As long I don't need to do a query with the data of all users, storing data like the zip code or city in the meta data as an serialized object works fine. But now I have to do a lot of different selects concerning users meta data, f.i. "select all users which are living in London". How can I do such a query in WordPress if CITY is not a single field in a table, but part of a bunch of serialized data in one field in the wp_usermeta table. I assume there is not an easy way to do this.
So my question, how to manage data that should be available as property of an object and could also be used in a query like mentioned above.