X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FMSSQL.pm;h=fedec7fa423533f1b36c0e65a3d61ee765b92f96;hb=0777ad33930b2c09258f9752e4e76c27ca75f347;hp=fe51f1b85a4b6d61594236299d1ea03c0f4ed285;hpb=5a77aa8ba52c50bdc4291ca22433f9c315234ad2;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Storage/DBI/MSSQL.pm b/lib/DBIx/Class/Storage/DBI/MSSQL.pm
index fe51f1b..fedec7f 100644
--- a/lib/DBIx/Class/Storage/DBI/MSSQL.pm
+++ b/lib/DBIx/Class/Storage/DBI/MSSQL.pm
@@ -3,38 +3,122 @@ package DBIx::Class::Storage::DBI::MSSQL;
 use strict;
 use warnings;
 
-use base qw/DBIx::Class::Storage::DBI::AmbiguousGlob DBIx::Class::Storage::DBI/;
+use base qw/DBIx::Class::Storage::DBI/;
 use mro 'c3';
 
 use List::Util();
 
+__PACKAGE__->mk_group_accessors(simple => qw/
+  _identity _identity_method
+/);
+
 __PACKAGE__->sql_maker_class('DBIx::Class::SQLAHacks::MSSQL');
 
+sub _set_identity_insert {
+  my ($self, $table) = @_;
+
+  my $sql = sprintf (
+    'SET IDENTITY_INSERT %s ON',
+    $self->sql_maker->_quote ($table),
+  );
+
+  my $dbh = $self->_get_dbh;
+  eval { $dbh->do ($sql) };
+  if ($@) {
+    $self->throw_exception (sprintf "Error executing '%s': %s",
+      $sql,
+      $dbh->errstr,
+    );
+  }
+}
+
+sub _unset_identity_insert {
+  my ($self, $table) = @_;
+
+  my $sql = sprintf (
+    'SET IDENTITY_INSERT %s OFF',
+    $self->sql_maker->_quote ($table),
+  );
+
+  my $dbh = $self->_get_dbh;
+  $dbh->do ($sql);
+}
+
 sub insert_bulk {
   my $self = shift;
   my ($source, $cols, $data) = @_;
 
-  my $identity_insert = 0;
+  my $is_identity_insert = (List::Util::first
+      { $source->column_info ($_)->{is_auto_increment} }
+      (@{$cols})
+  )
+     ? 1
+     : 0;
 
-  COLUMNS:
-  foreach my $col (@{$cols}) {
-    if ($source->column_info($col)->{is_auto_increment}) {
-      $identity_insert = 1;
-      last COLUMNS;
-    }
+  if ($is_identity_insert) {
+     $self->_set_identity_insert ($source->name);
   }
 
-  if ($identity_insert) {
-    my $table = $source->from;
-    $self->dbh->do("SET IDENTITY_INSERT $table ON");
+  $self->next::method(@_);
+
+  if ($is_identity_insert) {
+     $self->_unset_identity_insert ($source->name);
   }
+}
 
-  $self->next::method(@_);
+# support MSSQL GUID column types
+
+sub insert {
+  my $self = shift;
+  my ($source, $to_insert) = @_;
+
+  my $supplied_col_info = $self->_resolve_column_info($source, [keys %$to_insert] );
 
-  if ($identity_insert) {
-    my $table = $source->from;
-    $self->dbh->do("SET IDENTITY_INSERT $table OFF");
+  my %guid_cols;
+  my @pk_cols = $source->primary_columns;
+  my %pk_cols;
+  @pk_cols{@pk_cols} = ();
+
+  my @pk_guids = grep {
+    $source->column_info($_)->{data_type}
+    &&
+    $source->column_info($_)->{data_type} =~ /^uniqueidentifier/i
+  } @pk_cols;
+
+  my @auto_guids = grep {
+    $source->column_info($_)->{data_type}
+    &&
+    $source->column_info($_)->{data_type} =~ /^uniqueidentifier/i
+    &&
+    $source->column_info($_)->{auto_nextval}
+  } grep { not exists $pk_cols{$_} } $source->columns;
+
+  my @get_guids_for =
+    grep { not exists $to_insert->{$_} } (@pk_guids, @auto_guids);
+
+  my $updated_cols = {};
+
+  for my $guid_col (@get_guids_for) {
+    my ($new_guid) = $self->_get_dbh->selectrow_array('SELECT NEWID()');
+    $updated_cols->{$guid_col} = $to_insert->{$guid_col} = $new_guid;
+  }
+
+  my $is_identity_insert = (List::Util::first { $_->{is_auto_increment} } (values %$supplied_col_info) )
+     ? 1
+     : 0;
+
+  if ($is_identity_insert) {
+     $self->_set_identity_insert ($source->name);
   }
+
+  $updated_cols = { %$updated_cols, %{ $self->next::method(@_) } };
+
+  if ($is_identity_insert) {
+     $self->_unset_identity_insert ($source->name);
+  }
+
+
+  return $updated_cols;
 }
 
 sub _prep_for_execute {
@@ -44,10 +128,12 @@ sub _prep_for_execute {
 # cast MONEY values properly
   if ($op eq 'insert' || $op eq 'update') {
     my $fields = $args->[0];
-    my $col_info = $self->_resolve_column_info($ident, [keys %$fields]);
 
     for my $col (keys %$fields) {
-      if ($col_info->{$col}{data_type} =~ /^money\z/i) {
+      # $ident is a result source object with INSERT/UPDATE ops
+      if ($ident->column_info ($col)->{data_type}
+         &&
+         $ident->column_info ($col)->{data_type} =~ /^money\z/i) {
         my $val = $fields->{$col};
         $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
       }
@@ -59,14 +145,6 @@ sub _prep_for_execute {
   if ($op eq 'insert') {
     $sql .= ';SELECT SCOPE_IDENTITY()';
 
-    my $col_info = $self->_resolve_column_info($ident, [map $_->[0], @{$bind}]);
-    if (List::Util::first { $_->{is_auto_increment} } (values %$col_info) ) {
-
-      my $table = $ident->from;
-      my $identity_insert_on = "SET IDENTITY_INSERT $table ON";
-      my $identity_insert_off = "SET IDENTITY_INSERT $table OFF";
-      $sql = "$identity_insert_on; $sql; $identity_insert_off";
-    }
   }
 
   return ($sql, $bind);
@@ -77,16 +155,72 @@ sub _execute {
   my ($op) = @_;
 
   my ($rv, $sth, @bind) = $self->dbh_do($self->can('_dbh_execute'), @_);
+
   if ($op eq 'insert') {
-    $self->{_scope_identity} = $sth->fetchrow_array;
+
+    # this should bring back the result of SELECT SCOPE_IDENTITY() we tacked
+    # on in _prep_for_execute above
+    my ($identity) = eval { $sth->fetchrow_array };
+
+    # SCOPE_IDENTITY failed, but we can do something else
+    if ( (! $identity) && $self->_identity_method) {
+      ($identity) = $self->_dbh->selectrow_array(
+        'select ' . $self->_identity_method
+      );
+    }
+
+    $self->_identity($identity);
     $sth->finish;
   }
 
   return wantarray ? ($rv, $sth, @bind) : $rv;
 }
 
+sub last_insert_id { shift->_identity }
+
+#
+# MSSQL is retarded wrt ordered subselects. One needs to add a TOP
+# to *all* subqueries, but one also can't use TOP 100 PERCENT
+# http://sqladvice.com/forums/permalink/18496/22931/ShowThread.aspx#22931
+#
+sub _select_args_to_query {
+  my $self = shift;
+
+  my ($sql, $prep_bind, @rest) = $self->next::method (@_);
+
+  # see if this is an ordered subquery
+  my $attrs = $_[3];
+  if ( scalar $self->_parse_order_by ($attrs->{order_by}) ) {
+    $self->throw_exception(
+      'An ordered subselect encountered - this is not safe! Please see "Ordered Subselects" in DBIx::Class::Storage::DBI::MSSQL
+    ') unless $attrs->{unsafe_subselect_ok};
+    my $max = 2 ** 32;
+    $sql =~ s/^ \s* SELECT \s/SELECT TOP $max /xi;
+  }
+
+  return wantarray
+    ? ($sql, $prep_bind, @rest)
+    : \[ "($sql)", @$prep_bind ]
+  ;
+}
+
+
+# savepoint syntax is the same as in Sybase ASE
+
+sub _svp_begin {
+  my ($self, $name) = @_;
+
+  $self->_get_dbh->do("SAVE TRANSACTION $name");
+}
 
-sub last_insert_id { shift->{_scope_identity} }
+# A new SAVE TRANSACTION with the same name releases the previous one.
+sub _svp_release { 1 }
+
+sub _svp_rollback {
+  my ($self, $name) = @_;
+
+  $self->_get_dbh->do("ROLLBACK TRANSACTION $name");
+}
 
 sub build_datetime_parser {
   my $self = shift;
@@ -98,14 +232,35 @@ sub build_datetime_parser {
 
 sub sqlt_type { 'SQLServer' }
 
-sub _sql_maker_opts {
-  my ( $self, $opts ) = @_;
+sub _get_mssql_version {
+  my $self = shift;
+
+  my $data = $self->_get_dbh->selectrow_hashref('xp_msver ProductVersion');
 
-  if ( $opts ) {
-    $self->{_sql_maker_opts} = { %$opts };
+  if ($data->{Character_Value} =~ /^(\d+)\./) {
+    return $1;
+  } else {
+    $self->throw_exception(q{Your ProductVersion's Character_Value is missing or malformed!});
   }
+}
+
+sub sql_maker {
+  my $self = shift;
 
-  return { limit_dialect => 'Top', %{$self->{_sql_maker_opts}||{}} };
+  unless ($self->_sql_maker) {
+    unless ($self->{_sql_maker_opts}{limit_dialect}) {
+      my $version = eval { $self->_get_mssql_version; } || 0;
+
+      $self->{_sql_maker_opts} = {
+        limit_dialect => ($version >= 9 ? 'RowNumberOver' : 'Top'),
+        %{$self->{_sql_maker_opts}||{}}
+      };
+    }
+
+    my $maker = $self->next::method (@_);
+  }
+
+  return $self->_sql_maker;
 }
 
 1;
@@ -123,6 +278,8 @@ L<DBIx::Class::Storage::DBI::Sybase::Microsoft_SQL_Server>.
 
 =head1 IMPLEMENTATION NOTES
 
+=head2 IDENTITY information
+
 Microsoft SQL Server supports three methods of retrieving the IDENTITY
 value for inserted row: IDENT_CURRENT, @@IDENTITY, and SCOPE_IDENTITY().
 SCOPE_IDENTITY is used here because it is the safest.  However, it must
@@ -131,6 +288,74 @@ be called is the same execute statement, not just the same connection.
 So, this implementation appends a SELECT SCOPE_IDENTITY() statement
 onto each INSERT to accommodate that requirement.
 
+C<SELECT @@IDENTITY> can also be used by issuing:
+
+  $self->_identity_method('@@identity');
+
+it will only be used if SCOPE_IDENTITY() fails.
+
+This is more dangerous, as inserting into a table with an on insert trigger that
+inserts into another table with an identity will give erroneous results on
+recent versions of SQL Server.
+
+=head2 identity insert
+
+Be aware that we have tried to make things as simple as possible for our users.
+For MSSQL that means that when a user tries to create a row, while supplying an
+explicit value for an autoincrementing column, we will try to issue the
+appropriate database call to make this possible, namely C<SET IDENTITY_INSERT
+$table_name ON>. Unfortunately this operation in MSSQL requires the
+C<db_ddladmin> privilege, which is normally not included in the standard
+write-permissions.
+
+=head2 Ordered Subselects
+
+If you attempted the following query (among many others) in Microsoft SQL
+Server
+
+ $rs->search ({}, {
+  prefetch => 'relation',
+  rows => 2,
+  offset => 3,
+ });
+
+You may be surprised to receive an exception. The reason for this is a quirk
+in the MSSQL engine itself, and sadly doesn't have a sensible workaround due
+to the way DBIC is built. DBIC can do truly wonderful things with the aid of
+subselects, and does so automatically when necessary. The list of situations
+when a subselect is necessary is long and still changes often, so it can not
+be exhaustively enumerated here. The general rule of thumb is a joined
+L<has_many|DBIx::Class::Relationship/has_many> relationship with limit/group
+applied to the left part of the join.
+
+In its "pursuit of standards" Microsft SQL Server goes to great lengths to
+forbid the use of ordered subselects. This breaks a very useful group of
+searches like "Give me things number 4 to 6 (ordered by name), and prefetch
+all their relations, no matter how many". While there is a hack which fools
+the syntax checker, the optimizer may B<still elect to break the subselect>.
+Testing has determined that while such breakage does occur (the test suite
+contains an explicit test which demonstrates the problem), it is relative
+rare. The benefits of ordered subselects are on the other hand too great to be
+outright disabled for MSSQL.
+
+Thus compromise between usability and perfection is the MSSQL-specific
+L<resultset attribute|DBIx::Class::ResultSet/ATTRIBUTES> C<unsafe_subselect_ok>.
+It is deliberately not possible to set this on the Storage level, as the user
+should inspect (and preferrably regression-test) the return of every such
+ResultSet individually. The example above would work if written like:
+
+ $rs->search ({}, {
+  unsafe_subselect_ok => 1,
+  prefetch => 'relation',
+  rows => 2,
+  offset => 3,
+ });
+
+If it is possible to rewrite the search() in a way that will avoid the need
+for this flag - you are urged to do so. If DBIC internals insist that an
+ordered subselect is necessary for an operation, and you believe there is a
+differnt/better way to get the same result - please file a bugreport.
+
 =head1 AUTHOR
 
 See L<DBIx::Class/CONTRIBUTORS>.