title: How much real storage is used with a varchar(100) declaration in mysql?
body: <p>If I have a table with a field which is declared as accepting varchar(100) and then I actually insert the word "hello" how much real storage will be used on the mysql server?  Also will an insert of NULL result in no storage being used even though varchar(100) is declared?</p>
  
  <p>What ever the answer is, is it consistent accross different database implementations?</p>