Database error when setting session data

[eluser]Unknown[/eluser]
Hi.

I'm reworking the database design for my web application and I keep running into problems. I split up my user table into three different tables, and I'm now using a fairly complex (to me, at least) query with UNION statements to select across the three tables. All good till there. However, now that I got that working, I ran into a new problem.
I solved this by removing some code I forgot to remove.. /sigh

[eluser]R_Nelson[/eluser]
I realize you solved this problem but putting examples of your code and how you solved may help the next guy who has this problem.

thanks

[eluser]Unknown[/eluser]
I know, but the way I solved it wouldn't really help anyone because uh.. I just forgot to remove some code when cleaning stuff up.

I had a

Code:

$this->db->where('');

statement while I didn't need it anymore, and that gave me the error.