Permanently convert datetime to date

Question

I have a postgres database with a datetime field. I'd like to permanently convert it to a date field (i.e. remove the time element). What is the best way to go about that? Is there a way to do it in place without having to dump the table into a new table?

Answer 1

Assuming you mean a timestamp with "datetime".

ALTER TABLE foo ALTER COLUMN bar TYPE date;

Answer 2

Create new temporary field and UPDATE yourtable SET newfield = oldfield::date with proper conversion function and then just remove old field and rename the new field.