or_group_start Problem

What's the result if you put the query builder elements in this order:

PHP Code:

$this->db
->from('TABLE')
->where('Z',false)
->or_group_start()
   ->where('X',$x)
   ->where('Y',$y)
->group_end()
->count_all_results() 


I guess the or_group_start() only has effect if there's a preceding where clause.

Yes you right. It or_group_start connects only if there is a where before it.

I'm a person from Turkiye. I don't know English very well and i can't write what i want to say sometimes (as now happenes   ).

If i write something by mistake; please don't distress it and try to understand what i want to write.