title: Concatenated Field Join in Access
body: <p>I am trying to merge three tables into a single report and unfortunately do not have a unique key.  As a result, I need to concatenate 3 fields together into one unique key.  However since I am using a calculated field type, Access will not let me create a relationship between the tables.  Additionally when I update the tables with new data, I am losing my calculated column.  </p>
  
  <p>How can I create / use a unique key using concatenated strings? 
  How do I ensure that I don't lose the calculated column when I import new data?</p>