问题 单项选择题

关于SQL的超连接查询,说法错误的是( )。

A) 在SQL中可以进行内部连接、左连接、右连接和全连接
B) SQL的超连接运算符“*=”代表左连接,“=*’代表右连接
C) Visual FoxPro同样支持超连接运算符“*=”和“=*”
D) 利用全连接,即使两个表中的记录不满足连接条件,也会在目标表或查询结果中出现,只是不满足条件的记录对应部分为NULL

答案

参考答案:C

解析: SQL的连接运算符中“*=”代表左连接,“=*”代表右连接。但在Visual FoxPro中,不支持超连接运算符“*=”和“=*’,它有专门的连接运算语法格式,分别用LEFT JOIN和RIGHT JOIN表示。Visual FoxPro支持左连接和右连接运算查询,但不能使用“=*”和“*=”运算符查询,只能用Visual FoxPro中专用的命令短语才可以。

阅读理解

根据短文内容,判断句子的正(T)误(F)。

     James wrote a play for television about a family who came to England from India, and the play was

very interesting. It was bought by an American TV company.

     James was then invited to go to New York to help them. He lived in Washington, which is an hour

away from New York by air. The plane was going to take off at 8:30 in the morning. So he had to be

at the airport at about 7:30. He ordered a taxi for 6 :30 and went to sleep. He forgot to wind (土条)

the clock, and it stopped after midnight. Also the driver of the taxi had to work very late that night and

he got up very late the next morning.

     James woke with the feeling that something was wrong. He looked at his clock. It stood there silently

with the hands pointing to ten past twelve. He turned on the radio and knew it was ten. He was late for

the plane.

     He was just preparing his coffee when the radio sent out another news, ''Reports are coming in of a

plane crash (飞机坠落) near Washington airport. A Boeing 707 fly to New York crashed shortly after 

taking off this morning. Plane  number  2234…"

     James suddenly turned pale (苍白).

     "My plane,"  he said aloud.   "If I haven't been late,  I'd have been on the plane!"

( )1. James was a writer from England.

(     )2. He had to reach the airport at half past eight.

(     )3. James would like to take a taxi at six thirty.

(     )4. When he turned on the radio he heard the speaker saying that he missed the plane.

(     )5. James was lucky because he was not able to get on the plane.

多项选择题