title: ANSI SQL question - how to insert or update a record if it already exists?
body: <p>Although I am using mySQL (for now), I dont want any DB specific SQL. </p>
  
  <p>I am trying to insert a record if it doesn't exist, and update a field if it does exist. I want to use ANSI SQL. </p>
  
  <p>The table looks something like this:</p>
  
  <pre><code>create table test_table (id int, name varchar(16), weight double) ;
  
  //test data 
  insert into test_table (id, name, weight) values(1,'homer', 900);
  insert into test_table (id, name, weight) values(2,'marge', 85);
  insert into test_table (id, name, weight) values(3,'bart', 25);
  insert into test_table (id, name, weight) values(4,'lisa', 15);
  
  If the record exists, I want to update the weight (increase by say 10)
  </code></pre>