The suggestion is to not use foreign key constraints in the database.
The suggestion is not to eschew columns which might be JOINed on in a query.
I.e. "Don't enforce FK relationships with a constraint in the DB. Make sure the values in both tables which may be joined are consistent by using application code to enforce this."
> Don't enforce FK relationships with a constraint in the DB. Make sure the values in both tables which may be joined are consistent by using application code to enforce this.
For those reading at home who aren't good with databases. This is exactly the same statement as:
"Don't enforce valid inputs on the backend. The javascript front-end will enforce it for us".
Always validate your inputs at the appropriate layer. Your backend can never trust input from a web front-end (even if there is "only one web front-end"). Likewise, your database should never trust input from its clients (even if there is "only one client"). Ignore this rule at your own peril.
Are your engineers omnipotent beings who never fail, never make mistakes and understand the system entirely (even all the parts they don't know about)? Is your QA process perfect? Your servers never crash in weird states?
The suggestion is not to eschew columns which might be JOINed on in a query.
I.e. "Don't enforce FK relationships with a constraint in the DB. Make sure the values in both tables which may be joined are consistent by using application code to enforce this."