我的SELECT查询错了吗？

Question

嘿,我正在尝试验证我的xml文件中的用户名和密码是否与我的数据库中的用户名和密码相同,但mysql_num_rows为零.所以我的SELECT查询一定有问题.这是我的代码:

 public function verifyDB()
{
   //connection to database
    mysql_connect('localhost','root','') or die(mysql_error());
    mysql_select_db('proiect_is') or die(mysql_error());

     $data =mysql_query("SELECT id FROM users WHERE userName ='$this->xml->parameters->username' AND password ='$this->xml->parameters->pass'");
    //we check if any row was returned
    echo $data;
     echo $this->xml->parameters->username."<BR>";
     echo $this->xml->parameters->pass."<BR>";
     print_r(mysql_num_rows($data));
    if (mysql_num_rows($data))
    {

       $row = mysql_fetch_assoc($data);
       $this->_id= $row['id'];
       echo $row;
       return true;
    }
    else
    {return false;}

}  

这是我的xml登录文件:

 <xml version="">
  <action>log_in</action>
  <parameters>
    <username>Ionel P</username>
<pass>abdef01</pass>
  </parameters>
 </xml>

Answer 1

如果你在字符串中插入变量,你应该这样使用{}:

"SELECT id FROM users WHERE userName ='{$this->xml->parameters->username}' AND password ='{$this->xml->parameters->pass}'"

这告诉解析器插入变量$this->xml->parameters->username,否则它只会尝试使用$this(并留下->xml->parameters->username文本,最终会出现在" [toString-Text of your Object] - > xml-> parameters-> username "这显然是错误的).