public function on($localKey, $operator, $referenceKey, $type = 'and')
    {
        $this->ons[] = array($type, $localKey, $operator, $referenceKey); return $this;
    }
public function on($localKey, $operator, $referenceKey, $type = 'and')
    {
        $this->ons[] = array($type, $localKey, $operator, $referenceKey); return $this;
    }
public function on ( $ localKey , $ operator , $ referenceKey , $ type = 'and' ) { $ this -> ons [ ] = array ( $ type , $ localKey , $ operator , $ referenceKey ) ; return $ this ; }
Add an on condition to the join object

@param string                $localKey
@param string                $operator
@param string                $referenceKey

@return self
Add an on condition to the join object