Doc Patch: Subquery section to say that subqueries can't modify data
От | Karl O. Pinc |
---|---|
Тема | Doc Patch: Subquery section to say that subqueries can't modify data |
Дата | |
Msg-id | 1375822993.31841.1@slate обсуждение исходный текст |
Ответы |
Re: Doc Patch: Subquery section to say that subqueries can't modify
data
Re: Doc Patch: Subquery section to say that subqueries can't modify data |
Список | pgsql-hackers |
Hi, The attached documentation patch, doc-subqueries-v1.patch, applies against head. I wanted to document that subqueries can't modify data. This is mentioned in the documentation for SELECT and implied elsewhere but I was looking for something more than an 'in-passing' mention. (I wrote a bad query, modifying data in a subquery, couldn't recall where it was documented that you can't do this, and couldn't find the answer from the TOC or the index. Now that there's lots of statements with RETURNING clauses it's natural to want to use them in subqueries.) There seemed to be no good place to put this in the tutorial section of the documentation. I wound up adding a small, 2 paragraph, section describing subqueries to the chapter on queries. Although the first paragraph echos what's already documented the utility of subqueries is such that it's nice to have a place in the tutorial that serves as a single point of reference. The alternative seemed to be to put the 2nd paragraph in "9.22. Subquery Expressions", and this didn't seem to fit well. The last 2 sentences of the first paragraph are something in the way of helpful hints and may not be appropriate, or even accurate. I've left them in for review. Regards, Karl <kop@meme.com> Free Software: "You don't pay back, you pay forward." -- Robert A. Heinlein
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