public function joinLeftUsing(string $to, string $as, string $using, $usingParams = null): self
    {
        return $this->joinUsing($to, $as, $using, $usingParams, 'LEFT');
    }
public function joinLeftUsing(string $to, string $as, string $using, $usingParams = null): self
    {
        return $this->joinUsing($to, $as, $using, $usingParams, 'LEFT');
    }
public function joinLeftUsing ( string $ to , string $ as , string $ using , $ usingParams = null ) : self { return $ this -> joinUsing ( $ to , $ as , $ using , $ usingParams , 'LEFT' ) ; }
Join left using.
@param  string   $to
@param  string   $as
@param  string   $using
@param  any|null $usingParams
@return self
Join left using .