The incorrect MS SQL ADD/DROP syntax only happen when action on multi-columns, the syntax
ADD ..., ADD ..., ADD ...
should be ADD ..., ..., ...
Another problem is that the syntax to add comment to table/column, but I'm not sure what is the correct simple way to do that, it seems have to use sp_listextendedproperty, sp_addextendedproperty, sp_updateextendedproperty, and sp_dropextendedproperty on MS SQL?
Sorry for my poor English.