Question

我有一个4列表，主键是id，gameId和flag的组合。

id | gameId | score | flag
--------------------------
1  | 1      | 10    | 1
1  | 1      | 20    | 0
2  | 1      | 1     | 0
1  | 2      | 10    | 1
3  | 2      | 1     | 0

我需要更新表格，以便：

所有gameId 2分数都添加到gameId 1，其中id和flag是相同的。（例如，通过添加第1行和第4行的分数，第1行的得分为20）
如果发生以上情况，则需要删除gameId 2行。
如果未找到上述内容（例如，有一行gameId为2但id和flag与另一行不匹配），则gameId可以更改为1.

所以SQL完成后我的表应该如下所示：

id | gameId | score | flag
--------------------------
1  | 1      | 20    | 1
1  | 1      | 20    | 0
2  | 1      | 1     | 0
3  | 1      | 1     | 0

我怎样才能在SQL中写这个？谢谢:)）

Answer 1

认为这会起作用：

尝试1

UPDATE score_list AS t2
LEFT JOIN score_list AS t1 ON
  (t1.id = t2.id AND t1.flag = t2.flag AND t1.gameId = 1)
SET
  t1.score = t1.score + t2.score,
  t2.gameId = IF(t1.gameId IS NULL, 1, t2.gameId)
WHERE t2.gameId = 2;

DELETE FROM score_list WHERE gameId = 2;

尝试2

# add scores to gameId = 1
UPDATE score_list AS t2
LEFT JOIN score_list AS t1 ON
  (t1.id = t2.id AND t1.flag = t2.flag AND t1.gameId = 1)
SET
  t1.score = t1.score + t2.score
WHERE t2.gameId = 2;

# try to move gameID 2 to gameId 1, using ignore to allow rows to fail, as gameId alredy exists
UPDATE IGNORE score_list SET gameId = 1 WHERE gameId = 2;

# delete all not updated rows from last query
DELETE FROM score_list WHERE gameId = 2;

MySQL更新表，其中包含来自同一个表的值

1 个答案: