Choose threeide
Which three statements are true about views in an Orade batabase?对象
A) A SELECT statement cannot contain a where clause when querying a view contaning a WHERE clause in its defining querythree
B) Rows inserted into a table using a view are retained in the table if the view is doppedit
C) Views can join tables only if they belong to the same schema.table
D) Views have no segment.class
E) Views have no object number.object
F) A view can be created that refers to a non-existent table in its defining query.查询
Answer：BD?tab
(解析：di
通过实验，A 不对;C 不对，视图能够和不一样模式的表进行链接查询;F 不对，若是子查询中没有表，建立视图会报错;视图也是对象，因此答案 E 错误;