Modify table structure

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';