I don't know your business model or goals here so take the following with a grain of salt or two.
The "CATEGORY" may be a red herring. If you just want to define the customer type (e.g. retail, distributor, manufacturer, etc.), then a tag (value list field) on the CUSTOMER record may well do the trick. The "CATEGORY" for products may be more complex or dynamic and merit its own Table. What would be more important IMO is a join table linking CUSTOMERS to PRODUCTS. In other words:
CUSTOMER -< Customer_Product >- PRODUCT >- CATEGORY This assumes a PRODUCT can be assigned to only one CATEGORY
CUSTOMER -< Customer_Product >- PRODUCT -< Product_Category >- CATEGORY If the product can be assigned to many CATEGORIES
Neither is necessarily "better" than the other. Each defines a different type of relationship.
Table1::Table1ID = Table2::Table1ID
is a "one to many" relationship. One record in Table1 matches to many records in Table2. If you swap ID's around to get:
Table1::Table2ID = Table2::Table2ID
You have a "many to one" relationship and it's basically the same type of relationship but now it's a single record in Table 2 that matches to many records in table2.
But if you set up this system of relationships (called a data model):
Table1::Table1ID = Join::Table1ID
Table2::Table2ID = Join::Table2ID
You now have a "many to many" relationship between table1 and table2. One Record in Table1 can now match to many records in table2 and one record in Table 2 can match to many records in Table1.
So if a product can be a member of many categories and a category can list many products, this second set of relationships make sense. But if a Product can only be a member of a single category, then the second option is needlessly complex as you can simply use a one to many relationship.
thank you for the breakdown, I will make a custom value list for the customer category, and create a separate table for the product category.
btw, my goal here is to recreate the idea of dolibarr http://www.dolibarr.org/ into filemaker, im studying its relationships, and how i can apply it to filemaker. is mysql relationship different than filemakers?