From: | LaMi <lami(at)datalogiq(dot)net> |
---|---|
To: | Josip <josip(dot)2000(at)gmail(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: How ad an increasing index to a query result? |
Date: | 2009-10-17 12:58:36 |
Message-ID: | 4AD9BF7C.5000706@datalogiq.net |
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Thread: | |
Lists: | pgsql-general |
Josip wrote:
> Hello,
>
> Could somebody please try to help me with this problem?
> So, let’s say that I have the query:
>
> CREATE SEQUENCE c START 1;
>
> SELECT a, nextval('c') as b
> FROM table1
> ORDER BY a DESC LIMIT 5;
>
> I.e., I want to pick the 5 largest entries from table1 and show them
> alongside a new index column that tells the position of the entry. For
> example:
>
> a | b
> --------
> 82 | 5
> 79 | 4
> 34 | 3
> 12 | 2
> 11 | 1
>
> However, when I try this approach, the values of column b don’t follow
> the correct order. How should I go about and modify my code?
>
You can try using a sequence with a negative increment like below
CREATE SEQUENCE test_sequence
INCREMENT -1
START 100
MINVALUE 1
MAXVALUE 100;
- mrLami
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