html form, PHP insert data into database not working? - php

Question

I have HTML registration form when I submit the form the PHP code appears and data not insert to database i made my database using phpMyAdmin, what should I do?
Here my PHP code:
<?php
$con=mysqli_connect('localhost','root','');
$db=mysqli_select_db($con,'research_sys');
if ($con) {
echo "good";
}else {
die('error');
}
if(isset($_POST['submit'])){
$Fname = mysqli_real_escape_string($con,$_POST["Fname"]);
$Lname = mysqli_real_escape_string($con,$_POST["Lname"]);
$email = mysqli_real_escape_string($con,$_POST['email']);
$password = mysqli_real_escape_string($con,$_POST['password']);
$sql = mysqli_query($con,"INSERT INTO `research_sys`.`researcher` (Re_fname,Re_lname,Re_mobile,Re_password) values ('$Fname','$Lname','$email','$password ')");
if (mysqli_query($sql)){
echo "insert";
} else {
echo "error" .$sql ."<br>". mysqli_error($con);
}
}
?>
here my registration HTML code
<form method="post" action="connect.php">
<legend class="center">Register </legend>
<br>
<div>
<input type="text" name="Fname" placeholder="First Name"/>
</div>
<div>
<input type="text" name="Lname" placeholder="Last Name"/>
</div>
<div>
<input type="text" name="email" placeholder="Email"/>
</div>
<div>
<input type="password" name="password" placeholder="Password"/>
</div>
<div>
<input type="password" name="con_password" placeholder="Password confirm"/>
</div>
<input type="submit" name="submit" value="submit"/>
</form>

Answer 1

Look at the following:
$sql = mysqli_query($con,"INSERT INTO `research_sys`.`researcher`
^^^^^^^^^^^^ function
(Re_fname,Re_lname,Re_mobile,Re_password)
values ('$Fname','$Lname','$email','$password ')");
^ space
if (mysqli_query($sql)){
^^^^^^^^^^^^ function
You're using that mysqli_query() function twice, remove one and just do:
if ($sql){...}
and mysqli_error($con) should have thrown you an error about it.
If it didn't throw an error, then that may suggest you're using this as file:/// as opposed to http://localhost.
Edit:
"i have html registration form whin i submit the form the php code apears"
That's because of what I wrote above before quoting you. You need to run this off a webserver with php/mysql installed and running properly and as http://localhost.
Also, remove the space in this '$password '. That space counts as a character.
Double-check your column names also. There seems to be something that doesn't match (Re_fname,Re_lname,Re_mobile,Re_password) the Re_mobile and you're referencing an email '$email' in VALUES.
You also seem to store plain text passwords; don't, it's not safe if you intend on going live with this. Use password_hash() and a prepared statement.
Footnotes:
$con=mysqli_connect('localhost','root','');
$db=mysqli_select_db($con,'research_sys');
You can shorten that to using all 4 arguments in mysqli_connect():
$con=mysqli_connect('localhost','root', '', 'research_sys');