1 package DBIx::Class::Storage::DBI::MSSQL;
6 use base qw/DBIx::Class::Storage::DBI/;
11 __PACKAGE__->mk_group_accessors(simple => qw/
12 _identity _identity_method
15 __PACKAGE__->sql_maker_class('DBIx::Class::SQLAHacks::MSSQL');
17 sub _set_identity_insert {
18 my ($self, $table) = @_;
21 'SET IDENTITY_INSERT %s ON',
22 $self->sql_maker->_quote ($table),
25 my $dbh = $self->_get_dbh;
26 eval { $dbh->do ($sql) };
28 $self->throw_exception (sprintf "Error executing '%s': %s",
35 sub _unset_identity_insert {
36 my ($self, $table) = @_;
39 'SET IDENTITY_INSERT %s OFF',
40 $self->sql_maker->_quote ($table),
43 my $dbh = $self->_get_dbh;
49 my ($source, $cols, $data) = @_;
51 my $is_identity_insert = (List::Util::first
52 { $source->column_info ($_)->{is_auto_increment} }
58 if ($is_identity_insert) {
59 $self->_set_identity_insert ($source->name);
62 $self->next::method(@_);
64 if ($is_identity_insert) {
65 $self->_unset_identity_insert ($source->name);
69 # support MSSQL GUID column types
73 my ($source, $to_insert) = @_;
75 my $supplied_col_info = $self->_resolve_column_info($source, [keys %$to_insert] );
78 my @pk_cols = $source->primary_columns;
80 @pk_cols{@pk_cols} = ();
83 $source->column_info($_)->{data_type}
85 $source->column_info($_)->{data_type} =~ /^uniqueidentifier/i
88 my @auto_guids = grep {
89 $source->column_info($_)->{data_type}
91 $source->column_info($_)->{data_type} =~ /^uniqueidentifier/i
93 $source->column_info($_)->{auto_nextval}
94 } grep { not exists $pk_cols{$_} } $source->columns;
97 grep { not exists $to_insert->{$_} } (@pk_guids, @auto_guids);
99 my $updated_cols = {};
101 for my $guid_col (@get_guids_for) {
102 my ($new_guid) = $self->_get_dbh->selectrow_array('SELECT NEWID()');
103 $updated_cols->{$guid_col} = $to_insert->{$guid_col} = $new_guid;
106 my $is_identity_insert = (List::Util::first { $_->{is_auto_increment} } (values %$supplied_col_info) )
110 if ($is_identity_insert) {
111 $self->_set_identity_insert ($source->name);
114 $updated_cols = { %$updated_cols, %{ $self->next::method(@_) } };
116 if ($is_identity_insert) {
117 $self->_unset_identity_insert ($source->name);
121 return $updated_cols;
124 sub _prep_for_execute {
126 my ($op, $extra_bind, $ident, $args) = @_;
128 # cast MONEY values properly
129 if ($op eq 'insert' || $op eq 'update') {
130 my $fields = $args->[0];
132 for my $col (keys %$fields) {
133 # $ident is a result source object with INSERT/UPDATE ops
134 if ($ident->column_info ($col)->{data_type}
136 $ident->column_info ($col)->{data_type} =~ /^money\z/i) {
137 my $val = $fields->{$col};
138 $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
143 my ($sql, $bind) = $self->next::method (@_);
145 if ($op eq 'insert') {
146 $sql .= ';SELECT SCOPE_IDENTITY()';
150 return ($sql, $bind);
157 my ($rv, $sth, @bind) = $self->dbh_do($self->can('_dbh_execute'), @_);
159 if ($op eq 'insert') {
161 # this should bring back the result of SELECT SCOPE_IDENTITY() we tacked
162 # on in _prep_for_execute above
163 my ($identity) = eval { $sth->fetchrow_array };
165 # SCOPE_IDENTITY failed, but we can do something else
166 if ( (! $identity) && $self->_identity_method) {
167 ($identity) = $self->_dbh->selectrow_array(
168 'select ' . $self->_identity_method
172 $self->_identity($identity);
176 return wantarray ? ($rv, $sth, @bind) : $rv;
179 sub last_insert_id { shift->_identity }
182 # MSSQL is retarded wrt ordered subselects. One needs to add a TOP
183 # to *all* subqueries, but one also can't use TOP 100 PERCENT
184 # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
186 sub _select_args_to_query {
189 my ($sql, $prep_bind, @rest) = $self->next::method (@_);
191 # see if this is an ordered subquery
193 if ( scalar $self->_parse_order_by ($attrs->{order_by}) ) {
194 $self->throw_exception(
195 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL
196 ') unless $attrs->{unsafe_subselect_ok};
198 $sql =~ s/^ \s* SELECT \s/SELECT TOP $max /xi;
202 ? ($sql, $prep_bind, @rest)
203 : \[ "($sql)", @$prep_bind ]
208 # savepoint syntax is the same as in Sybase ASE
211 my ($self, $name) = @_;
213 $self->_get_dbh->do("SAVE TRANSACTION $name");
216 # A new SAVE TRANSACTION with the same name releases the previous one.
217 sub _svp_release { 1 }
220 my ($self, $name) = @_;
222 $self->_get_dbh->do("ROLLBACK TRANSACTION $name");
225 sub build_datetime_parser {
227 my $type = "DateTime::Format::Strptime";
229 $self->throw_exception("Couldn't load ${type}: $@") if $@;
230 return $type->new( pattern => '%Y-%m-%d %H:%M:%S' ); # %F %T
233 sub sqlt_type { 'SQLServer' }
235 sub _get_mssql_version {
238 my $data = $self->_get_dbh->selectrow_hashref('xp_msver ProductVersion');
240 if ($data->{Character_Value} =~ /^(\d+)\./) {
243 $self->throw_exception(q{Your ProductVersion's Character_Value is missing or malformed!});
250 unless ($self->_sql_maker) {
251 unless ($self->{_sql_maker_opts}{limit_dialect}) {
252 my $version = eval { $self->_get_mssql_version; } || 0;
254 $self->{_sql_maker_opts} = {
255 limit_dialect => ($version >= 9 ? 'RowNumberOver' : 'Top'),
256 %{$self->{_sql_maker_opts}||{}}
260 my $maker = $self->next::method (@_);
263 return $self->_sql_maker;
270 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
275 This is the base class for Microsoft SQL Server support, used by
276 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
277 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
279 =head1 IMPLEMENTATION NOTES
281 =head2 IDENTITY information
283 Microsoft SQL Server supports three methods of retrieving the IDENTITY
284 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
285 SCOPE_IDENTITY is used here because it is the safest. However, it must
286 be called is the same execute statement, not just the same connection.
288 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
289 onto each INSERT to accommodate that requirement.
291 C<SELECT @@IDENTITY> can also be used by issuing:
293 $self->_identity_method('@@identity');
295 it will only be used if SCOPE_IDENTITY() fails.
297 This is more dangerous, as inserting into a table with an on insert trigger that
298 inserts into another table with an identity will give erroneous results on
299 recent versions of SQL Server.
301 =head2 identity insert
303 Be aware that we have tried to make things as simple as possible for our users.
304 For MSSQL that means that when a user tries to create a row, while supplying an
305 explicit value for an autoincrementing column, we will try to issue the
306 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
307 $table_name ON>. Unfortunately this operation in MSSQL requires the
308 C<db_ddladmin> privilege, which is normally not included in the standard
311 =head2 Ordered Subselects
313 If you attempted the following query (among many others) in Microsoft SQL
317 prefetch => 'relation',
322 You may be surprised to receive an exception. The reason for this is a quirk
323 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
324 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
325 subselects, and does so automatically when necessary. The list of situations
326 when a subselect is necessary is long and still changes often, so it can not
327 be exhaustively enumerated here. The general rule of thumb is a joined
328 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
329 applied to the left part of the join.
331 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
332 forbid the use of ordered subselects. This breaks a very useful group of
333 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
334 all their relations, no matter how many". While there is a hack which fools
335 the syntax checker, the optimizer may B<still elect to break the subselect>.
336 Testing has determined that while such breakage does occur (the test suite
337 contains an explicit test which demonstrates the problem), it is relative
338 rare. The benefits of ordered subselects are on the other hand too great to be
339 outright disabled for MSSQL.
341 Thus compromise between usability and perfection is the MSSQL-specific
342 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
343 It is deliberately not possible to set this on the Storage level, as the user
344 should inspect (and preferably regression-test) the return of every such
345 ResultSet individually. The example above would work if written like:
348 unsafe_subselect_ok => 1,
349 prefetch => 'relation',
354 If it is possible to rewrite the search() in a way that will avoid the need
355 for this flag - you are urged to do so. If DBIC internals insist that an
356 ordered subselect is necessary for an operation, and you believe there is a
357 different/better way to get the same result - please file a bugreport.
361 See L<DBIx::Class/CONTRIBUTORS>.
365 You may distribute this code under the same terms as Perl itself.