SQL 在相关表中查找最近的生效日期

Question

我会先说明这个问题与SQL Join on Nearest Less Than Date 类似，但那里的解决方案不适用于我的问题。我不需要选择单个列，而是需要基于最近日期“过滤”的表的结果。

我有三张桌子。主表包含时间票数据，格式为：

ticketId 
ticketNumber 
ticketDate
projectId 

辅助表跟踪项目每张每日票的资源费率计划。它看起来像这样：

scheduleId
projectId
effectiveDate

还有一个与第二个相关的第三个表，其中实际包含适用的费率。像这样的：

scheduleId
straightTime
overTime

加入 projectId 上的前两个表（显然）会复制项目费率计划中每条记录的数据。如果我有项目 1 的 3 个费率表，则工单记录会产生如下结果：

 ticketNumber  | ticketDate   | projectId   | effectiveDate  | scheduleId
 ------------- | ------------ | ----------- | -------------- | ----------
 1234          | 2016-06-18   | 25          | 2016-06-01     | 1
 1234          | 2016-06-18   | 25          | 2016-06-15     | 2
 1234          | 2016-06-18   | 25          | 2016-06-31     | 3

在我的结果中选择有效日期很简单：

  SELECT *
    ,  (SELECT TOP 1 t1.effectiveFrom 
        FROM         dbo.labourRateSchedule t1
        WHERE        t1.effectiveFrom <= t2.[date] and t1.projectId = t2.projectId
        ORDER BY     t1.effectiveFrom desc) as effectiveDate

  FROM dbo.timeTicket t2
  ORDER BY t.date

但是，我需要能够将 dbo.labourRateSchedule 的 ID 加入到第三个表中以获取适用的实际费率。将 t1.ID 添加到 SELECT 语句不会使其可访问以 JOIN 到另一个相关表中。

我一直在尝试在 FROM 语句中加入 SELECT 语句，但结果仅是最后一个有效日期值，而不是最接近适用的票证日期的值。

我将非常感谢任何帮助！

Answer 1

您可以使用CROSS APPLY 将子查询移动到FROM 子句：

SELECT *
FROM dbo.timeTicket tt
CROSS APPLY
(
  SELECT TOP(1) *
  FROM dbo.labourRateSchedule lrs
  WHERE lrs.projectId = tt.projectId
    AND lrs.effectiveFrom <= tt.date
  ORDER BY lrs.effectiveFrom desc
) best_lrs
JOIN dbo.schedule s on s.schedule_id = best_lrs.schedule_id
ORDER BY tt.date

Answer 2

您可以尝试这样的事情吗（您应该更改一些内容，因为您没有发布所有信息）。

 SELECT A.*, C.*
  FROM timeTicket A
  INNER JOIN  (SELECT * , ROW_NUMBER() OVER (PARTITION BY projectId ORDER BY effectiveFrom DESC) AS RN
                FROM labourRateSchedule) B ON A.projectId=B.projectId AND B.RN=1
  INNER JOIN YOUR3TABLE C ON B.SCHEDULEID=C.SCHEDULEID

Answer 3

你可以通过 CTE 和 Rank 函数来做到这一点 -

create table timeTicket  (ticketId  int,
ticketNumber int ,
ticketDate smalldatetime ,
projectId int )
go

create table labourRateSchedule 
(scheduleId int,
projectId int,
effectiveDate smalldatetime ) 
go

create table ApplicableRates
(scheduleId int,
straightTime smalldatetime ,
overTime smalldatetime) 
go

insert into timeTicket
select 1 , 1234   ,'2016-06-18' ,25   
go

insert into labourRateSchedule
select 1 , 25   ,'2016-06-01'   
union all select 2 , 25   ,'2016-06-15'  
union all select 3 , 25   ,'2016-06-30'  
go

insert into ApplicableRates    
select 1 , '2016-06-07'    ,'2016-06-07'   
union all select 2 ,  '2016-06-17'      ,'2016-06-17'  
union all select 3 ,   '2016-06-22'     ,'2016-06-25'           
go

  with cte 
  as (
  select t1.ticketNumber    ,t1.ticketDate  ,t1.projectId       ,t2.effectiveDate   ,t3.scheduleId  ,t3.straightTime    
  ,t3.overTime , rank() over (  partition by t1.ticketNumber order by abs     (DATEDIFF(day,t1.ticketDate, t2.effectiveDate) ) )  DyaDiff 
  from  timeTicket t1 join  labourRateSchedule t2
  on t1.projectId = t2.projectId
  join ApplicableRates t3
  on t2.scheduleId = t3.scheduleId)
  select * from cte where DyaDiff = 1