Details on the project tables

> show tables;

authors
cities
departments
employees
flights
users
stocks
last_trade

> desc authors;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| author_id  | int(11)     |      | PRI | 0       |       |
| first_name | varchar(30) |      |     |         |       |
| last_name  | varchar(30) |      |     |         |       |
+------------+-------------+------+-----+---------+-------+

> desc cities;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| city_id   | int(11)     |      | PRI | 0       |       |
| city_name | varchar(30) |      |     |         |       |
+-----------+-------------+------+-----+---------+-------+

> desc departments;
+-----------------+-------------+------+-----+---------+-------+
| Field           | Type        | Null | Key | Default | Extra |
+-----------------+-------------+------+-----+---------+-------+
| department_id   | int(11)     |      | PRI | 0       |       |
| department_name | varchar(20) |      |     |         |       |
+-----------------+-------------+------+-----+---------+-------+

> desc employees;
+---------------+-------------+------+-----+---------+-------+
| Field         | Type        | Null | Key | Default | Extra |
+---------------+-------------+------+-----+---------+-------+
| employee_id   | int(11)     |      | PRI | 0       |       |
| first_name    | varchar(30) |      |     |         |       |
| last_name     | varchar(30) |      |     |         |       |
| work_phone    | varchar(12) |      |     |         |       |
| department_id | int(11)     |      |     | 0       |       |
+---------------+-------------+------+-----+---------+-------+

> desc flights;
+---------------+---------------+------+-----+------------+-------+
| Field         | Type          | Null | Key | Default    | Extra |
+---------------+---------------+------+-----+------------+-------+
| flight_id     | int(11)       |      | PRI | 0          |       |
| flight_date   | date          |      |     | 0000-00-00 |       |
| flight_number | int(11)       |      |     | 0          |       |
| city_id       | int(11)       |      |     | 0          |       |
| price         | decimal(12,2) |      |     | 0.00       |       |
+---------------+---------------+------+-----+------------+-------+

> desc users;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| user_id    | int(11)     |      | PRI | 0       |       |
| first_name | varchar(30) |      |     |         |       |
| last_name  | varchar(30) |      |     |         |       |
| email      | varchar(30) |      |     |         |       |
| author_id  | int(11)     |      |     | 0       |       |
+------------+-------------+------+-----+---------+-------+

> desc stocks;
+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| stock_id | int(11)     |      | PRI | 0       |       |
| symbol   | varchar(12) |      |     |         |       |
| volume   | int(11)     |      |     | 0       |       |
+----------+-------------+------+-----+---------+-------+

> desc last_trade
+----------+---------------+------+-----+---------+-------+
| Field    | Type          | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| stock_id | int(11)       |      | PRI | 0       |       |
| price    | decimal(12,2) |      |     | 0.00    |       |
+----------+---------------+------+-----+---------+-------+