DSXchange

I have an input file

This complex logic is too much for me. Could you please explain the rules in text as well?

You can use a stage variable in a transformer to hold the parent value.
If you define the stagevariable svParent as: The value of this variable will change if a new parent record is found, and stay the same if child records are found.

Then you can use this stage variable to load the first column in the output.

Also add the constraint NOT(IsNull(indata.Col1)) in transformer

JoshGeorge wrote:Also add the constraint NOT(IsNull(indata.Col1)) in transformer

Oops, yes, that would be useful too

Is this multi-level? Would you need to generate complete hierarchies, such as 1 2 3 4 5 6 ? That would add a deal of complexity (recursion), but could be solve using a carefully-designed hashed file and the little-known WITHIN query.