To insert form data into a MySQL database using PHP with procedural style, follow these steps:

Step-by-Step Process:

1. Create the HTML form: Collect user inputs via an HTML form.
2. Capture form data: Use $_POST (for POST method) to capture the form data.
3. Establish a connection to MySQL: Use mysqli_connect() to connect to your MySQL database.
4. Prepare the SQL Insert Query: Construct a SQL INSERT INTO statement to insert the data.
5. Execute the SQL query: Use mysqli_query() to execute the query.
6. Close the connection: Always close the database connection using mysqli_close().

Example:

1. Create the HTML form

<form action="insert.php" method="POST">
    <label for="name">Name:</label>
    <input type="text" name="name" id="name" required>
    <label for="email">Email:</label>
    <input type="email" name="email" id="email" required>
    <input type="submit" value="Submit">
</form>

2. Capture form data in insert.php

<?php
// Check if form is submitted
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    
    // Capture the form data
    $name = $_POST['name'];
    $email = $_POST['email'];

    // Step 1: Establish connection to MySQL
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "test_db";

    // Create connection
    $conn = mysqli_connect($servername, $username, $password, $dbname);

    // Check if connection was successful
    if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
    }

    // Step 2: Prepare the SQL query
    $sql = "INSERT INTO users (name, email) VALUES ('$name', '$email')";

    // Step 3: Execute the query
    if (mysqli_query($conn, $sql)) {
        echo "Record inserted successfully!";
    } else {
        echo "Error: " . $sql . "<br>" . mysqli_error($conn);
    }

    // Step 4: Close the connection
    mysqli_close($conn);
}
?>

Key Points:

1. Security Note: In the above example, raw input from the user is directly used in the query. To prevent SQL injection attacks, always sanitize input or use prepared statements.

   For example, use:

   $name = mysqli_real_escape_string($conn, $_POST['name']);
   

2. Error Handling: Always check for potential errors in connection and query execution.

3. Database Structure: Make sure you have a database (test_db) and a table (users) with the appropriate columns (name, email).

Here’s how the table might look:

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    email VARCHAR(50) NOT NULL
);