update MySQL row (You can't specify target table 'x' for update in FROM clause)

sql语句(update/delete都会出现此问题)

update x set available_material_id = null where id not in (select id from x where additional_info = 1);

mistake

大致意思是，在同一语句中，不能先select出同一表中的某些值，再update这个表。

You can't specify target table 'x' for update in FROM clause

mysql5.7解决办法

update x left join
       x xx
       on x.id = xx.id and xx.additional_info = 1
    set available_material_id = null
    where xx.id is null;

老办法(有人说5.7已经不能用了)

原始:

DELETE FROM tempA WHERE tid IN (
SELECT MAX(tid) AS tid FROM tempA GROUP BY name,age
)

改造后

DELETE FROM tempA WHERE tid NOT IN (
SELECT t.tid FROM (
SELECT MAX(tid) AS tid FROM tempA GROUP BY name,age
) t
)

查询的时候增加一层中间表，就可以避免该错误。

参考

https://stackoverflow.com/questions/51087937/on-update-mysql-row-you-cant-specify-target-table-x-for-update-in-from-claus
https://blog.csdn.net/h996666/article/details/81699255
https://stackoverflow.com/questions/4429319/you-cant-specify-target-table-for-update-in-from-clause/14302701  
https://tech.souyunku.com/pcheng/p/4950383.html  
https://blog.csdn.net/poetssociety/article/details/82391523

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