Evaluate these two SQL statements:What...

单项选择题 Evaluate these two SQL statements:

What is true about them?（）

A. The two statements produce identical results.
B. The second statement returns a syntax error.
C. There is no need to specify DESC because the results are sorted in descending order by default.
D. The two statements can be made to produce identical results by adding a column alias for the salary column in the second SQL statement.

点击查看答案

您可能感兴趣的试卷

你可能感兴趣的试题

1.单项选择题 You need to produce a report for mailing labels for all customers. The mailing label must have only the customer name and address. The CUSTOMERS table has these columns:
CUST_ID NUMBER(4) NOT NULL
CUST_NAME VARCHAR2(100) NOT NULL
CUST_ADDRESS VARCHAR2(150)
CUST_PHONE VARCHAR2(20)
Which SELECT statement accomplishes this task?（）

A. SELECT* FROM customers;
B. SELECT name, address FROM customers;
C. SELECT id, name, address, phone FROM customers;
D. SELECT cust_name, cust_address FROM customers;
E. SELECT cust_id, cust_name, cust_address, cust_phone FROM customers;

点击查看答案

2.多项选择题Which two statements complete a transaction?（）

A. DELETE employees;
B. DESCRIBE employees;
C. ROLLBACK TO SAVE POINT C;
D. GRANT SELECT ON employees TO SCOTH
E. ALTER TABLE employees SET UNUSED COLUMN sal;
F. Select MAX(sal) FROM employees WHERE department _ id 20;

点击查看答案

3.单项选择题 The DBA issues this SQL command:
CREATE USER scott
IDENTIFIES by tiger;
What privileges does the user Scott have at this point?（）

A. No privileges.
B. Only the SELECT privilege.
C. Only the CONNECT privilege.
D. All the privileges of a default user.

点击查看答案

4.单项选择题 The EMPLOYEES table has these columns:
LAST NAME VARCHAR2(35)
SALARY NUMBER(8,2)
HIRE_DATE DATE
Management wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement:
ALTER TABLE EMPLOYEES
MODIFY ( SALARY DEFAULT 5000);
What is true about your ALTER statement?（）

A. Column definitions cannot be altered to add DEFAULT values.
B. A change to the DEFAULT value affects only subsequent insertions to the table.
C. Column definitions cannot be altered at add DEFAULT values for columns with a NUMBER data type.
D. All the rows that have a NULL value for the SALARY column will be updated with the value 5000.

点击查看答案

5.单项选择题 Examine the data in the EMPLOYEES table.

On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column.
Evaluate this DELETE statement:

Why does the DELETE statement fail when you execute it?（）

A. There is no row with dept_id 90 in the EMPLOYEES table.
B. You cannot delete the JOB_ID column because it is a NOT NULL column.
C. You cannot specify column names in the DELETE clause of the DELETE statement.
D. You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.

点击查看答案

6.单项选择题Which substitution variable would you use if you want to reuse the variable without prompting the user each time?（）

A.&
B.ACCEPT
C.PROMPT
D.&&

点击查看答案

7.单项选择题What is true about the WITH GRANT OPTION clause?（）

A.It allows a grantee DBA privileges.
B.It is required syntax for object privileges.
C.It allows privileges on specified columns of tables.
D.It is used to grant an object privilege on a foreign key column.
E.It allows the grantee to grant object privileges to other users and roles.

点击查看答案

8.单项选择题 The EMP table has these columns:

Management wants a list of names of employees who have been with the company for more than five years. Which SQL statement displays the required results?（）

A. SELECT ENAME   FROM EMP   WHERE SYSDATE-HIRE_DATE > 5;
B. SELECT ENAME   FROM EMP   WHERE HIRE_DATE-SYSDATE > 5;
C. SELECT ENAME   FROM EMP   WHERE (SYSDATE-HIRE_DATE)/365 > 5;
D. SELECT ENAME   FROM EMP   WHERE (SYSDATE-HIRE_DATE)* 365 > 5;

点击查看答案

9.单项选择题Which constraint can be defines only at the column level?（）

A.UNIQUE
B.NOT NULL
C.CHECK
D.PRIMARY KEY
E.FOREIGN KEY

点击查看答案

10.单项选择题In which scenario would TOP N analysis be the best solution?（）

A. You want to identify the most senior employee in the company.
B. You want to find the manager supervising the largest number of employees.
C. You want to identify the person who makes the highest salary for all employees.
D. You want to rank the top three sales representatives who have sold the maximum number of products.

点击查看答案