 96
97=head2 Relationships
98
99=over 4
100
101=item .. tell DBIx::Class about relationships between my tables?
102
2a2ab6ab 103There are a variety of relationship types that come pre-defined for
e147365d 104you to use. These are all listed in L<DBIx::Class::Relationship>. If
105you need a non-standard type, or more information, look in
106L<DBIx::Class::Relationship::Base>.
81791ac3 107
108=item .. define a one-to-many relationship?
109
e147365d 110This is called a C<has_many> relationship on the one side, and a
111C<belongs_to> relationship on the many side. Currently these need to
112be set up individually on each side. See L<DBIx::Class::Relationship>
113for details.
81791ac3 114
115=item .. define a relationship where this table contains another table's primary key? (foreign key)
116
e147365d 117Create a C<belongs_to> relationship for the field containing the
118foreign key. See L<DBIx::Class::Relationship/belongs_to>.
81791ac3 119
40f2550b 120=item .. define a foreign key relationship where the key field may contain NULL?
81791ac3 121
e147365d 122Just create a C<belongs_to> relationship, as above. If the column is
123NULL then the inflation to the foreign object will not happen. This
124has a side effect of not always fetching all the relevant data, if you
125use a nullable foreign-key relationship in a JOIN, then you probably
126want to set the C<join_type> to C<left>.
81791ac3 127
128=item .. define a relationship where the key consists of more than one column?
129
130Instead of supplying a single column name, all relationship types also
131allow you to supply a hashref containing the condition across which
132the tables are to be joined. The condition may contain as many fields
133as you like. See L<DBIx::Class::Relationship::Base>.
134
d22aaf08 135=item .. define a relationship across an intermediate table? (many-to-many)
81791ac3 136
137Read the documentation on L<DBIx::Class::Relationship/many_to_many>.
138
2a2ab6ab 139=item .. stop DBIx::Class from attempting to cascade deletes on my has_many and might_have relationships?
81791ac3 140
141By default, DBIx::Class cascades deletes and updates across
2a2ab6ab 142C<has_many> and C<might_have> relationships. You can disable this
143behaviour on a per-relationship basis by supplying
144C<< cascade_delete => 0 >> in the relationship attributes.
145
146The cascaded operations are performed after the requested delete or
147update, so if your database has a constraint on the relationship, it
148will have deleted/updated the related records or raised an exception
149before DBIx::Class gets to perform the cascaded operation.
150
151See L<DBIx::Class::Relationship>.
81791ac3 152
153=item .. use a relationship?
154
e147365d 155Use its name. An accessor is created using the name. See examples in
156L<DBIx::Class::Manual::Cookbook/Using relationships>.
81791ac3 157
158=back
159
160=head2 Searching
161
162=over 4
163
164=item .. search for data?
165
c0e1e949 166Create a C<$schema> object, as mentioned above in L</.. connect to my
167database?>. Find the
168L<ResultSet|DBIx::Class::Manual::Glossary/ResultSet> that you want to
169search in, by calling C<< $schema->resultset('MySource') >> and call
170C<search> on it. See L<DBIx::Class::ResultSet/search>.
7f613f3a 171
81791ac3 172=item .. search using database functions?
173
7f613f3a 174Supplying something like:
175
176 ->search({'mydatefield' => 'now()'})
177
178to search, will probably not do what you expect. It will quote the
179text "now()", instead of trying to call the function. To provide
180literal, unquoted text you need to pass in a scalar reference, like
181so:
182
183 ->search({'mydatefield' => \'now()'})
184
81791ac3 185=item .. sort the results of my search?
186
e147365d 187Supply a list of columns you want to sort by to the C<order_by>
188attribute. See L<DBIx::Class::ResultSet/order_by>.
7f613f3a 189
190=item .. sort my results based on fields I've aliased using C<as>?
191
6aafb6a6 192You didn't alias anything, since L<as|DBIx::Class::ResultSet/as>
193B<has nothing to do> with the produced SQL. See
194L<DBIx::Class::ResultSet/select> for details.
7f613f3a 195
81791ac3 196=item .. group the results of my search?
197
7f613f3a 198Supply a list of columns you want to group on, to the C<group_by>
199attribute, see L<DBIx::Class::ResultSet/group_by>.
200
201=item .. group my results based on fields I've aliased using C<as>?
202
6aafb6a6 203You don't. See the explanation on ordering by an alias above.
b5871402 204
81791ac3 205=item .. filter the results of my search?
206
b5871402 207The first argument to C<search> is a hashref of accessor names and
208values to filter them by, for example:
209
36d41f4c 210 ->search({'created_time' => { '>=', '2006-06-01 00:00:00' } })
b5871402 211
f6a14bd4 212Note that to use a function here you need to make it a scalar
213reference:
b5871402 214
f6a14bd4 215 ->search({'created_time' => { '>=', \'yesterday()' } })
b5871402 216
81791ac3 217=item .. search in several tables simultaneously?
218
b5871402 219To search in two related tables, you first need to set up appropriate
220relationships between their respective classes. When searching you
221then supply the name of the relationship to the C<join> attribute in
222your search, for example when searching in the Books table for all the
223books by the author "Fred Bloggs":
224
36d41f4c 225 ->search({'authors.name' => 'Fred Bloggs'}, { join => 'authors' })
b5871402 226
227The type of join created in your SQL depends on the type of
228relationship between the two tables, see L<DBIx::Class::Relationship>
229for the join used by each relationship.
230
7f613f3a 231=item .. create joins with conditions other than column equality?
232
b5871402 233Currently, L<DBIx::Class> can only create join conditions using
f7a90adc 234equality, so you're probably better off creating a C<view> in your
e147365d 235database, and using that as your source. A C<view> is a stored SQL
236query, which can be accessed similarly to a table, see your database
f7a90adc 237documentation for details.
b5871402 238
1c133e22 239=item .. search with an SQL function on the left hand side?
240
b1d821de 241To use an SQL function on the left hand side of a comparison you currently need
242to resort to literal SQL:
1c133e22 243
b1d821de 244 ->search( \[ 'YEAR(date_of_birth) = ?', [ plain_value => 1979 ] ] );
49187c4f 245
0a7ed5b0 246Note: the C<plain_value> string in the C<< [ plain_value => 1979 ] >> part
247should be either the same as the name of the column (do this if the type of the
b1d821de 248return value of the function is the same as the type of the column) or in the
249case of a function it's currently treated as a dummy string (it is a good idea
250to use C<plain_value> or something similar to convey intent). The value is
251currently only significant when handling special column types (BLOBs, arrays,
252etc.), but this may change in the future.
1c133e22 253
81791ac3 254=item .. find more help on constructing searches?
255
256Behind the scenes, DBIx::Class uses L<SQL::Abstract> to help construct
e147365d 257its SQL searches. So if you fail to find help in the
81791ac3 258L<DBIx::Class::Manual::Cookbook>, try looking in the SQL::Abstract
259documentation.
260
f4db0d90 261=item .. make searches in Oracle (10gR2 and newer) case-insensitive?
262
263To make Oracle behave like most RDBMS use on_connect_do to issue
264alter session statements on database connection establishment:
265
266 ->on_connect_do("ALTER SESSION SET NLS_COMP = 'LINGUISTIC'");
267 ->on_connect_do("ALTER SESSION SET NLS_SORT = '<NLS>_CI'");
268 e.g.
269 ->on_connect_do("ALTER SESSION SET NLS_SORT = 'BINARY_CI'");
270 ->on_connect_do("ALTER SESSION SET NLS_SORT = 'GERMAN_CI'");
271
272
81791ac3 273=back
274
275=head2 Fetching data
276
277=over 4
278
d6702eab 279=item .. fetch as much data as possible in as few select calls as possible?
81791ac3 280
b5871402 281See the prefetch examples in the L<Cookbook|DBIx::Class::Manual::Cookbook>.
81791ac3 282
d6702eab 283=item .. fetch a whole column of data instead of a row?
284
40f2550b 285Call C<get_column> on a L<DBIx::Class::ResultSet>. This returns a
286L<DBIx::Class::ResultSetColumn>. See its documentation and the
d6702eab 287L<Cookbook|DBIx::Class::Manual::Cookbook> for details.
288
1697e138 289=item .. fetch a formatted column?
290
291In your table schema class, create a "private" column accessor with:
292
2acfa83c 293 __PACKAGE__->add_columns(my_column => { accessor => '_hidden_my_column' });
1697e138 294
295Then, in the same class, implement a subroutine called "my_column" that
296fetches the real value and does the formatting you want.
297
c0e1e949 298See the L<Cookbook|DBIx::Class::Manual::Cookbook> for more details.
1697e138 299
2486df86 300=item .. fetch a single (or topmost) row?
301
c0e1e949 302Use the L<DBIx::Class::ResultSet/rows> and
303L<DBIx::Class::ResultSet/order_by> attributes to order your data and
304pick off a single row.
305
306See also L<DBIx::Class::Manual::Cookbook/Retrieve_one_and_only_one_row_from_a_resultset>.
2486df86 307
38fc8cf6 308A less readable way is to ask a regular search to return 1 row, using
309L<DBIx::Class::ResultSet/slice>:
2486df86 310
2a2ab6ab 311 ->search->(undef, { order_by => "id DESC" })->slice(0)
2486df86 312
38fc8cf6 313which (if supported by the database) will use LIMIT/OFFSET to hint to the
314database that we really only need one row. This can result in a significant
315speed improvement. The method using L<DBIx::Class::ResultSet/single> mentioned
316in the cookbook can do the same if you pass a C<rows> attribute to the search.
2486df86 317
aefa6508 318=item .. refresh a row from storage?
319
c0e1e949 320Use L<DBIx::Class::Row/discard_changes>.
aefa6508 321
322 $row->discard_changes
323
324Discarding changes and refreshing from storage are two sides fo the same coin. When you
325want to discard your local changes, just re-fetch the row from storage. When you want
326to get a new, fresh copy of the row, just re-fetch the row from storage.
c0e1e949 327L<DBIx::Class::Row/discard_changes> does just that by re-fetching the row from storage
aefa6508 328using the row's primary key.
329
dc64f1b5 330=item .. fetch my data a "page" at a time?
331
332Pass the C<rows> and C<page> attributes to your search, eg:
333
334 ->search({}, { rows => 10, page => 1});
335
336=item .. get a count of all rows even when paging?
337
338Call C<pager> on the paged resultset, it will return a L<Data::Page>
339object. Calling C<total_entries> on the pager will return the correct
340total.
341
342C<count> on the resultset will only return the total number in the page.
343
81791ac3 344=back
345
81791ac3 346=head2 Inserting and updating data
347
348=over 4
349
b5871402 350=item .. insert a row with an auto incrementing primary key?
351
c0e1e949 352This happens automatically. After
353L<creating|DBIx::Class::ResultSet/create> a row object, the primary
354key value created by your database can be fetched by calling C<id> (or
355the access of your primary key column) on the object.
b5871402 356
357=item .. insert a row with a primary key that uses a sequence?
358
359You need to create a trigger in your database that updates your
c0e1e949 360primary key field from the sequence. To help PK::Auto find the next
361key value, you can tell it the name of the sequence in the
b5871402 362C<column_info> supplied with C<add_columns>.
363
838ef78d 364 ->add_columns({ id => { sequence => 'mysequence', auto_nextval => 1 } });
b5871402 365
81791ac3 366=item .. insert many rows of data efficiently?
367
fd2a5332 368The C<populate> method in L<DBIx::Class::ResultSet> provides
369efficient bulk inserts.
370
c0e1e949 371L<DBIx::Class::Fixtures> provides an alternative way to do this.
372
81791ac3 373=item .. update a collection of rows at the same time?
374
c0e1e949 375Create a resultset using a C<search>, to filter the rows of data you
376would like to update, then call C<update> on the resultset to change all
b5871402 377the rows at once.
378
81791ac3 379=item .. use database functions when updating rows?
380
381=item .. update a column using data from another column?
382
e6600283 383To stop the column name from being quoted, you'll need to tell DBIC
b1d821de 384that the right hand side is an SQL identifier (it will be quoted
e6600283 385properly if you have quoting enabled):
b5871402 386
e6600283 387 ->update({ somecolumn => { -ident => 'othercolumn' } })
b5871402 388
c0e1e949 389This method will not retrieve the new value and put it in your Row
390object. To fetch the new value, use the C<discard_changes> method on
391the Row.
392
393 # will return the scalar reference:
394 $row->somecolumn()
40f2550b 395
c0e1e949 396 # issue a select using the PK to re-fetch the row data:
397 $row->discard_changes();
40f2550b 398
c0e1e949 399 # Now returns the correct new value:
400 $row->somecolumn()
e338dbec 401
c0e1e949 402To update and refresh at once, chain your calls:
40f2550b 403
e6600283 404 $row->update({ 'somecolumn' => { -ident => 'othercolumn' } })->discard_changes;
40f2550b 405
75e75a9f 406=item .. store JSON/YAML in a column and have it deflate/inflate automatically?
1697e138 407
75e75a9f 408You can use L<DBIx::Class::InflateColumn> to accomplish YAML/JSON storage transparently.
409
410If you want to use JSON, then in your table schema class, do the following:
1697e138 411
412 use JSON;
413
414 __PACKAGE__->add_columns(qw/ ... my_column ../)
415 __PACKAGE__->inflate_column('my_column', {
416 inflate => sub { jsonToObj(shift) },
417 deflate => sub { objToJson(shift) },
418 });
419
75e75a9f 420For YAML, in your table schema class, do the following:
421
422 use YAML;
423
424 __PACKAGE__->add_columns(qw/ ... my_column ../)
425 __PACKAGE__->inflate_column('my_column', {
426 inflate => sub { YAML::Load(shift) },
427 deflate => sub { YAML::Dump(shift) },
428 });
429
430This technique is an easy way to store supplemental unstructured data in a table. Be
431careful not to overuse this capability, however. If you find yourself depending more
432and more on some data within the inflated column, then it may be time to factor that
433data out.
434
81791ac3 435=back
436
a14a46e2 437=head2 Custom methods in Result classes
438
439You can add custom methods that do arbitrary things, even to unrelated tables.
440For example, to provide a C<< $book->foo() >> method which searches the
441cd table, you'd could add this to Book.pm:
442
443 sub foo {
444 my ($self, $col_data) = @_;
445 return $self->result_source->schema->resultset('cd')->search($col_data);
446 }
447
448And invoke that on any Book Result object like so:
449
450 my $rs = $book->foo({ title => 'Down to Earth' });
451
452When two tables ARE related, L<DBIx::Class::Relationship::Base> provides many
453methods to find or create data in related tables for you. But if you want to
454write your own methods, you can.
455
456For example, to provide a C<< $book->foo() >> method to manually implement
457what create_related() from L<DBIx::Class::Relationship::Base> does, you could
458add this to Book.pm:
459
460 sub foo {
461 my ($self, $relname, $col_data) = @_;
462 return $self->related_resultset($relname)->create($col_data);
463 }
464
465Invoked like this:
466
467 my $author = $book->foo('author', { name => 'Fred' });
468
81791ac3 469=head2 Misc
470
471=over 4
472
473=item How do I store my own (non-db) data in my DBIx::Class objects?
474
b5871402 475You can add your own data accessors to your classes.
476
b7875f2b 477One method is to use the built in mk_group_accessors (via L<Class::Accessor::Grouped>)
478
479 package MyTable;
480
481 use parent 'DBIx::Class';
482
483 __PACKAGE__->table('foo'); #etc
484 __PACKAGE__->mk_group_accessors('simple' => qw/non_column_data/); # must use simple group
485
486An another method is to use L<Moose> with your L<DBIx::Class> package.
487
488 package MyTable;
489
490 use Moose; # import Moose
40f2550b 491 use Moose::Util::TypeConstraint; # import Moose accessor type constraints
b7875f2b 492
493 extends 'DBIx::Class'; # Moose changes the way we define our parent (base) package
494
495 has 'non_column_data' => ( is => 'rw', isa => 'Str' ); # define a simple attribute
496
497 __PACKAGE__->table('foo'); # etc
498
499With either of these methods the resulting use of the accesssor would be
500
501 my $row;
502
40f2550b 503 # assume that somewhere in here $row will get assigned to a MyTable row
b7875f2b 504
505 $row->non_column_data('some string'); # would set the non_column_data accessor
506
507 # some other stuff happens here
508
509 $row->update(); # would not inline the non_column_data accessor into the update
510
40f2550b 511
f7a90adc 512=item How do I use DBIx::Class objects in my TT templates?
81791ac3 513
e147365d 514Like normal objects, mostly. However you need to watch out for TT
515calling methods in list context. When calling relationship accessors
516you will not get resultsets, but a list of all the related objects.
517
c0e1e949 518Use the L<DBIx::Class::ResultSet/search_rs> method, or the
519relationship accessor methods ending with "_rs" to work around this
520issue.
521
522See also L<DBIx::Class::Relationship/has_many>.
b5871402 523
81791ac3 524=item See the SQL statements my code is producing?
525
c0e1e949 526Set the shell environment variable C<DBIC_TRACE> to a true value.
527
528For more info see L<DBIx::Class::Storage> for details of how
f7a90adc 529to turn on debugging in the environment, pass your own filehandle to
530save debug to, or create your own callback.
b5871402 531
81791ac3 532=item Why didn't my search run any SQL?
533
b5871402 534L<DBIx::Class> runs the actual SQL statement as late as possible, thus
535if you create a resultset using C<search> in scalar context, no query
536is executed. You can create further resultset refinements by calling
537search again or relationship accessors. The SQL query is only run when
e147365d 538you ask the resultset for an actual row object.
81791ac3 539
e4773415 540=item How do I deal with tables that lack a primary key?
541
542If your table lacks a primary key, DBIx::Class can't work out which row
543it should operate on, for example to delete or update. However, a
544UNIQUE constraint on one or more columns allows DBIx::Class to uniquely
545identify the row, so you can tell L<DBIx::Class::ResultSource> these
546columns act as a primary key, even if they don't from the database's
547point of view:
548
549 $resultset->set_primary_key(@column);
550
bc96f260 551=item How do I make my program start faster?
552
553Look at the tips in L<DBIx::Class::Manual::Cookbook/"STARTUP SPEED">
554
555=item How do I reduce the overhead of database queries?
556
557You can reduce the overhead of object creation within L<DBIx::Class>
40f2550b 558using the tips in L<DBIx::Class::Manual::Cookbook/"Skip row object creation for faster results">
bc96f260 559and L<DBIx::Class::Manual::Cookbook/"Get raw data for blindingly fast results">
560
3e89f284 561=item How do I override a run time method (e.g. a relationship accessor)?
562
563If you need access to the original accessor, then you must "wrap around" the original method.
564You can do that either with L<Moose::Manual::MethodModifiers> or L<Class::Method::Modifiers>.
565The code example works for both modules:
566
567 package Your::Schema::Group;
568 use Class::Method::Modifiers;
569
570 # ... declare columns ...
571
572 __PACKAGE__->has_many('group_servers', 'Your::Schema::GroupServer', 'group_id');
573 __PACKAGE__->many_to_many('servers', 'group_servers', 'server');
574
575 # if the server group is a "super group", then return all servers
576 # otherwise return only servers that belongs to the given group
577 around 'servers' => sub {
578 my $orig = shift;
579 my $self = shift;
580
581 return $self->$orig(@_) unless $self->is_super_group;
582 return $self->result_source->schema->resultset('Server')->all;
583 };
584
585If you just want to override the original method, and don't care about the data
586from the original accessor, then you have two options. Either use
587L<Method::Signatures::Simple> that does most of the work for you, or do
588it the "dirty way".
589
590L<Method::Signatures::Simple> way:
591
592 package Your::Schema::Group;
593 use Method::Signatures::Simple;
594
595 # ... declare columns ...
596
597 __PACKAGE__->has_many('group_servers', 'Your::Schema::GroupServer', 'group_id');
598 __PACKAGE__->many_to_many('servers', 'group_servers', 'server');
599
600 # The method keyword automatically injects the annoying my $self = shift; for you.
601 method servers {
602 return $self->result_source->schema->resultset('Server')->search({ ... });
603 }
604
605The dirty way:
606
607 package Your::Schema::Group;
608 use Sub::Name;
609
610 # ... declare columns ...
611
612 __PACKAGE__->has_many('group_servers', 'Your::Schema::GroupServer', 'group_id');
613 __PACKAGE__->many_to_many('servers', 'group_servers', 'server');
614
615 *servers = subname servers => sub {
616 my $self = shift;
617 return $self->result_source->schema->resultset('Server')->search({ ... });
618 };
619
81791ac3 620=back
462bb847 621
622=head2 Notes for CDBI users
623
624=over 4
625
626=item Is there a way to make an object auto-stringify itself as a
627particular column or group of columns (a-la cdbi Stringfy column
628group, or stringify_self method) ?
629
c6d52fe4 630See L<DBIx::Class::Manual::Cookbook/Stringification>
462bb847 631
632=back
acdda5b2 633
634=head2 Troubleshooting
635
636=over 4
637
638=item Help, I can't connect to postgresql!
639
640If you get an error such as:
641
642 DBI connect('dbname=dbic','user',...) failed: could not connect to server:
643 No such file or directory Is the server running locally and accepting
644 connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
645
646Likely you have/had two copies of postgresql installed simultaneously, the
647second one will use a default port of 5433, while L<DBD::Pg> is compiled with a
648default port of 5432.
649
8f97b72b 650You can change the port setting in C<postgresql.conf>.
acdda5b2 651
e416146e 652=item I've lost or forgotten my mysql password
653
654Stop mysqld and restart it with the --skip-grant-tables option.
655
656Issue the following statements in the mysql client.
657
658 UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
659 FLUSH PRIVILEGES;
660
661Restart mysql.
662
663Taken from:
664
665L<http://dev.mysql.com/doc/refman/5.1/en/resetting-permissions.html>.
666
acdda5b2 667=back