甚至将其转换后为varchar它给错误：错误转换数据类型为varchar浮动，

Question

SELECT a.[Emp_No], 
     a.[Emp_Name], 
     a.[Band], 
     b.[Max_Exp] AS Max_Yrs_Experience, 
     CASE WHEN a.Performance_Score = 0 AND (a.Status_Active > 0 OR a.Status_New > 0) 
      THEN CONVERT(varchar, 0) 
      WHEN a.Performance_Score > 0 
      THEN [Performance_Score] 
      ELSE 'No History Data Found' 
     END AS Performance_Score 
INTO #EXPER 
FROM #PERFORMANCE a, #agg_exp b 
WHERE a.[Emp_No] = b.[Emp_No] 
ORDER BY Performance_Score DESC 

Error converting varchar to float.

我不知道为什么我收到这个错误。

Answer 1

您遇到的困难是由于SQL Server要求在CASE表达式中生成的所有可能值具有相同的类型。由于您的ELSE使用的文本不能转换为任何数字类型，唯一的选择是将数字转换为文本。

CASE WHEN a.Performance_Score = 0 AND (a.Status_Active > 0 OR a.Status_New > 0) 
    THEN CONVERT (VARCHAR(10), 0)      -- zero as text 
    WHEN a.Performance_Score > 0 
    THEN CONVERT (VARCHAR(10), [Performance_Score]) -- performance score as text 
    ELSE 'No History Data Found'      -- this is already text 
END AS Performance_Score 

该错误消息去，我在这里假设[Performance Score]是float列。如果是其他类型，则必须适当修改呼叫CONVERT()。