如何显示与另一个表中的行不匹配的行? [英] How to display rows which don't match a row in another table?

问题描述

我想展示不是病房经理的员工.

I want to display staff that are not ward managers.

我有这个查询，其中显示了病房管理员:

I have this query which displays ward managers:

SELECT Name, Grade, WardManager, StaffNo  
FROM STAFF, WARD   
WHERE WARD.WardManager = STAFF.StaffNo;  

但是我不知道如何显示不是病房经理的员工.我尝试过将IS NOT，NOT LIKE，NOT IN等组合使用，但它们似乎都不起作用.

However I can't figure out how to display the staff who aren't ward managers. I have tried a combination of IS NOT, NOT LIKE, NOT IN etc and none of them seem to work.

推荐答案

我不确定我是否正确理解了表结构，但是当有人抱怨NOT IN不返回任何行时，使用的列中的NULL值几乎总是一个问题用于IN运算符.

Not sure I understand you table structure correctly, but when someone complains that NOT IN returns no rows, it's almost always a problem with NULL values in the column used for the IN operator.

尝试一下:

select *
from staff
where staffno not in (select wardmanager 
                      from ward 
                      where wardmanager IS NOT NULL)

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