mysql - MSSQL - 只能选择行中具有不同值的列

Question

想象一下，我有一个包含以下列的审计表:

id   schedule   weekday   weekday_old   weekend   weekend_old
1    week1      m,t,w     th,f          sa,su     sa,su
1    week2      m,t,w     m,t,w         sa,su     sa,su
1    week3      m,t,w     w,th,f        sa,su     sa
1    week4      m,t,w     m,t,w         sa,su     sa,su
1    week5      m,t,w     m,t,w         sa,su     sa,su
1    week6      m,t,w     m,t,w         sa        su    
1    week7      m,t,w     m,t,w         sa        su  

是否有一个sql命令允许我仅选择工作日/工作日_旧中的数据不同，或周末/周末_旧不同，或(当工作日/工作日_旧和周末/周末_旧)不同的行并将列中相同的值替换为 null？

因此，使用上表，我希望返回以下内容

week1      m,t,w     th,f          null     null
week3      m,t,w     w,th,f        sa,su    sa
week6      null      null          sa        su    
week7      null      null          sa        su  

这可能听起来很疯狂，但我们尝试用我们拥有的工具做我们被要求的事情。期待任何帮助。谢谢。

**我从结果表中删除了第 4 周。打错字了。

Answer 1

您所描述的内容与您的示例不符(为什么会选择 week4 并且不为空)。假设这是一个拼写错误:

SELECT schedule, 
NULLIF(weekday,weekday_old) AS weekday,
NULLIF(weekday_old,weekday) AS weekday_old,
NULLIF(weekend,weekend_old) AS weekend,
NULLIF(weekend_old,weekend) AS weekend_old
 FROM dbo.mytable 
 WHERE NULLIF(weekday,weekday_old) IS NOT NULL or NULLIF(weekend,weekend_old) IS NOT NULL;