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_rno = $self->_sql_server_2005_or_higher;
175 unless (defined $supports_rno) {
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 RNO is implemented.
181 $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
186 return $supports_rno ? 'RowNumberOver' : 'Top';
192 my $dbh = $self->_dbh or return 0;
194 local $dbh->{RaiseError} = 1;
195 local $dbh->{PrintError} = 0;
198 $dbh->do('select 1');
205 package # hide from PAUSE
206 DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
208 my $datetime_format = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
209 my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
211 my ($datetime_parser, $smalldatetime_parser);
215 require DateTime::Format::Strptime;
216 $datetime_parser ||= DateTime::Format::Strptime->new(
217 pattern => $datetime_format,
220 return $datetime_parser->parse_datetime(shift);
223 sub format_datetime {
225 require DateTime::Format::Strptime;
226 $datetime_parser ||= DateTime::Format::Strptime->new(
227 pattern => $datetime_format,
230 return $datetime_parser->format_datetime(shift);
233 sub parse_smalldatetime {
235 require DateTime::Format::Strptime;
236 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
237 pattern => $smalldatetime_format,
240 return $smalldatetime_parser->parse_datetime(shift);
243 sub format_smalldatetime {
245 require DateTime::Format::Strptime;
246 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
247 pattern => $smalldatetime_format,
250 return $smalldatetime_parser->format_datetime(shift);
257 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
262 This is the base class for Microsoft SQL Server support, used by
263 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
264 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
266 =head1 IMPLEMENTATION NOTES
268 =head2 IDENTITY information
270 Microsoft SQL Server supports three methods of retrieving the IDENTITY
271 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
272 SCOPE_IDENTITY is used here because it is the safest. However, it must
273 be called is the same execute statement, not just the same connection.
275 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
276 onto each INSERT to accommodate that requirement.
278 C<SELECT @@IDENTITY> can also be used by issuing:
280 $self->_identity_method('@@identity');
282 it will only be used if SCOPE_IDENTITY() fails.
284 This is more dangerous, as inserting into a table with an on insert trigger that
285 inserts into another table with an identity will give erroneous results on
286 recent versions of SQL Server.
288 =head2 identity insert
290 Be aware that we have tried to make things as simple as possible for our users.
291 For MSSQL that means that when a user tries to create a row, while supplying an
292 explicit value for an autoincrementing column, we will try to issue the
293 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
294 $table_name ON>. Unfortunately this operation in MSSQL requires the
295 C<db_ddladmin> privilege, which is normally not included in the standard
298 =head2 Ordered Subselects
300 If you attempted the following query (among many others) in Microsoft SQL
304 prefetch => 'relation',
309 You may be surprised to receive an exception. The reason for this is a quirk
310 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
311 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
312 subselects, and does so automatically when necessary. The list of situations
313 when a subselect is necessary is long and still changes often, so it can not
314 be exhaustively enumerated here. The general rule of thumb is a joined
315 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
316 applied to the left part of the join.
318 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
319 forbid the use of ordered subselects. This breaks a very useful group of
320 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
321 all their relations, no matter how many". While there is a hack which fools
322 the syntax checker, the optimizer may B<still elect to break the subselect>.
323 Testing has determined that while such breakage does occur (the test suite
324 contains an explicit test which demonstrates the problem), it is relative
325 rare. The benefits of ordered subselects are on the other hand too great to be
326 outright disabled for MSSQL.
328 Thus compromise between usability and perfection is the MSSQL-specific
329 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
330 It is deliberately not possible to set this on the Storage level, as the user
331 should inspect (and preferably regression-test) the return of every such
332 ResultSet individually. The example above would work if written like:
335 unsafe_subselect_ok => 1,
336 prefetch => 'relation',
341 If it is possible to rewrite the search() in a way that will avoid the need
342 for this flag - you are urged to do so. If DBIC internals insist that an
343 ordered subselect is necessary for an operation, and you believe there is a
344 different/better way to get the same result - please file a bugreport.
348 See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>.
352 You may distribute this code under the same terms as Perl itself.