Add ID and Type from supplemental tables to parent table using SQL (MySQL & Laravel Polymorphic relations)

Note. Also posted on Database Administrators

I have one table that records all sales and fourteen supplemental tables which contain extra information about a sale. The fourteen supplemental tables are for all intents and purposes the same. They were created long ago when the initial developer thought there would be more differences but actually now that the project has matured they are more similar than they are different. They are different however, and as such I need to keep them separate.

Current structure

Sales table

| id      | customer_id | customer_ref                         | ... |
|---------|-------------|--------------------------------------|-----|
| 1237567 | 354         | a6143f8c-b679-47be-9bc0-52457842913c | ... |
| 1237568 | 867         | ref89b72                             | ... |
| ...     | ...         | ...                                  | ... |

Supplemental table 1 Class: App\SuppOne

| id   | customer_id | customer_ref                         | ... |
|------|-------------|--------------------------------------|-----|
| 2857 | 10372       | 2016-07-01-ab5d09cc37ca              | ... |
| 2858 | 354         | a6143f8c-b679-47be-9bc0-52457842913c | ... |
| ...  | ...         | ...                                  | ... |

Supplemental table 2 Class: App\SuppTwo

| id    | customer_id | customer_ref | ... |
|-------|-------------|--------------|-----|
| 90488 | 867         | ref89b72     | ... |
| 90489 | 1024        | 0000080992   | ... |
| ...   | ...         | ...          | ... |

There are no foreign keys on the tables to join the sales table to the supplemental tables but there is a 'customer_id' and 'customer_reference' which are unique to both the sales tables and also the supplemental tables but they are not consistent. This is what is currently used to join the two as-and-when I need to get more information about a given sale.

I'm using Laravel 5.1 and a MySQL database and I'd like to add two fields to the sales table; supplemental_id and supplemental_type in order to quickly and efficiently create a polymorphic relation.

Desired structure

Sales table

| id      | supplemental_id | supplemental_type | customer_id | customer_ref                         | ... |
|---------|-----------------|-------------------|-------------|--------------------------------------|-----|
| 1237567 | 2858            | App\SuppOne       | 354         | a6143f8c-b679-47be-9bc0-52457842913c | ... |
| 1237568 | 90488           | App\SuppTwo       | 867         | ref89b72                             | ... |
| ...     | ...             | ...               | ...         | ...                                  | ... |

I need to add these two fields to each of the sales records but I am unsure how to do this with raw SQL as I expect it would be much quicker than if done in a migration. I'd like to know how (if possible) in SQL, do I deal with the mapping from table_name to App\ClassName. There are about 1.5m records in the sales table and looping over them all will not take an insignificant amount of time.

via Chebli Mohamed