从非规范化表

Question

我有这样

RepID|Role|Status|StartDate |EndDate | 
-----|----|------|----------|----------| 
10001|R1 |Active|01/01/2015|01/31/2015| 
-----|----|------|----------|----------| 
10001|R1 |Leavee|02/01/2015|02/12/2015| 
-----|----|------|----------|----------| 
10001|R1 |Active|02/13/2015|02/28/2015| 
-----|----|------|----------|----------| 
10001|R2 |Active|03/01/2015|03/18/2015| 
-----|----|------|----------|----------| 
10001|R2 |Leave |03/19/2015|04/10/2015| 
-----|----|------|----------|----------| 
10001|R2 |Active|04/11/2015|05/10/2015| 
-----|----|------|----------|----------| 
10001|R1 |Active|05/11/2015|06/13/2015| 
-----|----|------|----------|----------| 
10001|R1 |Leave |06/14/2015|12/31/9998| 
-----|----|------|----------|----------| 

我在寻找这样的输出在我的表中的数据标准化数据，

RepID|Role|StartDate |EndDate | 
-----|----|----------|----------| 
10001|R1 |01/01/2015|02/28/2015| 
-----|----|----------|----------| 
10001|R2 |03/01/2015|05/10/2015| 
-----|----|----------|----------| 
10001|R1 |05/11/2015|12/31/9998| 
-----|----|----------|----------| 

每当只有角色的变化发生，我需要捕获开始和结束日期。我尝试了不同的方式，但无法获得输出。

任何帮助表示赞赏。

下面是我试图与SQL，但它不帮助，

SELECT T1.RepID, T1.Role, Min(T1.StartDate)  AS StartDate,  Max(T1.EndDate) AS EndDate 
FROM 
(SELECT rD1.RepID, rD1.Role, rD1.StartDate, rD1.EndDate 
FROM repDetails rD1 
INNER JOIN repDetails rD2 
    ON rD2.RepID = rD1.RepID AND rD2.StartDate = DateAdd (Day, 1, rD1.EndDate)  AND (rD2.Role = rD1.Role OR (rD2.Role IS NULL AND rD1.Role IS NULL)   OR (rD2.Role = '' AND rD1.Role = '')) 

UNION 

SELECT rD2.RepID, rD2.Role, rD2.StartDate, rD2.EndDate 
FROM repDetails rD1 
INNER JOIN repDetails rD2 
    ON rD2.RepID = rD1.RepID AND rD2.StartDate = DateAdd (Day, 1, rD1.EndDate)  AND (rD2.Role = rD1.Role OR (rD2.Role IS NULL AND rD1.Role IS NULL)   OR (rD2.Role = '' AND rD1.Role = '')) 
    ) T1 
GROUP BY T1.RepID, T1.Role 

UNION 

SELECT EP.RepID, EP.Role AS DataValue, EP.StartDate, EP.EndDate 
FROM repDetails EP 
LEFT OUTER JOIN 
(SELECT rD1.RepID, rD1.Role, rD1.StartDate, rD1.EndDate 
FROM repDetails rD1 
INNER JOIN repDetails rD2 
    ON rD2.RepID = rD1.RepID AND rD2.StartDate = DateAdd (Day, 1, rD1.EndDate)  AND (rD2.Role = rD1.Role OR (rD2.Role IS NULL AND rD1.Role IS NULL)   OR (rD2.Role = '' AND rD1.Role = '')) 

UNION 

SELECT rD2.RepID, rD2.Role , rD2.StartDate, rD2.EndDate 
FROM repDetails rD1 
INNER JOIN repDetails rD2 
    ON rD2.RepID = rD1.RepID AND rD2.StartDate = DateAdd (Day, 1, rD1.EndDate)  AND (rD2.Role = rD1.Role OR (rD2.Role IS NULL AND rD1.Role IS NULL)   OR (rD2.Role = '' AND rD1.Role = '')) 
    ) T1 
ON EP.RepID = T1.RepID AND EP.StartDate = T1.StartDate 
WHERE T1.RepID IS NULL 

Answer 1

这里的关键是找出连续行，直到角色的转变。这可以通过使用lead函数和其他一些逻辑将所有前面的行分类到同一组中来比较下一行的角色来完成。

将它们分组后，您只需使用min和max即可获取开始日期和结束日期。

with groups as (
select x.* 
,case when grp = 1 then 0 else 1 end + sum(grp) over(partition by repid order by startdate) grps 
from (select t.* 
     ,case when lead(role) over(partition by repid order by startdate) = role then 0 else 1 end grp 
     from t) x 
) 
select distinct repid,role 
,min(startdate) over(partition by repid,grps) startdt 
,max(enddate) over(partition by repid,grps) enddt 
from groups 
order by 1,3 

Sample demo

Answer 2

你只想分钟（开始）/ MAX（完）每个REPID和角色的日期？ 如果是这样，请尝试：

Select 
    repID, role, 
    min(starDate), 
    max(endDate) 
from 
    tbl 
group by 
    repID, role 

- 更详细的解决方案，相当于VKP的：

SELECT 
    repid, ROLE, grpID, 
    MIN(startdate) AS min_startDateOverRole, 
    MAX(endDate) AS max_endDateOverRole 
FROM 
    (SELECT 
     *, CASE WHEN isGrpEnd = 1 THEN 0 ELSE 1 end + 
     -- when on group end row, don't increment grpID. 
     -- Wait until start of next group 
     SUM(isGrpEnd) OVER(ORDER BY startdate) grpID 
     -- sum(all group end rows up to this one) 
    FROM 
      (SELECT 
       *, 
       CASE WHEN lead(ROLE) OVER(ORDER BY startdate) = ROLE 
         THEN 0 ELSE 1 end isGrpEnd 
      FROM t) x ) 
GROUP BY 
    repid, ROLE, grpid 
ORDER BY 
    1,3