title: Foreign key referring to primary keys across multiple tables?
body: <p>I have to two tables namely employees_ce and employees_sn under the database employees. </p>
  
  <p>They both have their respective unique primary key columns. </p>
  
  <p>I have another table called deductions, whose foreign key column I want to reference to primary keys of employees_ce as well as employees_sn. Is this possible?</p>
  
  <p>for example</p>
  
  <pre><code>employees_ce
  --------------
  empid   name
  khce1   prince
  
  employees_sn
  ----------------
  empid   name
  khsn1   princess
  </code></pre>
  
  <p>so is this possible?</p>
  
  <pre><code>deductions
  --------------
  id      name
  khce1   gold
  khsn1   silver
  </code></pre>