Add postgresql enum's element in transaction

migration.sql

-- rename the old enum
ALTER TYPE country_code RENAME TO country_code__;

-- create the new enum with the old name
CREATE TYPE country_code AS ENUM ('DE', 'AT', 'NL', 'CH');

-- ALTER all you enum columns
ALTER TABLE user_address
    ALTER COLUMN country DROP DEFAULT;
ALTER TABLE user_address
    ALTER COLUMN country TYPE country_code 
    USING country::text::country_code; -- use old value -> to string -> to new enum
ALTER TABLE user_address
    ALTER COLUMN country SET DEFAULT 'DE';

-- drop the old enum
DROP TYPE country_code__;