T-SQL 如果日期大于或等于该日期，则返回 x 如果不​​返回 y

Question

我有一个交易日期，需要从另一个表返回一个字段。

Table A  Visit    Bill     Transaction Date
          1         1          12/20/2016

如果代码日期在交易日期之后，我需要返回另一个代码表。

Table B   Bill   CodeID  Effective Code Date         Code
           1        A        9/1/2015                  ABCDE
           1        B        9/1/2015                  FGHI 
           1        C        9/1/2015                  JKLM
           1        A        10/01/2016                ZQMOP
           1        B        10/01/2016                XYZNP
           1        C        10/01/2016                EFGHI 

我如何得到这个结果？

 Vist   Bill  TransactionDate   CodeID     Code
 1       1       12/20/2016      A        ZQMOP
 1       1       12/20/2016      B        XYZNP
 1       1       12/20/2016      C        EFGHI 

Answer 1

这是一种方法，但我想到了其他方法（例如使用 row_number）

前两个 CTE 只是设置您的数据。然后查询基本上提取10/01/2016 的所有内容。该日期由选择max(b.EffectiveCodeDate) 的子查询确定，该日期严格小于该账单的交易日期。

;with a as
(
    select visit = 1, bill = 1, transactiondate = cast('12/20/2016' as date)
), b (Bill, CodeId, EffectiveCodeDate, Code) as
(
              select 1, 'A', cast('9/1/2015' as date),'ABCDE'
    union all select 1, 'B', '9/1/2015','FGHI' 
    union all select 1, 'C', '9/1/2015','JKLM'
    union all select 1, 'A', '10/01/2016','ZQMOP'
    union all select 1, 'B', '10/01/2016','XYZNP'
    union all select 1, 'C', '10/01/2016','EFGHI' 
)
select *
from b
where b.EffectiveCodeDate = 
    (
        select max(b.EffectiveCodeDate)
        from b
        inner join a
            on a.Bill = b.Bill
            and b.EffectiveCodeDate < a.TransactionDate
    )

Answer 2

我认为下面的查询有效

样本数据：

create table #A (Visit int, Bill int, [Transaction Date] date)
insert into #A values (1, 1, '12/20/2016')

create table #B (Bill int, CodeID char(1),  [Effective Code Date] date, Code varchar(10))
insert into #B values
(1, 'A', '9/1/2015'  , 'ABCDE'),
(1, 'B', '9/1/2015'  , 'FGHI' ),
(1, 'C', '9/1/2015'  , 'JKLM' ),
(1, 'A', '10/01/2016', 'ZQMOP'),
(1, 'B', '10/01/2016', 'XYZNP'),
(1, 'C', '10/01/2016', 'EFGHI')

查询：

;with ct as (
    select *
    , ROW_NUMBER() over (partition by Bill, CodeID order by [Effective Code Date] desc) RN
    from #B
)
select #A.*, ct.CodeID, ct.Code
from #A 
    inner join ct on ct.Bill = #A.Bill and ct.RN = 1

Answer 3

我认为这会解决的：

DECLARE @MinimumDiffrence int = (select Min(ABS(DATEDIFF(MILLISECOND,transaction_date,Effective_Code_Date))) 
                                from A inner join B on A.Bill=B.Bill)
select * 
from A
inner join B 
on A.Bill = B.Bill
where ABS(DATEDIFF(MILLISECOND,transaction_date,Effective_Code_Date)) = @MinimumDiffrence

必须有一种方法，只需 1 个查询就可以做到这一点，我会努力找到它。

Answer 4

试试这个，

create table #A (Visit int, Bill int, [Transaction Date] date)
insert into #A values (1, 1, '12/20/2016')

create table #B (Bill int, CodeID char(1), 
 [Effective Code Date] date, Code varchar(10))
insert into #B values
(1, 'A', '9/1/2015'  , 'ABCDE'),
(1, 'B', '9/1/2015'  , 'FGHI' ),
(1, 'C', '9/1/2015'  , 'JKLM' ),
(1, 'A', '10/01/2016', 'ZQMOP'),
(1, 'B', '10/01/2016', 'XYZNP'),
(1, 'C', '10/01/2016', 'EFGHI')

select * from
#A a 
    inner join #B b on b.Bill = a.Bill 
 where DATEDIFF(day,[Effective Code Date],[Transaction Date]) =
(
select min(DATEDIFF(day,[Effective Code Date],[Transaction Date])) MinDiff
from #A a 
    inner join #B b on b.Bill = a.Bill 

) 

    drop table #A
    drop table #B

Answer 5

我认为这种方法，使用CROSS APPLY 最接近您要解决的问题的描述：

declare @ta table (Visit int not null, Bill int not null, TransactionDate date not null)
insert into @ta (Visit,Bill,TransactionDate) values
(1,1,'20161220')

declare @tb table (Bill int not null, CodeID char(1) not null, 
                   EffectiveCodeDate date not null, Code varchar(5) not null)
insert into @tb (Bill,CodeID,EffectiveCodeDate,Code) values
(1,'A','20150901','ABCDE'),
(1,'B','20150901','FGHI'),
(1,'C','20150901','JKLM'),
(1,'A','20161001','ZQMOP'),
(1,'B','20161001','XYZNP'),
(1,'C','20161001','EFGHI')

select
    *
from
    @ta a
        cross apply
    (select *,ROW_NUMBER() OVER (PARTITION BY CodeID ORDER by EffectiveCodeDate desc) as rn
    from @tb b
    where
        b.Bill = a.Bill and
        b.EffectiveCodeDate < a.TransactionDate) p
where
    rn = 1

也就是说，对于表 B 中的每一行，以及每个不同的 CodeID 值，我们希望从表 A 中选择早于 TransactionDate 的最新行。

结果：

Visit       Bill        TransactionDate Bill        CodeID EffectiveCodeDate Code  rn
----------- ----------- --------------- ----------- ------ ----------------- ----- --------------------
1           1           2016-12-20      1           A      2016-10-01        ZQMOP 1
1           1           2016-12-20      1           B      2016-10-01        XYZNP 1
1           1           2016-12-20      1           C      2016-10-01        EFGHI 1

（作为练习将结果集缩减为您需要的列）