set where_clause [expr {$where ne "" ? "WHERE $where" : ""}]
set offset_clause [expr {$offset ne "" ? "OFFSET $offset" : ""}]
set limit_clause [expr {$limit ne "" ? "LIMIT $limit" : ""}]
set order_clause [expr {$orderby ne "" ? "ORDER BY $orderby" : ""}]
set group_clause [expr {$groupby ne "" ? "GROUP BY $groupby" : ""}]
return"SELECT $vars FROM $from$where_clause$group_clause$order_clause$limit_clause$offset_clause"