sql – 不能在where子句中使用临时列？

select  cast(de.ApprovalOrder AS VARCHAR(32)) 
            + cast(de.EntityCode AS VARCHAR(32)) 
            + isnull(cast(de.DelegationCode AS VARCHAR(32)),'') as 'RowID',*
from    workflow.delegation_engine de
where   RowID <> NULL

当我尝试执行以下操作时收到错误：

Msg 207,Level 16,State 1,Line 13 Invalid column name ‘RowID’.

只是想知道我如何引用这个临时列？我搜索了以前的帖子,建议使用’have’来实现这一点,但这似乎也不起作用.

解决方法

select  *
from    (
          select  cast(de.ApprovalOrder AS VARCHAR(32)) 
                  + cast(de.EntityCode AS VARCHAR(32)) 
                  + isnull(cast(de.DelegationCode AS VARCHAR(32)),*
          from    workflow.delegation_engine de
        ) de 
where   de.RowID IS NOT NULL

另一种解决方案可能是重复WHERE子句中的整个子句

select  cast(de.ApprovalOrder AS VARCHAR(32)) 
        + cast(de.EntityCode AS VARCHAR(32)) 
        + isnull(cast(de.DelegationCode AS VARCHAR(32)),*
from    workflow.delegation_engine de
where   cast(de.ApprovalOrder AS VARCHAR(32)) 
        + cast(de.EntityCode AS VARCHAR(32)) 
        + isnull(cast(de.DelegationCode AS VARCHAR(32)),'') IS NOT NULL

或者您可以测试每个单独的字段为NULL

select  cast(de.ApprovalOrder AS VARCHAR(32)) 
        + cast(de.EntityCode AS VARCHAR(32)) 
        + isnull(cast(de.DelegationCode AS VARCHAR(32)),*
from    workflow.delegation_engine de
where   de.ApprovalOrder IS NOT NULL
        AND de.EntityCode IS NOT NULL

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