Re: [SQL] Odd unfamiliar Postgres SQL syntax

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От David G. Johnston
Тема Re: [SQL] Odd unfamiliar Postgres SQL syntax
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Msg-id CAKFQuwZNNo1jPcop8ZfN8SKmNhyBi3wKkM5htiv4jn79TB7yKA@mail.gmail.com
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Ответ на [SQL] Odd unfamiliar Postgres SQL syntax  (Sonny <sonny.chee@gmail.com>)
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On Mon, Jul 31, 2017 at 9:42 AM, Sonny <sonny.chee@gmail.com> wrote:
Can someone help me understand the following SQL?  What does the notation (i.keys).n and (i.keys).x mean... as indicated by the <<<=== in the query.  Any help would be appreciated.

​https://www.postgresql.org/docs/9.6/static/sql-expressions.html#FIELD-SELECTION

Basically:

i = relation name
keys = composite column name
x = component name within the composite

"keys.x"​ doesn't work because the system thinks that "keys" should be a relation name when written that way.

David J.

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