Question

我有一张桌子A

Trade#    Trade_DT
  1        08/10/2013
  2        08/20/2013

和表B

BaseRate   EffectiveDT
  1.5       08/01/2013
  2.0       08/15/2013
  3.0       08/25/2013

我希望有一个联接，以便在TradeDT之后获得EffectiveDT

Trade# Trade_DT   BaseRate    EffectiveDT
  1    08/10/2013  2.0        08/15/2013
  2    08/20/2013  3.0        08/25/2013

Answer 1

我猜你想要Trade_Dt后的最早生效日期。以下内容适用于任何SQL方言：

select a.*,
       (select min(EffectiveDt)
        from b
        where b.EffectiveDt > a.TradeDt
       ) as EffectiveDt
from a;

编辑：

要获取b表格中的所有值，只需将表格重新加入：

select t.Trade#, t.Trade_DT, b.BaseRate, b.EffectiveDt
from (select a.*,
             (select min(EffectiveDt)
              from b
              where b.EffectiveDt > a.TradeDt
             ) as EffectiveDt
      from a
     ) t join
     b
     on a.EffectiveDt = b.EffectiveDt;

Answer 2

在Oracle中，您可以使用：

  select distinct Trade,
           Trade_DT,
           FIRST_VALUE(BaseRate) Over (partition by Trade order by EffectiveDT desc) BaseRate,
           FIRST_VALUE(EffectiveDT) Over (partition by Trade order by EffectiveDT desc) EffectiveDT
      from tableA
inner join tableB 
        on tableA.Trade_DT >= tableB.EffectiveDT

这里是demo in SQLFiddle。

Answer 3

此代码仅使用标准SQL：

SELECT a.*, b.*
FROM TableA a
JOIN TableB b ON b.EffectiveDT =  
                 (SELECT MIN(EffectiveDT) 
                  FROM TableB b1 
                  WHERE a.TradeDT < b1.EffectiveDT)

关于2个表的SQL连接查询

3 个答案: