Question

在我的SELECT查询中，我想在CASE中为一个名为 IsActive 的值添加一个条件，以便在当前行的列类型中输入是＆＃34; adhoc＆＃34; 然后将IsActive的值设置为＆＃34; n / a＆＃34;。

SELECT CASE Type
            WHEN 'scheduled' THEN 'Scheduled'
            WHEN 'adhoc' THEN 'AdHoc'
            ELSE 'Unknown'
       END AS 'Type',
       CASE IsActive 
            WHEN (Type) = 'adhoc' THEN 'n/a'
            WHEN 0 THEN 'Stopped'
            WHEN 1 THEN 'Active'
       END AS 'Status'
FROM MyTable

但我在第WHEN (Type) = 'adhoc' THEN 'n/a'行上收到此错误：

＆＃39; =＆＃39;。
附近的语法不正确

如何根据当前行的条件做出决定？

Answer 1

您的第二个case基于一个列，然后您尝试在when中添加条件，这是不允许的：

CASE IsActive 
            WHEN (Type) = 'adhoc' THEN 'n/a'
            WHEN 0 THEN 'Stopped'
            WHEN 1 THEN 'Active'
       END AS 'Status'

我认为您打算这样做（使用不带列的case并将条件放在when中）：

CASE 
WHEN [Type] = 'adhoc' THEN 'n/a'
WHEN IsActive = 0 THEN 'Stopped'
WHEN IsActive = 1 THEN 'Active'
END AS 'Status'

Answer 2

试试这个：

SELECT (CASE Type
            WHEN 'scheduled' THEN 'Scheduled'
            WHEN 'adhoc' THEN 'AdHoc'
            ELSE 'Unknown'
        END) AS 'Type',
       (CASE 
            WHEN Type = 'adhoc' THEN 'n/a'
            WHEN IsActive = 0 THEN 'Stopped'
            WHEN IsActive = 1 THEN 'Active'
        END) AS 'Status'
FROM MyTable;

Answer 3

Pedram jaan您的查询将是这样的：

SELECT CASE [Type]
            WHEN 'scheduled' THEN 'Scheduled'
            WHEN 'adhoc' THEN 'AdHoc'
            ELSE 'Unknown'
       END AS 'Type',
       CASE  
            WHEN [Type] = 'adhoc' THEN 'n/a'
            WHEN IsActive = 0 THEN 'Stopped'
            WHEN IsActive = 1 THEN 'Active'
       END AS 'Status'
FROM dbo.MyTable

使用类似括号的类型[类型]。这是一个关键字。

Answer 4

SELECT CASE Type
        WHEN 'scheduled' THEN 'Scheduled'
        WHEN 'adhoc' THEN 'AdHoc'
        ELSE 'Unknown'
   END AS 'Type',
   CASE WHEN [Type] = 'adhoc' THEN 'n/a'                        
        WHEN IsActive = 0 THEN 'Stopped'
        WHEN IsActive = 1 THEN 'Active'
   END AS 'Status'
FROM MyTable

Answer 5

MS Sql Server不支持当前计算的行操作。要实现这个目标，你必须提到一个Cte

with cteType as (
SELECT CASE Type
            WHEN 'scheduled' THEN 'Scheduled'
            WHEN 'adhoc' THEN 'AdHoc'
            ELSE 'Unknown'
       END AS 'Type'
FROM MyTable)

select Type
,
       CASE IsActive 
            WHEN (Type) = 'adhoc' THEN 'n/a'
            WHEN 0 THEN 'Stopped'
            WHEN 1 THEN 'Active'
       END AS 'Status'
FROM cteType

这将有效

WHEN条件基于当前行值

5 个答案: