Create a database table and insert data with HTML forms - Using Wordpress

Here, We are gonna creating a MySQL database table, and inserting content using the WordPress class wpdb:

In this tutorial, we will learn:

How to create a new database table in WordPress
How to insert data into this newly created database table
You could use this process to record information about your audience or even use it for a plugin, etc.

First, and with PHP, the following code performs a MySQL query and creates a new database table if it does not exist already, and from this tutorial, the name of the table is my_table which of course you can change to something else:

global $wpdb;
// creates my_table in database if not exists
$table = $wpdb->prefix . "my_table"; 
$charset_collate = $wpdb->get_charset_collate();
$sql = "CREATE TABLE IF NOT EXISTS $table (
 `id` mediumint(9) NOT NULL AUTO_INCREMENT,
 `name` text NOT NULL,
UNIQUE (`id`)
) $charset_collate;";
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );

You may have noticed that the action is nothing but a hash, because we don’t work with PHP files here and complicated stuff..

The following step is the last one which detects what the viewer has typed, and inserts it to the database table using $wpdb->insert WordPress class function. If the name was not set (left empty by the viewer), there will be no insert, just a notice for the user to fill out that field :

if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] != "" ) {
 $table = $wpdb->prefix."my_table";
 $name = strip_tags($_POST["visitor_name"], "");
 $wpdb->insert( 
 $table, 
 array( 
 'name' => $name
 )
 );
 $html = "<p>Your name <strong>$name</strong> was successfully recorded. Thanks!!</p>";
}
// if the form is submitted but the name is empty
if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] == "" )
 $html .= "<p>You need to fill the required fields.</p>";

Full code

Now to make this easier to use, we are going to make a quick shortcode to use, so add the following code in your functions.php file, make sure you are working on a WordPress child theme :

function elh_insert_into_db() {
 
 global $wpdb;
 // creates my_table in database if not exists
 $table = $wpdb->prefix . "my_table"; 
 $charset_collate = $wpdb->get_charset_collate();
 $sql = "CREATE TABLE IF NOT EXISTS $table (
 `id` mediumint(9) NOT NULL AUTO_INCREMENT,
 `name` text NOT NULL,
 UNIQUE (`id`)
 ) $charset_collate;";
 require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
 dbDelta( $sql );
 // starts output buffering
 ob_start();
 ?>
 <form action="#v_form" method="post" id="v_form">
 <label for="visitor_name"><h3>Hello there! What is your name?</h3></label>
 <input type="text" name="visitor_name" id="visitor_name" />
 <input type="submit" name="submit_form" value="submit" />
 </form>
 <?php
 $html = ob_get_clean();
 // does the inserting, in case the form is filled and submitted
 if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] != "" ) {
 $table = $wpdb->prefix."my_table";
 $name = strip_tags($_POST["visitor_name"], "");
 $wpdb->insert( 
 $table, 
 array( 
 'name' => $name
 )
 );
 $html = "<p>Your name <strong>$name</strong> was successfully recorded. Thanks!!</p>";
 }
 // if the form is submitted but the name is empty
 if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] == "" )
 $html .= "<p>You need to fill the required fields.</p>";
 // outputs everything
 return $html;
 
}
// adds a shortcode you can use: [insert-into-db]
add_shortcode('elh-db-insert', 'elh_insert_into_db');

WordPress Shortcode

Now that we have added the above snippet of code to our functions file, the shortcode [elh-db-insert] is now ready to be used and you can insert it anywhere around your site, like in a post, page, widget, PHP template..

If the inserting process has worked for you, then play around with it, add other fields, name them, make test inserts, and have fun!

Credits :- samelh blog.