试题详情
- 单项选择题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
- D
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