Question

示例：

    Table B                        Table A
ID Item   Record                  ID  Date
1   pen    10                     1   1/1/2015
1   CD     40                     2   7/3/2015
2   pen    20                     3   5/8/2016
2   CD     50                     4   10/12/2016 
3   pen    8
3   CD     30
3   pen    5
4   pen    10
4   CD     35

结果如下：

ID  Item  Record  LowestRecord Date
1   pen     10        10       1/1/2015
1   CD      40        40       1/1/2015
2   pen     20        10       7/3/2015
2   CD      50        40       7/3/2015
3   pen     8         5        5/8/2016
3   CD      30        30       5/8/2016
3   pen     5         5        5/8/2016
4   pen     10        5        10/12/2016
4   CD      35        30       10/12/2016

所以它选择最小值直到当前日期记录。提前致谢。

Answer 1

假设日期列是日期类型，您可以加入行表，如下所示：

select
    a.*,
    min(a.record) over (partition by item order by b.date, b.id) minrecord,
    b.date
from tableA a
inner join tableB b
on a.id = b.id;

Answer 2

您可以使用窗口功能，按项目对记录进行分组，并限制帧仅用于日期小于当前记录日期的记录，然后取最小值。

SELECT a.*
    , min(a.record) 
    OVER (PARTITION BY Item ORDER BY b.[Date] DESC 
          ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW ) AS LowestRecord
    , b.[DATE]
FROM
    a JOIN b ON a.id = b.id

Sql根据日期从多个表中获取最小值

2 个答案: