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.
相关考题
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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
Examine the data from the ORDERS and CUSTOMERS tables. Evaluate the SQL statement: What is the result when the query is executed?（）
A.
B.
C.
D. The query fails because the subquery returns more than one row.
E. The query fails because the outer query and the inner query are using different tables. -
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
