Question

我有一个称为RECORDS的访问表，其中包含购买记录。

   Id   | Type |  Price  |     Date    |  Processed  |
------------------------------------------------------
   1    |  C   |   30€   |  01/01/2016 |    Null     |
------------------------------------------------------
   2    |  R   |  -30€   |  01/01/2016 |    Null     |
------------------------------------------------------
   3    |  C   |   10€   |  02/02/2016 |    Null     |
------------------------------------------------------
   4    |  C   |   10€   |  02/02/2016 |    Null     |
------------------------------------------------------
   5    |  R   |  -10€   |  02/02/2016 |    Null     |
------------------------------------------------------
   6    |  C   |   25€   |  03/02/2016 |    Null     |
------------------------------------------------------
   7    |  C   |   42€   |  04/02/2016 |    Null     |
------------------------------------------------------

我想做的是将具有一对相反的退款记录（类型“ R”）的费用（类型“ C”）记录设置为True。

就像这样： 1C和1R =真

   Id   | Type |  Price  |     Date    |  Processed  |
------------------------------------------------------
   1    |  C   |   30€   |  01/01/2016 |    True     |
------------------------------------------------------
   2    |  R   |  -30€   |  01/01/2016 |    True     |
------------------------------------------------------
   3    |  C   |   10€   |  02/02/2016 |    True     |
------------------------------------------------------
   4    |  C   |   10€   |  02/02/2016 |    Null     |
------------------------------------------------------
   5    |  R   |  -10€   |  02/02/2016 |    True     |
-----------------------------------------------------
   6    |  C   |   25€   |  03/02/2016 |    Null     |
------------------------------------------------------
   7    |  C   |   42€   |  04/02/2016 |    Null     |
------------------------------------------------------

到目前为止，我有这个设置，但它设置了所有N个费用“ C”记录均为

UPDATE 
RECORDS AS T1 
INNER JOIN RECORDS T2 
ON ABS(T1.Price) = ABS(T2.Price) AND T1.Date =T2.Date 
SET T1.Processed = TRUE
WHERE (T1.Type = 'C' AND T2.Type = 'R') OR (T1.Type = 'R' AND T2.Type = 'C')

Answer 1

使用EXISTS：

UPDATE RECORDS AS T 
SET T.Processed = TRUE
WHERE 
  (T.Type IN ('C', 'R') AND
    EXISTS (SELECT 1 FROM RECORDS 
      WHERE Type IN ('C', 'R') AND Type <> T.Type AND Date = T.Date AND Price + T.Price = 0
    )
  )
  AND T.Id = (SELECT MIN(ID) FROM RECORDS WHERE Date = T.Date AND Price = T.Price AND Type = T.Type)

WHERE中的最后一个条件包括Price，Date和Type列中重复的情况。
结果：

Id  Type    Price   Date        Processed
1   C       30,00   1/1/2016    True
2   R       -30,00  1/1/2016    True
3   C       10,00   2/2/2016    True
4   C       10,00   2/2/2016    NULL
5   R       -10,00  2/2/2016    True
6   C       25,00   3/2/2016    NULL
7   C       42,00   4/2/2016    NULL

选择同一表中的记录对SQL

1 个答案: