title: SQL split column
body: <p>I made an easy exemple to understand better what is my question. 
  So, i have 2 table and i have a selection based on <code>inner join</code> which is into a selection.</p>
  
  <pre><code>create table students(
  id_student number,
  name_student varchar2(15),
  id_advisor number,
  money number
  );
  
  insert into students values(1, 'Student_1', 1, 100);
  insert into students values(2, 'Student_2', 8,-200);
  insert into students values(4, 'Student_4', 7, 256);
  insert into students values(5, 'Student_5', 3, -305);   
  ----------------
  
  create table advisors(
  id_advisor number,
  name_advisor varchar2(15)
  );
  
  insert into advisors values(1, 'advisor_1');
  insert into advisors values(3, 'advisor_3'); 
  insert into advisors values(5, 'advisor_5');
  
  ------------------------------------------
  SELECT name_advisor, money as money_pozitive
  FROM(
  select name_student, name_advisor, money from students 
  inner join advisors on students.id_advisor = advisors.id_advisor)
  WHERE money &gt; 0 
  </code></pre>
  
  <p>With this code i have the following result:</p>
  
  <pre><code>name_advisor    |    money_pozitive
  ------------------------------------
  advisor_1       |    100
  </code></pre>
  
  <p>My question is, how I add an extra column named <code>money_negative</code>  with of course  negative values ? like this:</p>
  
  <pre><code>name_advisor    |    money_pozitive    |  money_negative
  ---------------------------------------------------------
  advisor_1       |    100               |  -305
  </code></pre>