先查询id

select CAST(group_concat(ids) AS CHAR(10000) CHARACTER SET utf8) as iid 

from (select SUBSTRING_INDEX(group_concat(id ORDER BY 字段),',',4) as ids from `table` group by 字段) as val

在根据id查询数据

SELECT * FROM table where id in ($id)

这种也是可以的

select 字段,substring_index(group_concat( concat(字段,':',字段) order by 字段 desc separator '|'),'|',5) from table group by 字段;

具体看情况