Specific query not working with Active Record Class and row grouping

[eluser]joergy[/eluser]
The problem is, that CI does not want to reimplement a complete SQL parser for Active Records.
So only very simple statements are possible.
Anything with "(" or "'" might fail.
Another restriction is, that Active Records do not support "bindings" from MySQLi.
In Your case You better build Your SQL completely Yourself.
Don't forget to escape Your values!