Question

我需要根据事务日期从Table2接收一个标志...我在表1和table2之间做了一个左外连接。我在左外连接后创建了2个计算字段：

Cal_Validfrom - If Validityfrom is null then 10000101 else Validityfrom end
Cal_ValidTo   - If ValidityTo   is null then 99991231 else Validityfrom end

我会过滤计算字段和交易日期

案例1）

Table 1 ->  Transaction ID   Transaction Date   Price
              123             02/15/2017        $100
Table 2  -> Transaction ID   ValidityFrom  ValidityTo  Flag
               123            01/01/2017   01/15/2017   A
               123            01/16/2017   02/01/2017   B 
               123            02/02/2017   12/31/9999   C

加入后

     Transaction ID    Transaction Date   Price    ValidityFrom  ValidityTo  Flag   Cal_Validfrom Cal_ValidTo
           123           02/15/2017        $100     01/01/2017   01/15/2017   A       01/01/2017   01/15/2017
           123           02/15/2017        $100     01/16/2017   02/01/2017   B       01/16/2017   02/01/2017
           123           02/15/2017        $100     02/02/2017   12/31/9999   C       02/02/2017   12/31/9999

然后过滤Cal_Validfrom＆lt; =交易日期＆lt; = Cal_ValidTo

     Transaction ID    Transaction Date   Price    ValidityFrom  ValidityTo  Flag   Cal_Validfrom Cal_ValidTo
           123           02/15/2017        $100     02/02/2017   12/31/9999   C       02/02/2017   12/31/9999

情况2）

Table 1 ->  Transaction ID   Transaction Date   Price
              123             02/15/2017        $100   
Table 2  -> ValidityFrom  ValidityTo
No Records

加入后

     Transaction ID    Transaction Date   Price    ValidityFrom  ValidityTo  Flag   Cal_Validfrom Cal_ValidTo
           123           02/15/2017        $100     Null          Null       Null    01/01/1000   12/31/9999

然后过滤Cal_Validfrom＆lt; =交易日期＆lt; = Cal_ValidTo

     Transaction ID    Transaction Date   Price    ValidityFrom  ValidityTo  Flag   Cal_Validfrom Cal_ValidTo
           123           02/15/2017        $100     Null          Null       Null    01/01/1000   12/31/9999

情形3）

Table 1 ->  Transaction ID   Transaction Date   Price
              123             02/15/2017        $100

Table 2  -> Transaction ID   ValidityFrom  ValidityTo  Flag
               123            01/01/2017   01/15/2017   A
               123            01/16/2017   02/01/2017   B

加入后

     Transaction ID    Transaction Date   Price    ValidityFrom  ValidityTo  Flag   Cal_Validfrom Cal_ValidTo
           123           02/15/2017        $100     01/01/2017   01/15/2017   A       01/01/2017   01/15/2017
           123           02/15/2017        $100     01/16/2017   02/01/2017   B       01/16/2017   02/01/2017

然后过滤Cal_Validfrom＆lt; =交易日期＆lt; = Cal_ValidTo

     Transaction ID    Transaction Date   Price    ValidityFrom  ValidityTo  Flag   Cal_Validfrom Cal_ValidTo

问题出在案例3中 - 我仍然需要查看交易 - 我不能松开交易或复制交易。

任何建议

Answer 1

问题是您在联接后过滤，这可能会消除交易记录。为了解决这个问题，你需要做一个左外连接，一个已经过滤的表，让我们调用那个表table2＆＃39;。表2＆＃39;是table2和table1之间（正常）连接的结果，您应用过滤器。由于您没有提供架构，我将用此说明：

select t1.[Transaction ID], t1.[Transaction Date], t1.[Price], 
       t2.[Transaction ID], t2.ValidityFrom , t2.ValidityTo,  t2.Flag
from table1 t1
    left outer join table2 t2 on t1.[Transaction ID] = t2.[Transaction ID]
where 
    t2.ValidityFrom <= [Transaction Date]  
    and [Transaction Date] <= t2.ValidityTo


-- SHOULD BECOME:


select t1.[Transaction ID], t1.[Transaction Date], t1.[Price], 
       t2.[Transaction ID], t2.ValidityFrom , t2.ValidityTo,  t2.Flag
from table1 t1
    left outer join 
    (   select t22.[Transaction ID], t22.ValidityFrom , t22.ValidityTo,  t22.Flag
        from table2 t22 join table1 t11 on t11.[Transaction ID] = t22.[Transaction ID]
        where 
            t22.ValidityFrom <= [Transaction Date]  
            and [Transaction Date] <= t22.ValidityTo    
    ) t2

带有效性检查的条件连接sql

1 个答案: