通过维护用户在数据库中设置用户的电子邮件

Question

This is how I want to find out about the user exists in the database but it will constantly keep themselves it exists when it does not do it.

What I want out of this code is to get the knowledge about the user in the database if it does not make it must clearly say it :)

}
    else
        {
            $email_1 = $_post["email"];
            $result = $this->mysqli->query("SELECT * FROM bruger WHERE email='$email_1'");
            if(mysqli_num_rows($resut) > 0)
            {
//code here!
}
        else
        {
        ?>
        <div class="article-main-content">
            <div class="alert-message" style="background-color:#c22525;"><span class="icon-text">&#9888;</span><span class="alert-content">Email Findes på hjemmesiden</span><a href="#" class="destroy-button"></a></div>
        </div>
        <?php
        }
    }
}

and i have try its here:

$email = $_post["email"]
    foreach($this->mysqli->query("SELECT * FROM `bruger` WHERE email='$email'") as $row) {
              if ($row['email'] !== $email) {

here are all my html code:

<form action="#" enctype="multipart/form-data" method="post">
    <table width="100%" cellpadding="5" cellspacing="5">
        <tr>
            <td><p>Email</p></td>
            <td><input type="text" name="email" class="ned_input"></td>
        </tr>
        <tr>
            <td><p>Adgangskode</p></td>
            <td><input type="password" name="password_adgangskode_1" class="ned_input"></td>
        </tr>
        <tr>
            <td><p>Adgangskode Gentag</p></td>
            <td><input type="password" name="password_adgangskode_2" class="ned_input"></td>
        </tr>
        <tr>
            <td><p>Fornavn</p></td>
            <td><input type="text" name="fornavn" class="ned_input"></td>
        </tr>
        <tr>
            <td><p>Efternavn</p></td>
            <td><input type="text" name="efternavn" class="ned_input"></td>
        </tr>
        <tr>
            <td><p>Profilbillede</p></td>
            <td><input type="file" name="file" /></td>
        </tr>
        <tr>
            <td></td>
            <td><input type="submit" name="opret" value="Opret bruger" style="margin-top:10px;"></td>
        </tr>
    </table>
</form>

EIDT HERE

if ($stmt = $this->mysqli->prepare("SELECT `id` FROM `bruger` WHERE `email`"))
             {
             $stmt->bind_param('s', $email_indhold);
             $email_indhold = $_POST["email"];


             $stmt->execute();
             $stmt->store_result();
             $stmt->bind_result($id);
             $stmt->fetch();
             $count = $stmt->num_rows;
             $stmt->close();

             if($count > 0)
             {

Answer 1

look the algorithm for this

PHP end

1. collect POST data first and sanitize the input.

2. check for the email

   SELECT email FROM table WHERE email = '$post_email' LIMIT 1

3. if result is not empty then go forward

4. else gives alert of duplicate entry

Database end

to add UNIQUE KEY constraint on your db

ALTER TABLE  <table name >
ADD CONSTRAINT uniqueEmail UNIQUE (< `email column` > )

using unique constraint will safe your table,it will give error when someone try to enter duplicate email.So when you execute INSERT query for the table, check what**mysqli_query** returns ( see below )

$qry = "SELECT INTO table (whatever) VALUE (whatever)";
$done = mysqli_query($qry);

check $done, if everything goes fine then it will return TRUE otherwise it will gives mysql_error( may be 1064), so by this way you can also prevent to stop duplicate email address