MySQl分組顯示組內前N項 及刪除重複保留最大id數據

分開查詢

 

先查詢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

在根據id查詢數據

SELECT * FROM table where id in ($id)

 

這種也是能夠的

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;

具體看狀況

DELETE FROM xxx WHERE id NOT IN(SELECT id FROM (SELECT MAX(b.id) AS id FROM xxx b GROUP BY b.xxxx) b)