Appending a comma separated field with values from another field?

[AaronB]

Hey all! I'm back with a new issue that I'm hoping won't be too hard to solve but I can't seem to find the solution myself. I have two fields that I need to combine. Field 1 contains a variable, such as GKM3, GKM5, etc. Field 2 contains comma-separated values like L16, L17, L18. I have been trying to find a formula to combine the value of Field 1 with each of the values of Field 2. So the output in the 3rd field would be GKM4L17, GKM4L17, GKM4L18. 

Unfortunately, when I try a concatenate or substitute function, it only appends the Field 1 value onto the first value in the list, like in Field 3. 

 

I would really appreciate any help! 

[Sho]

Hi @AaronB,

If Field 2 is a roll-up field, it can be 

{Field1}&ARRAYJOIN(values, ", "&{Field1})

[TheTimeSavingCo · Accepted solution]

You can also try:

{Field 1} & 
SUBSTITUTE(
  {Field 2},
  ', ',
  ', ' & {Field 1}
)