MySQL删除重复记录只保留一条
如何删除数据库中重复数据，只保留其中一条记录，下面sql语句是删除用户表ltb_user中手机号phone_number不为空且企业identerprise_id是256的重复的记录，但保留主键ltb_user_id最小的一条，这里可以保留最大一条，可以用函数max()，sql语句如下：
DELETE
FROM
ltb_user
WHERE
phone_number IN (
SELECT
phone_number
FROM
(
SELECT
phone_number
FROM
ltb_user
WHERE
phone_number != ''
AND enterprise_id = 265
GROUP BY
phone_number
HAVING
count(phone_number) > 1
) a
)
AND ltb_user_id NOT IN (
SELECT
ltb_user_id
FROM
(
SELECT
min(ltb_user_id) AS ltb_user_id
FROM
ltb_user
WHERE
phone_number != ''
AND enterprise_id = 265
GROUP BY
phone_number
HAVING
count(phone_number) > 1
) b
)