如何选择日期范围第一和最后一个数据

Question

我有一个SQL查询：

WITH Cte AS 
(
    SELECT DateTime, 

     rn1 = ROW_NUMBER() OVER(ORDER BY DateTime ASC), 
     rn2 = ROW_NUMBER() OVER(ORDER BY DateTime DESC) 
    FROM 
     Test 
    WHERE 
     Username = 'ME' 
     AND DateTime > '2016-01-05' 
     AND DateTime < '2016-01-06' 
) 
SELECT * FROM Cte WHERE rn1 = 1 UNION ALL 
SELECT * FROM Cte WHERE rn2 = 1 

与此查询我成功地获得在第一个和最后一个数据2016

1月5日，但我怎样才能得到第一个和最后一个数据，例如，从1月5日到1月8日？

也就是说，我想从1月5日开始获取第一个和最后一个数据，然后是1月6日的第一个数据和最后一个数据，然后是1月7日的第一个数据和最后一个数据，最后是第一个数据和最后一个数据数据来自1月8日。

UPDATE

，你可以看到，顺序是那种乱
的，我希望它看起来像这样

Answer 1

为了让每一天的第一个和最后一个数据从1月5日至8日，您需要在OVER条款中添加PARTITION BY：

WITH Cte AS(
    SELECT 
     DateTime, 
     rn1 = ROW_NUMBER() OVER(PARTITION BY CAST(DateTime AS DATE) ORDER BY DateTime ASC), 
     rn2 = ROW_NUMBER() OVER(PARTITION BY CAST(DateTime AS DATE) ORDER BY DateTime DESC) 
    FROM Test 
    WHERE 
     Username = 'ME' 
     AND DateTime >= '20160105' 
     AND DateTime < '20160109' 
) 
SELECT * FROM Cte WHERE rn1 = 1 OR rn2 = 1 

---

编辑：

WITH Cte AS(
    SELECT 
     CAST(DateTime AS DATE), 
     DateTime, 
     rn1 = ROW_NUMBER() OVER(PARTITION BY CAST(DateTime AS DATE) ORDER BY DateTime ASC), 
     rn2 = ROW_NUMBER() OVER(PARTITION BY CAST(DateTime AS DATE) ORDER BY DateTime DESC) 
    FROM Test 
    WHERE 
     Username = 'ME' 
     AND DateTime >= '20160105' 
     AND DateTime < '20160109' 
) 
SELECT * FROM Cte WHERE rn1 = 1 OR rn2 = 1 
ORDER BY CAST(DateTime AS DATE)