title: How to tell if a MySQL field has a default value of an empty string or no default value?
body: <p>If we use the "DESCRIBE table" syntax in MySQL it returns information about the table including the fields and their default value.</p>
  
  <p><a href="http://dev.mysql.com/doc/refman/5.0/en/describe.html" rel="nofollow">http://dev.mysql.com/doc/refman/5.0/en/describe.html</a></p>
  
  <p>However, how do we tell the difference between a field having a default value of an empty string versus not having a default value at all?</p>
  
  <p>In seems in both cases it returns an empty value for the "Default" column in the output of the DESCRIBE table statement.</p>
  
  <p>I would need to be able to parse the data using PHP to easily detect differences between an old table format and new table format.</p>