1 package DBIx::Class::Storage::DBI::MSSQL;
7 DBIx::Class::Storage::DBI::UniqueIdentifier
8 DBIx::Class::Storage::DBI::IdentityInsert
13 use DBIx::Class::_Util qw( dbic_internal_try sigwarn_silencer );
16 __PACKAGE__->mk_group_accessors(simple => qw/
17 _identity _identity_method _no_scope_identity_query
20 __PACKAGE__->sql_maker_class('DBIx::Class::SQLMaker::MSSQL');
22 __PACKAGE__->sql_quote_char([qw/[ ]/]);
24 __PACKAGE__->datetime_parser_type (
25 'DBIx::Class::Storage::DBI::MSSQL::DateTime::Format'
28 __PACKAGE__->new_guid('NEWID()');
30 sub _prep_for_execute {
32 my ($op, $ident, $args) = @_;
34 # cast MONEY values properly
35 if ($op eq 'insert' || $op eq 'update') {
36 my $fields = $args->[0];
38 my $colinfo = $ident->columns_info([keys %$fields]);
40 for my $col (keys %$fields) {
41 # $ident is a result source object with INSERT/UPDATE ops
43 $colinfo->{$col}{data_type}
45 $colinfo->{$col}{data_type} =~ /^money\z/i
47 my $val = $fields->{$col};
48 $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
53 my ($sql, $bind) = $self->next::method (@_);
55 # SELECT SCOPE_IDENTITY only works within a statement scope. We
56 # must try to always use this particular idiom first, as it is the
57 # only one that guarantees retrieving the correct id under high
58 # concurrency. When this fails we will fall back to whatever secondary
59 # retrieval method is specified in _identity_method, but at this
60 # point we don't have many guarantees we will get what we expected.
61 # http://msdn.microsoft.com/en-us/library/ms190315.aspx
62 # http://davidhayden.com/blog/dave/archive/2006/01/17/2736.aspx
63 if ($self->_perform_autoinc_retrieval and not $self->_no_scope_identity_query) {
64 $sql .= "\nSELECT SCOPE_IDENTITY()";
73 # always list ctx - we need the $sth
74 my ($rv, $sth, @bind) = $self->next::method(@_);
76 if ($self->_perform_autoinc_retrieval) {
78 # attempt to bring back the result of SELECT SCOPE_IDENTITY() we tacked
79 # on in _prep_for_execute above
82 # we didn't even try on ftds
83 unless ($self->_no_scope_identity_query) {
84 ($identity) = dbic_internal_try { $sth->fetchrow_array };
88 # SCOPE_IDENTITY failed, but we can do something else
89 if ( (! $identity) && $self->_identity_method) {
90 ($identity) = $self->_dbh->selectrow_array(
91 'select ' . $self->_identity_method
95 $self->_identity($identity);
98 return wantarray ? ($rv, $sth, @bind) : $rv;
101 sub last_insert_id { shift->_identity }
104 # MSSQL is retarded wrt ordered subselects. One needs to add a TOP
105 # to *all* subqueries, but one also *can't* use TOP 100 PERCENT
106 # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
108 sub _select_args_to_query {
109 #my ($self, $ident, $select, $cond, $attrs) = @_;
113 my $sql_bind = $self->next::method (@_);
115 # see if this is an ordered subquery
117 $$sql_bind->[0] !~ /^ \s* \( \s* SELECT \s+ TOP \s+ \d+ \s+ /xi
119 scalar $self->_extract_order_criteria ($attrs->{order_by})
121 $self->throw_exception(
122 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL'
123 ) unless $attrs->{unsafe_subselect_ok};
125 $$sql_bind->[0] =~ s/^ \s* \( \s* SELECT (?=\s) / '(SELECT TOP ' . $self->sql_maker->__max_int /exi;
132 # savepoint syntax is the same as in Sybase ASE
134 sub _exec_svp_begin {
135 my ($self, $name) = @_;
137 $self->_dbh->do("SAVE TRANSACTION $name");
140 # A new SAVE TRANSACTION with the same name releases the previous one.
141 sub _exec_svp_release { 1 }
143 sub _exec_svp_rollback {
144 my ($self, $name) = @_;
146 $self->_dbh->do("ROLLBACK TRANSACTION $name");
149 sub sqlt_type { 'SQLServer' }
151 sub sql_limit_dialect {
154 my $supports_rno = 0;
156 if (exists $self->_server_info->{normalized_dbms_version}) {
157 $supports_rno = 1 if $self->_server_info->{normalized_dbms_version} >= 9;
160 # User is connecting via DBD::Sybase and has no permission to run
161 # stored procedures like xp_msver, or version detection failed for some
163 # So, we use a query to check if RNO is implemented.
165 $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
170 return $supports_rno ? 'RowNumberOver' : 'Top';
176 my $dbh = $self->_dbh or return 0;
179 local $dbh->{RaiseError} = 1;
180 local $dbh->{PrintError} = 0;
182 $dbh->do('select 1');
186 # MSSQL is *really* annoying wrt multiple active resultsets,
187 # and this may very well be the reason why the _ping failed
189 # Proactively disconnect, while hiding annoying warnings if the case
192 # < check basic retryability prerequisites (e.g. no txn) >
194 # ->storage->connected()
196 # So if we got here with the in_handler bit set - we won't break
197 # anything by a disconnect
198 if( $self->{_in_do_block_retry_handler} ) {
199 local $SIG{__WARN__} = sigwarn_silencer qr/disconnect invalidates .+? active statement/;
208 package # hide from PAUSE
209 DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
211 my $datetime_format = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
212 my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
214 my ($datetime_parser, $smalldatetime_parser);
218 require DateTime::Format::Strptime;
219 $datetime_parser ||= DateTime::Format::Strptime->new(
220 pattern => $datetime_format,
223 return $datetime_parser->parse_datetime(shift);
226 sub format_datetime {
228 require DateTime::Format::Strptime;
229 $datetime_parser ||= DateTime::Format::Strptime->new(
230 pattern => $datetime_format,
233 return $datetime_parser->format_datetime(shift);
236 sub parse_smalldatetime {
238 require DateTime::Format::Strptime;
239 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
240 pattern => $smalldatetime_format,
243 return $smalldatetime_parser->parse_datetime(shift);
246 sub format_smalldatetime {
248 require DateTime::Format::Strptime;
249 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
250 pattern => $smalldatetime_format,
253 return $smalldatetime_parser->format_datetime(shift);
260 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
265 This is the base class for Microsoft SQL Server support, used by
266 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
267 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
269 =head1 IMPLEMENTATION NOTES
271 =head2 IDENTITY information
273 Microsoft SQL Server supports three methods of retrieving the IDENTITY
274 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
275 SCOPE_IDENTITY is used here because it is the safest. However, it must
276 be called is the same execute statement, not just the same connection.
278 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
279 onto each INSERT to accommodate that requirement.
281 C<SELECT @@IDENTITY> can also be used by issuing:
283 $self->_identity_method('@@identity');
285 it will only be used if SCOPE_IDENTITY() fails.
287 This is more dangerous, as inserting into a table with an on insert trigger that
288 inserts into another table with an identity will give erroneous results on
289 recent versions of SQL Server.
291 =head2 identity insert
293 Be aware that we have tried to make things as simple as possible for our users.
294 For MSSQL that means that when a user tries to create a row, while supplying an
295 explicit value for an autoincrementing column, we will try to issue the
296 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
297 $table_name ON>. Unfortunately this operation in MSSQL requires the
298 C<db_ddladmin> privilege, which is normally not included in the standard
301 =head2 Ordered Subselects
303 If you attempted the following query (among many others) in Microsoft SQL
307 prefetch => 'relation',
312 You may be surprised to receive an exception. The reason for this is a quirk
313 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
314 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
315 subselects, and does so automatically when necessary. The list of situations
316 when a subselect is necessary is long and still changes often, so it can not
317 be exhaustively enumerated here. The general rule of thumb is a joined
318 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
319 applied to the left part of the join.
321 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
322 forbid the use of ordered subselects. This breaks a very useful group of
323 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
324 all their relations, no matter how many". While there is a hack which fools
325 the syntax checker, the optimizer may B<still elect to break the subselect>.
326 Testing has determined that while such breakage does occur (the test suite
327 contains an explicit test which demonstrates the problem), it is relative
328 rare. The benefits of ordered subselects are on the other hand too great to be
329 outright disabled for MSSQL.
331 Thus compromise between usability and perfection is the MSSQL-specific
332 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
333 It is deliberately not possible to set this on the Storage level, as the user
334 should inspect (and preferably regression-test) the return of every such
335 ResultSet individually. The example above would work if written like:
338 unsafe_subselect_ok => 1,
339 prefetch => 'relation',
344 If it is possible to rewrite the search() in a way that will avoid the need
345 for this flag - you are urged to do so. If DBIC internals insist that an
346 ordered subselect is necessary for an operation, and you believe there is a
347 different/better way to get the same result - please file a bugreport.
349 =head1 FURTHER QUESTIONS?
351 Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
353 =head1 COPYRIGHT AND LICENSE
355 This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
356 by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
357 redistribute it and/or modify it under the same terms as the
358 L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.