Request for help on (My)SQL Statement

:::Novice Alert::: I've done simple select and insert statements, so I suppose this is the most complicated thing I've tried to do. but seems to me it should be pretty easy. But I'm a designer by background, not a developer or programmer. I've got everything else I'm trying to do working. I'm trying to take the largest value out of one table and update another table. The former is a PHPBB table and the latter is a table I created just to store the value of the date of the most recent post for use in something else. UPDATE ngc_polling SET lastrundate = max(nuke_phpbb_posts.post_time) It returns "Invalid use of group function." I've been looking at the documentation on MySQL.com to no avail. I'm testing my query in phpMyAdmin before I try to implement it elsewhere. This is what I'm trying to do, any help besides "RTFM" (been doing that) would be greatly appreciated. Thanks! John John Bedard | Interaction Designer (SWEIII) | Northrop Grumman Mission Systems | Helena, Montana, U.S.A. | john.bedard@ngc.com | 406.443.8630 | Fax 406.443.8601 |