SQL Query help

[reddogut]

I wanted to take a moment and thank everyone for helping me with my mysql questions.... Now, how about this one?

When I run

UPDATE npc_types SET STR = AVG(STR) WHERE LEVEL = 50;

I get a MYSQL error 1111, invalid use of group function

I scoured the internet to try to figure out why and I can't seem to find it.

Thanks again,

Mike