Your magcian prob sounds like your spawning magicain trainers rather than merchants maybe
as for your question on field types they are loads, this seems to be a good defination:
http://scibit.com/help/mascon/linux/...ield_types.htm
(*whew* save myself some work there =p)
and the bracketed number dictates field size i.e. varchar(13) is a variable length string.. max length 13 =)