使用标准偏差使用mysql删除异常值 [英] Deleting outliers with mysql using standard deviation

问题描述

我使用下面的查询删除异常值(标准误差的1.5倍).

I use the query below to delete outliers (1.5 times the sd).

DELETE FROM sv_condition_sw 
WHERE snow_mountain > (
    SELECT AVG(snow_mountain)+1.5*STDDEV(snow_mountain) 
    FROM sv_condition_sw 
    WHERE lud='2012-11-28' AND res_id=769)
AND lud='2012-11-28' 
AND res_id=769

但是会出现此错误:

查询:delete FROM sv_condition_sw WHERE snow_mountain > (SELECT AVG(snow_mountain)+1.5*STDDEV(snow_mountain) FROM sv_condition_sw WHER...

Error Code: 1093
You can't specify target table 'sv_condition_sw' for update in FROM clause

我不知道这意味着什么.

I do not know what it means.

推荐答案

您可以诱使MySQL通过另一个子选择来做到这一点

You can trick MySQL to do this with another subselect

DELETE FROM sv_condition_sw 
WHERE snow_mountain > (select * from (SELECT AVG(snow_mountain)+1.5*STDDEV(snow_mountain) 
                                      FROM sv_condition_sw 
                                      WHERE lud='2012-11-28' 
                                      AND res_id=769) x)
 AND lud='2012-11-28' AND res_id=769

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