从约会列表中选择第一个和最后一个分数

Question

我有一个约会数据库，每个约会都有一个人名，序号，约会日期和两个问卷调查分数。

我需要做的是为每个人物带回一行，显示他们与分数的第一次约会，以及他们上次与分数的约会，以及两者的分数。

在花了很长一段时间已经在什么可能是一个非常简单的查询，我试图使用以下方法来只是给我的第预约得分：

SELECT 
PERSONID, 
MIN(CONTACTDATE) AS 'FIRST_CONTACT', 
QUEST_1, 
QUEST_2 

FROM TBL_APPOINTMENTS 

GROUP BY 
PERSONID, 
CONTACTDATE, 
QUEST_1, 
QUEST_2 

ORDER BY 
PERSONID, 
FIRST_CONTACT 

正如你可能已经猜到了，每当QUEST_1或QUEST_2中的值发生更改时，这会给我重复的行。

任何人都可以帮忙吗？我相信这一切都很简单，但是它让我感动不已！

在此先感谢！

Answer 1

如果你正在寻找的结果是这样的：

PERSONID FIRST_CONTACT FIRST_QUEST_1 FIRST_QUEST_2 LAST_CONTACT LAST_QUEST_1 LAST_QUEST_2 
----------- ------------- ------------- ------------- ------------ ------------ ------------ 
1   2015-01-01 10   11   2015-01-21 21   211 
2   2015-01-01 11   24   2015-01-31 12   25 
3   2015-02-01 13   21   2015-03-01 14   28 
4   2015-03-01 15   29   2015-04-01 16   21 

然后将下面的查询会这样想的。请注意，如果一个人只有一条记录，则最大和最小日期和分数将是相同的。

SELECT 
    PERSONID, 
    FIRST_CONTACT, FIRST_QUEST_1, FIRST_QUEST_2, 
    LAST_CONTACT, LAST_QUEST_1, LAST_QUEST_2 
FROM (
    SELECT PERSONID, MIN(CONTACTDATE) AS 'FIRST_CONTACT', MAX(CONTACTDATE) AS 'LAST_CONTACT' 
    FROM TBL_APPOINTMENTS a 
    GROUP BY PERSONID 
) a 
CROSS APPLY (
    SELECT QUEST_1 AS 'FIRST_QUEST_1', QUEST_2 AS 'FIRST_QUEST_2' 
    FROM TBL_APPOINTMENTS 
    WHERE PERSONID = a.PERSONID AND CONTACTDATE = A.FIRST_CONTACT 
) o_first 
CROSS APPLY (
    SELECT QUEST_1 AS 'LAST_QUEST_1', QUEST_2 AS 'LAST_QUEST_2' 
    FROM TBL_APPOINTMENTS 
    WHERE PERSONID = a.PERSONID AND CONTACTDATE = A.LAST_CONTACT 
) o_last 
ORDER BY PERSONID, FIRST_CONTACT; 

同样的查询可以用写联接：

SELECT 
    A.PERSONID, 
    FIRST_CONTACT, 
    F.QUEST_1 AS FIRST_QUEST_1, 
    F.QUEST_2 AS FIRST_QUEST_2, 
    LAST_CONTACT, 
    L.QUEST_1 AS LAST_QUEST_1, 
    L.QUEST_2 AS LAST_QUEST_2 
FROM (
    SELECT PERSONID, MIN(CONTACTDATE) AS 'FIRST_CONTACT', MAX(CONTACTDATE) AS 'LAST_CONTACT' 
    FROM TBL_APPOINTMENTS a 
    GROUP BY PERSONID 
) a 
JOIN TBL_APPOINTMENTS F ON F.PERSONID = a.PERSONID AND A.FIRST_CONTACT = F.CONTACTDATE 
JOIN TBL_APPOINTMENTS L ON L.PERSONID = a.PERSONID AND A.LAST_CONTACT = L.CONTACTDATE 
ORDER BY A.PERSONID, FIRST_CONTACT; 

Answer 2

SELECT PERSONID, 
    MIN(CONTACTDATE) AS 'FIRST_CONTACT', MAX(CONTACTDATE) AS 'LAST_CONTACT' 
    QUEST_1, 
    QUEST_2 
    FROM TBL_APPOINTMENTS 
    GROUP BY PERSONID, 
CONTACTDATE, 
QUEST_1, 
QUEST_2 
ORDER BY 
    PERSONID, 
    FIRST_CONTACT 

Answer 3

使用ROW_NUMBER()您可以分配约会从1在每PERSONID基础开始连续值。

在下面的例子中，我创建了两个这样的序数，一个在时间上向前，另一个在时间上反向。那么我可以选择first going forward以及first going backwards。

WITH 
    sorted AS 
(
    SELECT 
    PERSONID, 
    CONTACTDATE, 
    QUEST_1, 
    QUEST_2, 
    ROW_NUMBER() OVER (PARTITION BY PERSONID ORDER BY CONTACTDATE ASC) AS ORD_FWD, 
    ROW_NUMBER() OVER (PARTITION BY PERSONID ORDER BY CONTACTDATE DESC) AS ORD_REV 
    FROM 
    TBL_APPOINTMENTS 
) 
SELECT 
    PERSONID, 
    CONTACTDATE, 
    QUEST_1, 
    QUEST_2 
FROM 
    sorted 
WHERE 
    ORD_FWD = 1 OR ORD_REV = 1 
ORDER BY 
    PERSONID, 
    CONTACTDATE 

编辑随着第一和最后到一个行汇总...

WITH 
    sorted AS 
(
    SELECT 
    PERSONID, 
    CONTACTDATE, 
    QUEST_1, 
    QUEST_2, 
    ROW_NUMBER() OVER (PARTITION BY PERSONID ORDER BY CONTACTDATE ASC) AS ORD_FWD, 
    ROW_NUMBER() OVER (PARTITION BY PERSONID ORDER BY CONTACTDATE DESC) AS ORD_REV 
    FROM 
    TBL_APPOINTMENTS 
) 
SELECT 
    PERSONID, 
    MAX(CASE WHEN ORD_FWD = 1 THEN CONTACTDATE END) AS FIRST_CONTACTDATE, 
    MAX(CASE WHEN ORD_FWD = 1 THEN QUEST_1  END) AS FIRST_QUEST_1, 
    MAX(CASE WHEN ORD_FWD = 1 THEN QUEST_2  END) AS FIRST_QUEST_2, 
    MAX(CASE WHEN ORD_REV = 1 THEN CONTACTDATE END) AS FINAL_CONTACTDATE, 
    MAX(CASE WHEN ORD_REV = 1 THEN QUEST_1  END) AS FINAL_QUEST_1, 
    MAX(CASE WHEN ORD_REV = 1 THEN QUEST_2  END) AS FINAL_QUEST_2 
FROM 
    sorted 
WHERE 
    ORD_FWD = 1 OR ORD_REV = 1 
GROUP BY 
    PERSONID 
ORDER BY 
    PERSONID 

注意：这可能是第一个和最后一个约会是相同的任命（如果该人只有一个预约）。