php tutorial date() converts mktime() into a readable date
The date/time functions allow you to extract and format the date and time on the server
The mktime() function returns the unix timestamp of a date.
The argument always represents a gmt date, so is_dst has no effect on the result.
The parameters can be left empty in order from right to left, and the empty parameters will be set to the corresponding current gmt value.
Grammar
mktime(hour,minute,second,month,day,year,is_dst)
$s =1294628667;
echo date("y-m-d h:i:s",$s);