php的mysql資料庫操作類

class dbconn {    var $conn = 0;    function dbconn($dbhost,$dbuser,$dbpw,$dbname){ $this->conn = mysql_connect($dbhost,$dbuser,$dbpw);        !$this->conn && $this->halt("Connect to MySQL failed");        $serverinfo = mysql_get_server_info($this->conn);        if ($serverinfo > '4.1' && $GLOBALS['charset']) {            mysql_query("SET character_set_connection=".$GLOBALS['charset'].",character_set_results=".$GLOBALS['charset'].",character_set_client=binary",$this->conn);        }        if ($serverinfo > '5.0') {            mysql_query("SET sql_mode=''",$this->conn);        }        if ($dbname && !@mysql_select_db($dbname,$this->conn)) {            $this->halt('Cannot use database');        }    }    function select_db($dbname){        if (!@mysql_select_db($dbname,$this->conn)) {            $this->halt('Cannot use database');        }    }    function server_info(){        return mysql_get_server_info($this->conn);    }    function insert_id(){        $arr = $this->fetch_array('SELECT LAST_INSERT_ID() as id');        return $arr["id"];    }    function get_value($SQL,$offset=0,$field=0){        $rt = $this->fetch_all($SQL);        if (isset($rt[$offset][$field])) {            return $rt[$offset][$field];        }        return false;    }    function query($SQL,$method = null,$error = true){        $query = mysql_query($SQL,$this->conn);        !$query && $error && $this->halt('Query Error: '.$SQL);        return $query;    }    function fetch_array($SQL){        $query = $this->query($SQL);        return mysql_fetch_array($query);    }    function fetch_all($SQL) {        $arr = array();        $query = $this->query($SQL);        while($data = mysql_fetch_array($query)) {            $arr[] = $data;        }        return $arr;    }    function affected_rows(){        return mysql_affected_rows($this->conn);    }    function num_rows($SQL){        $query = $this->query($SQL);        if (!is_bool($query)) {            return mysql_num_rows($query);        }        return 0;    }    function num_fields($SQL){        $query = $this->query($SQL);        return mysql_num_fields($query);    }    function escape_string($str){        return mysql_escape_string($str);    }    function free_result(){        $void = func_get_args();        foreach ($void as $query) {            if (is_resource($query) && get_resource_type($query)==='mysql result') {                mysql_free_result($query);            }        }        unset($void);    }    function close(){        $this->free_result();        return @mysql_close($this->conn);    }    function halt($msg=null){        exit($msg.'<br /><br />'.$sql.'<br /> '.mysql_error());    }}