mysql数据库连接的问题

Question

class connect
{
    var $host,$user,$password,$database,$linkID;
    function connect()
    {
        $this->host="hostname";
        $this->user="username";
        $this->password="password";
        $this->database="databasename";
        $this->createConnect();
        $this->openDatabase();
    }      function createConnect()
    {
        $this->linkID=mysql_connect("$this->host","$this->user","$this->password");
    }    function openDatabase()
    {
        mysql_select_db("$this->database",$this->linkID);
    }
}

Answer 1

        $this->host="hostname";
        $this->user="username";
        $this->password="password";"""改成"'"试试

Answer 2

$this->linkID=mysql_connect("$this->host","$this->user","$this->password");
改：
$this->linkID=mysql_connect($this->host,$this->user,$this->password);

Answer 3

看这个例子：
class DB_Sql_news {
  var $database = "";  var $link_id  = 0;
  var $query_id = 0;
  var $record   = array();  var $errdesc    = "";
  var $errno   = 0;
  var $reporterror = 1;  var $server   = "localhost";
  var $user     = "root";
  var $password = "";
  function connect() {
    // 连接数据库服务器    if ( 0 == $this->link_id ) {
      if ($this->password=="") {
        $this->link_id=mysql_pconnect($this->server,$this->user);
      } else {
        $this->link_id=mysql_pconnect($this->server,$this->user,$this->password);
      }
      if (!$this->link_id) {
        $this->halt("Link-ID == 失败, 连接失败");
      }
      if ($this->database!="") {
        if(!mysql_select_db($this->database, $this->link_id)) {
          $this->halt("cannot use database ".$this->database);
        }
      }
    }
  }