将`acc_dragon_mail`表的 `cid` 字段更新为`prize`字段的前三个字符 ~~~ UPDATE `acc_dragon_mail` SET `cid` = SUBSTR(`prize`, 1, 3) ~~~ 将`verify`表的 `character_id` 字段更新为`platformOrderId`字段的第3~8位置的字符 ~~~ UPDATE `verify` SET `character_id` = SUBSTR(`platformOrderId`, 3, 6); ~~~