Question

我想用SQL（No PL / SQL！或其他东西）选择最接近的值小于给定值的条目。

我到目前为止：

select max(RUN_ID) from RUN_TABLE where KEY = 'TEST#33' and RUN_ID < 3

这将返回与键匹配的最小值小于3的行，但我希望能够选择所有列。

Run_ID  Entity  Key
1         HK    TEST#11
2         AB    TEST#22
2         CK    TEST#33
3         TB    TEST#22
3         DB    TEST#33

我希望能够使用密钥TEST＃22和最大RUN_ID 4来选择行：

3   TB   TEST#22

当说最大RUN_ID 2要检索

时

2   AB   TEST#22

Answer 1

按运行ID降序排序，仅取第一行，对于Oracle：

select top 1 * from RUN_TABLE
where KEY = 'TEST#33' and RUN_ID < 3
order by RUN_ID desc
fetch first 1 rows

或SQL Server（因为SQLFiddle的Oracle选项已关闭）：

select top 1 * from RUN_TABLE
where KEY = 'TEST#33' and RUN_ID < 3
order by RUN_ID desc

live demo on SQLFiddle。

Answer 2

select Run_ID, Entity, Key from from RUN_TABLE a
where Run_ID = (select max(RUN_ID) from RUN_TABLE b where b.Key = a.Key and RUN_ID < 3)
and KEY = 'TEST#33'

Answer 3

类似的东西：

select t1.*
from RUN_TABLE t1
join (
   select max(RUN_ID) AS MAX_RUN_ID
   from RUN_TABLE 
   where KEY = 'TEST#33' and RUN_ID < 3
) t2 ON t1.RUN_ID = t2.MAX_RUN_ID
WHERE KEY = 'TEST#33'

选择最小值小于给定值的条目

3 个答案: