Here are a few things I strongly suggest in working with Qlik key fields.

  • Make separate key fields*
  • Prefix the field with %
  • Set HidePrefix variable to %
  • Use AutoNumber

Because of how the association engine works, you should never use a key field in an expression. It can return some very unexpected results. So to handle this, you should make a duplicate field to handle the association and then use the other field in your expressions.

Here is a visual of what I mean:

key

Source