Re: Database efficiency question

[Rick James]

Think of "entities" and "relationships".

A customer is an "entity"; make a table for customers (one row per customer). It would include a unique (PRIMARY KEY) column, say customer_id, plus various bits of data about the customer.

A product is an "entity"; make a table for products.

Then you have a "mapping" or "relationship" between customers and properties. It is probably many-to-many. Make this a table. It would have two imporant columns: customer_id and product_id.

Your queries will often need to do JOINs, maybe even LEFT JOINs. Example: Which product(s), if any, does a given customer have.