ALTER TABLE_NAME ADD COLUMN_NAME DATE; COMMENT ON COLUMN TABLE_NAME.COLUMN_NAME IS 'Date Column for xyz';
ALTER TABLE TABLE_NAME ADD NEW_COLUMN DATE;
ALTER TABLE TABLE_NAME DROP CONSTRAINT CONSTRAINT_NAME;
ALTER TABLE TABLE_NAME ADD CONSTRAINT CONSTRAINT_NAME primary key (COLUMN_NAME);
ALTER TABLE TABLE_NAME ADD CONSTRAINT CONSTRAINT_NAME primary key (COLUMN_1_NAME,COLUMN_2_NAME );