Re: Extended ability to alter column type when empty

2009/2/17 David Andersen <mrdavidandersen@gmail.com>:

> Hi,
>
> I am a real newbee and I hope this is the right place to post a feature
> request.
>
> I am receiving data from a csv file where one column has a strange data
> format. It would be nice if I could use Copy From with to_timestamp to
> transform the date. As far as I know this is not possible to do in one step
> (unlike MySQL I believe). I, therefore, have to first read large amounts of
> CSV data into one table where the data is a char(15) column. Then create
> another table using:
> CREATE TABLE  T (like tempT);
>
> ALTER TABLE T ALTER COLUMN thedate TYPE TIMESTAMP;
>
> However, then I run into:
> ERROR:  column "thedate" cannot be cast to type "pg_catalog.timestamp"
>
> This error comes even though the table is empty. Could it be an idea to
> allow this for empty tables? Am I missing something obvious in my
> unreasonably complicated approach?
>

Try:
ALTER TABLE T ALTER COLUMN thedate TYPE TIMESTAMP USING CAST (thedate
AS timestamp);

Osvaldo