如何比较表中同一行下的多个列？

Question

在where子句中，表的以下列不应该相等。

• cd_delivery_address
• cd_mail_delivery_address
• cd_st_code
• cd_mail_st_code
• cd_zip
• cd_mail_zip

请找到我的代码段来实现此目的：

     select * from table cd
     where
(
(cd_mail_delivery_address <> cd_delivery_address or    
(cd_mail_delivery_address is null and cd_delivery_address is not null) or
(cd_mail_delivery_address is not null and cd_delivery_address is null)
)
and (
cd.cd_city <> cd.cd_mail_city or 
(cd.cd_city is null and cd_mail_city is not null) or 
(cd_city is not null and cd_mail_city is null))
and (
cd.st_code <> cd.cd_mail_st_code or 
(cd.st_code is null and cd_mail_st_code is not null) or 
(st_code is not null and cd_mail_st_code is null)
)
and (
cd.cd_zip <> cd.cd_mail_zip or 
(cd.cd_zip is null and cd_mail_zip is not null) or 
(cd_zip is not null and cd_mail_zip is null)
)
)

所有列都是varchar2，我得到了此代码的正确输出。但它是比较pl sql中多个列的更好方法吗？我能改进这段代码吗？任何建议都会有所帮助。

Answer 1

您可以使用以下内容替换您的空检查：

...
NVL(cd_mail_delivery_address,'_') <> NVL(cd_delivery_address,'_')
...

它确实更具可读性，但我不确定查询效率

Answer 2

我使用连接在两列中完成了它：

select a.cd_delivery_address,b.cd_mail_delivery_address 
from cd a inner join cd b 
where a.cd_delivery_address <> b.cd_mail_delivery_address and
a.cd_delivery_address = b.cd_delivery_address

这里将忽略空检查条件并减少条件数，但由于涉及连接，因此会对性能产生影响。