I don't know where you going to code this batch exec code but can you do this?

if within sql then

declare @execstatementsbatch nvarchar(max)

select @execstatementsbatch = ''

SELECT @execstatementsbatch = @execstatementsbatch ...

You can make this function more generic by taking one more parameter

@Separator VARCHAR(5)

and inside the code instead of hard-coded comma you could use this parameter.

This will handle the cases...