我在Teradata中有一个表,由以下五列组成:
Old New Type_of_Old Type_of_New Change_Dt
----------------------------------------------------
A B 0 1 Date 1
B C 1 1 Date 2
C D 1 0 Date 3
D B 0 1 Date 4
B E 1 1 Date 5
我想绑定旧的-从第一个其type_of_old = 0的元素开始的新值,并在到达最后一个type_of_old = 1时切开边界。最后,我想获得此数据:
Fırst Next Change Dt
-------------------------------
A B Date 1
A C Date 2
A D Date 3
D B Date 4
D E Date 5
问题是,元素B是A和D的下一个元素,它们的更改日期不同。因此,当我使用WITH RECURSIVE脚本时,它将绑定B的下一个元素,并且两个A都以D结尾。
到目前为止,我已经编写了此脚本,但是当它达到type_of_old = 1时,我无法设法削减界限
CREATE MULTISET TABLE TEST.TABLE_A ( OLD_ELM VARCHAR(1), NEW_ELM VARCHAR(1),
TYPE_OF_OLD BYTEINT , TYPE_OF_NEW BYTEINT, CHANGE_DT DATE)
INSERT INTO TEST.TABLE_A ('A','B',0, 1, DATE '2018-01-01');
INSERT INTO TEST.TABLE_A ('B','C',1, 1, DATE '2018-02-01');
INSERT INTO TEST.TABLE_A ('C','D',1, 0, DATE '2018-03-01');
INSERT INTO TEST.TABLE_A ('D','B',0, 1, DATE '2018-04-01');
INSERT INTO TEST.TABLE_A ('B','E',1, 1, DATE '2018-05-01');
WITH RECURSIVE ELEMENT_PATH ( FIRST_ELM, NEXT_ELM, CHANGE_DT ) AS
( SELECT OLD_ELM, NEW_ELM, CHANGE_DT
FROM TEST.TABLE_A
WHERE TYPE_OF_OLD = 0
AND TYPE_OF_NEW = 1
UNION ALL
SELECT P.FIRST_ELM, A.NEW_ELM, A.CHANGE_DT
FROM ELEMENT_PATH P
JOIN TEST.TABLE_A A ON A.OLD_ELM = P.NEXT_ELM
WHERE A.CHANGE_DT > P.CHANGE_DT)
SELECT * FROM ELEMENT_PATH
此脚本中的数据如下:
FIRST_ELM NEXT_ELM CHANGE_DT
A B 01.01.2018
A C 01.02.2018
A D 01.03.2018
D B 01.04.2018
D E 01.05.2018
A B 01.04.2018 (Wrong)
A E 01.05.2018 (Wrong)
A E 01.05.2018 (Wrong)
我该如何解决?
预先感谢
致谢
答案 0 :(得分:0)
您需要在where子句中添加一个附加条件(AND TYPE_OF_OLD <> 0)以删除错误的记录。
WITH RECURSIVE ELEMENT_PATH ( FIRST_ELM, NEXT_ELM, CHANGE_DT ) AS
( SELECT OLD_ELM, NEW_ELM, CHANGE_DT
FROM DQRC.TABLE_A
WHERE TYPE_OF_OLD = 0
AND TYPE_OF_NEW = 1
UNION ALL
SELECT P.FIRST_ELM, A.NEW_ELM, A.CHANGE_DT
FROM ELEMENT_PATH P
JOIN DQRC.TABLE_A A
ON A.OLD_ELM = P.NEXT_ELM
WHERE A.CHANGE_DT > P.CHANGE_DT
AND TYPE_OF_OLD <> 0)
SELECT * FROM ELEMENT_PATH
不确定,因为我今天刚刚看过,它现在对您有用。