多项选择题

Which two statements about subqueries are true? （）

A. A subquery should retrieve only one row.
B. A subquery can retrieve zero or more rows.
C. A subquery can be used only in SQL query statements.
D. Subqueries CANNOT be nested by more than two levels.
E. A subquery CANNOT be used in an SQL query statement that uses group functions.
F. When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.

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单项选择题

Examine these statements:
CREATE ROLE registrar
GRANT UPDATE ON dtudent_grades TO registrar;
GRANT registrar to user1, user2, user3;
What does this set of SQL statements do? （）

A. The set of statements contains an error and does not work.
B. It creates a role called REGISTRAR, adds the MODIFY privilege on the STUDENT_GRADES object to the role, and gives the REGISTRAR role to three users.
C. It creates a role called REGISTRAR, adds the UPDATE privilege on the STUDENT_GRADES object to the role, and gives the REGISTRAR role to three users.
D. It creates a role called REGISTRAR, adds the UPDATE privilege on the STUDENT_GRADES object to the role, and creates three users with the role.
E. It creates a role called REGISTRAR, adds the UPDATE privilege on three users, and gives the REGISTRAR role to the STUDENT_GRADES object.
F. It creates a role called STUDENT_GRADES, adds the UPDATE privilege on three users, and gives the UPDATE role to the registrar.

单项选择题

Which view should a user query to display the columns associated with the constraints on a table owned by the user? （）

A. USER_CONSTRAINTS
B. USER_OBJECTS
C. ALL_CONSTRAINTS
D. USER_CONS_COLUMNS
E. USER_COLUMNS

单项选择题

The user Alice wants to grant all users query privileges on her DEPT table. Which SQL statement accomplishes this? （）

A. GRANT select ON dept TO ALL_ USER;
B. GRANT select ON dept TO ALL;
C. GRANT QUERY ON dept TO ALL_USERS
D. GRANT select ON dept TO PUBLIC;