Alter Table Update. Oracle 10G and later. Add a NOT NULL constraint.
To create a new table that contains only the columns of the old table that you want to keep and then you can drop the old table. MODIFY COLUMN column_name datatype. If you want to force space to be reclaimed you can forcibly update every row in the table or you can use CREATE TABLE AS.
ALTER TABLE accounts MODIFY status DEFAULT 0.
UPDATE Command is used to update existing records in a database. It lets you instruct Oracle Database to convert the metadata of the target table to conform with the latest version of each. When you rename columns using ALTER TABLE you risk breaking database dependencies. If you want to force space to be reclaimed you can forcibly update every row in the table or you can use CREATE TABLE AS.
