The CUSTOMERS table has these columns:CUSTOMER_ID NUMBER(4) NOT NULLCUSTOMER_NAME VARCHAR2(100) NOT NULLSTREET_ADDRESS VARCHAR2(150)CITY_ADDRESS VARCHAR2(50)STATE_ADDRESS VARCHAR2(50)PROVINCE_ADDRESS VARCHAR2(50)COUNTRY_ADDRESS VARCHAR2(50)POSTAL_CODE VARCHAR2(12)CUSTOMER_PHONE VARCHAR2(20)The CUSTOMER_ID column is the primary key for the table.You need to determine how dispersed your customer base is. Which expression finds the number of different countries represented in the CUSTOMERS table?()
A.COUNT(UPPER(country_address))
B.COUNT(DIFF(UPPER(country_address)))
C.COUNT(UNIQUE(UPPER(country_address)))
D.COUNT DISTINCT UPPER(country_address)
E.COUNT(DISTINCT (UPPER(country_address)))
第1题:
找出"作者"库表中没有出现在"获奖名单"库表中的所有作者信息的SQL语句,(提示:使用
NOT IN,NOT EXISTS,以及外部连接(+)三种方法),并说明那种方法是不优化的
出版社: 出版社代码 char(2),出版社名称 varchar2(32)
图书: 图书编号 char(8),图书名称 varchar2(128),出版社代码 char(2),作者代号
char(4),图书简介 varchar2(128)
作者: 作者代号 char(4),作者名称 varchar2(10),性别 char(1),年龄 number(3),文学
方向 varchar2(64)
获奖名单: 获奖日期 date,获奖人员 char(4)
第2题:
A.AutomaticstatisticscollectionisstoppedfortheCUSTOMERStable.
B.StatisticsfortheCUSTOMERStablearelockedandcannotbeoverwritten.
C.ExistingstatisticsfortheCUSTOMERStablebecomeunusableforthequeryoptimizer.
D.Subsequently,statisticsgatheredontheCUSTOMERStablearestoredaspendingstatistics
第3题:
23、假定 number=4,下面哪个语句不会出错?
A.print(format(number, "2d"), format(number ** 1.5, "4d"))
B.print(format(number, "2d"), format(number ** 1.5, "4.2d"))
C.print(format(number, "2d"), format(number ** 1.5, "4.2f"))
D.print(format(number, "2f"), format(number ** 1.5, "4.2d"))
第4题:
A.Sheetl,Sheet2,Sheet3,Sheet4,Sheet5
B.Table1,Table2,Table3,Table4,Table5
C.List1,List2,List3,List4,List5
D.Book1,Book2,Book3,Book4,Book5
第5题:
将students中的列变量重新命名为: (1)id_number, name, gender, score, has_graduate (2)选出Bob的性别gender,并存入变量bob_gender (3)选出列has_graduate,并存入向量status (4)创建数据框part_df,其中包含前三个学生的所有信息 (5)创建数据框rest_df,包含其余学生的所有信息
第6题:
16、MySQL数据库中,通常将用户写入对应的权限表来控制访问权限的,以下属于用户权限得选项()。
A.User
B.db
C.table_priv
D.columns_priv