修改table里面的sexcol 值男变女 值女变男update table_name set sexcol=( case sexcol when ‘男’ then ‘女’ when ‘女’ then ‘男’ end ) update tableset sex=(case when sex=’男’ then ‘女’ else ‘男’ end) 表table 里面有两个字段 id 和 lastupdatetime 。ID是序号 lastupdatetime是最后一次的更新时间用一条语句查询出lastupdatetime最大的序号值？select id from table_name where lastupdatetime in (select lastupdatetime from table_name group by lastupdatetime having count(lastupdatetime )>1)（这语句没进行验证）