Re: using ordinal_position

On 06/11/2012 06:53 AM, Igor Neyman wrote:
>
>> -----Original Message-----
>> From: John Fabiani [mailto:johnf(at)jfcomputer(dot)com]
>> Sent: Thursday, June 07, 2012 7:18 PM
>> To: pgsql-sql(at)postgresql(dot)org
>> Subject: using ordinal_position
>>
>> I'm attempting to retrieve data using a select statement without
>> knowing the column names. I know the ordinal position but not the name
>> of the column (happens to be a date::text and I have 13 fields).
>>
>> Below provides the name of the column in position 3:
>>
>> select column_name from (select column_name::text, ordinal_position
>> from information_schema.columns where
>> table_name='wk_test') as foo where ordinal_position = 3;
>>
>> But how can I use the above as a column name in a normal select
>> statement.
>>
>> Unlike other databases I just can't use ordinal position in the select
>> statement - RIGHT???
>>
>> Johnf
> David gave you already pretty complete answer.
> I just wonder what are these "other" RDBMSs that allow to use ordinal column positions in a query?
> I am familiar with a few (in addition to Postgress), and none of them does that, not in "select" list., though everybody allow ordinal position from "select" list in "order by" and "group by".
>
> Regards,
> Igor Neyman
>
>
>
VFP uses position (you might not consider DBF a database). MsSQl
(ordinal_position). Those are the only two I'm aware of.

Johnf