Sometimes, the normal approach for adding extra fields to a table will just not do. For example, if you don't really know what the other table is going to be. I came across this challenge some days ago. I was working on my sitemaps extension and wanted to have some nice options to use inside Google Sitemaps. To keep it flexible I didn't want to predefine the tables. So how do we add fields to a table, without actually adding them to a table?