title: Taking Sample in SQL Query
body: <p>I'm working on a problem which is something like this :</p>
  
  <p>I have a table with many columns but major are <code>DepartmentId</code> and <code>EmployeeIds</code></p>
  
  <pre><code>Employee Ids    Department Ids
  ------------------------------
  A                   1
  B                   1
  C                   1
  D                   1
  AA                  2
  BB                  2
  CC                  2
  A1                  3
  B1                  3
  C1                  3
  D1                  3
  </code></pre>
  
  <p>I want to write a SQL query such that I take out 2 sample <code>EmployeeIds</code> for each <code>DepartmentID</code>.</p>
  
  <p>like</p>
  
  <pre><code>Employee Id  Dept Ids
  B              1
  C              1
  AA             2
  CC             2
  D1             3
  A1             3
  </code></pre>
  
  <p>Currently I am writing the query,</p>
  
  <pre><code>select
     EmployeeId, DeptIds, count(*)
  from 
     table_name
  group by 1,2
  sample 2
  </code></pre>
  
  <p>but it gives me total two rows.</p>
  
  <p>Any help?</p>