Decrementing a counter

Hi Jerry,

There's nothing built-in, but you could copy it, rename it, change it to do what you want.

Here, I've done just that (changes in red.) Call it with -1 as the fourth parameter to decrement a counter.

function incrementCounterFieldBy($tablename, $fieldname, $recordNumber, $amount = 1) {
global $VIEWER_NAME;

// error checking
if (!$tablename) { die(__FUNCTION__ . ": No 'tablename' value specified!"); }
if (!$fieldname) { die(__FUNCTION__ . ": No 'fieldname' value specified!"); }
if (!$recordNumber) { die(__FUNCTION__ . ": No 'recordNumber' value specified!"); }

// update counter
$escapedTableName = mysql_escape(getTableNameWithPrefix($tablename));
$query = "UPDATE `$escapedTableName` SET `$fieldname` = IFNULL(`$fieldname`,0) + $amount";
$query .= " WHERE `num` = '" .mysql_escape($recordNumber). "'";
$result = @mysql_query($query);
if (!$result) { die(__FUNCTION__ . " MySQL Error: ". htmlspecialchars(mysql_error()) . "\n"); }
if (!mysql_affected_rows()) {
die(__FUNCTION__ . ": Couldn't find record '" .htmlspecialchars($recordNumber). "'!");
}

}