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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
You can join a maximum of two tables through an equijoin.
You can join a maximum of two columns through an equijoin.
You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.
To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.
You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.
相似问题和答案
第1题：
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.
第2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.
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3题：
Regarding the extended ping command; which of the statements below are true?
(Select all valid answer choices)
A．The extended ping command is supported from user EXEC mode.
B．The extended ping command is available from privileged EXEC mode.
C．With the extended ping command you can specify the TCP and UDP port to be pinged.
D．With the extended ping command you can specify the timeout value.
E．With the extended ping command you can specify the datagram size.
解析：Explanation:
The extended ping command works only at the privileged EXEC command line.
Some of the extended ping command values include the datagram size and timeout value as shown:
Datagram size [100]: Size of the ping packet (in bytes). Default: 100 bytes.
Timeout in seconds [2]: Timeout interval. Default: 2 (seconds). The ping is declared successful only if the ECHO REPLY packet is received before this time interval.
Incorrect Answers:
A. Regular pings are available in both user and privileged mode, but not extended pings.
C. Ports can not be specified.
第4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5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6题：
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.
第7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8题：
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.
第9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10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