Get the date from pgsql as a timestamp then use this:
/**
* Returns number of days between two given dates.
*
* @param string year in format CCYY
* @param string month in format MM
* @param string day in format DD
* @param string year in format CCYY
* @param string month in format MM
* @param string day in format DD
*
* @access public
*
* @return int absolute number of days between dates,
* -1 if there is an error.
*/
function dateDiff($day1,$month1,$year1,$day2,$month2,$year2)
{
if(!Date_Calc::isValidDate($day1,$month1,$year1))
return -1;
if(!Date_Calc::isValidDate($day2,$month2,$year2))
return -1;
return(abs((Date_Calc::dateToDays($day1,$month1,$year1))
- (Date_Calc::dateToDays($day2,$month2,$year2))));
} // end func dateDiff
That function is copied from the date/calc.php script in pear