OCP-1Z0-051 补充题库第13题 MERGE INTO语句

最新推荐文章于 2020-04-14 14:04:09 发布

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最新推荐文章于 2020-04-14 14:04:09 发布

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分类专栏： OCP-1Z0-051 文章标签： OCP-1Z0-051 MERGE INTO merge 11g

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本文详细分析了Oracle数据库中的MERGE INTO语句，通过举例说明了正确的使用方式。在提供的四个选项中，A选项是唯一正确的，它正确地使用了MERGE INTO语法进行数据匹配更新和插入操作。

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一、原题

Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables:

Which MERGE statement is valid?
A.
MERGE INTO new_employees c
USING employees e
ON (c.employee_id = e.employee_id)
WHEN MATCHED THEN
UPDATE SET name = e.first_name || ',' || e.last_name
WHEN NOT MATCHED THEN
INSERT value S
    (e.employee_id,
     e.first_name || ',
' || e.last_name);
B.
MERGE new_employees c
USING employees e
ON (c.employee_id = e.employee_id)
WHEN EXISTS THEN UPDATE SET name = e.first_name || ',' || e.last_name
WHEN NOT MATCHED THEN
INSERT
valueS
    (e.employee_id,
     e.first_name || ',
' || e.last_name);
C.
MERGE INTO new_employees c USING employees e
ON (c.employee_id = e.employee_id)
WHEN EXISTS THEN UPDATE SET name = e.first_name || ',' || e.last_name
WHEN NOT MATCHED THEN
INSERT value S
    (e.employee_id,
     e.first_name || ',
' || e.last_name);
D.
MERGE new_employees c FROM employees e
ON (c.employee_id = e.employee_id)
WHEN MATCHED THEN
UPDATE SET name = e.first_name || ',' || e.last_name
WHEN NOT MATCHED THEN
INSERT INTO new_employees
valueS
    (e.employee_id,
     e.first_name || ',
' || e.last_name);

答案: A

二、题目翻译

下面是EMPLOYEES和NEW_EMPLOYEES表的结构:
哪一个merge语句是有效的?

三、题目解析

A选项正确。
B选项和D选项不正确，merge into语法不正确，into关键字都没有。
C选项不正确，语法错误，WHEN EXISTS THEN，应该是 WHEN MATCHED THEN。