1 package DBIx::Class::Storage::DBI::MSSQL;
6 use base qw/DBIx::Class::Storage::DBI::UniqueIdentifier/;
9 use List::Util 'first';
12 __PACKAGE__->mk_group_accessors(simple => qw/
13 _identity _identity_method _pre_insert_sql _post_insert_sql
16 __PACKAGE__->sql_maker_class('DBIx::Class::SQLMaker::MSSQL');
18 __PACKAGE__->sql_quote_char([qw/[ ]/]);
20 __PACKAGE__->datetime_parser_type (
21 'DBIx::Class::Storage::DBI::MSSQL::DateTime::Format'
25 __PACKAGE__->new_guid('NEWID()');
27 sub _set_identity_insert {
28 my ($self, $table) = @_;
30 my $stmt = 'SET IDENTITY_INSERT %s %s';
31 $table = $self->sql_maker->_quote($table);
33 $self->_pre_insert_sql (sprintf $stmt, $table, 'ON');
34 $self->_post_insert_sql(sprintf $stmt, $table, 'OFF');
39 my ($source, $cols, $data) = @_;
41 my $is_identity_insert =
42 (first { $_->{is_auto_increment} } values %{ $source->columns_info($cols) } )
47 if ($is_identity_insert) {
48 $self->_set_identity_insert ($source->name);
51 $self->next::method(@_);
56 my ($source, $to_insert) = @_;
58 my $supplied_col_info = $self->_resolve_column_info($source, [keys %$to_insert] );
60 my $is_identity_insert =
61 (first { $_->{is_auto_increment} } values %$supplied_col_info) ? 1 : 0;
63 if ($is_identity_insert) {
64 $self->_set_identity_insert ($source->name);
67 my $updated_cols = $self->next::method(@_);
72 sub _prep_for_execute {
74 my ($op, $ident, $args) = @_;
76 # cast MONEY values properly
77 if ($op eq 'insert' || $op eq 'update') {
78 my $fields = $args->[0];
80 my $colinfo = $ident->columns_info([keys %$fields]);
82 for my $col (keys %$fields) {
83 # $ident is a result source object with INSERT/UPDATE ops
85 $colinfo->{$col}{data_type}
87 $colinfo->{$col}{data_type} =~ /^money\z/i
89 my $val = $fields->{$col};
90 $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
95 my ($sql, $bind) = $self->next::method (@_);
97 if ($op eq 'insert') {
98 if (my $prepend = $self->_pre_insert_sql) {
99 $sql = "${prepend}\n${sql}";
100 $self->_pre_insert_sql(undef);
102 if (my $append = $self->_post_insert_sql) {
103 $sql = "${sql}\n${append}";
104 $self->_post_insert_sql(undef);
106 $sql .= "\nSELECT SCOPE_IDENTITY()";
109 return ($sql, $bind);
116 my ($rv, $sth, @bind) = $self->next::method(@_);
118 if ($op eq 'insert') {
120 # this should bring back the result of SELECT SCOPE_IDENTITY() we tacked
121 # on in _prep_for_execute above
122 my ($identity) = try { $sth->fetchrow_array };
124 # SCOPE_IDENTITY failed, but we can do something else
125 if ( (! $identity) && $self->_identity_method) {
126 ($identity) = $self->_dbh->selectrow_array(
127 'select ' . $self->_identity_method
131 $self->_identity($identity);
135 return wantarray ? ($rv, $sth, @bind) : $rv;
138 sub last_insert_id { shift->_identity }
141 # MSSQL is retarded wrt ordered subselects. One needs to add a TOP
142 # to *all* subqueries, but one also *can't* use TOP 100 PERCENT
143 # http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
145 sub _select_args_to_query {
148 my ($sql, $prep_bind, @rest) = $self->next::method (@_);
150 # see if this is an ordered subquery
153 $sql !~ /^ \s* SELECT \s+ TOP \s+ \d+ \s+ /xi
155 scalar $self->_extract_order_criteria ($attrs->{order_by})
157 $self->throw_exception(
158 'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL
159 ') unless $attrs->{unsafe_subselect_ok};
160 my $max = $self->sql_maker->__max_int;
161 $sql =~ s/^ \s* SELECT \s/SELECT TOP $max /xi;
165 ? ($sql, $prep_bind, @rest)
166 : \[ "($sql)", @$prep_bind ]
171 # savepoint syntax is the same as in Sybase ASE
173 sub _exec_svp_begin {
174 my ($self, $name) = @_;
176 $self->_dbh->do("SAVE TRANSACTION $name");
179 # A new SAVE TRANSACTION with the same name releases the previous one.
180 sub _exec_svp_release { 1 }
182 sub _exec_svp_rollback {
183 my ($self, $name) = @_;
185 $self->_dbh->do("ROLLBACK TRANSACTION $name");
188 sub sqlt_type { 'SQLServer' }
190 sub sql_limit_dialect {
193 my $supports_rno = 0;
195 if (exists $self->_server_info->{normalized_dbms_version}) {
196 $supports_rno = 1 if $self->_server_info->{normalized_dbms_version} >= 9;
199 # User is connecting via DBD::Sybase and has no permission to run
200 # stored procedures like xp_msver, or version detection failed for some
202 # So, we use a query to check if RNO is implemented.
204 $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
209 return $supports_rno ? 'RowNumberOver' : 'Top';
215 my $dbh = $self->_dbh or return 0;
217 local $dbh->{RaiseError} = 1;
218 local $dbh->{PrintError} = 0;
221 $dbh->do('select 1');
228 sub bind_attribute_by_data_type {
229 shift->is_datatype_numeric(shift)
230 ? do { require DBI; DBI::SQL_INTEGER() }
234 package # hide from PAUSE
235 DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
237 my $datetime_format = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
238 my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
240 my ($datetime_parser, $smalldatetime_parser);
244 require DateTime::Format::Strptime;
245 $datetime_parser ||= DateTime::Format::Strptime->new(
246 pattern => $datetime_format,
249 return $datetime_parser->parse_datetime(shift);
252 sub format_datetime {
254 require DateTime::Format::Strptime;
255 $datetime_parser ||= DateTime::Format::Strptime->new(
256 pattern => $datetime_format,
259 return $datetime_parser->format_datetime(shift);
262 sub parse_smalldatetime {
264 require DateTime::Format::Strptime;
265 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
266 pattern => $smalldatetime_format,
269 return $smalldatetime_parser->parse_datetime(shift);
272 sub format_smalldatetime {
274 require DateTime::Format::Strptime;
275 $smalldatetime_parser ||= DateTime::Format::Strptime->new(
276 pattern => $smalldatetime_format,
279 return $smalldatetime_parser->format_datetime(shift);
286 DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
291 This is the base class for Microsoft SQL Server support, used by
292 L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
293 L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
295 =head1 IMPLEMENTATION NOTES
297 =head2 IDENTITY information
299 Microsoft SQL Server supports three methods of retrieving the IDENTITY
300 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
301 SCOPE_IDENTITY is used here because it is the safest. However, it must
302 be called is the same execute statement, not just the same connection.
304 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
305 onto each INSERT to accommodate that requirement.
307 C<SELECT @@IDENTITY> can also be used by issuing:
309 $self->_identity_method('@@identity');
311 it will only be used if SCOPE_IDENTITY() fails.
313 This is more dangerous, as inserting into a table with an on insert trigger that
314 inserts into another table with an identity will give erroneous results on
315 recent versions of SQL Server.
317 =head2 identity insert
319 Be aware that we have tried to make things as simple as possible for our users.
320 For MSSQL that means that when a user tries to create a row, while supplying an
321 explicit value for an autoincrementing column, we will try to issue the
322 appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
323 $table_name ON>. Unfortunately this operation in MSSQL requires the
324 C<db_ddladmin> privilege, which is normally not included in the standard
327 =head2 Ordered Subselects
329 If you attempted the following query (among many others) in Microsoft SQL
333 prefetch => 'relation',
338 You may be surprised to receive an exception. The reason for this is a quirk
339 in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
340 to the way DBIC is built. DBIC can do truly wonderful things with the aid of
341 subselects, and does so automatically when necessary. The list of situations
342 when a subselect is necessary is long and still changes often, so it can not
343 be exhaustively enumerated here. The general rule of thumb is a joined
344 L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
345 applied to the left part of the join.
347 In its "pursuit of standards" Microsft SQL Server goes to great lengths to
348 forbid the use of ordered subselects. This breaks a very useful group of
349 searches like "Give me things number 4 to 6 (ordered by name), and prefetch
350 all their relations, no matter how many". While there is a hack which fools
351 the syntax checker, the optimizer may B<still elect to break the subselect>.
352 Testing has determined that while such breakage does occur (the test suite
353 contains an explicit test which demonstrates the problem), it is relative
354 rare. The benefits of ordered subselects are on the other hand too great to be
355 outright disabled for MSSQL.
357 Thus compromise between usability and perfection is the MSSQL-specific
358 L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
359 It is deliberately not possible to set this on the Storage level, as the user
360 should inspect (and preferably regression-test) the return of every such
361 ResultSet individually. The example above would work if written like:
364 unsafe_subselect_ok => 1,
365 prefetch => 'relation',
370 If it is possible to rewrite the search() in a way that will avoid the need
371 for this flag - you are urged to do so. If DBIC internals insist that an
372 ordered subselect is necessary for an operation, and you believe there is a
373 different/better way to get the same result - please file a bugreport.
377 See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>.
381 You may distribute this code under the same terms as Perl itself.