Talk about the difference between INNER JOIN and LFET JOIN.
题目
Talk about the difference between INNER JOIN and LFET JOIN.
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参考答案和解析
更多“Talk about the difference between INNER JOIN and LFET JOIN. ”相关问题
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第1题：
查询商品单价在10到50之间、并且日销售数量高于20的商品名、单价、销售日期和销售数量，查询结果按单价降序。正确命令是
A．SELECT商品名，单价，销售日期，销售数量FROM商品JOIN销售 WHERE(单价BETWEEN 10 AND 50)AND销售数量>20 ORDER BY单价DESC
B．SELECT商品名，单价，销售日期，销售数量FROM商品JOIN销售 WHERE(单价BETWEEN 10 AND 50)AND销售数量>20 ORDER BY单价
C．SELECT商品名，单价，销售日期，销售数量FROM商品，销售 WHERE(单价BETWEEN 10 AND 50)AND销售数量>20 ON商品．商品号=销售．商品号ORDER BY单价
D．SELECT商品名，单价，销售日期，销售数量FROM商品，销售 WHERE(单价BETWEEN 10 AND 50)AND销售数量>20 AND商品．商品号=销售．商品号ORDER BY单价DESC
正确答案：D
解析：按单价降序排列应在ORDER BY后跟DESC短语，因此排除B)和C)选项。选行多表查询时，指定两表关键字进行连接时，JOIN短语必须与ON短语联合使用，故选项A)错误。 -
第2题：
A cool mass of air heads toward the United States from the upper regions of Canada and Alaska this week according to the National Weather Service.
According to the NWS a mass of cold air will drop from the Arctic regions to Canada and then the upper Midwest next week.
Temperatures across the Midwest will drop into the 60s and 70s-a sharp difference from the 80 degree and 90 degree temperatures from recent weeks. And the relatively cooler air may be felt as far East as New York and Washington
The cool breezes may be a welcome relief this time around but remember the last few times we got hit with Arctic air？
Temperatures in cities including Chicago Cleveland New York and Louisville fell into single-digit and negative territory for long stretches during the harsh winter months of early 2014. But we’re sure you remember
What’s the temperature when the report was written?A. About 60s and 70s
B. Between 60s and 90s
C. Below 60s
D. About 80s and 90s答案：D解析：细节题。根据文段定位到的“Temperatures across the Midwest will drop into the 60s and 70s-a sharp difference from the 80 degree and 90 degree temperatures from recent weeks”。我们从该句中可得知最近几周温度在80-90，因此答案选D。A项大约在60-70左右，这个温度是未来预计的温度。B项在60-90之间，不正确。C项在60之下。因此答案选D。 -
第3题：
Between 1845 and 1854,about 1.5 million Irishmen emigrated to United States because of（）
Afamine
BEnglish oppression
Cwar
DBoth A&B
D
略 -
第4题：
3．Is her lifestyle. the same as yours or ________? What are the________?
A． difference， different
B． different ，difference
C． different ，differences
D． difference ， differences
正确答案：C
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第5题：
资料：We never thought we'd say this, but we'd welcome back some chilly weather.
A cool mass of air heads toward the United States from the upper regions of Canada and Alaska this week, according to the National Weather Service.
According to the NWS, a mass of cold air will drop from the Arctic regions to Canada and then the upper Midwest next week.
Temperatures across the Midwest will drop into the 60s and 70s—a sharp difference from the 80 degree and 90 degree temperatures from recent weeks. And the relatively cooler air may be felt as far East as New York and Washington.
The cool breezes may be a welcome relief this time around, but remember the last few times we got hit with Arctic air?
Temperatures in cities including Chicago, Cleveland, New York, and Louisville fell into single-digit and negative territory for long stretches during the harsh winter months of early 2014. But we're sure you remember.
What’s the temperature when the report was written?A.About 60s and 70s.
B.Between 60s and 90s.
C.Below 60s.
D.About 80s and 90s.答案：D解析：本题考查的是细节理解。
【关键词】temperature；when the report was written
【主题句】Temperatures across the Midwest will drop into the 60s and 70s—a sharp difference from the 80 degree and 90 degree temperatures from recent weeks. 中西部地区的气温将下降到60-70华氏度，与最近几周的80-90华氏度的温度有很大的不同。
【解析】本题的问题是“写这篇报道时气温是多少？”。选项A意为“约为60-70华氏度”；选项B意为“为60和90华氏度之间”；选项C意为“华氏60度以下”；选项D 意为“约为80和90华氏度”。根据题目中关键词找到主题句，结合主题句故选D。 -
第6题：
4、以下内连接的语法格式正确吗？ select ＜列名列表＞ from ＜子表＞ [Inner] join ＜父表＞ on ＜子表.外键＞ = ＜父表.主键＞
SELECT 查询字段 FROM 表1 [INNER] JOIN 表2 ON 表1.关系字段 = 表2.关系字段