Increment Values in Field for Null Values

[John_Teh]

Hello,

I am having an issue incrementing values in my ID field. Is there a way to increase my Row ID in a single by one for each (and only) Null Values? 

Example:

Row Id

Null

Null

1

2

3

I'd want to fill 4 and 5 for the null values. I also want to do this with a formula tool. The formula I'm using in the formula tool is IF [Code]=Null() THEN [Code] = Max([Code], 1)
ELSE [Code] ENDIF but it doesn't seem to work. Does anyone have an idea to solve this?

Thanks.

[DavidP · Accepted solution]

So there's a couple of things to note.

- You have to determine Max RowID first - I use a Summarize tool

- Then you have to create a counter for the Null rows - I used the Tile tool for this

- Now you can add the counter and Max RowID's together for the Null rows in the formula tool.