单项选择题
Evaluate the set of SQL statements:
CREATE TABLE dept
(deptno NUMBER(2),
dname VARCHAR2(14),
loc VARCHAR2(13));
ROLLBACK;
DESCRIBE DEPT
What is true about the set?（）
A.The DESCRIBE DEPT statement displays the structure of the DEPT table.
B.The ROLLBACK statement frees the storage space occupied by the DEPT table.
C.The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist.
D.The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement.
相关考题
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单项选择题
Click the Exhibit button and examine the data in the EMPLOYEES and DEPARTMENTS tables. You want to retrieve all employees, whether or not they have matching departments in the departments table. Which query would you use?（）
A.SELECT last_name, department_name FROM employees NATURAL JOIN departments;
B.SELECT last_name, department_name FROM employees JOIN departments ;
C.SELECT last_name, department_name FROM employees e JOIN departments d ON (e.department_id = d.department_id);
D.SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);
E.SELECT last_name, department_name FROM employees FULL JOIN departments ON (e.department_id = d.department_id);
F.SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id); -
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
Examine the description of the EMPLOYEES table: EMP_ID NUMBER(4) NOT NULL LAST_NAME VARCHAR2(30) NOT NULL FIRST_NAME VARCHAR2(30) DEPT_ID NUMBER(2) Which statement produces the number of different departments that have employees with last name Smith?（）
A.SELECT COUNT(*) FROM employees WHERE last_name='Smith';
B.SELECT COUNT(dept_id) FROM employees WHERE last_name='Smith';
C.SELECT DISTINCT(COUNT(dept_id)) FROM employees WHERE last_name='Smith';
D.SELECT COUNT(DISTINCT dept_id) FROM employees WHERE last_name='Smith';
E.SELECT UNIQUE(dept_id) FROM employees WHERE last_name='Smith';
