Unique Order Number

Delete the wrong order

Let’s first delete the wrong order:

1 mysql> delete from orders where id = 2;
2 Query OK, 1 row affected (0.01 sec)
3
4 mysql> select * from orders;
5 +----+--------------+---------------------+-------------+
6 | id | order_number | ordered_at          | customer_id |
7 +----+--------------+---------------------+-------------+
8 |  1 | ABC001       | 2016-09-09 08:34:55 |   1         |
9 +----+--------------+---------------------+-------------+
10 1 row in set(0.00 sec)

Create a unique index

Now, let’s create a unique index on the order_number of the orders table. This will make our search queries quick and protect us from inserting the same order number twice. This is the command that will create the unique index. Let’s execute it: