title: Understanding Sum(1) sum(2) sum(3)
body: <p>Consider a table below having one column having 10 records.
  I am not able to understand how </p>
  
  <pre><code>SUM(1) gives output 10
  SUM(2) gives output 20
  SUM(3) gives output 30
  
  create table test_a4(idCol numeric);
  insert into test_a4(idCol) values (1),(2),  (3),  (4), (5) , (6), (7), (8), (9) , (10)
  Select SUM(1) FROM test_a4 -- SUM(1) gives output 10
  Select SUM(2) FROM test_a4 -- SUM(2) gives output 20
  Select SUM(3) FROM test_a4 -- SUM(3) gives output 30
  </code></pre>