public function get_sql_where() {
        list($where, $params) = parent::get_sql_where();
        $where = preg_replace('/firstname/', 'u.firstname', $where);
        $where = preg_replace('/lastname/', 'u.lastname', $where);
        return [$where, $params];
    }
public function get_sql_where() {
        list($where, $params) = parent::get_sql_where();
        $where = preg_replace('/firstname/', 'u.firstname', $where);
        $where = preg_replace('/lastname/', 'u.lastname', $where);
        return [$where, $params];
    }
public function get_sql_where ( ) { list ( $ where , $ params ) = parent :: get_sql_where ( ) ; $ where = preg_replace ( '/firstname/' , 'u.firstname' , $ where ) ; $ where = preg_replace ( '/lastname/' , 'u.lastname' , $ where ) ; return [ $ where , $ params ] ; }
Get sql to add to where statement.

@return string
Get sql to add to where statement .