Question

Warning: mysql_num_rows(): supplied argument is not a valid MySQL resultresource in

<?php
session_start();
$conn=mysql_connect(localhost,"root","123456");
if(!$conn)
{
die("连接错误的原因：".mysql_error());
}
$name=$_POST[name];
$password=$_POST[password];
if($_session[name]=="ture")
{
echo "用户已经登录";
}
if($_POST[name] && $_POST[password])
{
mysql_select_db("admin",$conn);

$sql="SELECT *FROM admin WHERE admin_name='$name' AND password='$password'";
$result=mysql_query($sql);
$rew=mysql_num_rows($result);
if($rew)
{
$_session[name]="ture";
echo "登录成功";
}
else
{
$_session[name]="flase";
echo "登录不成功";
}
}
else
{
echo "用户名和密码是空的！";
}

mysql_close($conn);
?>

运行时出现“Warning: mysql_num_rows(): supplied argument is not a valid MySQL resultresource in F:\CS\gl\yz.php on line 20

Answer 1

mysql_num_rows()需要的参数类型是 resource，如果你的$result为空，

那么再执行mysql_num_rows()就会有这个警告。

建议 $result && ($rew = mysql_num_rows($result))