有人会帮忙构建表并查询吗?谢谢你的时间!
假设以下是我拥有的手机的记录:
ID | Object | Start Month | End Month
1 | Phone 1 | 1 | 3
2 | Phone 1 OS Update | 2 | 3
3 | Phone 2 | 4 | 5
4 | Phone 3 | 6 | 7
Desired result
Query: Month = 2; Return ID = 1,2 (Logic: Phone 1 with its OS update)
Query: Month = 4; Return ID = 3 (Logic: Phone 2 replaces Phone 1 and update)
Query: Month = 6; Return ID = 4 (Logic: Phone 3 replaces Phone 2)
现在,我正在制作一个单独的表格,其打印时间如下。
ID | Object | Month
1 | Phone 1 | 1
1 | Phone 1 | 2
2 | Phone 1 OS Update | 2
1 | Phone 1 | 3
2 | Phone 1 OS Update | 3
3 | Phone 2 | 4
3 | Phone 2 | 5
4 | Phone 3 | 6
4 | Phone 3 | 7
SELECT [ID]
FROM Table
WHERE MONTH = 2
我还添加了一个额外的列,其id为下一个" superior"电话。是否可以自动生成此表而无需每月手动插入每一行?如果此表效率低下,我该如何构造表然后进行查询?
ID | Object | Month | Superior Object ID
1 | Phone 1 | 1 | 3
1 | Phone 1 | 2 | 3
2 | Phone 1 OS Update | 2 | 1
1 | Phone 1 | 3 | 3
2 | Phone 1 OS Update | 3 | 1
3 | Phone 2 | 4 | 4
3 | Phone 2 | 5 | 4
4 | Phone 3 | 6 | NULL
4 | Phone 3 | 7 | NULL