Cómo seleccionar el primer grupo continuo de filas utilizando Oracle SQL

Question

tengo los siguientes datos:

 
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 

Busco a una consulta capaz de seleccionar el primer grupo de registros con un GroupID continua cuando pido por Fecha. es decir, en este ejemplo me gustaría tener:

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

Como el grupo ID cambiado en la fila siguiente, que no conseguiría ningún dato posteriores.

ayuda será muy apreciada

Gracias

Elie

Answer 1

una manera de hacerlo:

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

Ésta es otra manera de cómo hacerlo

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. la consulta de Vincent no funcionará si todos los valores de mydate serán los mismos

Answer 3

Aunque ya se ha respondido, quería compartirlo. Utiliza JOINs en su lugar

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