mysql删除重复数据

Mysql 查询重复数据：

1.单条件查询：

SELECT id,model_id,reason FROM score WHERE type=1 GROUP BY user_id HAVING COUNT(*) > 1;

2.多条件查询：

SELECT id FROM score a WHERE 
( a.user_id, a.reason, a.model_id ) IN ( SELECT user_id, reason, model_id FROM score GROUP BY user_id, reason, model_id HAVING count(*) > 1 )

3.删除重复数据，只保留最小ID的数据：（多条件）

DELETE FROM score WHERE id IN (
SELECT z.id FROM (
SELECT
    id
FROM
    score a 
WHERE
    ( a.user_id, a.reason, a.model_id ) IN ( SELECT user_id, reason, model_id FROM score GROUP BY user_id, reason, model_id HAVING count(*) > 1 ) 
    AND id NOT IN (
    SELECT
        min( id ) 
    FROM
        score 
    GROUP BY
 user_id, reason, model_id
HAVING
    count(*)> 1)
)z
)