What is true regarding subqueries?（）

单项选择题What is true regarding subqueries?（）

A.The inner query always sorts the results of the outer query.
B.The outer query always sorts the results of the inner query.
C.The outer query must return a value to the inner query.
D.The inner query returns a value to the outer query.
E.The inner query must always return a value or the outer query will give an error.

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1.单项选择题 Examine the structure of the EMPLOYEES table:
EMPLOYEE_ID NUMBER Primary Key
FIRST_NAME VARCHAR2(25)
LAST_NAME VARCHAR2(25)
HIRE_DATE DATE
You issue these statements:
CREATE table new_emp ( employee_id NUMBER, name VARCHAR2(30));
INSERT INTO new_emp SELECT employee_id , last_name from employees;
Savepoint s1;
UPDATE new_emp set name = UPPER(name);
Savepoint s2;
Delete from new_emp;
Rollback to s2;
Delete from new_emp where employee_id =180;
UPDATE new_emp set name = 'James';
Rollback to s2;
UPDATE new_emp set name = 'James' WHERE employee_id =180;
Rollback;
At the end of this transaction, what is true?（）

A.You have no rows in the table.
B.You have an employee with the name of James.
C.You cannot roll back to the same savepoint more than once.
D.Your last update fails to update any rows because employee ID 180 was already deleted.

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2.多项选择题 Click the Exhibit button and examine the data in the EMPLOYEES table.
Which three subqueries work? （）

A.SELECT * FROM employees where salary > (SELECT MIN(salary) FROM employees GROUP BY department_id);
B.SELECT * FROM employees WHERE salary = (SELECT AVG(salary) FROM employees GROUP BY department_id);
C.SELECT distinct department_id FROM employees WHERE salary > ANY (SELECT AVG(salary) FROM employees GROUP BY department_id);
D.SELECT department_id FROM employees WHERE salary > ALL (SELECT AVG(salary) FROM employees GROUP BY department_id);
E.SELECT last_name FROM employees WHERE salary > ANY (SELECT MAX(salary) FROM employees GROUP BY department_id);
F.SELECT department_id FROM employees WHERE salary > ALL (SELECT AVG(salary) FROM employees GROUP BY AVG(SALARY));

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3.多项选择题Which three SELECT statements display 2000 in the format "$2,000.00"? （）

A. SELECT TO_CHAR(2000, '$#,###.##') FROM dual;
B. SELECT TO_CHAR(2000, '$0,000.00') FROM dual;
C. SELECT TO_CHAR(2000, '$9,999.00') FROM dual;
D. SELECT TO_CHAR(2000, '$9,999.99') FROM dual;
E. SELECT TO_CHAR(2000, '$2,000.00') FROM dual;
F. SELECT TO_CHAR(2000, '$N,NNN.NN') FROM dual;

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4.多项选择题 Examine the description of the STUDENTS table:
STD_ID NUMBER(4)
COURSE_ID VARCHAR2(10)
START_DATE DATE
END_DATE DATE
Which two aggregate functions are valid on the START_DATE column? ()

A.SUM（start_date）
B.AVG（start_date）
C.COUNT（start_date）
D.AVG（start_date，end_date）
E.MIN（start_date）
F.MAXIMUM（start_date）

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5.单项选择题 Examine this statement:
SELECT student_id, gpa
FROM student_grades
WHERE gpa > &&value;
You run the statement once, and when prompted you enter a value of 2.0. A report is produced. What happens when you run the statement a second time?（）

A.An error is returned.
B.You are prompted to enter a new value.
C.A report is produced that matches the first report produced.
D.You are asked whether you want a new value or if you want to run the report based on the previous value.

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6.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.

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7.单项选择题 Examine the structure of the EMPLOYEES and DEPARTMENTS tables:
EMPLOYEES
EMPLOYEE_ID NUMBER
DEPARTMENT_ID NUMBER
MANAGER_ID NUMBER
LAST_NAME VARCHAR2(25)
DEPARTMENTS
DEPARTMENT_ID NUMBER
MANAGER_ID NUMBER
DEPARTMENT_NAME VARCHAR2(35)
LOCATION_ID NUMBER
You want to create a report displaying employee last names, department names, and locations. Which query should you use?（）

A.SELECT e.last_name, d. department_name, d.location_id FROM employees e NATURAL JOIN departments D USING department_id ;
B.SELECT last_name, department_name, location_id FROM employees NATURAL JOIN departments WHERE e.department_id =d.department_id;
C.SELECT e.last_name, d.department_name, d.location_id FROM employees e NATURAL JOIN departments d;
D.SELECT e.last_name, d.department_name, d.location_id FROM employees e JOIN departments d USING (department_id );

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8.单项选择题What is true about sequences?（）

A.Once created, a sequence belongs to a specific schema.
B.Once created, a sequence is linked to a specific table.
C.Once created, a sequence is automatically available to all users.
D.Only the DBA can control which sequence is used by a certain table.
E.Once created, a sequence is automatically used in all INSERT and UPDATE statements.

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9.多项选择题Which two are true about aggregate functions? （）

A.You can use aggregate functions in any clause of a SELECT statement.
B.You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.
C.You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
D.You can pass column names, expressions, constants, or functions as parameters to an aggregate function.
E.You can use aggregate functions on a table, only by grouping the whole table as one single group.
F.You cannot group the rows of a table by more than one column while using aggregate functions.

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10.单项选择题 Evaluate the SQL statement:
SELECT LPAD(salary,10,*)
FROM EMP
WHERE EMP_ID = 1001;
If the employee with the EMP_ID 1001 has a salary of 17000, what is displayed?（）

A. 17000.00
B. 17000*****
C. ****170.00
D. **17000.00
E.an error statement

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