class dbmysq {

 var $querynum = 0;
 var $link;
 var $histories;
 var $time;
 var $tablepre;

 function connect($dbhost, $dbuser, $dbpw, $dbname = '', $dbcharset, $pconnect = 0, $tablepre='', $time = 0) {
  $this->time = $time;
  $this->tablepre = $tablepre;
  if ($pconnect) {
   if (!$this->link = mysql_pconnect($dbhost, $dbuser, $dbpw)) {
    $this->halt('can not connect to mysql server');
   }
  } else {
   if (!$this->link = mysql_connect($dbhost, $dbuser, $dbpw, 1)) {
    $this->halt('can not connect to mysql server');
   }
  }

  if ($this->version() > '4.1') {
   if ($dbcharset) {
    mysql_query("set character_set_connection=" . $dbcharset . ", character_set_results=" . $dbcharset . ", character_set_client=binary", $this->link);
   }

   if ($this->version() > '5.0.1') {
    mysql_query("set sql_mode=''", $this->link);
   }
  }

  if ($dbname) {
   mysql_select_db($dbname, $this->link);
  }
 }

 function fetch_array($query, $result_type = mysql_assoc) {
  return mysql_fetch_array($query, $result_type);
 }

 function result_first($sql, &$data) {
  $query = $this->query($sql);
  $data = $this->result($query, 0);
 }

 function fetch_first($sql, &$arr) {
  $query = $this->query($sql);
  $arr = $this->fetch_array($query);
 }

 function fetch_all($sql, &$arr) {
  $query = $this->query($sql);
  while ($data = $this->fetch_array($query)) {
   $arr[] = $data;
  }
 }

 function cache_gc() {
  $this->query("delete from {$this->tablepre}sqlcaches where expiry<$this->time");
 }

 function query($sql, $type = '', $cachetime = false) {
  $func = $type == 'unbuffered' && @function_exists('mysql_unbuffered_query') ? 'mysql_unbuffered_query' : 'mysql_query';
  if (!($query = $func($sql, $this->link)) && $type != 'silent') {
   $this->halt('mysql query error', $sql);
  }
  $this->querynum++;
  $this->histories[] = $sql;
  return $query;
 }

 function affected_rows() {
  return mysql_affected_rows($this->link);
 }

 function error() {
  return (($this->link) ? mysql_error($this->link) : mysql_error());
 }

 function errno() {
  return intval(($this->link) ? mysql_errno($this->link) : mysql_errno());
 }

 function result($query, $row) {
  $query = @mysql_result($query, $row);
  return $query;
 }

 function num_rows($query) {
  $query = mysql_num_rows($query);
  return $query;
 }

 function num_fields($query) {
  return mysql_num_fields($query);
 }

 function free_result($query) {
  return mysql_free_result($query);
 }

 function insert_id() {
  return ($id = mysql_insert_id($this->link)) >= 0 ? $id : $this->result($this->query("select last_insert_id()"), 0);
 }

 function fetch_row($query) {
  $query = mysql_fetch_row($query);
  return $query;
 }

 function fetch_fields($query) {
  return mysql_fetch_field($query);
 }

 function version() {
  return mysql_get_server_info($this->link);
 }

 function close() {
  return mysql_close($this->link);
 }

 function halt($message='', $sql='') {
  exit('<br/>提示：数据库错误<br/>sql语句：' . $sql . '<br/>错误关键字：' . mysql_error());
 }

}