Oracleテーブルから特定のレコードを含むビューを作成する

Question

次の表TB_STATUSからビューを作成したいとします。次のように

ID EVENT_DATE  REOPEN_DATE 
1 16/1/2013 16:16 
2 16/1/2013 16:38 
3 16/1/2013 18:18 
4 15/1/2013 0:00 
5 16/1/2013 16:36 16/1/2013 0:00 
6 16/1/2013 17:12 16/1/2013 0:00 
7 4/1/2014 9:00 4/1/2014 0:00 
8 5/1/2014 14:00 5/1/2014 0:00 
9 4/1/2014 11:00 
10 4/1/2014 16:00 
11 4/8/2013 11:00 
12 15/8/2013 1:00 

予想ビューコンテンツはREOPEN_DATE間でMIN(EVENT_DATE)ある：

ID EVENT_DATE  REOPEN_DATE 
4 15/1/2013 0:00 
5 16/1/2013 16:36 16/1/2013 0:00 
2 16/1/2013 16:38 
6 16/1/2013 17:12 16/1/2013 0:00 
11 4/8/2013 11:00 
7 4/1/2014 9:00 4/1/2014 0:00 
9 4/1/2014 11:00 
8 5/1/2014 14:00 5/1/2014 0:00 

任意の助けを大幅に高く評価されるであろう次のように上記データセットの

ID EVENT_DATE  REOPEN_DATE 
    MIN(EVENT_DATE) 
        REOPEN_DT 
    MIN(EVENT_DATE) 
        REOPEN_DT 
    MIN(EVENT_DATE) 
        REOPEN_DT 
    MIN(EVENT_DATE) 

期待される結果になります。

Answer 1

SQL Fiddle

Oracleの11グラムR2スキーマのセットアップ：1

CREATE TABLE TB_STATUS(
    ID   INTEGER PRIMARY KEY, 
    EVENT_DATE DATE NOT NULL, 
    REOPEN_DATE DATE 
); 

INSERT INTO TB_STATUS 
SELECT 1, TIMESTAMP '2013-01-16 16:16:00', NULL FROM DUAL UNION ALL 
SELECT 2, TIMESTAMP '2013-01-16 16:38:00', NULL FROM DUAL UNION ALL 
SELECT 3, TIMESTAMP '2013-01-16 18:18:00', NULL FROM DUAL UNION ALL 
SELECT 4, TIMESTAMP '2013-01-15 00:00:00', NULL FROM DUAL UNION ALL 
SELECT 5, TIMESTAMP '2013-01-16 16:36:00', TIMESTAMP '2013-01-16 00:00:00' FROM DUAL UNION ALL 
SELECT 6, TIMESTAMP '2013-01-16 17:12:00', TIMESTAMP '2013-01-16 00:00:00' FROM DUAL UNION ALL 
SELECT 7, TIMESTAMP '2014-01-04 09:00:00', TIMESTAMP '2014-01-04 00:00:00' FROM DUAL UNION ALL 
SELECT 8, TIMESTAMP '2014-01-05 14:00:00', TIMESTAMP '2014-01-05 00:00:00' FROM DUAL UNION ALL 
SELECT 9, TIMESTAMP '2014-01-04 11:00:00', NULL FROM DUAL UNION ALL 
SELECT 10, TIMESTAMP '2014-01-04 16:00:00', NULL FROM DUAL UNION ALL 
SELECT 11, TIMESTAMP '2013-08-04 11:00:00', NULL FROM DUAL UNION ALL 
SELECT 12, TIMESTAMP '2013-08-15 01:00:00', NULL FROM DUAL; 

CREATE VIEW TB_STATUS_MINS AS 
SELECT ID, 
     EVENT_DATE, -- CASE WHEN REOPEN_DATE IS NULL THEN EVENT_DATE END, 
     REOPEN_DATE 
FROM (
    SELECT t.*, 
     LAG(REOPEN_DATE, 1, DATE '1970-01-01') OVER (ORDER BY EVENT_DATE) AS prev_reopen 
    FROM TB_STATUS t 
) 
WHERE reopen_date IS NOT NULL 
OR  prev_reopen IS NOT NULL 

問合せ：

SELECT * 
FROM TB_STATUS_MINS 

Results：

| ID |   EVENT_DATE |   REOPEN_DATE | 
|----|----------------------|----------------------| 
| 4 | 2013-01-15T00:00:00Z |    (null) | 
| 5 | 2013-01-16T16:36:00Z | 2013-01-16T00:00:00Z | 
| 2 | 2013-01-16T16:38:00Z |    (null) | 
| 6 | 2013-01-16T17:12:00Z | 2013-01-16T00:00:00Z | 
| 3 | 2013-01-16T18:18:00Z |    (null) | 
| 7 | 2014-01-04T09:00:00Z | 2014-01-04T00:00:00Z | 
| 9 | 2014-01-04T11:00:00Z |    (null) | 
| 8 | 2014-01-05T14:00:00Z | 2014-01-05T00:00:00Z |