Question

在此表中，我存储了某些spid的可变值。随着时间的推移，这些值可能会发生变化，而spid可能会获得新值。

现在我想知道在启用某个值之前。

这是单个spid的数据

uid  spid   propertyvalue   creationdate      
--------------------------------------------------
1    3      First name       2010-01-17 22:34:00
37   3      Second name      2010-01-18 01:07:24
38   3      Third name       2010-01-18 01:09:00
39   3      Fourth name      2010-01-18 01:18:16
40   3      Fifth name       2010-01-18 01:20:02

所以第一个值从 2010-01-18 01:07:24 开始，并且在 2010-01-18 01:01:00 之前有效。< / p>

我已经尝试过此查询：

SELECT s1 . * , 
       s2.creationdate AS datetwo
  FROM salespointproperty s1
  JOIN salespointproperty s2 ON s1.spid = s2.spid
                            AND s1.creationdate < s2.creationdate

这给了我很多双记录（其中一些是错误的），它总是省略最后一个新名称（因为它没有新的创建日期）例如：

uid spid    propertyvalue    creationdate           datetwo
-------------------------------------------------------------- 
1   3       First name       2010-01-17 22:34:00    2010-01-18 01:07:24 *
1   3       First name       2010-01-17 22:34:00    2010-01-18 01:09:00
37  3       Second name      2010-01-18 01:07:24    2010-01-18 01:09:00 *
1   3       First name       2010-01-17 22:34:00    2010-01-18 01:18:16
37  3       Second name      2010-01-18 01:07:24    2010-01-18 01:18:16
38  3       Third name       2010-01-18 01:09:00    2010-01-18 01:18:16 *
1   3       First name       2010-01-17 22:34:00    2010-01-18 01:20:02
37  3       Second name      2010-01-18 01:07:24    2010-01-18 01:20:02
38  3       Third name       2010-01-18 01:09:00    2010-01-18 01:20:02
39  3       Fourth name      2010-01-18 01:18:16    2010-01-18 01:20:02 *

只有带星号的行是正确的。缺少第五个名字。

Answer 1

假设在你的例子中，uid 37在uid 38之前有效，uid 38有效直到uid 39等。

SELECT
  s1.uid,
  s1.spid,
  s1.propertyvalue,
  s1.creationdate,
  MIN(s2.creationdate) AS datetwo
FROM salespointproperty s1
INNER JOIN salespointproperty s2
    ON s1.spid = s2.spid
    AND s1.creationdate < s2.creationdate
GROUP BY
  s1.uid,
  s1.spid,
  s1.propertyvalue,
  s1.creationdate;

确定MySQL查询中的“有效直到”日期

1 个答案: