<?
/* db.php
 * This file contains database functions.  You can set the options for
 * DB_DIE_ON_FAIL and DB_DEBUG from your main program to affect the behavior
 * when errors occur.  The defaults are as follows:
 */

$DB_DIE_ON_FAIL	= true;		/* does script terminate if db call fails? */
$DB_DEBUG	= true;		/* provide detailed debugging messages? */

/*  Functions listed in this file:
		function db_connect($dbhost,$dbname,$dbuser,$dbpass) 
result	function db_query($query)
ass ary	function db_nextarray($result)
array	function db_nextrow($result)
value	function db_nextvalue($result)
object	function db_nextobject($result)
number	function db_numrows($result)
id		function db_insertid()
		function db_disconnect()
html	function db_listbox ($value_field,$label_field,$query,$default="") 
	function db_freeresult($result)
	function db_handleError($detail)

*/

/* This function establishes a database connection with the specified
 * parameters.  If it fails, it will halt the script and display an
 * error message.
 */
function db_connect(
	$dbhost,	/* hostname or ipaddress of db host (eg. "localhost") */
	$dbname,	/* name of the database */
	$dbuser,	/* user name to access database */
	$dbpass		/* password for user */
){
	global $DB_DIE_ON_FAIL, $DB_DEBUG;
	
	if (! mysql_pconnect($dbhost, $dbuser, $dbpass)) {
		if ($DB_DEBUG) {
			echo "<h2>Can't connect to $dbhost as $dbuser ($dbpass)</h2>";
			echo "<p><b>MySQL Error</b>: ", mysql_error();
		} else {
			echo "<h2>Database error (couldn't connect)</h2>";
		}
		
		if ($DB_DIE_ON_FAIL) {
			echo "<p>This script cannot continue, terminating.";
			die();
		}
	}

	if (! mysql_select_db($dbname)) {
		if ($DB_DEBUG) {
			echo "<h2>Can't select database $dbname</h2>";
			echo "<p><b>MySQL Error</b>: ", mysql_error();
		} else {
			echo "<h2>Database error (cant't connect to $dbname)</h2>";
		}

		if ($DB_DIE_ON_FAIL) {
			echo "<p>This script cannot continue, terminating.";
			db_disconnect();
			die();
		}
	}
}

/* This function attempts to execute a query, $query.  If it fails, it will
 * terminate the script with an error message and the query that was being
 * executed.  If it was successful, it will return a result ID.
 */
function db_query(
	$query	/* the SQL statement to send to the database */
){
	global $DB_DIE_ON_FAIL, $DB_DEBUG;
	// echo $query;	
	$result = mysql_query($query);

	if (! $result) {	
		if ($DB_DEBUG) {
			echo "<h2>Can't execute query</h2>";
			echo "<pre>$query</pre>";
			echo "<p><b>MySQL Error</b>: ", mysql_error();
		} else {
			echo "<h2>Database error (query error)</h2>";
		}

		if ($DB_DIE_ON_FAIL) {
			echo "<p>This script cannot continue, terminating.";
			db_disconnect();
			die();
		}
	}

	return $result;
}

/* This function returns an associative array containing the next row from
 * the query specified by the result ID.  If there is no more data, it returns
 * FALSE.
 */
function db_nextarray(
	$result	/* the id returned from a successful db_query */
){
	return mysql_fetch_array($result);
}

/* This function returns an array containing the next row from
 * the query specified by the result ID.  If there is no more data, it returns
 * FALSE.
 */
function db_nextrow(
	$result	/* the id returned from a successful db_query */
){
	return mysql_fetch_row($result);
}

/* This function returns a value with the first field from the next row from
 * the query specified by the result ID.  If there is no more data, it returns
 * FALSE.
 */
function db_nextvalue(
	$result	/* the id returned from a successful db_query */
){
	$array = mysql_fetch_row($result);
	return $array[0];
}

/* This function returns an object with properties corresponding to the colums
 * listed in a select query (specified by the result ID).  If there is no more
 * data, it returns FALSE.
 */
function db_nextobject(
	$result	/* the id returned from a successful db_query */
){
	$obj = mysql_fetch_object($result);
	return $obj;
}

/* This function returns the number of rows returned by the SELECT query
 * specified by the result ID.
 */
function db_numrows(
	$result=FALSE	/* the id returned from a successful db_query */
){
	if ($result === FALSE) {
		return mysql_affected_rows();
	} else {
		return mysql_num_rows($result);
	}
}

/* Returns the last ID of the last insert statement if any AUTO_INCREMENT
 * or auto sequence field was in the table.
 */
function db_insertid() {
	return mysql_insert_id();
}

/* This function closes the current database connection.
 */
function db_disconnect() {
	mysql_close();
}

// Returns the a set of <option value...> tags from a db query
function db_listbox (
        $value_field,   // field to use for <option value=VALUE>label
        $label_field,   // field to use for <option value=value>LABEL
        $query,                 // database query
        $default=""             // options with this value are selected by default, can be a scalar or a list
) {
        $output = "";
        $result = db_query($query);
        while ($r = db_nextarray($result)) {
                $value = $r[$value_field];
                $label = $r[$label_field];
                if (is_array($default))
                        $selected = empty($default[$value]) ? "" : "selected";
                else
                        $selected = $value == $default ? "selected" : "";
                $output .= "<option value='$value' $selected>$label\n";
        }
        return $output;
}

/* Release resources taken up by a query */
function db_freeresult($result) {
	mysql_free_result($result);
}

/* display a db error message */
function db_handleError($detail) {
  $msg = "$detail\n";
  $msg = $detail."\n"."Mysql error : ".mysql_errno()." - ".mysql_error();
  die ($msg);
}

?>