asked on

carry forward row values

I have got table with 10 rows and one column:
0
0
1
0
0
0
2
0
0
0

I want to write a select query which will carry forward any non-zero values to successive rows unless the value in the column changes.

This means that the query will return the following for the data shown above:
0 0
0 0
1 1 --value changed from 0 to 1 in column 1
0 1 --value '1' carried forward as the current value of column1 is zero
0 1 --value '1' carried forward as the current value of column1 is zero
0 1 --value '1' carried forward as the current value of column1 is zero
2 2 --value '1' not carried forward as the current value of column1 is 2
0 2 --value '1' carried forward as the current value of column1 is zero
0 2 --value '1' carried forward as the current value of column1 is zero
0 2 --value '1' carried forward as the current value of column1 is zero

Any idea anybody?
Thanks in advance.

Sean Stuber

you must have a second column in order to ensure the sorting order you have displayed.

otherwise there is no guarantee the rows will be sorted, and hence carried forward the same way.

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Sean Stuber

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subratoc

ASKER

OK. Let's say I have another column (not shown above) which ensures the order of the rows.
This revises the question to:
The query shouldreturn the following for the data shown above:
0 0
0 0
1 1 --value changed from 0 to 1 in column 1
0 1 --value '1' carried forward as the current value of column1 is zero
0 1 --value '1' carried forward as the current value of column1 is zero
0 1 --value '1' carried forward as the current value of column1 is zero
2 2 --value '1' not carried forward as the current value of column1 is 2
0 2 --value '2' carried forward as the current value of column1 is zero
0 2 --value '2' carried forward as the current value of column1 is zero
0 2 --value '2' carried forward as the current value of column1 is zero

Sean Stuber

see above

subratoc

ASKER

Please ignore the last post. Revised question is:
OK. Let's say I have another column (not shown above) which ensures the order of the rows.
This revises the question to:
The query shouldreturn the following for the data shown above:

0 0 1
0 0 2
1 1 3 --value changed from 0 to 1 in column 1
0 1 4 --value '1' carried forward as the current value of column1 is zero
0 1 5 --value '1' carried forward as the current value of column1 is zero
0 1 6 --value '1' carried forward as the current value of column1 is zero
2 2 7 --value '1' not carried forward as the current value of column1 is 2
0 2 8 --value '2' carried forward as the current value of column1 is zero
0 2 9 --value '2' carried forward as the current value of column1 is zero
0 2 10 --value '2' carried forward as the current value of column1 is zero
Here I am ensuring the order using the third column (1-10).

Sean Stuber

same as before except include the ordering column
ee.txt

subratoc

ASKER

Excellent! Thanks a ton. You are a genius indeed.