Below is a form which contain id field, name field, phone number filed, gender radio button and we are sending these data  by using post method.

<form name="user_registration" method="post" >
   Name: <input type="text" name="Name">
 
   <br><br>

    phone: <input type="text" name="phone">
    
    <br><br>
   
    E-mail: <input type="text" name="email">
  
    <br><br>

   Gender:
   <input type="radio" required name="gender" value="female">Female
   <input type="radio" required name="gender" value="male">Male
   
   <br><br>
   <input type="submit" name="submit" value="Submit">
</form>

For inserting data to database from form in php, first we have to create a connection from database by using following code.

<?php
$servername = "localhost";
$username = "root"; 
$password = "pass";
$database = "demo";  //this will contain name of a database

// Create connection
$conn = new mysqli($servername, $username, $password, $database);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
  echo "Connected successfully";

	
?> 

Below code will insert data from above form to database.

if ($_SERVER["REQUEST_METHOD"] == "POST") {

$id = $_POST['id']; // it stores id which we are providing in id field
$name = $_POST['Name']; // it stores name which we are providing in name field
$Phone = $_POST['phone']; // it stores phone number which we are providing in phone field
$email=$_POST['email']; // it stores email address which we are providing in email field
$Gender= $_POST['gender']; // it stores gender information which we are providing



// sgl query for inserting record

$sql = "INSERT INTO user(Name,email,phone,gender) VALUES ('".$name."','".$email."',".$Phone.",'".$Gender."')";


if ($conn->query($sql) === TRUE) {
    echo "New record created successfully";

} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

}