There are a lot of questions, that are tagged only with sql, but that are not answerable without specifying the RDBMS used (so the first comment usually is RDBMS?). Actually SQL without defined RDBMS makes sense only for theoritical questions and questions about standards (which are actually theoritical). How can we resolve this issue.
If elegant way of suggesting a relate tags to be picked up by the poster, this will resolve other similar issues as well, not only in the sql tag (although I can't think of an example, I'm sure there are other tags that are used, but does not make sense without another tag).
Another option, although I don't like it, is not to have stand-alone sql tag, but sql-theory (or sql-ansii, or sql-standards), and sql- tags, which are synonyms to corresponding rdbms.
Any other suggestions?