Which of the following can be us
题目
Which of the following can be used to ensure that once a row has been inserted in table TABLEX, the column MAINID in that row cannot be updated?（）
- A、Define the column MAINID as NOT UPDATABLE
- B、Define the column MAINID as a PRIMARY KEY
- C、Define the column MAINID as a FOREIGN KEY
- D、Define an UPDATE trigger on table TABLEX
