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* Change column data type
@ 2003-09-02 09:50 Senthil Kumar S <ssakkaravel@ivesia.com>
2003-09-05 08:15 ` Re: Change column data type Richard Huxton <dev@archonet.com>
0 siblings, 1 reply; 4+ messages in thread
From: Senthil Kumar S @ 2003-09-02 09:50 UTC (permalink / raw)
To: pgsql-sql
Dear Friends,
Using Postgres 7.3.4 over the linux server 7.3.
Is it possible to alter/change the data type of a existing table's column, with out dropping and recreating a column of same name.
Thanks for ur knowledge sharing.
Regards
Kumar
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Change column data type
2003-09-02 09:50 Change column data type Senthil Kumar S <ssakkaravel@ivesia.com>
@ 2003-09-05 08:15 ` Richard Huxton <dev@archonet.com>
0 siblings, 0 replies; 4+ messages in thread
From: Richard Huxton @ 2003-09-05 08:15 UTC (permalink / raw)
To: Senthil Kumar S <ssakkaravel@ivesia.com>; pgsql-sql
On Tuesday 02 September 2003 10:50, Senthil Kumar S wrote:
> Dear Friends,
>
> Using Postgres 7.3.4 over the linux server 7.3.
>
> Is it possible to alter/change the data type of a existing table's column,
> with out dropping and recreating a column of same name.
>
> Thanks for ur knowledge sharing.
If you mean changing a varchar to a date or int4 to text, then no. If you want
to change the size of a varchar field, people seem to have done that in the
past (check the archives for details).
Otherwise, you'll have to wrap the drop/recreate in a transaction along with
whatever supporting updates you need.
--
Richard Huxton
Archonet Ltd
^ permalink raw reply [nested|flat] 4+ messages in thread
* Fw: Change column data type
@ 2003-09-02 10:57 Kumar <sgnerd@yahoo.com.sg>
2003-09-04 15:16 ` Re: Fw: Change column data type scott.marlowe <scott.marlowe@ihs.com>
0 siblings, 1 reply; 4+ messages in thread
From: Kumar @ 2003-09-02 10:57 UTC (permalink / raw)
To: pgsql-sql
Dear Friends,
Using Postgres 7.3.4 over the linux server 7.3.
Is it possible to alter/change the data type of a existing table's column, with out dropping and recreating a column of same name.
Thanks for ur knowledge sharing.
Regards
Kumar
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Fw: Change column data type
2003-09-02 10:57 Fw: Change column data type Kumar <sgnerd@yahoo.com.sg>
@ 2003-09-04 15:16 ` scott.marlowe <scott.marlowe@ihs.com>
0 siblings, 0 replies; 4+ messages in thread
From: scott.marlowe @ 2003-09-04 15:16 UTC (permalink / raw)
To: Kumar <sgnerd@yahoo.com.sg>; +Cc: pgsql-sql
On Tue, 2 Sep 2003, Kumar wrote:
>
> Dear Friends,
>
> Using Postgres 7.3.4 over the linux server 7.3.
>
> Is it possible to alter/change the data type of a existing table's
> column, with out dropping and recreating a column of same name.
Only for certain types, and only by hacking the system catalogs, which is
a procedure fraught with danger. i.e. backup all your data, then proceed
with caution.
Generally, it's best to create a new column and put the data in there and
drop the old column. Note you can do this in a transaction, so you can
roll it back should you realize you've made some kind of error.
begin;
alter table t1 add column c1 int8;
update t1 set c1=c2;
alter table t1 drop column c2;
commit;
vacuum;
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2003-09-05 08:15 UTC | newest]
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2003-09-02 09:50 Change column data type Senthil Kumar S <ssakkaravel@ivesia.com>
2003-09-05 08:15 ` Richard Huxton <dev@archonet.com>
2003-09-02 10:57 Fw: Change column data type Kumar <sgnerd@yahoo.com.sg>
2003-09-04 15:16 ` scott.marlowe <scott.marlowe@ihs.com>
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