Forminator - select frrom external DB

<?php
add_filter(	'forminator_cform_render_fields', 'forminator_select_posts_list', 10, 2 );
function forminator_select_posts_list( $wrappers, $form_id ) {

	$allowed_forms = array( 16134 ); // IDs of forms to apply to (separated by comma if more)

	// which select fields to fill in with what post types
	// array key (left) = select field ID
	// array value (right) = post type name

	$select_fields_data = array(
		'select-3',
	);

	##### DO NOT EDIT BELOW #####;


	if ( ! in_array( $form_id, $allowed_forms) ) {
		return $wrappers;
	}



		foreach ( $wrappers as $wrapper_key => $wrapper ) {
			if ( ! isset( $wrapper[ 'fields' ] ) ) {
				continue;
			}

			if ( isset( $select_fields_data[ $wrapper[ 'fields' ][ 0 ][ 'element_id' ] ] ) ) {


				// here fetch your data from DB
				$conn = new mysqli('SERVERIP', 'USERNAME', 'PASSWORD', 'DBNAME') or die ('Cannot connect to db');
				$result = $conn->query("SELECT wdt_ID, clientname FROM wp_wpdatatable_2 ORDER BY clientname ASC");

				$row = $result;


					$new_options = array();



						$new_options[] = array(
							'label' => $row['clientname'],
							'value' => $row['wdt_ID'],
							'limit' => '',
							'key'   => forminator_unique_key(),
						);

						$opt_data['options'] = $new_options;


					$select_field = Forminator_API::get_form_field( $form_id, $wrapper['fields'][0]['element_id'], true );
					if( $select_field && !empty( $opt_data ) ){
						Forminator_API::update_form_field( $form_id, $wrapper['fields'][0]['element_id'], $opt_data );
						$wrappers[ $wrapper_key ][ 'fields' ][ 0 ][ 'options' ] = $new_options;
					}

			}
		}

		return $wrappers;
}