Re: [HACKERS] JOIN syntax. Examples?
От | Thomas G. Lockhart |
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Тема | Re: [HACKERS] JOIN syntax. Examples? |
Дата | |
Msg-id | 3675B4CD.99DC208D@alumni.caltech.edu обсуждение исходный текст |
Ответ на | Re: [HACKERS] JOIN syntax. Examples? ("Oliver Elphick" <olly@lfix.co.uk>) |
Список | pgsql-hackers |
> > This one conflicts with Postgres' operator extensibility features, > > since it would look just like a legal operator. > so does = But in fact its usage for joins matches the typical usage elsewhere. > Has anybody tried out DB2 ? > I have downloaded it (for linux) but have not yet tried it. Just downloaded it this morning (and afternoon, it's a thin pipe at home for 60MB of files :) Have you looked at what it takes to do an installation yet? > Not to mention that both =* and =(+) are more concise and easier to > follow, at least for one with my headshape. > The standard is probably the 'worst common denominator' or something > like that :( DeJuan points out a major strength of the SQL92 syntax, which allows multiple outer joins in the same query. One of my books shows an example: select * from q1 full outer join q2 on (q1.id = q2.id) full outer join q3 on (coalesce(q1.id,q2.id)=q3.id) fullouter join q4 on (coalesce(q1.id,q2.id,q3.id)=q4.id) I suppose one can do something similar using a *= operator by using parentheses? Not sure though... - Tom
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