mysql_num_rows（）错误

Question

<?php
$id=$_GET['id'];
$username="xxx";
$password="xxx";
$database="xxx";
$host="xxx";
mysql_connect($host,$username,$password);
$con = mysql_connect("$host","$username","$password");

$id=$_POST['ID'];
$query="SELECT * FROM vbots WHERE ID=$id";
$result = mysql_query("SELECT * FROM vbots");
$num=mysql_query($result,$con) or die("Error: ". mysql_error(). " with query ". $query);
mysql_close();

I keep getting

Error: Query was empty with query SELECT * FROM vbots WHERE ID=1"

How can i fix that? I get it from mysql_num_rows() , wrote die("Error: ". mysql_error(). " with query ". $query); for more info .

Thank you !

Answer 1

Your code should be

$id=$_POST['ID'];
$query="SELECT * FROM vbots WHERE ID=$id";
$result = mysql_query($query, $con) or die("Error: ". mysql_error(). " with query ". $query);
$num=mysql_num_rows($result);
mysql_close(); 

You are using

$num=mysql_query($result,$con)

Answer 2

You mixed something up with your query.

$result = mysql_query("SELECT * FROM vbots");
$num=mysql_query($result,$con); //! $result is already a result from a query. 
//You can't 'query a result'…

So this should just work:

$id=$_GET['id'];
$username="xxx";
$password="xxx";
$database="xxx";
$host="xxx";
$con = mysql_connect($host,$username,$password);
if (!mysql_select_db($database))
    die("Can't select database");

$id=$_POST['ID'];
$query="SELECT * FROM vbots WHERE ID=$id";
$result = mysql_query($query);
echo mysql_num_rows($result);
mysql_close();

Answer 3

I think you need check the query result at first.

if (!$result) {
    //handling empty set or error
}

Answer 4

I think you forgot to select your database:

if (!mysql_select_db($database))
    die("Can't select database");