Hi!
I'm writing to you about the syntax diagram that appears on
"http://sqlite.org/draft/lang_select.html";, and is a draft for the
next version of sqlite (3.8.3). I find this diagram confusing, and
would rather prefer to have something similar to
"http://sqlite.org/lang_select.html";, only of course updated to show
the syntax changes in 3.8.3.
I have two concrete problems with this diagram.
1. It seems to imply that LIMIT clauses are attached to each part of a
compound select. For example, in a select statement like this:
SELECT col1 FROM tbl1 UNION ALL SELECT col2 FROM tbl2 ORDER BY 1 LIMIT 5;
does the LIMIT clause cause sqlite3 to limit the result of the whole
compound statement, or does it ask only to limit the tbl2 branch and
then take the union? The text of the page later appears to imply that
the LIMIT applies to the whole statement (correct me if I'm wrong
here), but the new syntax diagram really seems to show the opposite.
2. This diagram for select too big. The diagram in the released docs
is broken down to smaller parts, and I find that easier to read.
In fact I don't like to read diagrams like this at all. I'd be
happier to read an alternate representation of the grammar without
images, using only a bnf-like text description. I'm not saying the
images should go away, only that a text representation should also be
available somewhere, possibly on a separate page like
"http://sqlite.org/draft/syntaxdiagrams.html"; if you don't want them
on the main pages.
That said, there is at least one change I like in the new diagram.
Namely, the grammar rule single-source is renamed to
table-or-subquery, and I think the new name is clearer, so thank you
for that.
Thank you for your work on improving sqlite3,
Ambrus
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