The database management systems can be classified based on several criteria. A.

Question

The database management systems can be classified based on several criteria. A. Based on data model: the relational data model; hierarchical data model|; network data model; or object-oriented data models. B. Based on the number of users: single user database system which supports one user at a time or multiuser systems which support multiple users concurrently. C. Based on the ways database is distributed: Centralized Systems (the system is stored at a single site.): Distributed database system (Actual database and DBMS software are distributed in various sites connected by a computer network.) - Homogeneous distributed Database Systems or Heterogeneous distributed Database Systems. Choose three different types of the database management systems. Do your research on these DBMS, explain and discuss about these different systems. (the main features, applications, comparisons of advantages or disadvantages.) Please cite the references (books. website, etc...)

Explanation / Answer

A database management system (DBMS) is a software package designed to define, manipulate, retrieve and manage data in a database. A DBMS generally manipulates the data itself, the data format, field names, record structure and file structure. It also defines rules to validate and manipulate this data. A DBMS relieves users of framing programs for data maintenance. Fourth-generation query languages, such as SQL, are used along with the DBMS package to interact with a database.

A DBMS receives instruction from a database administrator (DBA) and accordingly instructs the system to make the necessary changes. These commands can be to load, retrieve or modify existing data from the system.

A DBMS always provides data independence. Any change in storage mechanism and formats are performed without modifying the entire application. There are four main types of database organization:

Relational Database:

Data is organized as logically independent tables. Relationships among tables are shown through shared data. The data in one table may reference similar data in other tables, which maintains the integrity of the links among them. This feature is referred to as referential integrity - an important concept in a relational database system. Operations such as "select" and "join" can be performed on these tables. This is the most widely used system of database organization.

FEATURES:

1) It's Values are Atomic

2) In Each Row is alone.

3) Column Values are of the Same thing.

4) Columns is undistinguished.

5) Sequence of Rows is Insignificant.

6) Each Column has a common Name.

ADVANTAGES:

             DISADVANTAGES:

                    1) One disadvantage of relational databases is the expensive of setting up and maintaining the database system. In order to set up a relational database, you generally need to purchase special software.

                    2) Data in an RDBMS resides in multiple tables, which are linked to each other through shared key values. An RDBMS does not force database designers to impose a coherent table structure; inexperienced programmers may design systems that create unnecessary complexity or limit the future development of the database through poorly chosen data types. The flexibility of an RDBMS presents a double-edged sword. Experienced designers work magic, but inexperienced designers wreak havoc on a company's data.

                      3) Complex relational database systems can lead to these databases becoming "islands of information" where the information cannot be shared easily from one large system to another. Often, with big firms or institutions, you find relational databases grew in separate divisions differently.

Hierarchical-Data-Model:

The Hierarchical Data Model is a way of organizing a database with multiple one to many relationships. The structure is based on the rule that one parent can have many children but children are allowed only one parent. This structure allows information to be repeated through the parent child relations created by IBM and was implemented mainly in their Information Management System. (IMF), the precursor to the DBMS.

Advantages:

The model allows easy addition and deletion of new information. Data at the top of the Hierarchy is very fast to access. It was very easy to work with the model because it worked well with linear type data storage such as tapes. The model relates very well to natural hierarchies such as assembly plants and employee organization in corporations. It relates well to anything that works through a one to many relationship. For example; there is a president with many managers below them, and those managers have many employees below them, but each employee has only one manager.

Disadvantages:

This model has many issues that hold it back now that we require more sophisticated relationships. It requires data to be repetitively stored in many different entities. The database can be very slow when searching for information on the lower entities. We no longer use linear data storage mediums such as tapes so that advantage is null. Searching for data requires the DBMS to run through the entire model from top to bottom until the required information is found, making queries very slow. Can only model one to many relationships, many to many relationships are not supported. Clever manipulation of the model are required to make many to many relationships.

Object-OrientedModel:

In this Model we have to discuss the functionality of the object oriented Programming .It takes more than storage of programming language objects. Object DBMS's increase the semantics of the C++ and Java .It provides full-featured database programming capability, while containing native language compatibility. It adds the database functionality to object programming languages.This approach is the analogical of the application and database development into a constant data model and language environment. Applications require less code, use more natural data modeling, and code bases are easier to maintain. Object developers can write complete database applications with a decent amount of additional effort.

The object-oriented database derivation is the integrity of object-oriented programming language systems and consistent systems. The power of the  object-oriented databases comes from the cyclical treatment of both consistent data, as found in databases, and transient data, as found in executing programs.

Object-oriented databases use small, recyclable separated of software called objects. The objects themselves are stored in the object-oriented database. Each object contains of two elements:

ADVANTAGES:

1) It makes the requirement simple and easily understandable by representing simple diagrams.

2) One can covert ER diagrams into record based data model easily.

3) Easy to understand ER diagrams

Disadvantage of Object-oriented databases

Network Database:

A network databases are mainly used on a large digital computers. It more connections can be made between different types of data, network databases are considered more efficiency It contains limitations must be considered when we have to use this kind of database. It is Similar to the hierarchical databases, network databases .Network databases are similar to hierarchical databases by also having a hierarchical structure. A network database looks more like a cobweb or interconnected network of records.

In network databases, children are called members and parents are called occupier. The difference between each child or member can have more than one parent.

The Approval of the network data model similar with the esteem of the hierarchical data model. Some data were more naturally modeled with more than one parent per child. The network model authorized the modeling of many-to-many relationships in data.

The network model is very similar to the hierarchical model really. Actually the hierarchical model is a subset of the network model. However, instead of using a single-parent tree hierarchy, the network model uses set theory to provide a tree-like hierarchy with the exception that child tables were allowed to have more than one parent. It supports many-to-many relationships.

ADVANTAGES OF NETWORK MODEL:

The major advantage of network model are-

1.) Conceptual simplicity-Just like the hierarchical model,the network model is also conceptually simple and easy to design.

2.) Capability to handle more relationship types-The network model can handle the one to many and many to many relationships which is real help in modeling the real life situations.

3.) Ease of data access-The data access is easier and flexible than the hierarchical model.

4.) Data integrity- The network model does not allow a member to exist without an owner.

5.) Data independence- The network model is better than the hierarchical model in isolating the programs from the complex physical storage details.

6.) Database standards

DIS-ADVANTAGE OF NETWORK MODEL:

1.) System complexity- All the records are maintained using pointers and hence the whole database structure becomes very complex.

2.) Operational Anomalies- The insertion,deletion and updating operations of any record require large number of pointers adjustments.

3.) Absence of structural independence-structural changes to the database is very difficult.

Reference Books:

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.