如何使用Oracle SQL

Question

选择行的第一个连续组，我有以下数据：

 
Date    GroupID  Value 
1/01/2000 1     44 
2/01/2000 1     55 
3/01/2000 1     66 
4/01/2000 2     77 
5/01/2000 2     88 
6/01/2000 1     99 
7/01/2000 1     22 

我正在寻找能与连续组ID选择记录的第一组，当我为了通过查询日期。即在这个例子中我会得到：

 
1/01/2000 1     44 
2/01/2000 1     55 
3/01/2000 1     66 

随着组ID改变在下一行，我不会得到任何后续数据。

帮助将不胜感激

感谢

埃利

做

Answer 1

一个办法：

SQL> WITH DATA AS (
    2 SELECT '1/01/2000' mydate, 1 GroupID, 44 Value FROM DUAL 
    3 UNION ALL SELECT '2/01/2000', 1, 55 FROM DUAL 
    4 UNION ALL SELECT '3/01/2000', 1, 66 FROM DUAL 
    5 UNION ALL SELECT '4/01/2000', 2, 77 FROM DUAL 
    6 UNION ALL SELECT '5/01/2000', 2, 88 FROM DUAL 
    7 UNION ALL SELECT '6/01/2000', 1, 99 FROM DUAL 
    8 UNION ALL SELECT '7/01/2000', 1, 22 FROM DUAL 
    9 ) 
10 SELECT mydate, groupid, VALUE 
11 FROM (SELECT mydate, groupid, VALUE, 
12     SUM(gap) over(ORDER BY mydate) contiguous_group 
13    FROM (SELECT mydate, groupid, VALUE, 
14       CASE 
15        WHEN lag(groupid) 
16         over(ORDER BY mydate) != groupid 
17        THEN 
18        1 
19        ELSE 
20        0 
21       END gap 
22      FROM DATA)) 
23 WHERE contiguous_group = 0; 

MYDATE  GROUPID  VALUE 
--------- ---------- ---------- 
1/01/2000   1   44 
2/01/2000   1   55 
3/01/2000   1   66 

Answer 2

这是另一种方式如何做到这一点

WITH data AS 
(SELECT '1/01/2000' mydate, 
     1 groupid, 
     44 VALUE 
    FROM dual 
    UNION ALL 
    SELECT '2/01/2000', 
     1, 
     55 
    FROM dual 
    UNION ALL 
    SELECT '3/01/2000', 
     1, 
     66 
    FROM dual 
    UNION ALL 
    SELECT '4/01/2000', 
     2, 
     77 
    FROM dual 
    UNION ALL 
    SELECT '5/01/2000', 
     2, 
     88 
    FROM dual 
    UNION ALL 
    SELECT '6/01/2000', 
     1, 
     99 
    FROM dual 
    UNION ALL 
    SELECT '7/01/2000', 
     1, 
     22 
    FROM dual) 
SELECT * 
    FROM data 
WHERE rownum <= (SELECT MAX(rwn) 
        FROM (SELECT COUNT(*) over(PARTITION BY groupid ORDER BY rownum) cnt, 
           rownum rwn 
          FROM data) 
        WHERE rwn = cnt); 

P.S.查询文森特将无法工作，如果所有mydate值将相同

Answer 3

虽然已经回答，想分享它。它使用JOINs代替

WITH DATA AS (
SELECT '1/01/2000' mydate, 1 GroupID, 44 v 
UNION ALL SELECT '2/01/2000', 1, 55 
UNION ALL SELECT '3/01/2000', 1, 66 
UNION ALL SELECT '4/01/2000', 2, 77 
UNION ALL SELECT '5/01/2000', 2, 88 
UNION ALL SELECT '6/01/2000', 1, 99 
UNION ALL SELECT '7/01/2000', 1, 22 
) 

SELECT 
    a.GroupID, 
    a.mydate 
FROM 
    DATA a 
    JOIN DATA b ON (b.mydate <= a.mydate) 
GROUP BY 
    a.GroupID, 
    a.mydate 
HAVING 
    MAX(b.GroupID) = MIN (b.GroupID) 
ORDER BY 
    a.mydate