如何在MySQL中获得对应于MAX（DATE）的FIELD？

Question

我的两个表如下：

Table 1 : Transaction
TRANS_ID (primary key), TRANS_DATE, TRANS_STATUS, USER_ID (Foreign_Key) 

状态更改时将重复相同的user_id

Table 2 : Users
USER_ID (Primary_Key), USER_NAME, USER_DOB, OTHER_INFO

我想获取用户信息以及上次交易状态。

我熟悉以下查询。

SELECT MAX(Transaction.TRANS_DATE),Transaction.TRANS_STATUS, Users.USER_NAME, Users.USER_DOB
FROM Users
INNER_JOIN Transaction ON Transaction.USER_ID = Users.USER_ID 
WHERE Transaction.USER_ID = @UserID    

我通过Parameter.AddWithValue传递了UserID 。 不幸的是，这种方法不返回TRANS_STATUS为MAX(TRANS_DATE) 它返回MAX(TRANS_DATE)但TRANS_STATUS是第一次出现，没有相应的STATUS以MAX(TRANS_DATE)记录。

请让我知道我怎么能得到TRANS_STATUS为MAX(TRANS_DATE) 我更喜欢使用INNER JOIN但建议INNER JOIN赞赏。

我仍然无法上班。

这是我的表格脚本。

CREATE TABLE `Transactions` (
  `TRANS_ID` int(11) NOT NULL,
  `TRANS_DATE` datetime NOT NULL,
  `TRANS_STATUS` varchar(45) NOT NULL,
  `USER_ID` int(11) NOT NULL,
  PRIMARY KEY (`TRANS_ID`),
  UNIQUE KEY `TRANS_ID_UNIQUE` (`TRANS_ID`),
  KEY `USER_ID_idx` (`USER_ID`),
  CONSTRAINT `USER_ID` FOREIGN KEY (`USER_ID`) REFERENCES `Users` (`USER_ID`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8

CREATE TABLE `Users` (
  `USER_ID` int(11) NOT NULL AUTO_INCREMENT,
  `USER_NAME` varchar(45) NOT NULL,
  `USER_DOB` datetime NOT NULL,
  `OTHER_INFO` varchar(45) NOT NULL,
  PRIMARY KEY (`USER_ID`),
  UNIQUE KEY `USER_ID_UNIQUE` (`USER_ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

Answer 1

您可以在子查询上使用联接的最大TRANS_DATE

    select t.max_trans, t.USER_NAME, t.USER_DOB
    from Transaction 
    INNER JOIN 
    (
        SELECT MAX(Transaction.TRANS_DATE) max_trans, 
             Transaction.USER_ID, Users.USER_NAME, Users.USER_DOB
        FROM Users
        INNER_JOIN Transaction ON Transaction.USER_ID = Users.USER_ID 
        WHERE Transaction.USER_ID = @UserID
    ) t on Transaction.USER_ID = t.USER_ID and t.max_trans = Transaction.TRANS_DATE

Answer 2

如果我理解正确，这可能对您有用

SELECT A.USER_ID AS USER_ID, A.TRANS_DATE AS TRANS_DATE, TRANS_STATUS, USER_NAME, USER_DOB
FROM
(SELECT USER_ID, MAX(TRANS_DATE) AS TRANS_DATE FROM TRANSACTION
GROUP BY USER_ID) A
INNER JOIN
(SELECT USER_ID, TRANS_DATE, TRANS_STATUS FROM TRANSACTION) B
ON A.USER_ID = B.USER_ID
AND A.TRANS_DATE=B.TRANS_DATE
INNER JOIN USERS U
ON A.USER_ID=U.USER_ID;

Answer 3

SELECT Users.USER_NAME, Users.USER_DOB
FROM Users usr INNER JOIN(
    SELECT Transaction.TRANS_STATUS, MAX(Transaction.TRANS_DATE)
    FROM Transaction GROUP BY Transaction.TRANS_STATUS) trs ON trs.USER_ID=usr.USER_ID

Answer 4

您可以使用LAST_VALUE函数

SELECT Top 1 
      u.User_ID
     ,u.user_name
     ,u.user_dob
     ,u.other_info
    ,LAST_VALUE(t.Trans_Date) OVER (PARTITION BY t.user_id ORDER BY 
              t.Trans_Date RANGE BETWEEN UNBOUNDED PRECEDING AND
            UNBOUNDED FOLLOWING) AS Max_Tran_Date
    ,LAST_VALUE(t.trans_status) OVER (PARTITION BY t.user_id ORDER BY 
              t.Trans_Date RANGE BETWEEN UNBOUNDED PRECEDING AND
            UNBOUNDED FOLLOWING) as Last_Status
FROM #Users as u
INNER JOIN #Transaction as t ON t.user_id = u.user_id
WHERE u.User_ID = @UserID