title: Query to find pairs of employees who have the same birthdate
body: <p>I have a table EMPLOYEE with 100 people. I would like to write a query to find pairs of employees who have the same BIRTHDATE.</p>
  
  <p>The result should return EMPNO, LASTNAME and BIRTHDATE for each employee in the pair (a 6-column result table).</p>
  
  <p>I thought something like that</p>
  
  <pre><code>SELECT  t1.EmpNo
         ,t1.LastName
         ,t1.BirthDate
          ,t2.EmpNo
          ,t2.LastName
          ,t2.BirthDate
    FROM Employee t1
    INNER JOIN (
    SELECT EmpNo
          ,LastName
          ,BirthDate
    FROM Employee ) t2 ON t2.BirthDate = t1.BirthDate 
    WHERE t2.EmpNo != t1.EmpNo
  </code></pre>
  
  <p>Do you think it is correct?</p>