title: How to create a foreign key for a non-key table field?
body: <p>Simply put, i want to create a structure that has a component MAKTX, and to have a foreign key relation with MAKT-MAKTX.
  More generally i want to have a foreign key check for a field that's not part of a primary key.</p>
  
  <p>I see the button "Non-key-fields/candidates", but i don't really know how to use it.</p>
  
  <p>Also, i don't want to use the "key fields of a text table" relation... but i don't know if that's relevant.</p>
  
  <p>Is this even a good thing that i'm trying to do? I don't see any reason why it shouldn't be possible, but you might object.</p>
  
  <p>[EDIT]: I have to mention that I don't really know what I'm doing. I really just want to fill a table i created with values from another, and to make sure that those values (namely MAKTX - kind ofvalues) in my table are always values from MAKT. Suppose i do the initial filling with a SELECT statement, i want the consistency to work even if i later insert new entries manually.
  So I don't know whether this makes sense or not, it just sounds to me like a good idea to have the system perform this check automatically, if possible.</p>