1 package DBIx::Class::Storage::DBI::MSSQL;
7 DBIx::Class::Storage::DBI::UniqueIdentifier
8 DBIx::Class::Storage::DBI::IdentityInsert
13 use List::Util 'first';
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 __sql_server_x_or_higher {
31 my ($self, $version) = @_;
33 if (exists $_[0]->_server_info->{normalized_dbms_version}) {
34 if ($_[0]->_server_info->{normalized_dbms_version} >= $version) {
43 sub __offset_bindtype { +{ dbd_attrs => DBI::SQL_INTEGER() } }
44 sub __rows_bindtype { +{ dbd_attrs => DBI::SQL_INTEGER() } }
46 sub _sql_server_2005_or_higher { shift->__sql_server_x_or_higher(9) }
47 sub _sql_server_2012_or_higher { shift->__sql_server_x_or_higher(11) }
49 sub _prep_for_execute {
51 my ($op, $ident, $args) = @_;
53 # cast MONEY values properly
54 if ($op eq 'insert' || $op eq 'update') {
55 my $fields = $args->[0];
57 my $colinfo = $ident->columns_info([keys %$fields]);
59 for my $col (keys %$fields) {
60 # $ident is a result source object with INSERT/UPDATE ops
62 $colinfo->{$col}{data_type}
64 $colinfo->{$col}{data_type} =~ /^money\z/i
66 my $val = $fields->{$col};
67 $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
72 my ($sql, $bind) = $self->next::method (@_);
74 # SELECT SCOPE_IDENTITY only works within a statement scope. We
75 # must try to always use this particular idiom first, as it is the
76 # only one that guarantees retrieving the correct id under high
77 # concurrency. When this fails we will fall back to whatever secondary
78 # retrieval method is specified in _identity_method, but at this
79 # point we don't have many guarantees we will get what we expected.
80 # http://msdn.microsoft.com/en-us/library/ms190315.aspx
81 # http://davidhayden.com/blog/dave/archive/2006/01/17/2736.aspx
82 if ($self->_perform_autoinc_retrieval and not $self->_no_scope_identity_query) {
83 $sql .= "\nSELECT SCOPE_IDENTITY()";
92 # always list ctx - we need the $sth
93 my ($rv, $sth, @bind) = $self->next::method(@_);
95 if ($self->_perform_autoinc_retrieval) {
97 # attempt to bring back the result of SELECT SCOPE_IDENTITY() we tacked
98 # on in _prep_for_execute above
101 # we didn't even try on ftds
102 unless ($self->_no_scope_identity_query) {
103 ($identity) = try { $sth->fetchrow_array };
107 # SCOPE_IDENTITY failed, but we can do something else
108 if ( (! $identity) && $self->_identity_method) {
109 ($identity) = $self->_dbh->selectrow_array(
110 'select ' . $self->_identity_method
114 $self->_identity($identity);
117 return wantarray ? ($rv, $sth, @bind) : $rv;
120 sub last_insert_id { shift->_identity }
123 # MSSQL is retarded wrt ordered subselects. One needs to add a TOP
124 # to *all* subqueries, but one also *can't* use TOP 100 PERCENT
125 # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
127 sub _select_args_to_query {
128 #my ($self, $ident, $select, $cond, $attrs) = @_;
132 my $sql_bind = $self->next::method (@_);
134 # see if this is an ordered subquery
136 $$sql_bind->[0] !~ /^ \s* \( \s* SELECT \s+ TOP \s+ \d+ \s+ /xi
138 scalar $self->_extract_order_criteria ($attrs->{order_by})
140 $self->throw_exception(
141 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL'
142 ) unless $attrs->{unsafe_subselect_ok};
144 $$sql_bind->[0] =~ s/^ \s* \( \s* SELECT (?=\s) / '(SELECT TOP ' . $self->sql_maker->__max_int /exi;
151 # savepoint syntax is the same as in Sybase ASE
153 sub _exec_svp_begin {
154 my ($self, $name) = @_;
156 $self->_dbh->do("SAVE TRANSACTION $name");
159 # A new SAVE TRANSACTION with the same name releases the previous one.
160 sub _exec_svp_release { 1 }
162 sub _exec_svp_rollback {
163 my ($self, $name) = @_;
165 $self->_dbh->do("ROLLBACK TRANSACTION $name");
168 sub sqlt_type { 'SQLServer' }
170 sub sql_limit_dialect {
173 my $supports_ofn = $self->_sql_server_2012_or_higher;
175 unless (defined $supports_ofn) {
176 # User is connecting via DBD::Sybase and has no permission to run
177 # stored procedures like xp_msver, or version detection failed for some
179 # So, we use a query to check if OFN is implemented.
181 $self->_get_dbh->selectrow_array('SELECT 1 ORDER BY 1 OFFSET 0 ROWS');
185 return 'OffsetFetchNext' if $supports_ofn;
187 my $supports_rno = $self->_sql_server_2005_or_higher;
189 unless (defined $supports_rno) {
190 # User is connecting via DBD::Sybase and has no permission to run
191 # stored procedures like xp_msver, or version detection failed for some
193 # So, we use a query to check if RNO is implemented.
195 $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
199 return 'RowNumberOver' if $supports_rno;
207 my $dbh = $self->_dbh or return 0;
209 local $dbh->{RaiseError} = 1;
210 local $dbh->{PrintError} = 0;
213 $dbh->do('select 1');
220 package # hide from PAUSE
221 DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
223 my $datetime_format = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
224 my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
226 my ($datetime_parser, $smalldatetime_parser);
230 require DateTime::Format::Strptime;
231 $datetime_parser ||= DateTime::Format::Strptime->new(
232 pattern => $datetime_format,
235 return $datetime_parser->parse_datetime(shift);
238 sub format_datetime {
240 require DateTime::Format::Strptime;
241 $datetime_parser ||= DateTime::Format::Strptime->new(
242 pattern => $datetime_format,
245 return $datetime_parser->format_datetime(shift);
248 sub parse_smalldatetime {
250 require DateTime::Format::Strptime;
251 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
252 pattern => $smalldatetime_format,
255 return $smalldatetime_parser->parse_datetime(shift);
258 sub format_smalldatetime {
260 require DateTime::Format::Strptime;
261 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
262 pattern => $smalldatetime_format,
265 return $smalldatetime_parser->format_datetime(shift);
272 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
277 This is the base class for Microsoft SQL Server support, used by
278 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
279 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
281 =head1 IMPLEMENTATION NOTES
283 =head2 IDENTITY information
285 Microsoft SQL Server supports three methods of retrieving the IDENTITY
286 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
287 SCOPE_IDENTITY is used here because it is the safest. However, it must
288 be called is the same execute statement, not just the same connection.
290 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
291 onto each INSERT to accommodate that requirement.
293 C<SELECT @@IDENTITY> can also be used by issuing:
295 $self->_identity_method('@@identity');
297 it will only be used if SCOPE_IDENTITY() fails.
299 This is more dangerous, as inserting into a table with an on insert trigger that
300 inserts into another table with an identity will give erroneous results on
301 recent versions of SQL Server.
303 =head2 identity insert
305 Be aware that we have tried to make things as simple as possible for our users.
306 For MSSQL that means that when a user tries to create a row, while supplying an
307 explicit value for an autoincrementing column, we will try to issue the
308 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
309 $table_name ON>. Unfortunately this operation in MSSQL requires the
310 C<db_ddladmin> privilege, which is normally not included in the standard
313 =head2 Ordered Subselects
315 If you attempted the following query (among many others) in Microsoft SQL
319 prefetch => 'relation',
324 You may be surprised to receive an exception. The reason for this is a quirk
325 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
326 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
327 subselects, and does so automatically when necessary. The list of situations
328 when a subselect is necessary is long and still changes often, so it can not
329 be exhaustively enumerated here. The general rule of thumb is a joined
330 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
331 applied to the left part of the join.
333 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
334 forbid the use of ordered subselects. This breaks a very useful group of
335 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
336 all their relations, no matter how many". While there is a hack which fools
337 the syntax checker, the optimizer may B<still elect to break the subselect>.
338 Testing has determined that while such breakage does occur (the test suite
339 contains an explicit test which demonstrates the problem), it is relative
340 rare. The benefits of ordered subselects are on the other hand too great to be
341 outright disabled for MSSQL.
343 Thus compromise between usability and perfection is the MSSQL-specific
344 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
345 It is deliberately not possible to set this on the Storage level, as the user
346 should inspect (and preferably regression-test) the return of every such
347 ResultSet individually. The example above would work if written like:
350 unsafe_subselect_ok => 1,
351 prefetch => 'relation',
356 If it is possible to rewrite the search() in a way that will avoid the need
357 for this flag - you are urged to do so. If DBIC internals insist that an
358 ordered subselect is necessary for an operation, and you believe there is a
359 different/better way to get the same result - please file a bugreport.
363 See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>.
367 You may distribute this code under the same terms as Perl itself.