Getting record from three wpdb tables

Question

You don’t want to ask wpdb for each field. This is the wrapper for SQL queries

Like so (not tested):

<?php
$my_results = $wpdb->get_results(
    SELECT
        posts.post_author, dopbsp_calendars.user_id, dopbsp_reservations.price_total, dopbsp_reservations.check_in, dopbsp_reservations.check_out, dopbsp_reservations.start_hour, dopbsp_reservations.end_hour, dopbsp_calendars.id, posts.post_title, posts.ID As ID1, posts.post_parent, dopbsp_reservations.transaction_id
    FROM wp_posts
    INNER JOIN
        posts.post_author
    ON
        dopbsp_calendars.user_id
        dopbsp_calendars
    ON
        wp_posts.post_author = dopbsp_calendars.user_id,
        dopbsp_reservations
);

Then see what you get in this object:

<?php
echo '<pre>';
print_r($my_results);
echo '</pre>';

Warning: Methods in the wpdb() class should not be called directly.
Use the global $wpdb object instead! Class Reference/wpdb

So, it’s better to make $wpdb global:

global $wpdb;
$my_results = $wpdb->get_results(..................);

Notice: I didn’t checked the query itself.