Modify the table structure:
1. Add table fields:
form, alter table table name add table field name field type; for example
alter table SERIAL_NUM_INFO add SUPPLIER_CODE varchar2(20);
2. Delete table fields:
alter table PERSON drop column Birthday;
3. Modify the field length
alter table order_sync_history
modify (ORDER_CHANGE_STATUS varchar2(5));
4. Add unique constraint
alter table order_sync
add constraint order_sync_unique unique(order_id,create_time);
5. Add notes to table fields
comment on column PHONENUMBER.DUE_TIME is 'expiration time';