系统设计与数据库系统 作业三 Normalisation

Posted 2021-07-31 上山打老虎D

Normalisation

• Question 1:A college keeps details about a student and the various modules the student studied. These details comprise
• Question 2: Classify the following relations as UNNORMALISED, 1NF, 2NF or 3NF. If the
• Question 3: Identify any repeating groups and functional dependences in the PATIENT
• Question 4: A software consulting firm wishes to keep the following data for an employee and costing database:

Question 1:A college keeps details about a student and the various modules the student studied. These details comprise

• regno - registration number (Unique)
• name - student name
• addr - student address
• Tno – Teacher ID
• Tname - Teacher name
• DC - diploma code
• DN - diploma name
• MC - module code
• MN - module name
• Grade - module exam Grade
  DC -> DN
  Tno -> Tname
  Regno, MC -> Grade
  name -> addr
  mc -> mn
  Reduce the relation DETAILS to BCNF

Solution：
DD(DC,DN) DC->DN
TT(Tno,Tname) Tno->Tname
RMG(regno,Mc,Grade) Regno,Mc->Grade
NA(name,addr) name->addr
MM(MC,MM) MC->MM

Question 2: Classify the following relations as UNNORMALISED, 1NF, 2NF or 3NF. If the

relation is not in 3NF, normalize the relation to 3NF.

1. EMPLOYEE(empno,empname,jobcode)
   empno -> empname
   empno -> jobcode
   Solution:
   3NF
   Emp(empname, empno)
   Job(jobcode, empno)

2. EMPLOYEE(empno,empname,(jobcode,years))
   empno -> empname
   empno,jobcode -> years
   Solution:
   UNNORMALISED:

3. EMPLOYEE(empno,empname,jobcode,jobdesc)
   empno -> empname,jobcode
   jobcode -> jobdesc
   Solution:
   2NF
   Emp(empname, empno)
   Job_info(jobcode, jobdesc)
   Job(jobcode, empno)

4. EMPLOYEE(empno,empname,project,hoursworked)
   empno -> empname
   empno,project -> hoursworked
   Solution:
   1NF
   Emp(empname, empno)
   Info(hoursworked, project, empno)

Question 3: Identify any repeating groups and functional dependences in the PATIENT

relation. Show all the intermediate steps to derive the third normal form
for PATIENT.
PATIENT(patno,patname,gpno,gpname,appdate,consultant,conaddr,sample)

• patno: Patient number
• patname: Patient Name
• gpno: General Practitioner Number
• gpname: General Practitioner Name
• appdate: Appointment Date
• conaddr: Consultant Address
  
  Solution:
  1NF:
  Patient (patno, patname, gpno, gpname)
  Appt (patno, appdate, consultant, conaddr, sample)
  2NF:
  Patient (patno, patname, gpno, gpname)
  Appt (patno, appdate, consultant, sample)
  Consultant (consultant, conaddr)
  3NF:
  Patient (patno, patname, gpno)
  GP (gpno, gpname)
  App (patno, appdate, consultant, sample)
  Consultant (consultant, conaddr)

Question 4: A software consulting firm wishes to keep the following data for an employee and costing database:

• employee number
• employee name
• employee address
• salary
• current job code
• job history (job promotion code + year)
• office location
• telephone number
• project number
• project name
• task number
• task name
• project budget
• task expenditure to date
• department number
• department name

There are none, one or more job promotion code/year entries per employee.
The office location uniquely depends on the telephone number, and there
may be more than one employee using the same telephone and more than one
telephone in the one office. Tasks are numbered uniquely only within each
project. An employee may be concurrently assigned to more than one project
and task, but belongs to one department. Reduce this data to third normal
form.

Solution:
1NF:
Employee(employee number, employee name, employee address, salary, current job code, job promotion code, year, office location, telephone number, project number, project name, task number, task name, project budget, task expenditure to date, department number, department name)
2NF:
Department(department number, department name)
Project(project number, project name, project budget)
Office(telephone number, office location)
Task(task number, task name, task expenditure to date, project number)
Employee(employee number, employee name, employee address, salary, current job code, job promotion code, year, telephone number, department number)
3NF:
Department(department number, department name)
Office(telephone number, office location)
Employee(employee number, employee name, employee address, salary, current job code, telephone number, department number)
Job_History(employee number, job promotion code, year)
Project(project number, project name, project budget)
Task(task number, task name, task expenditure to date, project number)
Employee_Task(employee number, task number)