(PHP 4 >= 4.1.0, PHP 5 <= 5.0.5, PECL dbx >= 1.1.0)
dbx_compare — Compare two rows for sorting purposes
$row_a
   , array $row_b
   , string $column_key
   [, int $flags = DBX_CMP_ASC | DBX_CMP_NATIVE
  ] )dbx_compare() is a helper function for dbx_sort() to ease the make and use of the custom sorting function.
row_aFirst row
row_bSecond row
column_keyThe compared column
flags
       The flags can be set to specify comparison
       direction: 
       
DBX_CMP_ASC - ascending order
         
        DBX_CMP_DESC - descending order
         
        DBX_CMP_NATIVE - no type conversion
         
        DBX_CMP_TEXT - compare items as strings
         
        DBX_CMP_NUMBER - compare items numerically
         
        
   Returns 0 if the row_a[$column_key]
   is equal to row_b[$column_key], and 1
   or -1 if the former is greater or is smaller than the 
   latter one, respectively, or vice versa if the flag 
   is set to DBX_CMP_DESC.
  
Example #1 dbx_compare() example
<?php
function user_re_order($a, $b) 
{
    $rv = dbx_compare($a, $b, "parentid", DBX_CMP_DESC);
    if (!$rv) {
        $rv = dbx_compare($a, $b, "id", DBX_CMP_NUMBER);
    }
    return $rv;
}
$link   = dbx_connect(DBX_ODBC, "", "db", "username", "password")
    or die("Could not connect");
$result = dbx_query($link, "SELECT id, parentid, description FROM table ORDER BY id");
    // data in $result is now ordered by id
dbx_sort($result, "user_re_order");
    // date in $result is now ordered by parentid (descending), then by id
dbx_close($link);
?>