title: MySQL date conversion
body: <p>I have inherited a MySQL database which (for historical reasons) contains a field which stores a date as number of days since <strong>1900-01-01</strong>. I want to be able to select a date_format() version of this date but can't figure a way of doing so.<br>
  Is there a way of manipulating the contents of the column such that I can pass the manipulated value to date_format() so it is recognised as a valid date?<br>
  I realise there is a solution to this which involves doing one query, then manipulating the field (in PHP) then passing back in as a secondary query - but I need this to be a single query solution.</p>