在 DATEDIFF 之后使用 CASE 逻辑答案

【问题标题】：Using CASE logic after DATEDIFF在 DATEDIFF 之后使用 CASE 逻辑
【发布时间】：2018-05-18 18:06:10
【问题描述】：

我正在成功地使用 DATEDIFF 逻辑来计算年龄。然后我需要能够获取 Age 并将其用作 CASE 逻辑中的列。当我尝试这样做时，SMSS 会在红色下划线 Age 并指示它是无效列。我该如何解决这个问题？

USE DataWarehouse
SELECT DISTINCT
M.[Account Name Birth Date] as 'Birth Date',
M.[Mailing Address State] as 'State',
E.[ANSVIES2] as 'Income',
E.[FICO] as 'FICO Score',

DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 as [Age],

CASE WHEN [Age] >= 18 AND [Age] <= 34 AND E.[ANSVIES2] >= 50 THEN 'Credit 
Driven'
WHEN [Age] < 45 AND E.[ANSVIES2] < 50 THEN 'Fee Driven'
WHEN [Age] >= 35 AND [Age] <= 54 AND E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 
125 THEN 'Middle Market'
WHEN [Age] >= 45 AND E.[ANSVIES2] < 50 THEN 'Low Income Depositor'
WHEN [Age] >= 55 AND E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 125 THEN 'Middle 
Income Depositor'
WHEN [Age] >= 35 AND E.[ANSVIES2] >= 125 THEN 'Upscale'
ELSE 'Unclassified' END as 'Consumer Segment'

【问题讨论】：

将其转储到临时表中，然后从那里与您的案例块一起选择
我从未使用过临时表。我会研究一下。感谢您的回复。
它非常简单。你只需要做select whatever fields into #temp from table 然后select case when... from #temp

标签： sql sql-server tsql case datediff

【解决方案1】：

或使用子选择（根据您的数据库大小和索引，临时表或临时表可能会更好，但这应该可行）：

   Select CASE WHEN [Age] >= 18 AND [Age] <= 34 AND E.[ANSVIES2] >= 50 THEN 'Credit 
Driven'
WHEN [Age] < 45 AND E.[ANSVIES2] < 50 THEN 'Fee Driven'
WHEN [Age] >= 35 AND [Age] <= 54 AND E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 
125 THEN 'Middle Market'
WHEN [Age] >= 45 AND E.[ANSVIES2] < 50 THEN 'Low Income Depositor'
WHEN [Age] >= 55 AND E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 125 THEN 'Middle 
Income Depositor'
WHEN [Age] >= 35 AND E.[ANSVIES2] >= 125 THEN 'Upscale'
ELSE 'Unclassified' END as 'Consumer Segment'
, OtherColumnsHere
FROM (
     SELECT DISTINCT
     M.[Account Name Birth Date] as 'Birth Date',
     M.[Mailing Address State] as 'State',
     E.[ANSVIES2] as 'Income',
     E.[FICO] as 'FICO Score',    
     DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 as [Age],
     FROM RestOfYourSelectStatementHere
) SubSelect

【讨论】：

我无法成功地将其应用到我的代码中，但这个解决方案有效 -

【解决方案2】：

SSMS 突出显示您的语法的原因是logical-processing order of SQL。

简单地说，选择阶段中使用的别名“Age”，不能在同一阶段引用——它可以在后续阶段引用——（例如下一阶段 - ORDER BY）。

因此，一个解决方法是创建一个 CTE 或 嵌套表。

查询的逻辑步骤顺序：

FROM/JOIN/APPLY/PIVOT/UNPIVOT
在哪里
分组依据
有
选择列表/DISTINCT
订购人
TOP/OFFSET-FETCH

【讨论】：

很好的解释，我只是给了他一个可能的解决方案你解释了它。

【解决方案3】：

你不需要使用subquery，你可以直接使用value构造来表达：

 SELECT  . . . ,
        (CASE WHEN tt.Age >= 18 AND tt.Age <= 34 AND t.[ANSVIES2] >= 50 
              THEN 'Credit Driven'
              WHEN [Age] < 45 AND E.[ANSVIES2] < 50 THEN 'Fee Driven'
              WHEN [Age] >= 35 AND [Age] <= 54 AND 
                   E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 125 
              THEN 'Middle Market'
              WHEN [Age] >= 45 AND E.[ANSVIES2] < 50 
              THEN 'Low Income Depositor'
              WHEN [Age] >= 55 AND E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 125 
              THEN 'Middle Income Depositor'
              WHEN [Age] >= 35 AND E.[ANSVIES2] >= 125 THEN 'Upscale'
              ELSE 'Unclassified'
         END) AS [Consumer Segment]
FROM table t 
CROSS APPLY (VALUES 
                (DATEDIFF(DD, t.[Account Name Birth Date],GETDATE())/365)
            ) tt(Age);

【讨论】：

我觉得有趣的是您仍然继续使用 子查询 :)

【解决方案4】：

上面发布的代码由于某种原因不起作用。不过，我能够成功实施此解决方案 -

USE DataWarehouse
SELECT DISTINCT
M.[Symitar Account Id] as 'Symitar ID',
M.[Account Name Birth Date] as 'Birth Date',
M.[Account Name Death Date] as 'Death Date',
M.[Mailing Address State] as 'State',
E.[ANSVIES2] as 'Income',
E.[FICO] as 'FICO Score',
M.[Loan Type] as 'Loan Description',
M.[Loan Type Code] as 'Loan Type',
M.[Share Type] as 'Share Description',
M.[Share Type Code] as 'Share Type',

DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 as [Age],

CASE WHEN DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 >= 18 AND 
DATEDIFF(DD,M.[Account Name Birth Date],
GETDATE())/365 <= 34 AND E.[ANSVIES2] >= 50 THEN 'Credit Driven'
WHEN DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 < 45 AND E. 
[ANSVIES2] < 50 THEN 'Fee Driven'
WHEN DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 >= 35 AND 
DATEDIFF(DD,M.[Account Name Birth Date],
GETDATE())/365 <= 54 AND E.[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 125 THEN 
'Middle Market'
WHEN DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 >= 45 AND E. 
[ANSVIES2] < 50 THEN 'Low Income Depositor'
WHEN DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 >= 55 AND E. 
[ANSVIES2] >= 50 AND E.[ANSVIES2] <= 125 
THEN 'Middle Income Depositor'
WHEN DATEDIFF(DD,M.[Account Name Birth Date],GETDATE())/365 >= 35 AND E. 
[ANSVIES2] >= 125 THEN 'Upscale'
ELSE 'Unclassified' END as 'Consumer Segment'

FROM Accounts.ExperianData E
INNER JOIN Accounts.MemberCube M
ON E.[Symitar Account Id] = M.[Symitar Account Id]
WHERE M.[Account Name Type] = 'Primary' AND /* Primary acct holders */
M.[Account Status] = 'Open' AND 
M.[Account Type] IN ('General Membership', 'Indirect Account', 'Employee Acc 
ount') AND 
/* Remove businesses and internal accounts */
M.[Account Name Birth Date] <= '05/18/1997' /* Older than 21 */ AND
M.[Mailing Address State] IN('UT', 'ID', 'AZ', 'NV', 'NM')

【讨论】：