在MySQL datetime附近自动发送邮件

In my MySQL database I have a table containing a datetime column. I'd like to send emails whenever current time is 30 minutes before one of the datetime values. E.g. datetime value is '20140623180000' the server should send a mail at 17:30 on 23rd June 2014. The values in the datetime column aren't regular. Anyone knows how to do this in an easy way? (Linux running on server)In my MySQL database I have a table containing