Re: ORDER BY TABLENAME, possible bug
От | Thomas Kellerer |
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Тема | Re: ORDER BY TABLENAME, possible bug |
Дата | |
Msg-id | o0o3ch$k0v$1@blaine.gmane.org обсуждение исходный текст |
Ответ на | Re: ORDER BY TABLENAME, possible bug ("David G. Johnston" <david.g.johnston@gmail.com>) |
Список | pgsql-bugs |
David G. Johnston schrieb am 18.11.2016 um 23:48: > > Is this somewhere in the documentation? The only place I could find > where there is a hint of this use, is the Note in Row Constructors in > https://www.postgresql.org/docs/current/static/sql-expressions.html > <https://www.postgresql.org/docs/current/static/sql-expressions.html> > that uses a table alias without the .* in an expression: ROW(t, 42) > > âhttps://www.postgresql.org/docs/9.6/static/rowtypes.html > > â"Whenever you create a table, a composite type is also automatically created, with the same name as the table, to representthe table's row type." > > So, its documented and in technically correct location. I'm not sure > if introducing this material in a "tutorial" would be a gain or just > confuse the student. It seems to be something one picks up somehow > (trial and error, mailing list, stumbling upon it in the docs or > elsewhere on the Internet) as one increases their knowledge of SQL to > an intermediate level. I think the chapter about "Select Lists"[1] would be the approriate place to explain this. I would also love to see an explanation there on why "select (a,b,c)" is something different then "select a,b,c" I see far too many people putting the columns of the select list between parentheses and then being confused about the output. I don't know if the Postgres behaviour is mandated by the SQL standard. If it's not, that should be documented, maybe in the chapter I mentioned above or in the compatibility section of SELECT. If that _is_ mandated by the standard, then I think some small note/warning might be useful (especially to newcomers) Thomas [1] https://www.postgresql.org/docs/current/static/queries-select-lists.html
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