discuz X5 推荐用 utf8mb4，老表是 utf8mb3

如何更新呢？如下sql执行

ALTER TABLE pre_common_member_temp___ CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE pre_forum_postposition CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;