Updating the "Post" table
 

A user asked to be deleted, which I did, but I intentionally did not prune the user's posts because she started a number of threads. I was thinking that the username would be changed to 'Guest', but I see that the username remains by all the posts and just the title changes to 'Guest'. I'd like to update the 'Post' table to change the username to something less familiar to other users. If I ever get this request again I will probably change the username before deleting, but for now I think the only way to get her name out of there is with an update statement.

Can you tell me if I have the correct syntax for this statement?

UPDATEpost
SETusername = "zzzzz"
WHEREpost.username = "sue"
ANDpost.userid = 0