Mysql查詢某字段重復值並刪除重復值

1.查詢重復值：

select code,count(*) as count from hospital group by code having count>1;

該語句查詢code重復值大於1的記錄

2.刪除重復：

DELETE FROM hospital 
WHERE
    id NOT IN (SELECT 
        dt.minno
    FROM
        (SELECT 
            MIN(id) AS minno
        FROM
            hospital
        GROUP BY code) dt);

該語句保留id最小的記錄，其余code重復的記錄全部刪除