SQL CASE語句

Question

我的數據庫表PE中有兩個字段（BIT數據類型），而PER需要編寫一個sql case語句來執行以下任務。

當PER = 0然後打印「非必需」 當PER = 1，則檢查是否PE = 0然後打印「未完成」時PE = 1個打印「已完成」

以下是查詢我試圖而這是不工作

CASE pc.PER WHEN '0' THEN 'Not Required' 
            WHEN '1' THEN (CASE pc.PE WHEN '0' THEN 'Not Completed' 
         WHEN '1' THEN 'Completed') end as ab 

Answer 1

我想這可能是更容易把它寫成：

CASE 
    WHEN pc.PER = '0' THEN 'Not Required' 
    WHEN pc.PER = '1' AND pc.PE = '0' THEN 'Not Completed' 
    ELSE 'Completed' 
END 

或者你就必須後添加在您的查詢中：

CASE pc.PER WHEN '0' THEN 'Not Required' 
      WHEN '1' THEN (CASE pc.PE WHEN '0' THEN 'Not Completed' 
             WHEN '1' THEN 'Completed' 
          END) 
END AS ab 

Answer 2

您缺少一個結尾。

CASE pc.PER 
    WHEN 0 THEN 'Not Required' 
    WHEN 1 THEN 
     CASE pc.PE 
      WHEN 0 THEN 'Not Completed' 
      WHEN 1 THEN 'Completed' 
     END 
END as ab 

Answer 3

嘗試下面的語句來代替：

CASE WHEN pc.PER =0 THEN 'Not Required' 
    WHEN pc.PER =1 THEN 
     CASE WHEN pc.PE = 0 THEN 'Not Completed' 
       WHEN pc.PE = 1 THEN 'Completed' 
    End 
End as ab