On 5/9/62 00:13, David Raymond wrote:
Kind of annoying that when the author shows a screenshot of the sample data he's using
for his queries that he doesn't include 2 of the fields that are in the queries. Makes it
harder to "play along at home"
For their ntile example (on page2) I don't think I've seen a window function used with a
"group by". Does the ntile un-group the groups? Something just looks wrong
there between the query and the results shown below it. But like you I don't know enough
to say if that's right or if it's on crack.
You can run window functions on aggregate queries. The windowing step
occurs logically after the aggregation.
It still looks right to me. Each output row contains a unique
combination of territoryid/customerid, so no need for any "un-grouping".
Of course, the input data doesn't feature any rows with duplicate
territoryid/customerid values, so running the query without the GROUP BY
and replacing "sum(subtotal)" with "subtotal" would produce the same
results.
Dan
-----Original Message-----
From: sqlite-users <sqlite-users-boun...@mailinglists.sqlite.org> On Behalf Of
Simon Slavin
Sent: Wednesday, September 04, 2019 12:15 PM
To: SQLite mailing list <sqlite-users@mailinglists.sqlite.org>
Subject: [sqlite] Window functions
I ran into this two-part article, probably on Hacker News:
<http://www.helenanderson.co.nz/sql-window-functions-part-1/>
I tried comparing it with
<https://www.sqlite.org/windowfunctions.html>
but I don't know enough to be able to tell whether the language used in the
article is compatible with the way window functions are implemented in SQLite.
Could someone who knows more than I do take a look and post a summary ?
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