A question, "How to Model Inheritance of Two Tables MYSQL" was migrated to this forum from Stackoverflow. Unfortunately, my answer to that question contained references to three tags that do not exist (yet) in this forum.

The "info" tab on those three tags contained the nitty-gritty details concerning three techniques that I consider helpful to the asker. Those three tag references are now orphans.

What's the right solution? Is it replicating the three tags over here, and filling in the info tab with the same info? That seems like a violation of DRY (aka "harmful redundancy"). Is it plugging the details about the three techniques into the answer itself? That's also a violation of DRY. Is there a way of making a tag reference point to the tag in its original location? Is that a good idea?

I haven't had this much fun since the last time I tried to shuffle records in a pre-relational database (little joke).

As a side issue, I have to wonder why the question was migrated off of SO. Anybody who has done both object modeling and data modeling realizes that there is an enormous overlap between the two disciplines. That's notwithstanding the infamous "object relational impedance mismatch". I don't see how a moderator could consider object modeling questions on topic in SO but data modeling questions off topic.

2 Answers 2


One option would be to link to the SO tags directly: eg https://stackoverflow.com/tags/single-table-inheritance/info though I don't think there is any harm just summarising the relevant info over here: SO is a completely different universe which means the 'Y' in 'DRY' doesn't apply ;)

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    I think you are right about the separate universes. I have tended to hang out over in SO even though I was a DBA at one stage of my career. I'm guessing that whoever migrated the question over here has a different idea of what a DBA does than I do. To me, data modeling is closer to the SO universe than the DBA universe. Mar 15, 2013 at 12:14
  • I wasn't very clear: I didn't mean there is no overlap between the sites (there is), but that it is ok for information to be repeated between the sites. Check the FAQ for a short summary of what's on-topic here, you might be surprised how broadly we interpret the DBA scope. The main difference imo is that we focus on expert database Q&A. Mar 15, 2013 at 12:18
  • I've seen the DBA job title used to cover everything from a database babysitter to the only person in a large enterprise who really understands the significance of the data. On my very first Oracle contract, I was introduced to some other group as "our Oracle DBA". I was embarassed. I had expertise on a different product, but I was just coming up to speed on Oracle. But I was way ahead of the other members of the team. Sigh. Mar 15, 2013 at 16:54
  • For your amusement: meta.dba.stackexchange.com/questions/495/… :) Mar 15, 2013 at 18:06
  • Great, thanks! And more amusement... Q: Isn't DBA work boring? A: Only when you're doing it right. Mar 16, 2013 at 0:11
  • The best jokes are true ;) Mar 16, 2013 at 9:47

Regarding the question of "how do the tags work" -

Each site has it's own tag tables, right? That much is pretty evident. The SE team could migrate the tag over if it doesn't exist on each question, but that would create a lot of cruft because different sites may use different tags in different ways. Right now the solution is to keep tags that already exist on the Q and flush all the rest.

In the case of "what do I do" you either create the tags you want anew, or, if you don't have the rep, flag it for someone to add the tags for you. You could also pop into chat and ask someone to add it.

But, and here's the thing, you should only copy the tags that are appropriate to Database Administrators.Stack Exchange. In this case the choices were and .

and are both sort of crappy tags, but could be appropriate here. On SO they're a better way to funnel stuff down.

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    Speaking of crappy tags, I consider single-table-inheritance, class-table-inheritance, and shared-primary-key (over in SO) to be crappy tags, even though I consider each of the techniques to be very valuable. The reason I think they are crappy tags is that they pertain to the answer, and almost never to the question. The people who need to be exposed to these techniques are the people who never heard of them, but are trying to do class/subclass modeling in a relational context. The only people who are going to use these tags are people who aren't going to ask the questions. Mar 17, 2013 at 11:52
  • I could be wrong about the above comment. Mar 17, 2013 at 11:55

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