I have about 500 people in the "users" group that are also in the "members" group, how do I make them to be just in the "members" group? Just need to drop anyone that is a member from the user group.

Ok, first lets get your group numbers:

SELECT * FROM w3t_Groups

For my board it is:

code:
 
G_Name                    G_Id 
Administrators            1 
Moderators                2 
Users                     3 
Guests                    4 

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Yours may vary, so for the sake of this demo we'll say your "Member" group is G_Id 5 and your "Users" G_Id is 3.

UPDATE w3t_Users SET U_Groups = '-5-' WHERE U_Groups = '-3-5-'

That should do it. Be sure to make a backup of the db first. Always make a backup before doing anything else if you're tinkering directly with the database.

Remember to check those group numbers first!

I've noticed that the group numbers are not always in numerical order, i.e., w3t_Users.U_Groups might be '-5-3-'.

A better query might be:
UPDATE w3t_Users SET U_Groups='-5-' WHERE U_Groups='-3-5-' OR U_Groups='-5-3-'

Thank's guys, worked like a charm, it didn't do the moderator's that were in this situation but I only have a handfull and just did them by hand.