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} >= $version) {
43 sub _sql_server_2005_or_higher { shift->__sql_server_x_or_higher(9) }
44 sub _sql_server_2012_or_higher { shift->__sql_server_x_or_higher(11) }
46 sub _prep_for_execute {
48 my ($op, $ident, $args) = @_;
50 # cast MONEY values properly
51 if ($op eq 'insert' || $op eq 'update') {
52 my $fields = $args->[0];
54 my $colinfo = $ident->columns_info([keys %$fields]);
56 for my $col (keys %$fields) {
57 # $ident is a result source object with INSERT/UPDATE ops
59 $colinfo->{$col}{data_type}
61 $colinfo->{$col}{data_type} =~ /^money\z/i
63 my $val = $fields->{$col};
64 $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
69 my ($sql, $bind) = $self->next::method (@_);
71 # SELECT SCOPE_IDENTITY only works within a statement scope. We
72 # must try to always use this particular idiom first, as it is the
73 # only one that guarantees retrieving the correct id under high
74 # concurrency. When this fails we will fall back to whatever secondary
75 # retrieval method is specified in _identity_method, but at this
76 # point we don't have many guarantees we will get what we expected.
77 # http://msdn.microsoft.com/en-us/library/ms190315.aspx
78 # http://davidhayden.com/blog/dave/archive/2006/01/17/2736.aspx
79 if ($self->_perform_autoinc_retrieval and not $self->_no_scope_identity_query) {
80 $sql .= "\nSELECT SCOPE_IDENTITY()";
89 # always list ctx - we need the $sth
90 my ($rv, $sth, @bind) = $self->next::method(@_);
92 if ($self->_perform_autoinc_retrieval) {
94 # attempt to bring back the result of SELECT SCOPE_IDENTITY() we tacked
95 # on in _prep_for_execute above
98 # we didn't even try on ftds
99 unless ($self->_no_scope_identity_query) {
100 ($identity) = try { $sth->fetchrow_array };
104 # SCOPE_IDENTITY failed, but we can do something else
105 if ( (! $identity) && $self->_identity_method) {
106 ($identity) = $self->_dbh->selectrow_array(
107 'select ' . $self->_identity_method
111 $self->_identity($identity);
114 return wantarray ? ($rv, $sth, @bind) : $rv;
117 sub last_insert_id { shift->_identity }
120 # MSSQL is retarded wrt ordered subselects. One needs to add a TOP
121 # to *all* subqueries, but one also *can't* use TOP 100 PERCENT
122 # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
124 sub _select_args_to_query {
125 #my ($self, $ident, $select, $cond, $attrs) = @_;
129 my $sql_bind = $self->next::method (@_);
131 # see if this is an ordered subquery
133 $$sql_bind->[0] !~ /^ \s* \( \s* SELECT \s+ TOP \s+ \d+ \s+ /xi
135 scalar $self->_extract_order_criteria ($attrs->{order_by})
137 $self->throw_exception(
138 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL'
139 ) unless $attrs->{unsafe_subselect_ok};
141 $$sql_bind->[0] =~ s/^ \s* \( \s* SELECT (?=\s) / '(SELECT TOP ' . $self->sql_maker->__max_int /exi;
148 # savepoint syntax is the same as in Sybase ASE
150 sub _exec_svp_begin {
151 my ($self, $name) = @_;
153 $self->_dbh->do("SAVE TRANSACTION $name");
156 # A new SAVE TRANSACTION with the same name releases the previous one.
157 sub _exec_svp_release { 1 }
159 sub _exec_svp_rollback {
160 my ($self, $name) = @_;
162 $self->_dbh->do("ROLLBACK TRANSACTION $name");
165 sub sqlt_type { 'SQLServer' }
167 sub sql_limit_dialect {
170 my $supports_rno = $self->_sql_server_2005_or_higher;
172 unless (defined $supports_rno) {
173 # User is connecting via DBD::Sybase and has no permission to run
174 # stored procedures like xp_msver, or version detection failed for some
176 # So, we use a query to check if RNO is implemented.
178 $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
183 return $supports_rno ? 'RowNumberOver' : 'Top';
189 my $dbh = $self->_dbh or return 0;
191 local $dbh->{RaiseError} = 1;
192 local $dbh->{PrintError} = 0;
195 $dbh->do('select 1');
202 package # hide from PAUSE
203 DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
205 my $datetime_format = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
206 my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
208 my ($datetime_parser, $smalldatetime_parser);
212 require DateTime::Format::Strptime;
213 $datetime_parser ||= DateTime::Format::Strptime->new(
214 pattern => $datetime_format,
217 return $datetime_parser->parse_datetime(shift);
220 sub format_datetime {
222 require DateTime::Format::Strptime;
223 $datetime_parser ||= DateTime::Format::Strptime->new(
224 pattern => $datetime_format,
227 return $datetime_parser->format_datetime(shift);
230 sub parse_smalldatetime {
232 require DateTime::Format::Strptime;
233 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
234 pattern => $smalldatetime_format,
237 return $smalldatetime_parser->parse_datetime(shift);
240 sub format_smalldatetime {
242 require DateTime::Format::Strptime;
243 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
244 pattern => $smalldatetime_format,
247 return $smalldatetime_parser->format_datetime(shift);
254 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
259 This is the base class for Microsoft SQL Server support, used by
260 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
261 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
263 =head1 IMPLEMENTATION NOTES
265 =head2 IDENTITY information
267 Microsoft SQL Server supports three methods of retrieving the IDENTITY
268 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
269 SCOPE_IDENTITY is used here because it is the safest. However, it must
270 be called is the same execute statement, not just the same connection.
272 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
273 onto each INSERT to accommodate that requirement.
275 C<SELECT @@IDENTITY> can also be used by issuing:
277 $self->_identity_method('@@identity');
279 it will only be used if SCOPE_IDENTITY() fails.
281 This is more dangerous, as inserting into a table with an on insert trigger that
282 inserts into another table with an identity will give erroneous results on
283 recent versions of SQL Server.
285 =head2 identity insert
287 Be aware that we have tried to make things as simple as possible for our users.
288 For MSSQL that means that when a user tries to create a row, while supplying an
289 explicit value for an autoincrementing column, we will try to issue the
290 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
291 $table_name ON>. Unfortunately this operation in MSSQL requires the
292 C<db_ddladmin> privilege, which is normally not included in the standard
295 =head2 Ordered Subselects
297 If you attempted the following query (among many others) in Microsoft SQL
301 prefetch => 'relation',
306 You may be surprised to receive an exception. The reason for this is a quirk
307 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
308 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
309 subselects, and does so automatically when necessary. The list of situations
310 when a subselect is necessary is long and still changes often, so it can not
311 be exhaustively enumerated here. The general rule of thumb is a joined
312 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
313 applied to the left part of the join.
315 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
316 forbid the use of ordered subselects. This breaks a very useful group of
317 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
318 all their relations, no matter how many". While there is a hack which fools
319 the syntax checker, the optimizer may B<still elect to break the subselect>.
320 Testing has determined that while such breakage does occur (the test suite
321 contains an explicit test which demonstrates the problem), it is relative
322 rare. The benefits of ordered subselects are on the other hand too great to be
323 outright disabled for MSSQL.
325 Thus compromise between usability and perfection is the MSSQL-specific
326 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
327 It is deliberately not possible to set this on the Storage level, as the user
328 should inspect (and preferably regression-test) the return of every such
329 ResultSet individually. The example above would work if written like:
332 unsafe_subselect_ok => 1,
333 prefetch => 'relation',
338 If it is possible to rewrite the search() in a way that will avoid the need
339 for this flag - you are urged to do so. If DBIC internals insist that an
340 ordered subselect is necessary for an operation, and you believe there is a
341 different/better way to get the same result - please file a bugreport.
345 See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>.
349 You may distribute this code under the same terms as Perl itself.