1.查找重复的行
SELECT
*
FROM
blog_user_relation a
WHERE
(a.account_instance_id,a.follow_account_instance_id)
IN
(
SELECT
account_instance_id,follow_account_instance_id
FROM
blog_user_relation
GROUP
BY
account_instance_id, follow_account_instance_id
HAVING
COUNT
(
*
)
>
1
)
2.删除重复的行(保留一条)
PS：因为mysql的delete，如果被删的表的where条件里有in，且in里面也有此表，那就删除不了。
/*
创建个临时表
*/
CREATE
TABLE
blog_user_relation_temp
AS
(
SELECT
*
FROM
blog_user_relation a
WHERE
(a.account_instance_id,a.follow_account_instance_id)
IN
(
SELECT
account_instance_id,follow_account_instance_id
FROM
blog_user_relation
GROUP
BY
account_instance_id, follow_account_instance_id
HAVING
COUNT
(
*
)
>
1
)
AND
relation_id
NOT
IN
(
SELECT
MIN
(relation_id)
FROM
blog_user_relation
GROUP
BY
account_instance_id, follow_account_instance_id
HAVING
COUNT
(
*
)
>
1
));
/*
删除数据
*/
DELETE
FROM
`blog_user_relation`
WHERE
relation_id
IN
(
SELECT
relation_id
FROM
blog_user_relation_temp);
/*
删除临时表
*/
DROP
TABLE
blog_user_relation_temp;
