title: Setup SQL relationship so that Excel can link 3 tables
body: <p>I need to establish a relationship in an existing database containing 3 tables for 3 measurement devices A, B, C that will populate these 3 tables independently:</p>
  
  <pre><code>[table1] [table2] [table3]
  id       id       id    
  mesA_1   mesB_1   mesC_1
  mesA_2   mesB_2   mesC_2
  </code></pre>
  
  <p>Each sample is assigned a unique id, and that's how we can associates the 3 sets of measurements that correspond to the same sample.
  So I have to create the 3 tables and the relationship between the three id keys.
  In the end I want to be able to query the database from Excel to display in a single line the measurements of the 3 devices.</p>
  
  <p>I followed tutorials but most of the time they're for 2 tables and not 3. Basically I set every id key as PRIMARY but then I do not know if the relationship is two-way or not, if must chain the 3 tables or define a master and two childs. In short I'm clueless.</p>