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Comment on How does this pic show that Elon Musk doesnt know SQL?

turtle@lemm.ee ⁨1⁩ ⁨week⁩ ago

I saw a comment about this in the last couple of days that was really interesting and educational. Unfortunately I can’t seem to find it again to link it, but the gist of it was that there would be two things wrong with using SSNs as primary keys in a SQL database:

You should not use externally generated data as primary keys
You should not use personally identifying data as primary keys

Using SSNs as keys would violate both.

I went looking for best practices regarding SQL primary keys and found this really interesting post and discussion on Stack Overflow:

stackoverflow.com/…/whats-the-best-practice-for-p…

My first thought was that people’s SSNs can and do change, and sometimes (rarely?) people may have more than one SSN. Like someone mentions in that link, human error would be another reason why you would not want to use external data and particularly SSNs as primary keys.

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BananaOnionJuice@lemmy.dbzer0.com ⁨1⁩ ⁨week⁩ ago
It may be bad practice to use SSN as a primary key, but that won’t deter thousands of companies from doing exactly that.

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- turtle@lemm.ee ⁨1⁩ ⁨week⁩ ago
  Oh, I hear you!
  
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DahGangalang@infosec.pub ⁨1⁩ ⁨week⁩ ago
From what I’m seeing in other comments, it seems SSNs aren’t used as primary keys, but they are part of generating the primary key. I haven’t seen anyone directly say it, but it sounds like the primary key is a hash of SSN + DOB (I hope with more data to add entropy, because thats still a tiny bit of data to build a rainbow table from).

Still, assuming we haven’t begun re-using SSNs, it seems concerning to me that a SSN is appearing multiple times in the database. It seems a safe assumption that the uniqueness of a SSN should make the resultant hash unique, so a SSN appearing as associated to multiple primary keys should be a concern, right?

Other comments have led me to believe the “duplicate SSNs” are probably appearing in “different fields” (e.g. a dead man’s SSN would appear directly associated to him, but also as a sort of “collecting payments from” entry in his living wife’s entry). That would a misrepresentation of the facts (which we know Vice Bro, Elon Musk the Wise and Honest would never do). Occam’s Razor though has me leaning in that direction.

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- jballs@sh.itjust.works ⁨1⁩ ⁨week⁩ ago
  I think the thing that’s catching you up the most is that you’re assuming Elon has the slightest clue what he’s talking about about. In your mind, you’ve read the words “the social security database” from his post and have made assumptions about what that means.
  
  I’ve worked with databases for 20+ years, several of those being years working on federal government systems. Each agency has dozens or possibly hundreds of databases all used for different purposes. Saying “the social security database” is so fucking general that it’s basically nonsensical. It’d be like saying “Ford’s car database”.
  
  Elon clearly heard someone technical talking about something, them misinterpreted it for his own purposes to justify what he is doing by destroying our government institutions. His follow up of saying the government doesn’t use SQL just reinforces that point.
  
  Trying to logically backtrack into what he actually meant - and what the primary keys should be - is just sane washing an insane statement.
  
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- turtle@lemm.ee ⁨1⁩ ⁨week⁩ ago
  That all makes sense, except if someone’s SSN changes (which happens under certain circumstances), doesn’t that invalidate their primary key or require a much more complicated operation of issuing a new record and relinking all the existing relationships?
  
  I can imagine an SSN existing in more than one primary key due to errors. If they use SSNs in the primary key at all, but combined with something else, that leads me to believe that the designers felt that SSNs were reliable for being a pure primary key.
  
  I agree with you about Occam’s Razor. The guy has demonstrated multiple times that he’s a dishonest moron.
  
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  - DahGangalang@infosec.pub ⁨1⁩ ⁨week⁩ ago
    I’m not familiar with cases where someone’s SSN could change. Could you link to resources on when that would happen?
    
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    turtle@lemm.ee ⁨1⁩ ⁨week⁩ ago
    I don’t have any resources handy, but I do know someone who this happened to: they were an immigrant who got an SSN the first time they migrated to the US, went back to live in their country for a number of years, then returned to the US and I guess applied for an SSN again. Voilá, two SSNs and a mess.
    
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  - spankmonkey@lemmy.world ⁨1⁩ ⁨week⁩ ago
    
    That all makes sense, except if someone’s SSN changes (which happens under certain circumstances), doesn’t that invalidate their primary key or require a much more complicated operation of issuing a new record and relinking all the existing relationships?
    
    Yes, in the case of duplicate SSN assignments l you would need to change their records to align with the new SSN while not changing the records that go the the person who keeps the SSN. We do it with state identifiers and it is a gigantic pain in the ass.
    
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    turtle@lemm.ee ⁨1⁩ ⁨week⁩ ago
    I can definitely imagine all that. Thanks!
    
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