title: Mysql add 1 day to timestamp
body: <p>I've  field in my db named "eventstart". The value in there is a unix timestamp. I want to add 1 day to this, but it only stores 0. </p>
  
  <p>I tried: </p>
  
  <pre><code>UPDATE mytable SET eventstart=TIMESTAMPADD(DAY,1,eventstart) WHERE 1
  
  UPDATE mytable SET eventstart=TIMESTAMPADD(DAY,1,DATE_FORMAT(FROM_UNIXTIME(eventstart), '%d-%m-%Y')) WHERE 1
  
  UPDATE mytable SET eventstart=UNIX_TIMESTAMP(TIMESTAMPADD(DAY,1,DATE_FORMAT(FROM_UNIXTIME(eventstart), '%d-%m-%Y'))) WHERE 1
  </code></pre>
  
  <p>...and things like that. </p>