Hello,
this mail is about the aggregate feature that was unveiled in the
release log of version 3.17.11, http://www.sqlite.org/releaselog/3_7_11.html
:
A query of the form: "SELECT max(x), y FROM table" returns the value
of y on the same row that contains the maximum x value.
I just want to point to a construction where one would expect this to
work however it does not. I tried a query that returns only the value
of y and intuitively wrote:
select y from (select max(x), y from t);
This however no longer returns the value of y corresponding to the
maximum x.
It looks a consequence of query optimization. The query satisfies all
conditions for "Query Flattening" in http://www.sqlite.org/optoverview.html
. The max(x) column is then eliminated.
Hope this is useful to know for who is using the feature.
EPasma
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