mysqli_num_rows（）期望参数1为mysqli_result错误[重复]

Question

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• mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to be resource or result 32 answers

What is the type returned by a mysqli_query, and why can't it be cast into a mysqli_result, so that I can pass it to mysqli_result?

I am creating a login page that connects to a database and validates the log in credentials. I am having trouble with the code and can't seem to figure out why I am having errors:

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in ....on line 8

 <?php

     if(isset($_POST['bttlogin'])){
        require 'connection.php';
        $email= $_POST['email'];

        $password= $_POST['password'];
        $result = mysqli_query($conn, "SELECT * FROM Users WHERE email=`$email` && password= `$password`");
        if(mysqli_num_rows($result) == 1){         
            echo "Welcome";    
        }            

        else{       

        echo "Error";
        }
     }
     ?>


     <form action = "http://raptor.kent.ac.uk/~fn40/index1.php" method= "POST">
        <table cellpadding="2" cellspacing="2" border="0">
            <tr>

                <td>Email</td>
                <td><input type="text" name="email"></td>
            </tr>
            <tr>

                <td>Password</td>
                <td><input type="password" name="password"></td>
            </tr>
            <tr>
                 <td></td>

                 <td><input type="submit" name="bttlogin" value="Login"></td>
                 <tr>
             </table>
    </form>

</div>

Answer 1

The function mysql_query returns FALSE on failure.

See more in the php manual:

http://php.net/manual/en/mysqli.query.php

Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE.

So, there is something wrong with the query itself.

Try:

"SELECT * FROM Users WHERE email='{$email}' AND password='{$password}'"