mysql - 我在 MYSQL 查询中的 SELF JOIN 中遇到问题。请查表并查询

Question

请通过以下查询创建表:

 CREATE TABLE `trade` 
      ( 
         `order`      VARCHAR(10) DEFAULT NULL, 
         `positionid` INT(11) DEFAULT NULL, 
         `time`       DATETIME DEFAULT NULL, 
         `volume`     FLOAT NOT NULL 
      ) 
    engine=innodb 
    DEFAULT charset=latin1; 

插入查询

 INSERT INTO `trade` 
                (`order`, 
                 `positionid`, 
                 `time`, 
                 `volume`) 
    VALUES      ('42556', 
                 1111, 
                 '2018-08-15 07:27:44', 
                 2), 
                ('42560', 
                 1111, 
                 '2018-08-18 08:32:47', 
                 2), 
                ('42564', 
                 1235, 
                 '2018-08-21 07:10:12', 
                 5), 
                ('42572', 
                 1235, 
                 '2018-08-23 17:20:26', 
                 2), 
                ('42580', 
                 1235, 
                 '2018-08-23 17:03:30', 
                 3); 

我尝试过以下查询:

 SELECT b.`order` AS `TICKET`, 
           b.`time`  AS `OPEN_TIME`, 
           j.`time`  AS `CLOSE_TIME` 
    FROM   trade AS b 
           LEFT JOIN trade AS j 
                  ON b.`positionid` = j.`positionid` 
    WHERE  b.`time` != j.`time`; 

表:

错误输出:

该图像显示重复数据:

所需输出:

此图像将显示所需的输出:

描述:

当我们打开交易时，它将存储到交易表中。之后，当我们关闭交易时，它将以不同的时间和交易量进行另一个输入(如果交易将部分关闭，则交易量将不同，否则将完全关闭交易)。这里第一个条目是 OPEN_TIME，存储为 Time，第二个条目是 CLOSE_TIME。那么如何将两个或多个记录转换为具有 OPEN_TIME 和 CLOSE_TIME 的单个记录呢？

Answer 1

检查这个

SELECT j.`order` AS `TICKET`, 
b.`positionid` AS `PositionID`,
   b.`time`  AS `OPEN_TIME`, 
   j.`time`  AS `CLOSE_TIME` ,
   j.`volume` AS `Volume`
FROM   trade AS b 
   INNER JOIN trade AS j 
          ON b.`positionid` = j.`positionid` 
where b.time = (select min(time) from trade as c1 where b.positionid=c1.positionid)
AND b.time!=j.time;