Question

我正在使用CASE命令将字符串查询结果从数字更改为名称。

事情似乎工作正常，但我很难弄清楚为什么结果只显示字符串的第一个值。

Declare @OverrideON INT, @OverrideOFF INT 
SET @OverrideON = 1  SET @OverrideOFF = 0

SELECT LonDeviceName,
CASE  WHEN SUBSTRING (PointValue,65,1) = @OverrideON  THEN 'Fan In Override' 
      WHEN SUBSTRING (PointValue,67,1) = @OverrideON  THEN 'HW In Override'    
      WHEN SUBSTRING (PointValue,69,1) = @OverrideON  THEN 'CHW In Override'
      WHEN SUBSTRING (PointValue,71,1) = @OverrideON  THEN 'OAD In Override'
      WHEN SUBSTRING (PointValue,73,1) = @OverrideON  THEN 'VFD In Override'
      WHEN SUBSTRING (PointValue,65,1) = @OverrideOFF THEN 'Fan Normal' 
      WHEN SUBSTRING (PointValue,67,1) = @OverrideOFF THEN 'HW Normal'    
      WHEN SUBSTRING (PointValue,69,1) = @OverrideOFF THEN 'CHW Normal'
      WHEN SUBSTRING (PointValue,71,1) = @OverrideOFF THEN 'OAD Normal'
      WHEN SUBSTRING (PointValue,73,1) = @OverrideOFF THEN 'VFD Normal'
      ELSE '**StringError**'
END as 'Manual Overrides'
FROM dbo.Points
WHERE LogicName like '%override%'

当代码运行时，它会创建一个标题为Manual Overrides的列，该列正确，在该列中显示字符串中的第一个值。但是，字符串中其他四个值的结果在哪里。任何帮助或想法将不胜感激。

感谢。

Answer 1

这样的事情怎么样：

SELECT LonDeviceName,
    CASE  WHEN SUBSTRING (PointValue,65,1) = @OverrideON  THEN 'In Override'
          WHEN SUBSTRING (PointValue,65,1) = @OverrideOFF THEN 'Normal'
          ELSE '**StringError**'
    END as 'Fan',
    CASE  WHEN SUBSTRING (PointValue,67,1) = @OverrideON  THEN 'In Override' 
          WHEN SUBSTRING (PointValue,67,1) = @OverrideOFF THEN 'Normal'
          ELSE '**StringError**'
    END as 'HW',
    CASE  WHEN SUBSTRING (PointValue,69,1) = @OverrideON  THEN 'In Override'
          WHEN SUBSTRING (PointValue,69,1) = @OverrideOFF THEN 'Normal'
          ELSE '**StringError**'
    END as 'CHW',
    CASE  WHEN SUBSTRING (PointValue,71,1) = @OverrideON  THEN 'In Override'
          WHEN SUBSTRING (PointValue,71,1) = @OverrideOFF THEN 'Normal'
          ELSE '**StringError**'
    END as 'OAD',
    CASE  WHEN SUBSTRING (PointValue,73,1) = @OverrideON  THEN 'In Override'
          WHEN SUBSTRING (PointValue,73,1) = @OverrideOFF THEN 'Normal'
          ELSE '**StringError**'
    END as 'VFD'
FROM dbo.Points
WHERE LogicName like '%override%'

Answer 2

你真的需要这些庞大的变量来代表1和0吗？真？无论如何，真的猜测你想要输出什么。也许这个：

SELECT LonDeviceName, [Manual Overrides] = '' 
    + 'Fan '  + CASE SUBSTRING (PointValue,65,1) 
                WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + ',HW '  + CASE SUBSTRING (PointValue,67,1) 
                WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + ',CHW ' + CASE SUBSTRING (PointValue,69,1) 
                WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + ',OAD ' + CASE SUBSTRING (PointValue,71,1) 
                WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + ',VFD ' + CASE SUBSTRING (PointValue,73,1) 
                WHEN '1' THEN 'In Override' ELSE 'Normal' END
FROM dbo.Points
WHERE LogicName LIKE '%override%';

或者您可能只想查看实际覆盖的值：

SELECT LonDeviceName, [Manual Overrides] = '' 
    + 'Fan '  + CASE SUBSTRING (PointValue,65,1) 
                WHEN '1' THEN 'In Override' ELSE '' END
    + ',HW '  + CASE SUBSTRING (PointValue,67,1) 
                WHEN '1' THEN 'In Override' ELSE '' END
    + ',CHW ' + CASE SUBSTRING (PointValue,69,1) 
                WHEN '1' THEN 'In Override' ELSE '' END
    + ',OAD ' + CASE SUBSTRING (PointValue,71,1) 
                WHEN '1' THEN 'In Override' ELSE '' END
    + ',VFD ' + CASE SUBSTRING (PointValue,73,1) 
                WHEN '1' THEN 'In Override' ELSE '' END
FROM dbo.Points
WHERE LogicName LIKE '%override%';

或许你想要单独的列：

SELECT LonDeviceName, 
    + [Fan] = CASE SUBSTRING (PointValue,65,1) 
              WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + [HW]  = CASE SUBSTRING (PointValue,67,1) 
              WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + [CHW] = CASE SUBSTRING (PointValue,69,1) 
              WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + [OAD] = CASE SUBSTRING (PointValue,71,1) 
              WHEN '1' THEN 'In Override' ELSE 'Normal' END
    + [VFD] = CASE SUBSTRING (PointValue,73,1) 
              WHEN '1' THEN 'In Override' ELSE 'Normal' END
FROM dbo.Points
WHERE LogicName LIKE '%override%';

或许完全不同的东西。如果我们看不到源数据或您想要的结果，那么很难将您编写的查询与您想要的结果之间的差距缩小。

SQL Server CASE函数仅返回string中的第一个值

2 个答案: