Contact Form 7 to External DB

cf7_external_db.php

<?php
/*
Plugin Name: Contact Form 7 to External DB
Plugin URI: http://thedrawingroomcreative.com
Description: This plugin uses the wpcf7_before_send_mail hook to post a specific form to an external database. Upon use the details for your external database will need to be entered. Private use only.
Author: The Drawing Room
Version: 0.1
Author URI: http://thedrawingroomcreative.com
*/

function wpcf7_send_to_external ( $cf7 ) {

	//external db details
	$username = 'username';
	$password = 'password';
	$database = 'database';
	$host = 'host_ip';

	//create new wpdb instance
	$mydb = new wpdb($username, $password, $database, $host);
    
    	//limit hook to only fire on particular form ID (optional)
	if ( $cf7->id == 1 ) {

		//get select box for different enquiry types (optional)
		$type = $cf7->posted_data["your-select"];

		//if form type is equal to above value (optional)
		if ( $type == 'Form Name' ){

			//get posted form fields
			$field1 = $cf7->posted_data["your-field"];
			$field2 = $cf7->posted_data["your-field"];
			$field3 = $cf7->posted_data["your-field"];

			//insert into external db
			$mydb->insert( 
				//name of external db table
				'table_name',
				//name of table columns and which fields to insert 
				array( 
					'column1' => $field1, 
					'column2' => $field2,
					'column3' => $field3,

				),
				//field formats: %s = string, %d = integer, %f = float
				array( 
					'%s','%s','%s'
				) 
			);

		}

	}

}
add_action("wpcf7_before_send_mail", "wpcf7_send_to_external");

Automatically generate MySQL table and columns https://wpdebuglog.com/forums/topic/contact-form-7-external-database-mysql-easy-method/