This one works:

mysql> SELECT node.title AS node_title, node.nid AS nid, flag_content.content_id AS flag_content_content_id, book_menu_links.weight AS book_menu_links_weight
    -> FROM
    -> node node
    -> LEFT JOIN flag_content flag_content_node ON node.nid = flag_content_node.content_id AND (flag_content_node.fid = '2' AND flag_content_node.uid = '1')
    -> LEFT JOIN flag_content flag_content ON node.nid = flag_content.content_id AND (flag_content.fid = '2' AND flag_content.uid = '1' AND flag_content.sid = '0')
    -> LEFT JOIN book book ON node.nid = book.nid
    -> LEFT JOIN menu_links book_menu_links ON book.mlid = book_menu_links.mlid
    -> WHERE (( (node.status = '1') AND (node.type IN  ('topic')) ))
    -> ORDER BY book_menu_links_weight ASC
    -> LIMIT 15 OFFSET 0;
+---------------------------------------+-----+-------------------------+------------------------+
| node_title                            | nid | flag_content_content_id | book_menu_links_weight |
+---------------------------------------+-----+-------------------------+------------------------+
| Reference Sheets                      | 180 |                     180 |                   NULL |
| Bonus Workbooks                       |  66 |                      66 |                   NULL |
| CSS notes                             |  73 |                    NULL |                   NULL |
| HTML                                  |  53 |                    NULL |                    -15 |
| Designing With Grids                  |  64 |                    NULL |                    -15 |
| Intro to Responsive Design            | 107 |                    NULL |                    -15 |
| Introduction to the Fusion Base Theme | 161 |                    NULL |                    -15 |
| Installing Drupal                     |  67 |                    NULL |                    -15 |
| Setup                                 | 126 |                    NULL |                    -15 |
| Introduction to the Omega Base Theme  | 143 |                    NULL |                    -15 |
| Setup                                 | 144 |                    NULL |                    -14 |
| Setup                                 | 162 |                    NULL |                    -14 |
| Adding New Style Sheets               | 127 |                    NULL |                    -14 |
| Installing the Acquia Dev Desktop     |  76 |                    NULL |                    -14 |
| Creating Your First Grid Layout       |  79 |                    NULL |                    -14 |
+---------------------------------------+-----+-------------------------+------------------------+
15 rows in set (0.00 sec)






This one doesn't work:

mysql> SELECT node.title AS node_title, node.nid AS nid, flag_content.content_id AS flag_content_content_id, book_menu_links.weight AS book_menu_links_weight
    -> FROM
    -> node node
    -> LEFT JOIN flag_content flag_content_node ON node.nid = flag_content_node.content_id AND (flag_content_node.fid = '2' AND flag_content_node.uid = '1')
    -> LEFT JOIN flag_content flag_content ON node.nid = flag_content.content_id AND (flag_content.fid = '2' AND flag_content.uid = '1' AND flag_content.sid = '0')
    -> LEFT JOIN book book ON node.nid = book.nid
    -> LEFT JOIN menu_links book_menu_links ON book.mlid = book_menu_links.mlid
    -> WHERE (( (node.status = '1') AND (node.type IN  ('lesson_topic')) ))
    -> ORDER BY book_menu_links_weight ASC;
+------------------+-----+-------------------------+------------------------+
| node_title       | nid | flag_content_content_id | book_menu_links_weight |
+------------------+-----+-------------------------+------------------------+
| Learning Modules |   2 |                       2 |                    -15 |
| Lesson Topics    |   3 |                    NULL |                    -14 |
+------------------+-----+-------------------------+------------------------+
2 rows in set (0.00 sec)