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 );
14 use List::Util 'first';
17 __PACKAGE__->mk_group_accessors(simple => qw/
18 _identity _identity_method _no_scope_identity_query
21 __PACKAGE__->sql_maker_class('DBIx::Class::SQLMaker::MSSQL');
23 __PACKAGE__->sql_quote_char([qw/[ ]/]);
25 __PACKAGE__->datetime_parser_type (
26 'DBIx::Class::Storage::DBI::MSSQL::DateTime::Format'
29 __PACKAGE__->new_guid('NEWID()');
31 sub _prep_for_execute {
33 my ($op, $ident, $args) = @_;
35 # cast MONEY values properly
36 if ($op eq 'insert' || $op eq 'update') {
37 my $fields = $args->[0];
39 my $colinfo = $ident->columns_info([keys %$fields]);
41 for my $col (keys %$fields) {
42 # $ident is a result source object with INSERT/UPDATE ops
44 $colinfo->{$col}{data_type}
46 $colinfo->{$col}{data_type} =~ /^money\z/i
48 my $val = $fields->{$col};
49 $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
54 my ($sql, $bind) = $self->next::method (@_);
56 # SELECT SCOPE_IDENTITY only works within a statement scope. We
57 # must try to always use this particular idiom first, as it is the
58 # only one that guarantees retrieving the correct id under high
59 # concurrency. When this fails we will fall back to whatever secondary
60 # retrieval method is specified in _identity_method, but at this
61 # point we don't have many guarantees we will get what we expected.
62 # http://msdn.microsoft.com/en-us/library/ms190315.aspx
63 # http://davidhayden.com/blog/dave/archive/2006/01/17/2736.aspx
64 if ($self->_perform_autoinc_retrieval and not $self->_no_scope_identity_query) {
65 $sql .= "\nSELECT SCOPE_IDENTITY()";
74 # always list ctx - we need the $sth
75 my ($rv, $sth, @bind) = $self->next::method(@_);
77 if ($self->_perform_autoinc_retrieval) {
79 # attempt to bring back the result of SELECT SCOPE_IDENTITY() we tacked
80 # on in _prep_for_execute above
83 # we didn't even try on ftds
84 unless ($self->_no_scope_identity_query) {
85 ($identity) = dbic_internal_try { $sth->fetchrow_array };
89 # SCOPE_IDENTITY failed, but we can do something else
90 if ( (! $identity) && $self->_identity_method) {
91 ($identity) = $self->_dbh->selectrow_array(
92 'select ' . $self->_identity_method
96 $self->_identity($identity);
99 return wantarray ? ($rv, $sth, @bind) : $rv;
102 sub last_insert_id { shift->_identity }
105 # MSSQL is retarded wrt ordered subselects. One needs to add a TOP
106 # to *all* subqueries, but one also *can't* use TOP 100 PERCENT
107 # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
109 sub _select_args_to_query {
110 #my ($self, $ident, $select, $cond, $attrs) = @_;
114 my $sql_bind = $self->next::method (@_);
116 # see if this is an ordered subquery
118 $$sql_bind->[0] !~ /^ \s* \( \s* SELECT \s+ TOP \s+ \d+ \s+ /xi
120 scalar $self->_extract_order_criteria ($attrs->{order_by})
122 $self->throw_exception(
123 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL'
124 ) unless $attrs->{unsafe_subselect_ok};
126 $$sql_bind->[0] =~ s/^ \s* \( \s* SELECT (?=\s) / '(SELECT TOP ' . $self->sql_maker->__max_int /exi;
133 # savepoint syntax is the same as in Sybase ASE
135 sub _exec_svp_begin {
136 my ($self, $name) = @_;
138 $self->_dbh->do("SAVE TRANSACTION $name");
141 # A new SAVE TRANSACTION with the same name releases the previous one.
142 sub _exec_svp_release { 1 }
144 sub _exec_svp_rollback {
145 my ($self, $name) = @_;
147 $self->_dbh->do("ROLLBACK TRANSACTION $name");
150 sub sqlt_type { 'SQLServer' }
152 sub sql_limit_dialect {
155 my $supports_rno = 0;
157 if (exists $self->_server_info->{normalized_dbms_version}) {
158 $supports_rno = 1 if $self->_server_info->{normalized_dbms_version} >= 9;
161 # User is connecting via DBD::Sybase and has no permission to run
162 # stored procedures like xp_msver, or version detection failed for some
164 # So, we use a query to check if RNO is implemented.
166 $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
171 return $supports_rno ? 'RowNumberOver' : 'Top';
177 my $dbh = $self->_dbh or return 0;
180 local $dbh->{RaiseError} = 1;
181 local $dbh->{PrintError} = 0;
183 $dbh->do('select 1');
187 # MSSQL is *really* annoying wrt multiple active resultsets,
188 # and this may very well be the reason why the _ping failed
190 # Proactively disconnect, while hiding annoying warnings if the case
193 # < check basic retryability prerequisites (e.g. no txn) >
195 # ->storage->connected()
197 # So if we got here with the in_handler bit set - we won't break
198 # anything by a disconnect
199 if( $self->{_in_do_block_retry_handler} ) {
200 local $SIG{__WARN__} = sigwarn_silencer qr/disconnect invalidates .+? active statement/;
209 package # hide from PAUSE
210 DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
212 my $datetime_format = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
213 my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
215 my ($datetime_parser, $smalldatetime_parser);
219 require DateTime::Format::Strptime;
220 $datetime_parser ||= DateTime::Format::Strptime->new(
221 pattern => $datetime_format,
224 return $datetime_parser->parse_datetime(shift);
227 sub format_datetime {
229 require DateTime::Format::Strptime;
230 $datetime_parser ||= DateTime::Format::Strptime->new(
231 pattern => $datetime_format,
234 return $datetime_parser->format_datetime(shift);
237 sub parse_smalldatetime {
239 require DateTime::Format::Strptime;
240 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
241 pattern => $smalldatetime_format,
244 return $smalldatetime_parser->parse_datetime(shift);
247 sub format_smalldatetime {
249 require DateTime::Format::Strptime;
250 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
251 pattern => $smalldatetime_format,
254 return $smalldatetime_parser->format_datetime(shift);
261 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
266 This is the base class for Microsoft SQL Server support, used by
267 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
268 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
270 =head1 IMPLEMENTATION NOTES
272 =head2 IDENTITY information
274 Microsoft SQL Server supports three methods of retrieving the IDENTITY
275 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
276 SCOPE_IDENTITY is used here because it is the safest. However, it must
277 be called is the same execute statement, not just the same connection.
279 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
280 onto each INSERT to accommodate that requirement.
282 C<SELECT @@IDENTITY> can also be used by issuing:
284 $self->_identity_method('@@identity');
286 it will only be used if SCOPE_IDENTITY() fails.
288 This is more dangerous, as inserting into a table with an on insert trigger that
289 inserts into another table with an identity will give erroneous results on
290 recent versions of SQL Server.
292 =head2 identity insert
294 Be aware that we have tried to make things as simple as possible for our users.
295 For MSSQL that means that when a user tries to create a row, while supplying an
296 explicit value for an autoincrementing column, we will try to issue the
297 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
298 $table_name ON>. Unfortunately this operation in MSSQL requires the
299 C<db_ddladmin> privilege, which is normally not included in the standard
302 =head2 Ordered Subselects
304 If you attempted the following query (among many others) in Microsoft SQL
308 prefetch => 'relation',
313 You may be surprised to receive an exception. The reason for this is a quirk
314 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
315 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
316 subselects, and does so automatically when necessary. The list of situations
317 when a subselect is necessary is long and still changes often, so it can not
318 be exhaustively enumerated here. The general rule of thumb is a joined
319 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
320 applied to the left part of the join.
322 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
323 forbid the use of ordered subselects. This breaks a very useful group of
324 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
325 all their relations, no matter how many". While there is a hack which fools
326 the syntax checker, the optimizer may B<still elect to break the subselect>.
327 Testing has determined that while such breakage does occur (the test suite
328 contains an explicit test which demonstrates the problem), it is relative
329 rare. The benefits of ordered subselects are on the other hand too great to be
330 outright disabled for MSSQL.
332 Thus compromise between usability and perfection is the MSSQL-specific
333 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
334 It is deliberately not possible to set this on the Storage level, as the user
335 should inspect (and preferably regression-test) the return of every such
336 ResultSet individually. The example above would work if written like:
339 unsafe_subselect_ok => 1,
340 prefetch => 'relation',
345 If it is possible to rewrite the search() in a way that will avoid the need
346 for this flag - you are urged to do so. If DBIC internals insist that an
347 ordered subselect is necessary for an operation, and you believe there is a
348 different/better way to get the same result - please file a bugreport.
350 =head1 FURTHER QUESTIONS?
352 Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
354 =head1 COPYRIGHT AND LICENSE
356 This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
357 by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
358 redistribute it and/or modify it under the same terms as the
359 L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.