Q71. Which statements are true? (Choose all that apply.)
A. The data dictionary is created and maintained by the database administrator.
B. The data dictionary views consists of joins of dictionary base tables and user-defined tables.
C. The usernames of all the users including the database administrators are stored in the data dictionary.
D. The USER_CONS_COLUMNS view should be queried to find the names of the columns to which a constraint applies.
E. Both USER_OBJECTS and CAT views provide the same information about all the objects that are owned by the user.
F. Views with the same name but different prefixes, such as DBA, ALL and USER, use the same base tables from the data dictionary.
Correct Answer: CDF
Explanation/Reference:
References:
https://docs.oracle.com/cd/B10501_01/server.920/a96524/c05dicti.htm
A：数据字典是由oracle服务器创建和维护的一组只读的系统表。
B：数据字典视图总结了基础表的信息，无user defined tables.
C:正确
D：user_cons_columns用来查询有约束应用于列的列名。正确
E：USER_CATALOG和cat是一样的
F：dba,all只比user表 多了owner列，其他结构一致，内容随权限不同而不同，都是基于数据字典中一张基础表之上。