Re: Alter table

On Wed, 10 Mar 2004, David wrote:

> Ok another very newbie question. How can i change the data type a column can
> accept? at the moment it will only take character(7) i want to change it to
> varchar(30), but i cant figure how, ideas?

While there are ways to tinker with the system catalogs to change between
different text types / lengths, none of these are "officially supported"
and may well screw up your database if you do something wrong. I believe
the archives likely have this question over and over in them.

The proper way to do this is to make a new column, put the old column in
it, and then drop the old column:

create table test (a char(7));
insert a few thousand lines to test...;
begin;
alter table test add column b varchar(30);
update test set b=a;
alter table test drop column a;
commit; (or rollback; should things go horribly wrong...)
vacuum full test;