title: Composite Primary Key Cascading
body: <p>Two fields, Building and Room, make up a unique primary composite key in my rooms table. The key validates and saves, etc.</p>
  
  <p>I have a BLANK Objects table which has three fields which will make it unique (again a composite primary key). The tables are as follows:</p>
  
  <pre><code>ROOM TABLE
  [Building]     [Room]
  01             101A
  01             102
  02             101A
  
  OBJECT TABLE
  [Building]     [Room]     [Number]
  01             101A       1
  01             101A       2
  01             102        1
  02             101A       1
  </code></pre>
  
  <p>How do I enforce referential integrity? When editing the relationships in MS Access' relationship tool, I get the following error: <code>No unique index found for the referenced field of the primary table</code>. I know (by trying non-unique values) that the composite keys for the primary (Object) table is correct. What am I doing wrong? How do I set up the proper relationships and maintain integrity (as updates will be a gruelling challenge without them)?</p>