从被调查对象的母体中选出部分个体进行调查，并用个体特征推断出总体特征的调查称之为（）。

提示：未搜索到的试题可在搜索页快速提交，您可在会员中心"提交的题"快速查看答案。

答案

查看答案

搜题

相关试题

Review the definition of the phone_list view. CHEATE OR REPLACE ALGORITHM=MERGE DEFINER= 'root'@localhost' SQL SECURITY DEFINER VIEW 'phone_list' AS SELECT e . id as id 'e . first_name AS 'first_name' 'e . last_name AS 'last_name' 'coalesce ( ph1.phone_no, ' – ') AS 'office_no' 'coalesce (ph2 .phone_no, ' – ') AS 'cell_no' FROM employees e LEFT JOIN employee_phone ph1 ON ph1.emp_id = e.id AND ph1.type = 'office' LEFT JOIN employee_phone ph2 ON ph2 .emp_id = e.id AND ph2 .type = 'mobile' The tables employees and employee_phone are InnoDB tables; all columns are used in this view. The contents of the phone_list view are as follows: Mysql> select * from phone_list; 1 row in set (0.00 sec) Which method can you use to change the cell_no value to '555-8888' for John Doe?（）

A、INSERT INTO employee_phone (emp_id, phone_no, type) VALUES (1, '555-8888','mobile')

B、UPDATE phone_list SET cell_name '555-8888' WHERE first_name= 'John' and last_name= 'Doe'

C、DELETE FROM phone_list WHERE first_name= 'John' and last_name= 'Doe'; INSERT INTO phone_list (first_name, last_name, office_no, cell_no) VALUES ('John' , 'Doe' , 'x1234' , '555-8888)

D、UPDATE employee_phone SET phone_no= '555-8888' where emp_id=1

查看答案解析

IP地址可分为五类，分别是A类IP地址、B类IP地址、C类IP地址、D类IP地址和（）。

A、其他选项都不对

B、局域网类IP地址

C、E类IP地址

D、F类IP地址

查看答案解析

网络运营者，是指网络的所有者、管理者和网络服务提供者。

A、对

B、错

查看答案解析