Examine the data in the EMPLOYEES table.On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column.Evaluate this DELETE statement:Why does the DELETE statement

题目

Examine the data in the EMPLOYEES table.On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column.Evaluate this DELETE statement:Why does the DELETE statement fail when you execute it?（）

A. There is no row with dept_id 90 in the EMPLOYEES table.

B. You cannot delete the JOB_ID column because it is a NOT NULL column.

C. You cannot specify column names in the DELETE clause of the DELETE statement.

D. You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.

相似考题

1.现有如下两个关系模式：Employees(Eid，Name，DeptNO)Departments(DeptNO，DeptName，TotalNumber)Employees关系模式描述了职工编号、姓名和所在部门编号；Departments关系模式描述了部门编号、名称和职工总人数。请按SQL Server所采用的’rransact—SQL语法格式编写实现具有如下功能的后触发型触发器：每当在Employees表中插入一行数据时，相应部门的职工总人数就加1。

2.I have never worked for such a considerate________; I think all the other________ have the same opinion.A.employee...employerB.employee...employersC.employer...employeeD.employer...employees

3.Examine the statement: Create synonym emp for hr. employees; What happens when you issue the statement? ()A. An error is generated.B. You will have two identical tables in the HR schema with different names.C. You create a table called employees in the HR schema based on you EMP table.D. You create an alternative name for the employees table in the HR schema in your own schema.

4.（ 2 ）现有如下两个关系模式：Employees （ Eid ， Name ， DeptNO ）Departments （ DeptNO ， DeptName ， TotalNumber ）Employees 关系模式描述了职工编号、姓名和所在部门编号； Departments 关系模式描述了部门编号、名称和职工总人数。请 按 SQL Serve r 所采用 的 Tansact — SQ L 语法格式编写实现具有功能的后触发型触发器 ： 每当在Employee s表中插入一行数据时，相应部门的职工总人数就加 1 。（ 10 分）

参考答案和解析
参考答案：C
更多“Examine the data in the EMPLOYEES table.On the EMPLOYEES table, EMPLOYEE_ID is the primary ”相关问题

  • 第1题：

    You added a PHONE_NUMBER column of NUMBER data type to an existing EMPLOYEES table. The EMPLOYEES table already contains records of 100 employees. Now, you want to enter the phone numbers of each of the 100 employees into the table. Some of the employees may not have a phone number available. Which data manipulation operation do you perform? （）

    A. MERGE

    B. INSERT

    C. UPDATE

    D. ADD

    E. ENTER

    F. You cannot enter the phone numbers for the existing employee records.


    参考答案：C

  • 第2题：

    YouneedtoimportalldefinitionsofobjectsbelongingtotheTS_EMPLOYEEStablespacebyusingtheexportfileexpdat.dmp.Whichimportstatementiscorrect?()

    A.imphr/hrTABLES=（ts_employees）rows=y

    B.impsystem/managerFROMUSER=hrfile=expdat.dmp

    C.imphr/hrTRANSPORT_TABLESPACE=yfile=expdat.dmp

    D.impsystem/managerTRANSPORT_TABLESPACE=yTABLESPACE=ts_employees


    参考答案：C

  • 第3题：

    Wal-Mart has been criticized by some groups for its .（ ）

    [A] low service quality

    [B] employees' low salary

    [C] high pressure on the other companies

    [D] discrimination against women


    正确答案：D

  • 第4题：

    Examinethefollowingcommandsexecutedinyourdatabase：SQL>ALTERSESSIONRECYCLEBIN=ON；SessionalteredSQL>CREATETABLEempTABLESPACEtbsfdASSELECT*FROMhr.employees；Tablecreated.Further，youexecutedthefollowingcommandtodropthetable：SQL>DROPTABLEemp；Tabledropped.Whathappensinthisscenario？（）

    A.ThetableismovedtotheSYSAUXtablespace.

    B.ThetableismovedtotheSYSTEMtablespace.

    C.Thetableisremovedfromthedatabasepermanently.

    D.ThetableisrenamedandremainsintheTBSFDtablespace.


    参考答案：D

  • 第5题：

    TheCiscoSA500SeriesSecurityAppliancesarebuiltspecificallyforbusinesseswithlessthan100employees.Whatarethreeimportantbenefitsofthisdevice?()

    A.site-to-siteVPNforremoteoffices

    B.business-gradefirewall

    C.CiscoIOSsoftware-based

    D.emailsecurity

    E.XMLsupport

    F.premiumsupportviaSMARTnet


    参考答案：A, B, D

  • 第6题：

    用所给的词和词组写出符合逻辑的句子。 a number of/have been/smoking/received from/requests/employees/in offices/asking that/be banned
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