单选题What is true about joining tables through an equijoin?()A You can join a maximum of two tables through an equijoin.B You can join a maximum of two columns through an equijoin.C You specify an equijoin condition in the SELECT or FROM clauses of a SELECT

题目
单选题
What is true about joining tables through an equijoin?()
A

You can join a maximum of two tables through an equijoin.

B

You can join a maximum of two columns through an equijoin.

C

You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.

D

To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.

E

You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.


相似考题
参考答案和解析
正确答案: E
解析: 暂无解析
更多“单选题What is true about joining tables through an equijoin?()A You can join a maximum of two tables through an equijoin.B You can join a maximum of two columns through an equijoin.C You specify an equijoin condition in the SELECT or FROM clauses of a SELECT”相关问题
  • 第1题:

    You are the administrator of a database that contains 64 lookup tables. These tables store static data that should not change. However, users report that some of this data is being changed. You need to prevent users from modifying the data.

    You want to minimize changes to your security model and to your database applications. How should you modify the database?

    A.Create a filegroup named LOOKUP. Move the lookup tables to this filegroup. Select the read only check box for the filegroup.

    B.Create a database role named datamodifier. Grant SELECT permissions to the datamodifier role. Add all users to the role.

    C.Deny INSERT, UPDATE, and DELETE permissions for all users. Create stored procedures that modify data in all tables except lookup tables. Require users to modify data through these stored procedures.

    D.Create a view of the lookup tables. Use the view to allow users access to the lookup tables.


    正确答案:A
    解析:Explanation:SQLServer2000allowsfilegroupsotherthantheprimaryfilegrouptobemarkedasreadonly.Afilegroupthatismarkedread-onlycannotbemodified.Tablesthatmustnotbemodifiedcanbeplacedonafilegroupthatcanthenbemarkasread-only.Thiswillpreventsaccidentalupdates.IncorrectAnswers:B:Thissolutioneffectivelypermitsalluserstomodifyanytableinthedatabase,astheywouldallhaveSELECTpermissionstothedatabase.C:ThissolutionwilleffectivelypreventallusersfrombeingabletoperformingthesetasksonalltablesinthedatabaseastheyaredeniedpermissionstorunINSERT,UPDATE,orDELETEstatementsagainstthedatabase.Abettersolutionwouldbetoapplythedenypermissionsatthetablelevelofthelookuptables.Thiswould,however,requireunnecessaryadministrativetime.D:Viewsarevirtualtablesthatareusedtofiltertablesorrowsthattheusersshouldnothaveaccessto,however,iftheusershaveaccesstothebasetables,theycanstillrunINSERT,UPDATE,andDELETEstatementsagainstthebasetable.

  • 第2题:

    What is true about joining tables through an equijoin?()

    • A、You can join a maximum of two tables through an equijoin.
    • B、You can join a maximum of two columns through an equijoin.
    • C、You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.
    • D、To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.
    • E、You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.

    正确答案:E

  • 第3题:

    Which two are true about aggregate functions? ()

    • A、You can use aggregate functions in any clause of a SELECT statement.
    • B、You can use aggregate functions only in the column list of the select clause and in the WHERE clause of a SELECT statement.
    • C、You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
    • D、You can pass column names, expressions, constants, or functions as parameter to an aggregate function.
    • E、You can use aggregate functions on a table, only by grouping the whole table as one single group.
    • F、You cannot group the rows of a table by more than one column while using aggregate functions.

    正确答案:A,D

  • 第4题:

    What is necessary for your query on an existing view to execute successfully? ()

    • A、The underlying tables must have data.
    • B、You need SELECT privileges on the view.
    • C、The underlying tables must be in the same schema.
    • D、You need SELECT privileges only on the underlying tables.

    正确答案:B

  • 第5题:

    What is true about updates through a view? ()

    • A、You cannot update a view with group functions.
    • B、When you update a view group functions are automatically computed.
    • C、When you update a view only the constraints on the underlying table will be in effect.
    • D、When you update a view the constraints on the views always override the constraints on the underlying tables.

    正确答案:A

  • 第6题:

    Which two statements are true regarding the usage of the SQL*Loader utility()

    • A、You can load data into multiple tables during the same load session.
    • B、You can load data from multiple files to a table during the same load session.
    • C、You cannot perform selective data loading based on the values available in the records.
    • D、You can use an export file generated by the EXPDP utility as an input data file to load the data.
    • E、You can load data only if the input file is available on the disk and tape but not in a named pipes.

    正确答案:A,B

  • 第7题:

    Which two statements are true regarding the Oracle Data Pump export and import operations()

    • A、You cannot export data from a remote database.
    • B、You can rename tables during an import operation.
    • C、You can overwrite existing dump files during an export operation.
    • D、You can compress the data during export but not the metadata because it is not supported.

    正确答案:B,C

  • 第8题:

    You have two computers named Computer1 and Computer2 that run Windows 7. You need to ensure thatyou can remotely execute commands on Computer2 from Computer1.  What should you do?()

    • A、Run Winrm quickconfig on Computer1.
    • B、Run Winrm quickconfig on Computer2.
    • C、Enable Windows Remote Management (WinRM) through Windows Firewall on Computer1.
    • D、Enable Windows Remote Management (WinRM) through Windows Firewall on Computer2.

    正确答案:B

  • 第9题:

    单选题
    You have two computers named Computer1 and Computer2 that run Windows 7. You need to ensure thatyou can remotely execute commands on Computer2 from Computer1.  What should you do?()
    A

    Run Winrm quickconfig on Computer1.

    B

    Run Winrm quickconfig on Computer2.

    C

    Enable Windows Remote Management (WinRM) through Windows Firewall on Computer1.

    D

    Enable Windows Remote Management (WinRM) through Windows Firewall on Computer2.


    正确答案: B
    解析: 暂无解析

  • 第10题:

    多选题
    In which three cases would you use the USING clause?()
    A

    You want to create a nonequijoin.

    B

    The tables to be joined have multiple NULL columns.

    C

    The tables to be joined have columns of the same name and different data types.

    D

    The tables to be joined have columns with the same name and compatible data types.

    E

    You want to use a NATURAL join, but you want to restrict the number of columns in the join condition.


    正确答案: C,B
    解析: 暂无解析

  • 第11题:

    多选题
    In which two cases would you use an outer join? ()
    A

    The tables being joined have NOT NULL columns.

    B

    The tables being joined have only matched data.

    C

    The columns being joined have NULL values.

    D

    The tables being joined have only unmatched data.

    E

    The tables being joined have both matched and unmatched data.

    F

    Only when the tables have a primary key-foreign key relationship.


    正确答案: D,C
    解析: 暂无解析

  • 第12题:

    单选题
    What is true about joining tables through an equijoin?()
    A

    You can join a maximum of two tables through an equijoin.

    B

    You can join a maximum of two columns through an equijoin.

    C

    You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.

    D

    To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.

    E

    You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.


    正确答案: B
    解析: 暂无解析

  • 第13题:

    Which two statements are true regarding the USING clause in table joins?()

    • A、It can be used to join a maximum of three tables 
    • B、It can be used to restrict the number of columns used in a NATURAL join 
    • C、It can be used to access data from tables through equijoins as well as nonequijoins 
    • D、It can be used to join tables that have columns with the same name and compatible data types

    正确答案:B,D

  • 第14题:

    Click the Exhibit button and examine the data in the EMPLOYEES and DEPARTMENTS tables.You want to retrieve all employees, whether or not they have matching departments in the departments table. Which query would you use?()

    • A、SELECT last_name, department_name FROM employees NATURAL JOIN departments;
    • B、SELECT last_name, department_name FROM employees JOIN departments ;
    • C、SELECT last_name, department_name FROM employees e JOIN departments d ON (e.department_id = d.department_id);
    • D、SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);
    • E、SELECT last_name, department_name FROM employees FULL JOIN departments ON (e.department_id = d.department_id);
    • F、SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id);

    正确答案:F

  • 第15题:

    Which two statements are true regarding the ORDER BY clause? ()

    • A、It is executed first in the query execution 
    • B、It must be the last clause in the SELECT statement 
    • C、It cannot be used in a SELECT statement containing a HAVING clause
    • D、You cannot specify a column name followed by an expression in this clause 
    • E、You can specify a combination of numeric positions and column names in this clause

    正确答案:B,E

  • 第16题:

    What are two reasons to create synonyms? ()

    • A、You have too many tables.
    • B、Your tables are too long.
    • C、Your tables have difficult names.
    • D、You want to work on your own tables.
    • E、You want to use another schema's tables.
    • F、You have too many columns in your tables.

    正确答案:C,E

  • 第17题:

    Which two statements about views are true?()

    • A、A view can be created as read only.
    • B、A view can be created as a join on two or more tables.
    • C、A view cannot have an ORDER BY clause in the SELECT statement.
    • D、A view cannot be created with a GROUP BY clause in the SELECT statement.
    • E、A view must have aliases defined for the column names in the SELECT statement.

    正确答案:A,B

  • 第18题:

    Which two statements are true regarding the USING and ON clauses in table joins?()

    • A、Both USING and ON clauses can be used for equijoins and nonequijoins 
    • B、Amaximum of one pair of columns can be joined between two tables using the ON clause 
    • C、The ON clause can be used to join tables on columns that have different names but compatible data types 
    • D、The WHERE clause can be used to apply additional conditions in SELECT statements containing the ON or the USING clause 

    正确答案:C,D

  • 第19题:

    In which two cases would you use an outer join? ()

    • A、The tables being joined have NOT NULL columns.
    • B、The tables being joined have only matched data.
    • C、The columns being joined have NULL values.
    • D、The tables being joined have only unmatched data.
    • E、The tables being joined have both matched and unmatched data.
    • F、Only when the tables have a primary key/foreign key relationship.

    正确答案:C,E

  • 第20题:

    多选题
    Which two statements are true regarding the USING clause in table joins?()
    A

    It can be used to join a maximum of three tables

    B

    It can be used to restrict the number of columns used in a NATURAL join

    C

    It can be used to access data from tables through equijoins as well as nonequijoins

    D

    It can be used to join tables that have columns with the same name and compatible data types


    正确答案: A,C
    解析: 暂无解析

  • 第21题:

    多选题
    Which two statements are true regarding the USING and ON clauses in table joins?()
    A

    Both USING and ON clauses can be used for equijoins and nonequijoins

    B

    Amaximum of one pair of columns can be joined between two tables using the ON clause

    C

    The ON clause can be used to join tables on columns that have different names but compatible data types

    D

    The WHERE clause can be used to apply additional conditions in SELECT statements containing the ON or the USING clause


    正确答案: A,C
    解析: 暂无解析

  • 第22题:

    单选题
    What is true about updates through a view?()
    A

    You cannot update a view with group functions.

    B

    When you update a view group functions are automatically computed.

    C

    When you update a view only the constraints on the underlying table will be in effect.

    D

    When you update a view the constraints on the views always override the constraints on the underlying tables.


    正确答案: B
    解析: 暂无解析

  • 第23题:

    多选题
    Which two statements about views are true?()
    A

    A view can be created as read only.

    B

    A view can be created as a join on two or more tables.

    C

    A view cannot have an ORDER BY clause in the SELECT statement.

    D

    A view cannot be created with a GROUP BY clause in the SELECT statement.

    E

    A view must have aliases defined for the column names in the SELECT statement.


    正确答案: D,E
    解析: 暂无解析

  • 第24题:

    问答题
    Practice 1  ● Your company ordered from Maximum Company 50 tables. But when the goods arrived, you found that the sides of nearly all the tables are badly scratched. The damage appears to have been caused by rough handling before dispatch.  ● You are asked to write to Mr. Cooper, sales manager of Maximum, and complain about the damage.  ● Write about 60—80 words.

    正确答案: 【参考范文】
    Dear Mr. Cooper,
    We duly received the 50 tables from you, but regret to tell you that we find that the sides of nearly all the tables are badly scratched.
    It seems that the damage has been caused by rough handling before the dispatch, so we would appreciate it if you could inform us of what measures you are about to take as for the compensation for the damage as soon as possible.
    We look forward to hearing from you soon.
    Yours sincerely,
    Signature
    解析: 暂无解析