表（order_test）结构：
mysql 语句：
DELETE FROM order_test WHERE
(
name IN ( SELECT n.name FROM
( SELECT name FROM order_test GROUP BY name HAVING COUNT(name) > 1 ) n )
) AND (
id NOT IN (
SELECT i.id FROM
( SELECT max(id) AS id FROM order_test GROUP BY name HAVING COUNT(name) > 1 ) i
)
)
执行结果：
eg：这里用的max(id),保留最新数据。保留最开始的数据采用min(id)
原文链接：根据字段删除重复的记录保留最新数据
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