Re: About changing type af a column

On Wed, 2003-03-26 at 04:56, Victor Yegorov wrote:
> * Marc Soler <msoler@el-valles.com> [26.03.2003 11:48]:
> > Hi all,
> >
> > I need to change a column length.
> >
> > >From varchar(150) to varchar(250).
> >
> > It's easy to change with an ALTER command? Or I need to create a new
> column,
> > copy all data from the old column to the new one, then drop the old
> and
> > rename the new.
> >
> > If only exists the second solutions, the new column it will be created
> last
> > one of the columns, then I must change all INSERT and UPDATE commands
> in my
> > application.
>
> How order of fields in the table can affect UPDATE statements?
>
> About INSERTs - it's a good thing to specify all fields being inserted
> just
> to prevent 'inconveniences' like you've mentioned.
>

And actually relational theory states that column orders in tables is
irrelevant, so it's really a good idea to make sure you keep from
falling into this trap. This means referencing result set array by field
name rather than by number (ie. $arr[2] - which implies field position)

> > It's possible to create a column in a given position in the columns
> > structure of a table?.
>
> Yes. create a new table with same design except for the field you'd like
> to
> change, than copy all data into new table, drop old one and rename new
> one.
>

funny part is I just answered this question on the -sql list yesterday,
so I happen to have the link handy to my archived post from several
months back that also answers this same question; check it out:

http://fts.postgresql.org/db/mw/msg.html?mid=1071582


Robert Treat