错误：mysql_num_rows（）需要参数1

Question

尝试运行此代码时出错：

        $sql = "SELECT * FROM user WHERE username = '$uname' AND password = '$password'";
        $result=mysql_query($sql);
        $num_row=mysql_num_rows($sql);
        $row=mysql_fetch_array($result);

问题在于行$num_row=mysql_num_rows($sql);

错误消息是：

Warning: mysql_num_rows() expects parameter 1 to be resource, string given

Answer 1

$num_row=mysql_num_rows($sql);

应该是

$num_row=mysql_num_rows($result);

Answer 2

试试这个：

查询执行后计算行数并获取记录。

$sql = "SELECT * FROM user WHERE username = '$uname' AND password = '$password'";
$result = mysql_query($sql);

$num_row=mysql_num_rows($result);
$row=mysql_fetch_array($result);

Answer 3

尝试此查询

 $sql = "SELECT * FROM user WHERE username = '$uname' AND password = '$password'";
        $result=mysql_query($sql);

        $num_row=mysql_num_rows($result);

        $row=mysql_fetch_array($result);