weekly reflection 3

class start mcm biasa pukol10pg.
kami diberi rehat pada pukul 9 pg, selama satu jam.
kemudian, kami diberikan latihan rdms

Answer:

Question 1
a)Database management system (DBMS) is a software system that enable users to define, create and maintain   the database and provides control access to this database.
b)Procedural access is to access data without any compliented coding.
c)Database tuning is includes tools such as utility programs to monitor and improve database performance.

Question 2
a)Differences between a file based database and DBMS:
  -File based database
     1)each application program had its own files.
     2)take time to manipulate data
     3)information is entered many times in many formats due to output, which is required.
 -DBMS
     1)database system
     2)each database file is shared by many application programs and data can be modified easily.
     3)gathers stores and manipulate data quickly.

b)Disadvantages of file Based Database:
    -duplication of data
    -data integrity problem
    -limited data sharing
    -lenght development

c)data dictionary is might be a catalogue that can be retrieved by user and also DBMS.its hold data about the scheme , user , application , and etc.

Question 3.
a)features  of  DBMS:
   -definition of database
   - nonprocedural access
   -application development
   -procedural language interface
   -transaction processing
   -database tuning

b)advantages of data dictionary;
    -information about data can be assembled and stored permanently as a source.
    -the enhancement of security level
    -integration can be identified
    -provide audit information

Question 4.
a)the complex structures are created by the DBMS in order to allow multiuser access to the database.By using sophisticated algorithms, multiple users can access the database concurrently without compromising the integrity of the database.

b)advantages of DBMS;
   -control of data redundancy
   - file consolidation
   -data consistency
   -improve data integrity
   -improve security
   -access versatility
   -program and file independence


Section C.
Question 1.
a)functions of DBMS:
   -data storage, retrieval and update
   -data dictionary management
   -transaction support
   -multiuser access control
   -backup and recovery management
   -security management
   -support for data communication
   -data integrity management
   -services to promote data independence
   -utility services

b)primary key:
   the most important and most commonly used.every table should have primary key because primary
   key  provides a link between tables.

  foreign key:
   which must be enforced by the DBMS, must ensure that no component of the primary key is allowed
    to take the undefined value.

Question 2
a)Agree .database security is a protection from an authorized user, without a suitable security level ,
   data integration will be easier to change compared to the file based system.
b)characteristics of a DBMS:
   -persistent
   -shared
   -interrelated

Section b

a)*create the database and relation structures
   *perform basic data management , task such as insention, modification deletion of data from relations.
   *perform both simple and complex queries to transform the ran data into information
   *controlling database security

b)data definition language
   - a part of SQL used to create a database, modify its stucture and destroy it after no longer its need it.
 
   data manipulation language
  -performs database maintenance which user can used to manipulate data in database such as retrieve,
   add modify.

  data control language
   -provides security for the database to avoid database become corrupted.

Question 2

b)4 function of CASE tools:
    -diagramming
    -documentation
    -analysis
    -prototyping tools

c)conceptual design: the design must be software independent because the system can be set up within
   any hardware and software choose later.

   logical design: translate to conceptual design into the internal model for a selected dbms , examples access,            

  physical design:concering with the selection of the database data storage and data access characteristics.

Question rdms.
question 1.
a)What is a DBMS?
b)What do you mean by procedual access?
c)What do you mean by database tuning?

question 2.
a)What is the different between a file based database and DBMS?
b)List down some of the disadvantages of the file based database?
c)Define briefly the term data dictionary.

question 3.
a)Write down the features of a DBMS.
b)Give some advantages of data dictionary.

question 4.
a)Explain with an example what do you mean by multiuser access.
b)list some advantages of a DBMS.


Question C.
This section contains 2 question.Answer only 1 question.

Question 1.
a)List down some functions of a DBMS.
b)Write a short note on the following.
  a) Primary key     b) Constraints

Question 2
a)Data in a dbms is more secure more than are data in a file based database . Do you agree and why?
b)List some characteristics of a DBMS?

Section B
Question 1.
a)Briefly explain the objectives of SQL(Structure Query Language)
b)There are 3 major scopes in SQL which is Data Definition Language(DDL), Data Manipulation Language (DML) and Data Control Language (DCL).Give explaination for each scopes.

Question 2.
a)Briefly explain 2 goals of database development.
b)There are many tools on the market that come under the general category of computer AIDED Software System (CASE) goals for database design . List down 4 functions of CASE tools.
c)Briefly explain about conceptual design , logical design and physical design.

RDMS QUESTIONS

a)

b)

c)

d)

monday  28/2/2011

Question 1
a)define what DBMS?
 -is a software system that enables users to define,create and maintain the database and provides control access to this database.
b)give two advantages of using a DBMS?
 -control of data redundancy
 -data consistency
c)explain what are the 3 main database characteristic?
    -persistent
data that repetitively used for example data about customers,employees and inventory are usually stored on stable storage such as magnetic disk.
    -shared
database can have multiple uses and shared by multiple users. Many users can access a database simultaneously.
    -interrelated
data stored as separate units can be connected to provide a whole picture. Databases contain both entities and relationship among entities. 

Question 2 (EER)

weekly reflection 2

CHAPTER 3:

A system is a set of components that interact with each other to form a whole and work together toward a common goal.

Components of information system are database, people, procedures, software, hardware and data.

5 phase of System Development Life Cycle (SDLC):

• Preliminary study phase
• Systems analysis phase
• Systems design phase
• System implementation phase
• Maintenance phase

4 goals of database development are:

Ø  Develop a common vocabulary

Ø  Define the meaning of data

Ø  Ensure data quality

Ø  Find an efficient implementation

 6 phase of database life cycle (DBLC):

      The database initial study

      Database design

      Implementation and loading

      Testing and evaluation

      Operation

      Maintenance and evolution

Two types of skills are needed in database developments which are the soft skills and the hard skills.

weekly reflection 1

CHAPTER 1:

Database system have taken us from a paradigm of data processing in which each application defined and maintained its own data to one in which the data is defined and administered centrally.

Database is a collection of related data. Database characteristics are persistent, shared, and interrelated.

Database system is a system with a database, a DBMS and a full description of the structure and constraints of the data stored in the database.

Database management system (DBMS) is a software system that enables users to define create, and maintain the database and providers control access to this database.

Functions of Database management system:

• Data storage, retrieval and update.
• Data dictionary management.
• Transaction support.
• Multiuser access control.
• Backup and recovery management.
• Security management.
• Support for data communication
• Data integrity management.
• Services to promote data independence.
• Utility services.

The advantages of Database management system:

§  Control of data redundancy

§  Data consistency

§  Access versatility

§  Program and file independence

§  File consolidation.

§  Improved security

§  Improved data integrity

Three schemes supported by client server architecture are:

Ø  Client, server and database on the same computer.

Ø  Multiple clients and one server on different computers.

Ø  Multiple servers and database on different computers.

Two types of Data Independence:

v  Logical data independence

              Protection from changes in logical structure of data.

v  Physical data independence

              Protection from changes in physical structure of data.

Three levels of database system architecture

ü  External level: users’ view of the database

ü  Conceptual level: Community view of the database        

ü  Internal level: physical representation of the database on the computer

The 6 components of DBMS

1. Query  processor
2. Database manager
3. File manager
4. Data manipulation language processor
5. Data definition language compiler
6. Dictionary manager

CHAPTER 2:

Specialization:  A specialized kind of entity set may be derived from a given entity set.

Generalization:  Several entity sets can be abstracted by a more general entity set.

Categorization is the modelling of a single subclass with a relationship that involves more than one distinct superclass.

The relational data model has one data structure, the relation. The relation is a restricted table.

Relations are defined in terms of attributes, tuples, primary keys, foreign keys and domains.

A special character exists in relational systems for representing incomplete or missing information.-null

The model also has two inherent integrity rules: entity and referential integrity and enterprise constraints.

Normalization is a process for assigning attributes into table and reduces data redundancy and helps eliminate the data anomalies that associated with poor database design (unnormalized).

Four levels of normalization:

• 1NF –a relation where the intersection of each row and column contains no repeating values. (only one values)
• 2NF –a relation that is in 1NF and every non-key primary key attribute is fully functionally dependent on primary key.
• 3NF –a relational based on the concept of transitive dependency.
• BCNF –a relational based on the concept of the determinant.