title: Implement an "ISA" Relationship in Microsoft Access
body: <p>I would like to implement an "ISA" relationship with a for some arbitrary testing tables in Microsoft Access RDBMS. The "Parent" table, say, would have the following column only:</p>
  
  <p>Parent:<br></p>
  
  <ul>
  <li>Num (primary key)</li>
  </ul>
  
  <p>And then, I would have the following child tables, which all may have different property types other than the one referencing Parent.Num, and they are called "Child #" where "#" is the number of the child:</p>
  
  <p>Child 1:</p>
  
  <ul>
  <li>Parent num (primary key, and foreign key referencing Parent.Num)</li>
  <li>Property 1</li>
  <li>Property 2</li>
  <li>...</li>
  </ul>
  
  <p>Child 2:</p>
  
  <ul>
  <li>Parent num (primary key, and foreign key referencing Parent.Num)</li>
  <li>Property 1</li>
  <li>Property 2</li>
  <li>...</li>
  </ul>
  
  <p>Child 3:</p>
  
  <ul>
  <li>Parent num (primary key, and foreign key referencing Parent.Num)</li>
  <li>Property 1</li>
  <li>Property 2</li>
  <li>...</li>
  </ul>
  
  <p>I tried making the "Parent" table have a 1-1 relationship with the "Child #" tables, by having the Parent.Num references in all the "Child #" tables refer back to the "Parent" table, and I successfully managed to add these kinds of relationships. However, insertion was a problem here. I successfully managed to add an entry to the first "Child #" to have its "ISA" relationship attached to the "Parent" table, but I was not able to do the same for the other "Child # table". I would like to know if this is a correct example of "ISA" relationship, or am I doing something wrong?</p>