登录mysql_num_rows错误

Question

This is my Check Login file... Its shows an error: Call to undefined function mysql_num_row() Whats the problem?

$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:login_success.php");
}

Answer 1

The error:

 Call to undefined function mysql_num_row()

Means that you are using mysql_num_row() when you should be using mysql_num_rows() . Note the s at the end.

Answer 2

Call to undefined function mysql_num_row() this shows you have a typo:

Change mysql_num_row() to mysql_num_rows()

You should also change your MySQL to MySQLi or PDO as MySQL is depreciated as of PHP 5.5.

Example of MySQLi usage from your example:

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysqli_query($sql);

$count=mysqli_num_rows($result);

Answer 3

As said your mysql_error you use mysql_num_row() instead mysql_num_rows(), but on your code I see mysql_num_rows(). Can you check it?

In general, I would advise you to use PDO extension instead of mysql, because mysql will be removed in the future version of PHP.

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";

Use this code can be unsafe for security reasons, depending on what type of validation pass these variables. If you'll use PDO you can do the same code as most safety case:

// Initialize the database connection
$pdo = new PDO('mysql:host='.$your_hostname.';dbname=.'$your_db, $user, $pass, 
    array(
        PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8'
    )
);
$sql="SELECT count(username) FROM $tbl_name WHERE username=:myusername and password=:mypassword";

// Create prepared statement
$stm = $pdo->prepare($sql);
$stm->bindParam(':myusername', $myusername, PDO::PARAM_STR);
$stm->bindParam(':mypassword', $mypassword, PDO::PARAM_STR);
$stm->execute();

if($stm->fetchColumn()){
    session_register("myusername");
    session_register("mypassword");
    header("location:login_success.php");
}

Answer 4

最好使用mysqli ext：

$count=mysqli_num_rows($result);