提交表单后显示错误消息

Question

i have a registration form in which i have placed a check on email id and status so that a person cannot signup again with the same email. Both the form and script are on a single page and the page is in .php format. The problem is that although the check works fine but i am not able to display an error message in front of email box. would appreciate if someone could help me

<form role="form" action="" autocomplete="off" method="POST">

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="name" class="form-control" name="name" placeholder="Company Name" required>
    </div>
    <span class="help-block"></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="email" class="form-control" name="email" placeholder="email address" required>
    </div>
    <span><?php echo $errormsg;?></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-lock"></i></span>
            <input  type="password" class="form-control" name="password" placeholder="Password" required>
    </div>
    <span class="help-block"></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="tel" id="tel" class="form-control" name="phoneno" pattern="\d{10}" placeholder="Please enter a ten digit phone number" required />
    </div>
    <span class="help-block"></span>
    <input class="form-control" value="" type="hidden" name="status">

    <button class="btn btn-lg btn-primary btn-block" name="submit" type="submit">Sign Up</button>

</form>

<?php
$con=mysqli_connect("localhost","root","","db");
// Check connection
if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

// escape variables for security
$name = mysqli_real_escape_string($con, $_POST['name']);
$email = mysqli_real_escape_string($con, $_POST['email']);
$password = mysqli_real_escape_string($con, $_POST['password']);
$phoneno = mysqli_real_escape_string($con, $_POST['phoneno']);
$status = mysqli_real_escape_string($con, $_POST['status']);

$sql = "SELECT * FROM register WHERE email='".$email."' AND status='1'";
$result = mysqli_query($con, $sql); 
if (mysqli_num_rows($result) > 0)
{
    $errormsg="email already exist";
}
else
{
    $sql="INSERT INTO register (name,email,password,phoneno,status) VALUES ('$name','$email','$password','$phoneno','1')";
    if (!mysqli_query($con,$sql)) 
    {
        die('Error: ' . mysqli_error($con));
    }
    exit;
    mysqli_close($con);
}
?>

Answer 1

If all code is in single file then you shift the PHP code above the html code, why the error is not showing the html is rendering first before executing the PHP code? ie:

<?php
$con=mysqli_connect("localhost","root","","db");
// Check connection
if (mysqli_connect_errno()) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

// escape variables for security
$name = mysqli_real_escape_string($con, $_POST['name']);
$email = mysqli_real_escape_string($con, $_POST['email']);
$password = mysqli_real_escape_string($con, $_POST['password']);
$phoneno = mysqli_real_escape_string($con, $_POST['phoneno']);
$status = mysqli_real_escape_string($con, $_POST['status']);

$sql = "SELECT * FROM register WHERE email='".$email."' AND status='1'";
$result = mysqli_query($con, $sql); 
if (mysqli_num_rows($result) > 0)
    {
        $errormsg="email already exist";
    }
else{
$sql="INSERT INTO register (name,email,password,phoneno,status) VALUES ('$name','$email','$password','$phoneno','1')";
        if (!mysqli_query($con,$sql)) 
            {
                die('Error: ' . mysqli_error($con));
            }
        exit;
mysqli_close($con);
}
?>
<form role="form" action="" autocomplete="off" method="POST">

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="name" class="form-control" name="name" placeholder="Company Name" required>
    </div>
    <span class="help-block"></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="email" class="form-control" name="email" placeholder="email address" required>
    </div>
    <?php echo $errormsg;?></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-lock"></i></span>
            <input  type="password" class="form-control" name="password" placeholder="Password" required>
    </div>
    <span class="help-block"></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="tel" id="tel" class="form-control" name="phoneno" pattern="\d{10}" placeholder="Please enter a ten digit phone number" required />
    </div>
    <span class="help-block"></span>
    <input class="form-control" value="" type="hidden" name="status">

    <button class="btn btn-lg btn-primary btn-block" name="submit" type="submit">Sign Up</button>

</form>

Answer 2

You should set/initialize the error container above, and make those checking above the html first.

And don't forget to use prepared statements!

<?php

$errormsg = '';
$con = mysqli_connect("localhost","root","","db_name");
// Check connection
if (mysqli_connect_errno()) {
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$name = $_POST['name'];
$email =  $_POST['email'];
$password = $_POST['password'];
$phoneno = $_POST['phoneno'];
$status = $_POST['status'];

$sql = "SELECT * FROM register WHERE email = ? AND status = '1' ";
$check = $con->prepare($sql);
$check->bind_param('s', $email);
$check->execute();

if ($check->num_rows > 0) {
    $errormsg = "email already exist";
}
else{

    $sql = "INSERT INTO register (name,email,password,phoneno,status) VALUES (?, ?, ?, ?, '1')";
    $insert = $con->prepare($sql);
    $insert->bind_param('ssss', $name, $email, $password, $phoneno);
    $insert->execute();

}
?>
<form role="form" action="" autocomplete="off" method="POST">

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="name" class="form-control" name="name" placeholder="Company Name" required>
    </div>
    <span class="help-block"></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="email" class="form-control" name="email" placeholder="email address" required>
    </div>
    <?php echo $errormsg; ?></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-lock"></i></span>
            <input  type="password" class="form-control" name="password" placeholder="Password" required>
    </div>
    <span class="help-block"></span>

    <div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="tel" id="tel" class="form-control" name="phoneno" pattern="\d{10}" placeholder="Please enter a ten digit phone number" required />
    </div>
    <span class="help-block"></span>
    <input class="form-control" value="" type="hidden" name="status">

    <button class="btn btn-lg btn-primary btn-block" name="submit" type="submit">Sign Up</button>

</form>

Answer 3

<div class="input-group">
        <span class="input-group-addon"><i class="fa fa-user"></i></span>
            <input type="email" class="form-control" name="email" placeholder="email address" required>
      <br><span><?php echo $errormsg;?></span>
    </div>