I would probably go with one table for the categories and a table for each distinct type of item group. (It looks like the items are too different to go into one big table).

For fast searching, look at the latest Swish-E. You can do a "streaming" database dump formatted as simple XML and have swish-e read and index that.

In my experience you end up doing table scans if you need any kind of advanced searching. If you insist on doing it with SQL, then be sure to get as few tables as possibly (or group them as much as possibly based on how they are going to be used). You don't want to run a thousand queries to search all categories.

 - ask

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ask bjoern hansen, http://ask.netcetera.dk/   !try; do();