title: How to do relation between some tables in one column?
body: <p>I would to ask you how to do relation between some tables in one column?</p>
  
  <ul>
  <li>Tasks Table</li>
  <li>Customers Table</li>
  <li>Partners Table</li>
  <li>Competitors Table</li>
  </ul>
  
  <p>Tasks table relation with (Customers, Partners and Competitors), and it have two columns (RelatedBy, WhoRelatedBy). <br></p>
  
  <p>RelatedBy have list contain (Customers, Partners and Competitors) <br></p>
  
  <p>WhoRelatedBy have value to determine ID of records as below:</p>
  
  <ul>
  <li>When select Customers in RelatedBy the WhoRelatedBy contain CustomerID</li>
  <li>When select Partners in RelatedBy the WhoRelatedBy contain PartnerID</li>
  <li>When select Competitors in RelatedBy the WhoRelatedBy contain CompetitorID</li>
  </ul>
  
  <p>How do that?</p>