更新與同桌

Question

百分比計算研究我有一個這樣的表：

ItemID  PersonID Score  Percentage 
========================================== 
1    1  10   [ = 10/10+30 = 25%] 
1    2  30   [ = 30/10+30 = 75%] 
2    1  20   [ = 20/20+40 = 33%] 
2    2  40   [ = 40/20+40 = 67%] 

的「百分比」中的數據沒有進入，但是自動計算的，在一定的時間間隔。 計算是百分比=分數/總項目ID分數

而不是使用「選擇做數學更新」方法，我試圖編寫單個SQL來更新「百分比」。

我想什麼是這樣的：

UPDATE tb_temp AS t1 
    SET t1.Percentage = 
     CEIL(t1.Score/
      (SELECT SUM(t2.Score) FROM tb_temp AS t2 WHERE t2.ItemID = t1.ItemID) 
     ); 

但它不工作（錯誤代碼：1093你不能指定FROM子句中更新目標表「T1」）。

有什麼想法？

Answer 1

嘗試：

UPDATE tb_temp t1 
    JOIN (SELECT ItemId, SUM(t2.Score) TotalScore 
      FROM tb_temp 
      group by ItemId) t2 ON t2.ItemID = t1.ItemID 
    SET t1.Percentage = CEIL(t1.Score/t2.TotalScore) 

Answer 2

UPDATE tb_temp AS t1 
    SET t1.Percentage = 
     CEIL(t1.Score/
      (SELECT SUM(t2.Score) FROM tb_temp AS t2 left join tb_temp AS t3 on t2.ItemID = t3.ItemID) 
     );