Basic Database Concepts
Database system is an excellent computer-based record-keeping system. A collection of data, commonly called a database, contains information about a particular enterprise. It maintains any information that may necessary to the decision-making process involved in the management of that organization. It can also be defined as a collection of interrelated data stored together to serve multiple applications, the data is stored so that it is independent of programs that use the data. A generic and controlled approach is used to add new data and modify and retrieve existing data within the database. The data is structured so as to provide the basis for future application development.
Purpose of Database
The intent of a database is that a collection of data should serve as many applications as possible. Therefore, a database is often thought of as a repository of information needed to run certain functions in a corporation or organization. It would permit only the retrieval of data but also the continuous modification of data needed for the control of operations. It may be possible to search the database to obtain answers to questions or information for planning purposes.
In a typical file-processing system, permanent records are stored in different files. Many different application programs are written to extract the records and add the records to the appropriate files. But this scheme has several major limitations and disadvantages, such as data redundancy (duplication of data), data inconsistency, maladaptive data, non-standard data, insecure data, incorrect data, etc. A database management system is an answer to all these problems as it provides centralized control of the data.
A major purpose of a database is to provide the user with only as much information as is required of them. This means that the system does not disclose all the details of the data, rather it hides some details of how the data is stored and maintained. The complexity of databases is hidden from them which, if necessary, are ordered through multiple levels of abstraction to facilitate their interaction with the system. The different levels of the database are implemented through three layers:
- Internal Level(Physical Level): The lowest level of abstraction, the internal level, is closest to physical storage. It describes how the data is stored concretely on the storage medium.
- Conceptual Level: This level of abstraction describes what data is concretely stored in the database. It also describes the relationships that exist between the data. At this level, databases are described logically in terms of simple data structures. Users at this level are not concerned with how these logical data structures will be implemented at the physical level.
- External Level(View Level): It is the level closest to users and is related to the way the data is viewed by individual users.
Since a database can be viewed through three levels of abstraction, any change at one level can affect plans at other levels. As databases continue to grow, there may be frequent changes to it at times. This should not lead to redesign and re-implementation of the database. In such a context the concept of data independence proves beneficial.
Concept of Database
To store and manage data efficiently in the database let us understand some key terms:
1. Database Schema: It is a design of the database. Or we can say that it is a skeleton of the database that is used to represent the structure, types of data will be stored in the rows and columns, constraints, relationships between the tables.
2. Data Constraints: In a database, sometimes we put some restrictions on the table that what type of data can be stored in one or more columns of the table, it can be done by using constraints. Constraints are defined while we are creating a table.
3. Data dictionary or Metadata: Metadata is known as the data about the data. Or we can say that the database schema along with different types of constraints on the data is stored by DBMS in the dictionary is known as metadata.
4. Database instance: In a database, a database instance is used to define the complete database environment and its components. Or we can say that it is a set of memory structures and background processes that are used to access the database files.
5. Query: In a database, a query is used to access data from the database. So users have to write queries to retrieve or manipulate data from the database.
6. Data manipulation: In a database, we can easily manipulate data using the three main operations that is Insertion, Deletion, and updation.
7. Data Engine: It is an underlying component that is used to create and manage various database queries.
Advantages of Database
Let us consider some of the benefits provided by a database system and see how a database system overcomes the above-mentioned problems:-
- Reduces database data redundancy to a great extent
- The database can control data inconsistency to a great extent
- The database facilitates sharing of data.
- Database enforce standards.
- The database can ensure data security.
- Integrity can be maintained through databases.
Therefore, for systems with better performance and efficiency, database systems are preferred.
Disadvantages of Database
With the complex tasks to be performed by the database system, some things may come up which can be termed as the disadvantages of using the database system. These are:-
- Security may be compromised without good controls.
- Integrity may be compromised without good controls.
- Extra hardware may be required
- Performance overhead may be significant.
- The system is likely to be complex.
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