问题
单项选择题
对于成长型客户，开放式柜台柜员后应注意跟进，联系不少于多少次（）。
A.1
B.2
C.3
D.4
答案
参考答案：C
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对于成长型客户，开放式柜台柜员后应注意跟进，联系不少于多少次（）。
A.1
B.2
C.3
D.4
参考答案：C
以下是课程(CLASS)表和教师(INSTRUCTOR)表中的数据：
| CLASS | |||
| CLASS_ID | CLASS_NAME | HOURS_CREDIT | INSTRUCTOR_ID |
| 1 | Introduction to Accounting | 3 | 4 |
| 2 | Computer Basics | 3 | 1 |
| 3 | Tax Accounting Principles | 3 | 4 |
| 4 | American History | 3 | 2 |
| 5 | Basic Engineering | 3 | |
| INSTRUCTOR | ||
| INSTRUCTOR_ID | LAST_NAME | FIRST_NAME |
| 1 | Chao | Ling |
| 2 | Vanderbilt | Herbert |
| 3 | Wigley | Martha |
| 4 | Page | Albert |
A．SELECT i.last_name, i.first_name, c.class_name
FROM instructor i, class c;
B．SELECT i.last name, i.first_name,c.class_name
FROM class c LEFT OUTER JOIN instructor I
ON (i.instructor_id=c.instructor_id)
ORDER BY i.instructor_id;
C．SELECT i.last_name, i.first_name, c.class_name
FROM instructor i, class c
WHERE i.instructor_id=c.instructor_id (+)
ORDER BY i.instructor_id;
D．SELECT i.last_name, i.first_name, c.class_name
FROM instructor i LEFT OUTER JOIN class c
ON (i.instructor id=c.instructor_id)
ORDER BY i.instructor_id;
E．SELECT i.last_name, i.first_name, c.class_name
FROM instructor i, class c
WHERE i.instructor_id (+)=c.instructor_id
ORDER BY i.instructor_id;
F．SELECT i.last_name, i.first_name, c.class_name
FROM instructor i NATURAL JOIN class c
ON (i.instructor_id=c.instructor_id);