警告：mysql_num_rows（）期望参数1是资源，布尔在/home/folder/public_html/folder/folder/login.php在第18行 [英] Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in /home/folder/public_html/folder/folder/login.php on line 18

问题描述

我尝试设置我的数据库，但我遇到了一些问题。我看到许多人问了相同或相似的问题，但无论我怎么看我的代码，并修改它。我更困惑，并添加更多的错误。因此，如果有人可以向我解释如何尝试解决它，我会很感激。

I'm trying to set up my database however I ran into some issues sadly. I've seen that many people asked either the same or similar question but no matter how I look at my code, and modify it. I get confused more, and add more errors. So if someone could explain to me how I can attempt to fix it I'd appreciate it.

是错误消息：

Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in /home/folder/public_html/folder/folder/login.php on line 18

---

以下是代码：

<link rel="Stylesheet" type="text/css" href="style.css" />
<link href='http://fonts.googleapis.com/css?family=Karla:400,700,700italic,400italic' rel='stylesheet' type='text/css'>
<?php
$filename = 'install.php';
if (file_exists($filename)) {
echo ("<center><font color='red'><b>/install.php still exists<br>
After installing please delete install.php</center></font></b>");
} else {
if (isset($_POST['Login'])){
include('config.php');
    if (!mysql_connect($host, $username, $password)) die("Can't connect to database");
    if (!mysql_select_db($db_name)) die("Can't select database");
    $myusername=$_POST['myusername'];
    $mypassword=$_POST['mypassword'];

    $sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
    $result=mysql_query($sql);
    $count=mysql_num_rows($result);
    if($count >= 1){
    session_register("myusername");
    session_register("mypassword");
    header("location: index.php");
    } else {
        echo "<center><font color='red'><b>Wrong Username or Password</center></font></b>";
    }
}
?>
<br>
<form method="post" action=""><td>
<table width="325" border="0" align="center" cellpadding="2" cellspacing="0" bgcolor="#212121">
<td><table width="100%" border="0" cellpadding="3" cellspacing="0" bgcolor="#404040"></td>
<tr colspan="3"><strong><center> <font color="ECECEC"> Admin Login </font></center></strong></tr>
<tr>
<td>
<font color="ECECEC">Username </font><input name="myusername" type="text" id="myusername">
<font color="ECECEC">Password </font><input name="mypassword" type="password" id="mypassword">
</td>
<center><td><input type="submit" name="Login" value="Login"></td></center>
</table></table>
</form>
<?php
}
?>

---

这里是第18行

        $count=mysql_num_rows($result);

推荐答案

此错误是因为之前调用 mysql_query 不产生结果集，而是一个 false 说明查询失败。

This error is because the previous call to mysql_query is not producing a result set, but a false stating that the query had failed.

mysql_query() or die(mysql_error());

来查看问题。试试上面的代码。从您发布的代码 $ tbl_name 不是可见的变量名称。

to see the problem. try the above code. From the code you have posted $tbl_name is not a visible variable name.

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