不能在 where 子句中使用临时列? [英] Can't use temporary column in where clause?

问题描述

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:

When I try to execute the following I receive the error:

消息 207，级别 16，状态 1，第 13 行无效的列名称RowID".

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

只是想知道如何引用这个临时列?我搜索了以前的帖子，这些帖子建议为此使用拥有"，但这似乎也不起作用.

Just wondering how I can reference this temporary column? I searched for previous postings which suggested using 'having' for this however that doesn't appear to work either.

推荐答案

一种解决方案是对整个语句进行子选择，对其结果应用 where 子句

One solution would be to make a subselect of the entire statement, applying the where clause on its result

select  *
from    (
          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
        ) de 
where   de.RowID IS NOT NULL

<小时>

另一种解决方案可能是在 WHERE 子句中重复整个子句

---

Another solution could be to repeat the entire clause in the WHERE clause

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   cast(de.ApprovalOrder AS VARCHAR(32)) 
        + cast(de.EntityCode AS VARCHAR(32)) 
        + isnull(cast(de.DelegationCode AS VARCHAR(32)), '') IS NOT NULL

<小时>

或者您可以测试每个单独的字段是否为 NULL

---

Or you could test each individual field for NULL

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   de.ApprovalOrder IS NOT NULL
        AND de.EntityCode IS NOT NULL

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