Re: [GENERAL] Using Variables in Queries

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От David G. Johnston
Тема Re: [GENERAL] Using Variables in Queries
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Msg-id CAKFQuwbJVx-x16mjym=0KU-3ncs9-=7LfRgC2+v3X35HZswHow@mail.gmail.com
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Ответ на Re: [GENERAL] Using Variables in Queries  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [GENERAL] Using Variables in Queries  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Thu, Oct 19, 2017 at 12:14 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
FROM  products,
      (values ('red widget'::text)) consts(target)
WHERE similarity(target, item_name) > 0.25
ORDER BY target <<-> item_name

PG 9.5 and up will flatten out cases like this to be exactly what you
wrote out longhand.

​Does it matter if the values expression is embedded in a CTE?​  I find the construct:

WITH constants AS (  VALUES (,,) )
SELECT * FROM tbl CROSS JOIN constants

nice as it keeps the constants at the top of the query string.  I presume pure style differences between using multiple from items and an explicit cross join.

David J.

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