我自己写的mysql类

---------- php debug ----------
Server=localhost;DataBase=mysql;UserID=root;PassWord=123456
resource(5) of type (mysql result)
Output completed (1 sec consumed) - Normal Termination
//debug 调试开关
var $debug = true;
//debuginfo 错误信息，调试信息
var $debuginfo = "debug informations:
";
//db_server MySQL主机地址
var $db_server;
//db_name 数据库名
var $db_name;
//db_user 数据库用户名
var $db_user;
//db_passwd 密码
var $db_passwd;
//db_links  数据库连接
var $db_link;
//db_query_sql SQL语句
var $db_query_sql = "show tables";
//db_recordset 结果集，记录集
var $db_recordset;
//ready        就绪开关
var $conntstr_ready = false;
var $link_ready = false;
var $db_ready = false;
//set or return Connection String  返回，或者设定连接字符串
function connection_string($connstr="")
{
  if("" == $connstr)
  {
   //如果没有参数传入，返回已有的连接字符
   return "Server=".$this->db_server.";DataBase=".$this->db_name.";UserID=".$this->db_user.";PassWord=".$this->db_passwd;
  }
  else
  {
   //否则，解析连接字符，初始化变量
   preg_match_all("|([a-zA-Z0-9]*)=([a-zA-Z0-9]*);*|", $connstr,   $tmparr, PREG_PATTERN_ORDER);
   $this->db_server = (strtolower($tmparr[1][0]) == "server")?$tmparr[2][0]:"";
   $this->db_name   = (strtolower($tmparr[1][1]) == "database")?$tmparr[2][1]:"";
   $this->db_user   = (strtolower($tmparr[1][2]) == "userid")?$tmparr[2][2]:"";
   $this->db_passwd = (strtolower($tmparr[1][3]) == "password")?$tmparr[2][3]:"";
   //var_dump($tmparr);
   if("" == $this->db_server or "" == $this->db_name or "" == $this->db_user or "" == $this->db_passwd)
    $this->conntstr_ready = false; //如果有其中一个以上变量被赋以空字符串"",准备未就绪
   else
    $this->conntstr_ready = true;
   return $this->conntstr_ready;
  }
}
//连接数据库，返回连接对象
function connect()
{
  if(!$this->conntstr_ready)
  {
   if($this->debug){$this->debuginfo .= "连接字符串无效！
";}
   return $this->link_ready;
  }
  if($this->db_link = @mysql_connect($this->db_server, $this->db_user, $this->db_passwd))
  {
   $this->link_ready = true;
   return $this->link_ready;
  }
}
//选择数据库
function select($db = "")
{
  if(!$this->db_link)
  {
   if($this->debug){$this->debuginfo .= "没有可用的数据库连接！
";}
   $this->db_ready = false;
  }
  if("" == $db)
  {
   if(mysql_select_db($this->db_name))
    $this->db_ready = true;
  }
  if(mysql_select_db($this->db_name = $db))
   $this->db_ready = true;
  return $this->db_ready;
}
//执行查询
function execute($SQL = "")
{
  if("" != $SQL)
  {
   $this->db_query_sql = $SQL;
   //if($this->debug){$this->debuginfo .= "SQL is null!
";}
   //return false;
  }
  if("" == $this->db_query_sql)
  {
   if($this->debug){$this->debuginfo .= "SQL is null!
";}
   return false;
  }
  $this->db_recordset = mysql_query($this->db_query_sql);
  return true;
}
}
$dbmy = new DBCLS(); //创建一个DBCLS对象
if(!$dbmy->connection_string("Server=localhost;DataBase=mysql;UserID=root;PassWord=123456"))//初始化DBCLS对象dbmy
print $dbmy->debuginfo; //初始化失败，输出错误信息
else
print $dbmy->connection_string(); //初始化成功，输出连接字符串
print "
";
if(!($dbmy->connect()) or !($dbmy->select())) //如果连接数据库，或者选择数据库失败
print $dbmy->debuginfo;                               //输出出错信息
//$dbmy->db_query_sql = "select * from user";
if($dbmy->execute())              //执行查询指令
{                                 //如果不出错
var_dump($dbmy->db_recordset);//输出返回的结果集
}
?>
输出信息：
---------- php debug ----------
Server=localhost;DataBase=mysql;UserID=root;PassWord=123456
resource(5) of type (mysql result)
Output completed (1 sec consumed) - Normal Termination