From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Sonny <sonny(dot)chee(at)gmail(dot)com> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Odd unfamiliar Postgres SQL syntax |
Date: | 2017-07-31 19:03:17 |
Message-ID: | 9468.1501527797@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-sql |
Sonny <sonny(dot)chee(at)gmail(dot)com> writes:
> 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.
"(i.keys).n" is selecting the column named "n" from the composite-valued
column "i.keys", where "i" is a table alias exposed by the FROM clause.
The reason we don't just write "i.keys.n" is that the SQL standard says
that should mean column "n" in a table "i.keys" exposed by the FROM
clause --- that is, "i" would be a schema name not a table alias, and
"keys" would be a table name not a column name.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Majid Khan | 2017-08-01 12:01:36 | PostgreSQL connection with Android Studio |
Previous Message | Pavel Stehule | 2017-07-31 19:02:13 | Re: Odd unfamiliar Postgres SQL syntax |