Increment value to a integer variable in PipeLine

I think you need to use a "helper" variable to achieve this:

https://learn.microsoft.com/en-us/azure/data-factory/control-flow-set-variable-activity#incrementing-a-variable

Because there seems to be a limitation that variables cannot be self-referencing.

So you would need to use two variables, e.g.:

counter_i

temp_j

Choose your initial value for your variable (counter_i), e.g. counter_i = 0.

Then, use these two activities to increment counter_i:

First, you set temp_j equal to counter_i.

Then, you set counter_i equal to temp_j + 1.

You can repeat these two steps multiple times in order to keep incrementing the variables.