甚至將其轉換後爲varchar它給錯誤：錯誤轉換數據類型爲varchar浮動，

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.

我不知道爲什麼我收到這個錯誤。

Answer 1

您遇到的困難是由於SQL Server要求在CASE表達式中生成的所有可能值具有相同的類型。由於您的ELSE使用的文本不能轉換爲任何數字類型，唯一的選擇是將數字轉換爲文本。

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 

該錯誤消息去，我在這裏假設[Performance Score]是float列。如果是其他類型，則必須適當修改呼叫CONVERT()。