如何解决为什么以下查询不起作用您不能在FROM子句中指定目标表'p1'进行更新?
delete from Person p1
where p1.id NOT IN (
select *
from (select min(id) from Person p2 where p2.Email=p1.Email) p
);
此查询有效,但如果我删除select *,它会说(您无法在FROM子句中指定目标表'p1'用于更新。为什么会这样?
delete from Person p1
where p1.id NOT IN (select min(id) from Person p2 where p2.Email=p1.Email);
解决方法
MySQL不支持在WHERE
子句中重新打开DML语句的目标表。您可以使用join
来代替嵌套选择,这可以使代码更简洁:
delete p1
from person p1
inner join (select email,min(id) min_id from person group by email) p2
on p1.email = p2.email and p1.id > p2.min_id
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