Allowing SQL Server to dump non-standard primary keys via the schema dumper by implementing pk_and_sequence_for.

Note that this code originally came from http://github.com/adzap/sqlserver_adapter_mods

Author: adzap

lib/active_record/connection_adapters/sqlserver_adapter.rb

@@ -668,7 +668,7 @@ def add_lock!(sql, options)
         end
       end
 
-      def recreate_database(name)      
+      def recreate_database(name)
         # Switch to another database or we'll receive a "Database in use" error message.
         existing_database = current_database.to_s
         if name.to_s == existing_database
@@ -817,6 +817,21 @@ def remove_index(table_name, options = {})
         execute "DROP INDEX #{table_name}.#{quote_column_name(index_name(table_name, options))}"
       end
 
+      # Returns a table's primary key and belonging sequence (not applicable to SQL server).
+      def pk_and_sequence_for(table_name)
+        @connection["AutoCommit"] = false
+        keys = []
+        execute("EXEC sp_helpindex '#{table_name}'") do |handle|
+          if handle.column_info.any?
+            pk_index = handle.detect {|index| index[1] =~ /primary key/ }
+            keys << pk_index[2] if pk_index
+          end
+        end
+        keys.length == 1 ? [keys.first, nil] : nil
+      ensure
+        @connection["AutoCommit"] = true
+      end
+
       private
         def __indexes(table_name, name = nil)
           indexes = []