X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBI%2FMSSQL.pm;h=a147091eec8046d5244507edf5b90b56cdfb558e;hb=3e4a74aa6eeb3ad2b9d5979ec7d41adc6efe9be2;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..a147091 100644
--- a/lib/DBIx/Class/Storage/DBI/MSSQL.pm
+++ b/lib/DBIx/Class/Storage/DBI/MSSQL.pm
@@ -3,51 +3,63 @@ 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::UniqueIdentifier
+  DBIx::Class::Storage::DBI::IdentityInsert
+/;
 use mro 'c3';
 
-use List::Util();
+use Try::Tiny;
+use List::Util 'first';
+use namespace::clean;
 
-__PACKAGE__->sql_maker_class('DBIx::Class::SQLAHacks::MSSQL');
+__PACKAGE__->mk_group_accessors(simple => qw/
+  _identity _identity_method _no_scope_identity_query
+/);
 
-sub insert_bulk {
-  my $self = shift;
-  my ($source, $cols, $data) = @_;
+__PACKAGE__->sql_maker_class('DBIx::Class::SQLMaker::MSSQL');
 
-  my $identity_insert = 0;
+__PACKAGE__->sql_quote_char([qw/[ ]/]);
 
-  COLUMNS:
-  foreach my $col (@{$cols}) {
-    if ($source->column_info($col)->{is_auto_increment}) {
-      $identity_insert = 1;
-      last COLUMNS;
-    }
-  }
+__PACKAGE__->datetime_parser_type (
+  'DBIx::Class::Storage::DBI::MSSQL::DateTime::Format'
+);
 
-  if ($identity_insert) {
-    my $table = $source->from;
-    $self->dbh->do("SET IDENTITY_INSERT $table ON");
-  }
+__PACKAGE__->new_guid('NEWID()');
 
-  $self->next::method(@_);
+sub __sql_server_x_or_higher {
+  my ($self, $version) = @_;
 
-  if ($identity_insert) {
-    my $table = $source->from;
-    $self->dbh->do("SET IDENTITY_INSERT $table OFF");
+  if (exists $_[0]->_server_info->{normalized_dbms_version}) {
+    if ($_[0]->_server_info->{normalized_dbms_version} >= $version) {
+       return 1
+    } else {
+       return 0
+    }
   }
+  return undef;
 }
 
+sub _sql_server_2005_or_higher { shift->__sql_server_x_or_higher(9) }
+sub _sql_server_2012_or_higher { shift->__sql_server_x_or_higher(11) }
+
 sub _prep_for_execute {
   my $self = shift;
-  my ($op, $extra_bind, $ident, $args) = @_;
+  my ($op, $ident, $args) = @_;
 
 # 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]);
+
+    my $colinfo = $ident->columns_info([keys %$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 (
+        $colinfo->{$col}{data_type}
+          &&
+        $colinfo->{$col}{data_type} =~ /^money\z/i
+      ) {
         my $val = $fields->{$col};
         $fields->{$col} = \['CAST(? AS MONEY)', [ $col => $val ]];
       }
@@ -56,17 +68,16 @@ sub _prep_for_execute {
 
   my ($sql, $bind) = $self->next::method (@_);
 
-  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; $identity_insert_off";
-    }
+  # SELECT SCOPE_IDENTITY only works within a statement scope. We
+  # must try to always use this particular idiom first, as it is the
+  # only one that guarantees retrieving the correct id under high
+  # concurrency. When this fails we will fall back to whatever secondary
+  # retrieval method is specified in _identity_method, but at this
+  # point we don't have many guarantees we will get what we expected.
+  # http://msdn.microsoft.com/en-us/library/ms190315.aspx
+  # http://davidhayden.com/blog/dave/archive/2006/01/17/2736.aspx
+  if ($self->_perform_autoinc_retrieval and not $self->_no_scope_identity_query) {
+    $sql .= "\nSELECT SCOPE_IDENTITY()";
   }
 
   return ($sql, $bind);
@@ -74,38 +85,166 @@ sub _prep_for_execute {
 
 sub _execute {
   my $self = shift;
-  my ($op) = @_;
 
-  my ($rv, $sth, @bind) = $self->dbh_do($self->can('_dbh_execute'), @_);
-  if ($op eq 'insert') {
-    $self->{_scope_identity} = $sth->fetchrow_array;
-    $sth->finish;
+  # always list ctx - we need the $sth
+  my ($rv, $sth, @bind) = $self->next::method(@_);
+
+  if ($self->_perform_autoinc_retrieval) {
+
+    # attempt to bring back the result of SELECT SCOPE_IDENTITY() we tacked
+    # on in _prep_for_execute above
+    my $identity;
+
+    # we didn't even try on ftds
+    unless ($self->_no_scope_identity_query) {
+      ($identity) = try { $sth->fetchrow_array };
+      $sth->finish;
+    }
+
+    # 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);
   }
 
   return wantarray ? ($rv, $sth, @bind) : $rv;
 }
 
+sub last_insert_id { shift->_identity }
 
-sub last_insert_id { shift->{_scope_identity} }
-
-sub build_datetime_parser {
+#
+# 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, $ident, $select, $cond, $attrs) = @_;
   my $self = shift;
-  my $type = "DateTime::Format::Strptime";
-  eval "use ${type}";
-  $self->throw_exception("Couldn't load ${type}: $@") if $@;
-  return $type->new( pattern => '%Y-%m-%d %H:%M:%S' );  # %F %T
+  my $attrs = $_[3];
+
+  my $sql_bind = $self->next::method (@_);
+
+  # see if this is an ordered subquery
+  if (
+    $$sql_bind->[0] !~ /^ \s* \( \s* SELECT \s+ TOP \s+ \d+ \s+ /xi
+      and
+    scalar $self->_extract_order_criteria ($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};
+
+    $$sql_bind->[0] =~ s/^ \s* \( \s* SELECT (?=\s) / '(SELECT TOP ' . $self->sql_maker->__max_int /exi;
+  }
+
+  $sql_bind;
+}
+
+
+# savepoint syntax is the same as in Sybase ASE
+
+sub _exec_svp_begin {
+  my ($self, $name) = @_;
+
+  $self->_dbh->do("SAVE TRANSACTION $name");
+}
+
+# A new SAVE TRANSACTION with the same name releases the previous one.
+sub _exec_svp_release { 1 }
+
+sub _exec_svp_rollback {
+  my ($self, $name) = @_;
+
+  $self->_dbh->do("ROLLBACK TRANSACTION $name");
 }
 
 sub sqlt_type { 'SQLServer' }
 
-sub _sql_maker_opts {
-  my ( $self, $opts ) = @_;
+sub sql_limit_dialect {
+  my $self = shift;
 
-  if ( $opts ) {
-    $self->{_sql_maker_opts} = { %$opts };
+  my $supports_rno = $self->_sql_server_2005_or_higher;
+
+  unless (defined $supports_rno) {
+    # User is connecting via DBD::Sybase and has no permission to run
+    # stored procedures like xp_msver, or version detection failed for some
+    # other reason.
+    # So, we use a query to check if RNO is implemented.
+    try {
+      $self->_get_dbh->selectrow_array('SELECT row_number() OVER (ORDER BY rand())');
+      $supports_rno = 1;
+    };
   }
 
-  return { limit_dialect => 'Top', %{$self->{_sql_maker_opts}||{}} };
+  return $supports_rno ? 'RowNumberOver' : 'Top';
+}
+
+sub _ping {
+  my $self = shift;
+
+  my $dbh = $self->_dbh or return 0;
+
+  local $dbh->{RaiseError} = 1;
+  local $dbh->{PrintError} = 0;
+
+  return try {
+    $dbh->do('select 1');
+    1;
+  } catch {
+    0;
+  };
+}
+
+package # hide from PAUSE
+  DBIx::Class::Storage::DBI::MSSQL::DateTime::Format;
+
+my $datetime_format      = '%Y-%m-%d %H:%M:%S.%3N'; # %F %T
+my $smalldatetime_format = '%Y-%m-%d %H:%M:%S';
+
+my ($datetime_parser, $smalldatetime_parser);
+
+sub parse_datetime {
+  shift;
+  require DateTime::Format::Strptime;
+  $datetime_parser ||= DateTime::Format::Strptime->new(
+    pattern  => $datetime_format,
+    on_error => 'croak',
+  );
+  return $datetime_parser->parse_datetime(shift);
+}
+
+sub format_datetime {
+  shift;
+  require DateTime::Format::Strptime;
+  $datetime_parser ||= DateTime::Format::Strptime->new(
+    pattern  => $datetime_format,
+    on_error => 'croak',
+  );
+  return $datetime_parser->format_datetime(shift);
+}
+
+sub parse_smalldatetime {
+  shift;
+  require DateTime::Format::Strptime;
+  $smalldatetime_parser ||= DateTime::Format::Strptime->new(
+    pattern  => $smalldatetime_format,
+    on_error => 'croak',
+  );
+  return $smalldatetime_parser->parse_datetime(shift);
+}
+
+sub format_smalldatetime {
+  shift;
+  require DateTime::Format::Strptime;
+  $smalldatetime_parser ||= DateTime::Format::Strptime->new(
+    pattern  => $smalldatetime_format,
+    on_error => 'croak',
+  );
+  return $smalldatetime_parser->format_datetime(shift);
 }
 
 1;
@@ -123,6 +262,8 @@ 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
@@ -131,9 +272,77 @@ 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:
+
+ $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
+different/better way to get the same result - please file a bugreport.
+
 =head1 AUTHOR
 
-See L<DBIx::Class/CONTRIBUTORS>.
+See L<DBIx::Class/AUTHOR> and L<DBIx::Class/CONTRIBUTORS>.
 
 =head1 LICENSE