需要为每个empId计算列

Question

表1（包含更多其他字段的主表）

----------------------------------------------------------
    Emp Id  Pgm_Start Date End Date       Total_No_of_Days
----------------------------------------------------------
 - ID001    11/04/2103    11/10/2013       7
 - ID001    10/05/2013    10/08/2013       4
 - ID002    10/09/2013    10/15/2013       7
 - ID002    09/02/2013    09/06/2013       5

我的以下查询提供以下内容：

SELECT EmpID,COUNT(ProgramID) AS Total_Programs, 
SUM(CAST(Total_No_Of_Days AS INT)) AS Total_Program_Days from table1  
GROUP BY empid ORDER BY Total_Programs desc,Total_Program_Days desc  

--------------------------------------------------------------------------
Emp Id  Total_Program   Total_Program_Days   Days_since_last_Program
 -------------------------------------------------------------------------
 - ID001     2            11                     ---need this value---
 - ID002     2            12                     ---need this value----

我想基于table1为每个员工计算最后一个字段（Days_since_last_Program）..

所以我锻炼......

此查询为“ID001”

提供最后一个程序End_date

 SELECT * from table1 where  End_Date= (select
 MAX(Convert(Date,End_Date))  from table1 where EmpId=’ID001’) and
 EmpID=ID001

---

所以，最后获得价值但是我为单个用户提供了这个：

 SELECT ABS( DATEDIFF(DAY,CURRENT_TIMESTAMP,
(SELECT End_date from table1 where  
 End_Date = (select    MAX(Convert(Date,End_Date))  
 FROM table1 where EmpId=ID001) and
 EmpID=ID001))) as "Days_since_last_Program"

我希望所有员工的这个计算值为“自上次计划以来的天数”列，但无法弄清楚如何，请帮我弄清楚.. 提前谢谢..

Answer 1

它不仅仅是......

SELECT 
    EmpID,
    COUNT(ProgramID) AS Total_Programs, 
    SUM(CAST(Total_No_Of_Days AS INT)) AS Total_Program_Days,
    DATEDIFF(DAY, MAX(CONVERT(DATE,End_Date)), GETDATE()) AS Days_Since_Last_Program
FROM table1
GROUP BY empid 
ORDER BY Total_Programs DESC,Total_Program_Days DESC

Answer 2

在你的查询中发布了很少的修改..

SELECT *
  FROM table1 t1
 WHERE end_date = (SELECT MAX(convert(DATE, t2.end_date)) 
                     FROM table1 t2 
                    WHERE t2.empid = t1.empid)

只需要让一个用户认为end_date没有重复。 否则你可能会为同一个用户获得多行。

Answer 3

这将使用相关子查询：

SELECT
    *,
    ABS(DATEDIFF(DAY,CURRENT_TIMESTAMP,(
        SELECT MAX(Convert(Date,t2.End_Date))  
        from table1 t2
        where t2.EmpId=t1.EmpId
    ))) AS [Days_since_last_Program]

FROM table1 t1;