Re: changing a column's position in table, how do you do that

On Sep 29, 2005, at 4:38 , Daryl Richter wrote:

> Ferindo Middleton Jr wrote:
>
>> Is there a way to change the position attribute of a column in a
>> table? I have data that I need to import into various tables in my
>> db on a consistent basis... I usually us e the COPY ... FROM query
>> but I can't control the -order- of the fields my client dumps the
>> data so I would like to be able to change the position the columns
>> in my table to be able to better align the data to be imported
>> with the format of my table. I was thinking I could do something
>> like "ALTER TABLE ALTER COLUMN ... " or something like that to
>> change the columns position in the table but I can't figure out how.
>> Ferindo
>> ---------------------------(end of
>> broadcast)---------------------------
>> TIP 6: explain analyze is your friend
>>
>
> Constantly changing the column order of a table doesn't make sense
> (and is a pain!).
>
> I would suggest setting up a temporary staging table with generic
> column names to take in the input data and then using SQL to move
> it into its permanent location.

Or specify the columns directly in the copy statement. Instead of
copy foo from <file>, do copy foo (bar,baz,bat) from <file>. Then you
only have to change the copy statement.

While SQL does allow columns to be referenced by column order, it's
far, far better to consider the columns of a table to be unordered
and (nearly) always specify your columns explicitly. It gives you
much more flexibility. Changing a few SQL statements to return (or
insert) the columns how you want them is much easier than changing
the underlying table structure and having to make sure *all* of your
queries then fit the new table structure.

Michael Glaesemann
grzm myrealbox com