问题 填空题

在SQL分组与计算查询中,利用______短语可以对分组条件进一步加以限定。

答案

参考答案:HAVING

解析: 在实际的应用中,除了简单的计算查询外,我们还可以加上GROUP BY子句进行分组计算查询。 通常来说,一个计算函数的范围是满足WHERE子句指定条件的所有记录。当加上GROUP BY子句后,系统会将查询结果按指定列分成集合组。当一个计算函数和一个GROUP BY子句一起使用时,计算函数的范围变为每组所有的记录。也就是说,一个结果是由组成一组的每个记录集合产生的。 另外,使用HAVING子句可以对这些组进一步加以控制。用这个子句定义这些组所必须满足的条件,以便将其包含在结果中。

阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项.选项中的两项为多余选项.

        1   This date was the old mid-winter festival in pre-Christmas times, around the time

of the longest night and the shortest day. Christmas in the 21st century has many traditions:

Christmas trees, cards and presents. Shops can make about 60 percent of their year's income

in the three months before Christmas, so most shops get ready for it in October.    2   The first

time this happened was in 1867 when Macy's famous shop in New York, stayed open until

midnight on Christmas Eve.

    By mid-December, almost every shop and street has a Christmas tree.     3   In the northern

countries, winter is cold and dark and most trees are decorated with lights and colored glass

balls give people hope that spring will come.

    Father Christmas is known across the world with his white hair, red coat and big bag of toys.

Young children are told that he lives in the north of Finland and makes toys for them.    4  

   On Christmas Day a traditional meal is eaten, usually a turkey and a rich, spicy cake. Some

 people hate Christmas.     5   They love seeing family and friends; they also love the traditions.

Love it or hate it, Christmas is a time to look back over the old year and forward to the new one.

A. This tradition was started by the Germans as early as 700 AD.

B. Believe it or not.

C. Since about 400 AD, Christmas Day has been celebrated.

D. Others feel it is a magical and exciting time.

E. The shopping centers are beautifully decorated and stay open late at night.

F. It was really beautiful indeed.

G. By tradition, he brings the toys to children at night, on the night before

Christmas.

单项选择题