Question

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：

消息207，级别16，状态1，行13无效的列名称'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”，但这似乎不起作用。

Answer 1

一种解决方案是对整个语句进行子选择，在结果上应用where子句

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

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)), '') 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

或者您可以测试每个字段的空白

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

Answer 2

您必须使用WHERE子句中的express，或者使用SELECT查询作为子查询，如下所示：

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 
)
where RowID is not NULL

或者，更粗略的（在我看来）路线将是：

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

我每次都会选择第一个解决方案。

另请注意，我已从

更改了WHERE条款

RowID <> NULL

要

RowID is not NULL

这是因为<> NULL永远不会评估为真。 SQL Server使用NULL和IS测试IS NOT（即未知）。

在where子句中不能使用临时列？

2 个答案: