X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FMSSQL.pm;h=d9c8ee0442fd4fc7018275150cf75cba982b92b9;hb=6d766626a066b757058d023830f93cf39bb9c302;hp=dcfe8952f24a156831a57a581c2078899ea05fef;hpb=d4f16b21abb7a541e0c44bfe3ec68309a8d722fa;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Storage/DBI/MSSQL.pm b/lib/DBIx/Class/Storage/DBI/MSSQL.pm
index dcfe895..d9c8ee0 100644
--- a/lib/DBIx/Class/Storage/DBI/MSSQL.pm
+++ b/lib/DBIx/Class/Storage/DBI/MSSQL.pm
@@ -3,12 +3,191 @@ package DBIx::Class::Storage::DBI::MSSQL;
 use strict;
 use warnings;
 
-use base qw/DBIx::Class::Storage::DBI/;
+use base qw/DBIx::Class::Storage::DBI::UniqueIdentifier/;
+use mro 'c3';
 
-sub _dbh_last_insert_id {
-  my ($self, $dbh, $source, $col) = @_;
-  my ($id) = $dbh->selectrow_array('SELECT @@IDENTITY');
-  return $id;
+use List::Util();
+
+__PACKAGE__->mk_group_accessors(simple => qw/
+  _identity _identity_method
+/);
+
+__PACKAGE__->sql_maker_class('DBIx::Class::SQLAHacks::MSSQL');
+
+sub _set_identity_insert {
+  my ($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 $is_identity_insert = (List::Util::first
+      { $source->column_info ($_)->{is_auto_increment} }
+      (@{$cols})
+  )
+     ? 1
+     : 0;
+
+  if ($is_identity_insert) {
+     $self->_set_identity_insert ($source->name);
+  }
+
+  $self->next::method(@_);
+
+  if ($is_identity_insert) {
+     $self->_unset_identity_insert ($source->name);
+  }
+}
+
+sub insert {
+  my $self = shift;
+  my ($source, $to_insert) = @_;
+
+  my $supplied_col_info = $self->_resolve_column_info($source, [keys %$to_insert] );
+
+  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);
+  }
+
+  my $updated_cols = $self->next::method(@_);
+
+  if ($is_identity_insert) {
+     $self->_unset_identity_insert ($source->name);
+  }
+
+  return $updated_cols;
+}
+
+sub _prep_for_execute {
+  my $self = shift;
+  my ($op, $extra_bind, $ident, $args) = @_;
+
+# cast MONEY values properly
+  if ($op eq 'insert' || $op eq 'update') {
+    my $fields = $args->[0];
+
+    for my $col (keys %$fields) {
+      # $ident is a result source object with INSERT/UPDATE ops
+      if ($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 => $val ]];
+      }
+    }
+  }
+
+  my ($sql, $bind) = $self->next::method (@_);
+
+  if ($op eq 'insert') {
+    $sql .= ';SELECT SCOPE_IDENTITY()';
+
+  }
+
+  return ($sql, $bind);
+}
+
+sub _execute {
+  my $self = shift;
+  my ($op) = @_;
+
+  my ($rv, $sth, @bind) = $self->dbh_do($self->can('_dbh_execute'), @_);
+
+  if ($op eq 'insert') {
+
+    # this should bring back the result of SELECT SCOPE_IDENTITY() we tacked
+    # on in _prep_for_execute above
+    my ($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 $name");
+}
+
+# A new SAVE TRANSACTION with the same name releases the previous one.
+sub _svp_release { 1 }
+
+sub _svp_rollback {
+  my ($self, $name) = @_;
+
+  $self->_get_dbh->do("ROLLBACK TRANSACTION $name");
 }
 
 sub build_datetime_parser {
@@ -16,32 +195,142 @@ sub build_datetime_parser {
   my $type = "DateTime::Format::Strptime";
   eval "use ${type}";
   $self->throw_exception("Couldn't load ${type}: $@") if $@;
-  return $type->new( pattern => '%m/%d/%Y %H:%M:%S' );
+  return $type->new( pattern => '%Y-%m-%d %H:%M:%S' );  # %F %T
+}
+
+sub sqlt_type { 'SQLServer' }
+
+sub sql_maker {
+  my $self = shift;
+
+  unless ($self->_sql_maker) {
+    unless ($self->{_sql_maker_opts}{limit_dialect}) {
+
+      my $version = $self->_server_info->{normalized_dbms_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;
+}
+
+sub _ping {
+  my $self = shift;
+
+  my $dbh = $self->_dbh or return 0;
+
+  local $dbh->{RaiseError} = 1;
+  local $dbh->{PrintError} = 0;
+
+  eval {
+    $dbh->do('select 1');
+  };
+
+  return $@ ? 0 : 1;
 }
 
 1;
 
 =head1 NAME
 
-DBIx::Class::Storage::DBI::MSSQL - Storage::DBI subclass for MSSQL
+DBIx::Class::Storage::DBI::MSSQL - Base Class for Microsoft SQL Server support
+in DBIx::Class
 
 =head1 SYNOPSIS
 
-This subclass supports MSSQL, and can in theory be used directly
-via the C<storage_type> mechanism:
+This is the base class for Microsoft SQL Server support, used by
+L<DBIx::Class::Storage::DBI::ODBC::Microsoft_SQL_Server> and
+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
+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 preferably regression-test) the return of every such
+ResultSet individually. The example above would work if written like:
 
-  $schema->storage_type('::DBI::MSSQL');
-  $schema->connect_info('dbi:....', ...);
+ $rs->search ({}, {
+  unsafe_subselect_ok => 1,
+  prefetch => 'relation',
+  rows => 2,
+  offset => 3,
+ });
 
-However, as there is no L<DBD::MSSQL>, you will probably want to use
-one of the other DBD-specific MSSQL classes, such as
-L<DBIx::Class::Storage::DBI::Sybase::MSSQL>.  These classes will
-merge this class with a DBD-specific class to obtain fully
-correct behavior for your scenario.
+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
+different/better way to get the same result - please file a bugreport.
 
-=head1 AUTHORS
+=head1 AUTHOR
 
-Brian Cassidy <bricas@cpan.org>
+See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>.
 
 =head1 LICENSE