Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?()A. ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;B. ALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHE

题目
Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?()

A. ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;

B. ALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;

C. ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn NOT NULL;

D. ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn IS NOT NULL;

E. ALTER TABLE customers MODIFY name CONSTRAINT cust_name_nn NOT NULL;

F. ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name NOT NULL;

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更多“Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?() ”相关问题

  • 第1题：

    Youexecutedthefollowingcommands：SQL>ALTERSESSIONSETOPTIMIZER_USE_PENDING_STATISTICS=false；SQL>EXECUTEDBMS_STATS.SET_TABLE_PREFS（’SH’，’CUSTOMERS’，’PUBLISH’，’false’）；SQL>EXECUTEDBMS_STATS.GATHER_TABLE_STATS（’SH’，’CUSTOMERS’）；WhichstatementiscorrectregardingtheabovestatisticscollectionontheSH.CUSTOMERStableintheabovesession？（）

    A.Thestatisticsarestoredinthependingstatisticstableinthedatadictionary.

    B.Thestatisticsaretreatedasthecurrentstatisticsbytheoptimizerforallsessions.

    C.Thestatisticsaretreatedasthecurrentstatisticsbytheoptimizerforthecurrentsessionsonly.

    D.Thestatisticsaretemporaryandusedbytheoptimizerforallsessionsuntilthissessionterminates.


    参考答案：A

  • 第2题：

    从以下备选答案内为程序中(5)～(9)处空缺部分选择正确答案。(5)A．CreatObject B．Connect C．ExecuteSQL D．Open()(6)A．＜body＞ B．＜html＞ C．＜head＞ D．＜table＞(7)A．number B．recordnumber C．count D．recordcount(8)A．skip B．end for C．next D．loop(9)A．＜input type="submit" name="add" value="添加"＞

    B．＜input type="post" name="add" value="添加"＞

    C．＜input type="submit" name="添加" value="add"＞

    D．＜input type="post" name="添加" value="add"＞


    正确答案：(5)A或CreatObject (6)A或body＞ (7)D或recordcount (8)C或next (9)A或input type="submit" name="add" value="添加"＞
    (5)A或CreatObject (6)A或body＞ (7)D或recordcount (8)C或next (9)A或input type="submit" name="add" value="添加"＞ 解析：本问题考查的是HTML和ASP编程的语法知识。
    我们常说，ASP并不是一种语言，尽管看起来ASP的代码是以脚本的形式出现。Microsoft把ASP定义为一个脚本语言执行的环境。在HTML语言里，标示一个标签是用尖括号，在ASP语言里其实没有什么不同，唯一的区别仅仅是使用%%＞来表示一个 ASP的脚本语言的开始和结尾。

  • 第3题：

    【填空题】删除“供货商表”的“联系电话”字段。 必须先删除该字段上的默认电话、“电话约束”惟一约束。代码如下： USE diannaoxs ______ TABLE 供货商表 ______ constraint 电话约束


    AC

  • 第4题：

    Examine this command:SQL > exec DBMS_STATS.SET_TABLE_PREFS (‘SH’, ‘CUSTOMERS’, ‘PUBLISH’, ‘false’);Which three statements are true about the effect of this command?()

    A. Statistics collection is not done for the CUSTOMERS table when schema stats are gathered.

    B. Statistics collection is not done for the CUSTOMERS table when database stats are gathered.

    C. Any existing statistics for the CUSTOMERS table are still available to the optimizer at parse time.

    D. Statistics gathered on the CUSTOMERS table when schema stats are gathered are stored as pending statistics.

    E. Statistics gathered on the CUSTOMERS table when database stats are gathered are stored as pending statistics.


    参考答案：A, C, D

  • 第5题：

    Examinethecommand:SQL>DBMS_STATS.SET_TABLE_PREFS(’SH’,’CUSTOMERS’,’PUBLISH’,’false’);Whichstatementdescribestheeffectoftheabovecommand()

    A.AutomaticstatisticscollectionisstoppedfortheCUSTOMERStable.

    B.StatisticsfortheCUSTOMERStablearelockedandcannotbeoverwritten.

    C.ExistingstatisticsfortheCUSTOMERStablebecomeunusableforthequeryoptimizer.

    D.Subsequently，statisticsgatheredontheCUSTOMERStablearestoredaspendingstatistics


    参考答案：D

  • 第6题：

    设置多列布局的属性值为（）。

    A．columns-width

    B．column-count

    C．column-gap

    D．column-rule


    A 解析：Columns属性返回或设置一个值，以决定控件是水平还是垂直滚动以及如何显示列中的项目。Columns属性值为0时，控件为垂直滚动；Columns属性等于1时，则列表框呈多行多列显示： Columns属性值大于1时，为水平滚动，Columns属性值的数量决定在控件中的可见宽度内显示列的数量。Columns属性用来确定列表框的列数。

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