I’m a tech interested guy. I’ve touched SQL once or twice, but wasn’t able to really make sense of it. That combined with not having a practical use leaves SQL as largely a black box in my mind (though I am somewhat familiar with technical concepts in databasing).
With that, I keep seeing [pic related] as proof that Elon Musk doesn’t understand SQL.
Can someone give me a technical explanation for how one would come to that conclusion? I’d love if you could pass technical documentation for that.
If SSNs are used as a primary key (a unique identifier for a row of data) then they’d have to be duplicated to be able to merge data together.
However, even if they aren’t using ssn as an identifier as it’s sensitive information. It’s not uncommon to repeat data either for speed/performance sake, simplicity in table design, it’s in a lookup table, or you have disconnected tables.
Having a value repeated doesn’t tell you anything about fraud risk, efficency, or really anything. Using it as the primary piece of evidence for a claim isn’t a strong arguement.
This sounds like a reasonable argument.
Can you pass any resources with examples on when having duplicate values would be useful/best practices?
Sure, basically any time you have a many-to-many relationship you’ll have to repeat keys multiple times. Think students taking courses. You’d have a students table and a courses table, but the relationship is many students take many courses. So you’d want a third table for lookups where each row is [student_id, course_id].
This stackoverflow post has a similar example with authors and books - https://stackoverflow.com/questions/13970628/how-do-i-model-a-many-to-many-relation-in-sql-server#13970688
This is the answer… it seems few on lemmy have ever normalized a database. But they do know how to give answers!
Thanks, OP seemed more curious about the technical aspects than just the absurdity of the comment (since pretty much every business uses SQL) so hoped a more technical explanation might be appreciated.