[英]my sql num rows returns 0
我检查了所有变量。 它们都包含正确的数据。 但是,当我调用mysql_num_rows()时,它返回NULL而不是1。因此,我的登录脚本在用户名和密码正确时说“用户名和密码错误”。
<?php
ini_set('display_errors', 'On');
error_reporting(E_ALL | E_STRICT);
ob_start();
$host="mywebsite.it"; // Host name
$username="whateveruser"; // Mysql username
$password="whateverpassword"; // Mysql password
$db_name="whateverdb"; // Database name
$tbl_name="whatevertable"; // Table name
// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
print "$db_name\n";/*These is correct*/
print "$tbl_name\n";/*These is correct*/
// Define $myusername and $mypassword
$myusername=$_POST['myusername'];
$mypassword=$_POST['mypassword'];
/*To protect MySQL injection*/
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);
print "\n$result"; /*These is correct*/
// Mysql_num_row is counting table row
$count = mysql_num_rows($result); /*This isn't actually returning 1*/
echo '<pre>'; var_dump($count); echo '</pre>';
// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword");
header("Location:Target.php");
}
else {
echo "Wrong Username or Password"; /*my script always goes here*/
}
ob_end_flush();
?>
看起来应该可以。 但是,请停止使用mysql_ *函数。 它们已被弃用,并且存在许多安全问题。
相反,我强烈建议您使用支持本机编码(如PDO)的库。 ( http://www.php.net/manual/zh/class.pdo.php )具体来说,我建议您使用准备好的语句。 ( http://www.php.net/manual/zh/pdo.prepare.php )
我在下面提供了一个简单的示例。
这是一个快速连接功能:
<?php
function connectToDb($dbms, $host, $port, $username, $password) {
$dsn = sprintf('%s:host=%s;port=%d', $dbms, $host, $port);
$attributes = array(
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
);
// Wrap PDO instantiation in a try->catch so credentials don't end up in
// stack traces
try {
$connection = new PDO(
$dsn, $username, $password, $attributes
);
} catch (Exception $exception) {
throw new Exception($exception->getMessage());
}
return $connection;
}
这是一个如何使用它的简单示例:
// Connect to the database
$connection = connectToDb(
'mysql', 'localhost', '3306', 'bryan', ''
);
// Prepare the statement with parameters we can bind user input to
// These parameters will be properyly encoded to prevent SQL injection
$statement = $connection->prepare(
'SELECT user,password FROM mysql.user WHERE user = :username'
);
// Perform the search with the user-supplied data
// We'll pretend here with $usernameSearch
$usernameSearch = 'bryan';
$statement->execute(
array(':username' => $usernameSearch)
);
// Get the result set row count
$rowCount = $statement->rowCount();
// Do What you need to do
if ($rowCount > 0) {
// Fetch a row
$result = $statement->fetch(PDO::FETCH_ASSOC);
printf("Found a record for %s!\n", $result['user']);
} else {
echo "No record found!\n";
}
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