IIF function in update Query

[bclmx]

This is my first time here so please be patient. I am having some troubles with IIF function. Hope this is just a dummy question and there is a simple solution for it.
I am creating an update query where I want all the fields to be updated. That is not an issue here really what the problem is that I have one calculated field that needs to be updated according to values in other columns. So I am trying to tell access to update column A only if value in that column is null. ( I am not updating to rows in other table, I am updating to text. ie. Update to “A”)
Is there a way to tell access to "do nothing" for the false part in IIF function?
Here is an example: update column A if value is null. Do nothing if value in column A is not null.

IIF(

.[a] is null, do this, do nothing)


The true part of the function works ok only I need to tell access to omit the false part.

Hope this makes sense.
Any help would be greatly appreciated.

Andy

 

[boblarson]

really what the problem is that I have one calculated field that needs to be updated according to values in other columns.

That is a big normalization no, no. You should not be storing calculated values, and beyond that you should not be storing values that are dependent upon other columns.

 

[Scooterbug]

it would be IIF(isnull(

.[a]),True Part, false Part)

FYI...you shouldn't store calculated fields. Makes things a mess if you need to go and change any part of the calculation later on. You can use queries to calculate things later on if need be.

 

[bclmx]

I think I did not express myself properly. But that's ok.
I've solved the issue in the mean time. Thank you for the effort.

Andy