anchor.diff:  <%= banner("DDL for Schema '#{schema.name}'") %>
   <% schema.object_types.select{|object_type| !object_type.abstract?}.each do |object_type| %>
   CREATE TABLE <%= sql_qualify(object_type.schema, object_type.sql.table_name) %>(
  -<% object_type.attributes.each do |a|
  +<% object_type.attributes.select {|a| a.persistent?}.each do |a|
   %>  <%= q(a.sql.column_name) %> <%= q(a.sql.sql_type) %> <%= a.length.nil? ? '' : "(#{a.length}) " %><%= a.sql.identity? ? 'IDENTITY(1,1) ' : '' %><%= a.nullable? ? '': 'NOT '%>NULL,
   <% end
   %>  CONSTRAINT PK_<%= object_type.name %> PRIMARY KEY <%= (object_type.sql.indexes.select{|i| i.cluster?}.size == 0) ? '' : 'NON' %>CLUSTERED (<%= q(object_type.primary_key.sql.column_name) %> ASC)
  
positive.code: GO
  <%    end
      end
     immutable_attributes = object_type.attributes.select {|a| a.immutable? }
     if immutable_attributes.size > 0
      pk = object_type.primary_key
  %>
  
negative.code: )
  GO
  <% end %>
  <% object_type.attributes.select {|a| a.persistent? && a.reference?}.each do |a| %>
  ALTER TABLE <%= sql_qualify(object_type.schema, object_type.sql.table_name) %>
    ADD CONSTRAINT [FK_<%= object_type.name %>_<%= a.sql.column_name %>] FOREIGN KEY (<%= q(a.sql.column_name) %>)
    REFERENCES <%= sql_qualify(a.referenced_object.schema, a.referenced_object.sql.table_name) %> (<%= q(a.referenced_object.primary_key.sql.column_name) %>)
  GO
  <%
    end
    if object_type.sql.constraints.size > 0 %><%=
      banner("Constraints for #{sql_qualify(object_type.schema, object_type.sql.table_name)}")
  