Table update in oracle

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1.00/5 (1 vote)

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ID  VAL CNT
1-  45	-5
2-  40	-8
3-  30	-9
4-  78	-6
5-  88	-4
6-  0   -0
7-  0	-0
8-  0   -0
9-  45	-8
10- 83  -9
11- 0   -0

I want to update the all the VAL column where CNT is 0 with its previous value where where CNT > 0.So, the o/p should be :

ID  VAL CNT
1-  45	-5
2-  40	-8
3-  30	-9
4-  78	-6
5-  88	-4
6-  88  -0
7-  88	-0
8-  88  -0
9-  45	-8
10- 83  -9
11- 83  -0

I know it is a silly question,but i am stuck.
Any help?
Thanks

Posted 26-Jun-15 20:16pm

Deepak.xip

Updated 29-Jun-15 0:59am

Jörgen Andersson

v2

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CHill60 27-Jun-15 10:43am

I'm not posting this as a solution as I couldn't get it to work and I'm rushing now to catch a plane! However, I think you need to use the LAG and MERGE functions/methods. Something like
MERGE INTO yourTable USING
(SELECT
ID, LAG(VAL,1) over(ORDER BY ID) previous_VAL
FROM yourTable ) CT ON (CP.ID=CT.ID)
WHEN MATCHED THEN UPDATE SET yourTable.VAL = CT.previous_VAL;

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Jörgen Andersson · Answer 1 · 2015-06-29T01:41:00

Here's a select that will give you the values needed, now you just need to merge them.

SQL

WITH connected as (
    SELECT  ID
           ,LAG(ID,1) OVER(ORDER BY ID) PREVID
           ,VAL
           ,CNT
    FROM    Table1
    )
,CTE(ID,VAL,CNT) as (    
    SELECT  ID
           ,VAL
           ,CNT
    FROM    connected
    WHERE   PREVID IS NULL
    UNION ALL
    SELECT  c.ID
           ,NVL(NULLIF(c.VAL,0),CTE.VAL) VAL
           ,c.CNT
    FROM    connected c
    JOIN    CTE
        ON  CTE.ID = c.PREVID
    )
SELECT  ID,VAL,CNT
FROM    CTE