DEFINITION of DATABASE MANAGEMENT SYSTEM

Database Management System (DBMS)

Database Management System (DBMS ) is a system or software designed to manage a database and run the operations of the requested data to many users. Typical examples of DBMS is the accounting, human resources, and customer support systems, DBMS has evolved into a standard part of the support (back office) of a company. Examples of DBMS are Oracle, SQL server 2000/2003, MS Access, MySQL and so on. DBMS is a software designed to perform and manage the utilization of data collection in the sheer number of great. DBMS is also designed to be able to make data more easily masnipulasi. Prior to the BMS then the data is generally stored in a flatfile, which is a text file that is on the operating system. Until now there is an application that saves data in a flat directly. Storing data in flat file form has advantages and disadvantages. Storage in this form will have the optimum benefit if the file size is relatively small, such as the passwd file. Passwd file is generally only used to store the name of the amount is not more than 1000 people. In addition in the form of flat files, data storage can also be done using the auxiliary program like a spreadsheet. Use of this software to fix some weaknesses of the flat file, such as increased speed in data processing. However, this method still has many drawbacks, including the management and data security issues are still lacking.

Data storage in the form of DBMS has many benefits and advantages as compared to storage in the form of flat file or spreadsheet, including:

1. Performance obtained by storage in a DBMS is quite large, vastly different from the performance data stored in flat files. Besides having a better performance, also will get efficient use of storage media and memory

2. Data integrity is further assured by the use of DBMS . Redundancy problems often occur in the DBMS . Data redundancy is a repeat occurrence or set of similar data in a database that result in waste of storage media.

3. Independence. Changes in database structure was possible without having to modify applications that access them, so making the interface to the data will be easier with the use of DBMS .

4. Centralization. The data will facilitate centralized database management. ease of use in the conduct of the DBMS and also consistency of data that are accessed together will lebiih assured of the data is stored in a file or worksheet to spread.

5. Securities. DBMS has a security system that is more flexible than the security of the operating system file. Security in the DBMS will provide flexibility in granting access to users.

Overview History

The first-generation DBMS designed by Charles Bachman at General Electric Company in the early 1960s, called the Integrated Data Storage (Integrated Data Store). Formed the basis for the network data model is then standardized by the Conference on Data Systems Languages ​​(CODASYL). Bachman then received the ACM Turing Award (a sort of Nobel Prize in computer science) in 1973. And at the end of 1960, IBM developed the information management system (Information Management System) DBMS. IMS was formed from the data representation framework called hierarchical data model. At the same time, the SABRE system was developed as a result of collaboration between IBM with American airlines. This system allows the user to access the same data on computer networks. Then in 1970, Edgar Codd, the Research Laboratory in San Jose, proposed the relational data model. In 1980, the relational model DBMS becomes the dominant paradigm. SQL query language for relational database developed as part of IBM's System R project. SQL standardized in late 1980, and SQL-92 was adopted by the American National Standards Institute (ANSI) and International Standards Organization (ISO). The program used for concurrent execution of transactions in the database is called. The user writes the program, and is responsible for running the program simultaneously to the DBMS. In 1999, James Gray won the Turing Award for his contribution to transaction management in a DBMS . In late 1980 and early 1990, many areas of the Database system being developed. Research in the field of the Database includes a powerful query language, a complete data model, and an emphasis on complex data analysis support from all parts of the organization. Some vendors are expanding the system with new types of data storage capabilities such as image and text, and complex query capabilities. Specialized systems / specials developed by many vendors to create a data warehouse, consolidate data from multiple databases. The most interesting phenomenon is the existence of enterprise resource planning (ERP) and management resource planning (MRP), which adds a substantial layer of application-oriented features. Packages that include include Baan, Oracle, PeopleSoft, SAP, and Siebel. These packages identify a set of common tasks (such as inventory management, human resource planning, financial analysis) and provide a common application layer to handle such needs. Data is stored in a relational DBMS , and application layer can be adjusted for different companies. Furthermore, the DBMS into the world of internet. At the time of the first generation of Web sites store their data exclusively in the operating system file, then the current DBMS can be used to store data that can be accessed through a Web browser. Queries can be generated through a Web form, and answer format uses a markup language such as HTML for easy display in the browser. All database vendors are adding features to their DMS. Database management to consider the importance of the data is on-line, and can be accessed through computer networks. The present is embodied in fields such as multimedia databases, interactive video, digital libraries, such as mapping project scientist on the project, a project of NASA's Earth observation systems, etc..

A. DBMS components

The main components of DBMS can be divided into 4 types:

    Hardware
    Software
    Data
    Users
DBMS usually contains the following components:
1. Data Dictionary
Data dictionary (data dictionary) is used to store the description of the data used in the database. Each element of data among other types and sizes. Sometimes the data dictionary also contains provisions that regulate the value that could be included in the field. For example, if the definition of a field that only the letters P and W are inserted into the field named gender, then the system will reject Had the user to enter data into that field L.
2. Utilities
The utility is used to facilitate the user in creating databases and tables as well as in manipulating data.
3. Generating Reports
The report generator is a facility provided to users to create reports with ease.
4. Application Generator
The application generator is a facility used to create a display that is used by users who will use a database application (such as the display is known as a form), for example, to fill in the data.
5. Access Security
Access security facility is used to set user permissions. Access security settings may be authorized access to specific users. For example, the user can change the contents of the table Student, but user B does not. DBMS such as user B does not.
6. Recovery System
Recovery facility serves to restore data to the original database Had a system failure. Some of the techniques commonly used to handle the mirroring system recovery, reprocessing, and rollback.

B. Advantages The use of DBMS

The use DMBS to manage the data have several advantages, namely:

    Freedoms of data and efficient access
    Reduce application development time
    Integrity and data security
    Administration of the uniformity of data
    Concurrent access and improvement of the crashes (collision of processes simultaneously).

DBMS functions:
DBMS consists of functions that support all the existing database in which the Atomicity, Consistency, Isolation, Durability (ACID). With ACID, DBMS to guarantee that data stored on it have good quality.
• Atomicity
Given this function, the DBMS ensures that stored data will be complete at the time of processing. For example: If there are processes that are running but there is a failure due to network conditions broke up the process, then the atomicity is all the data already in the process will be canceled. So it can be concluded that the event is canceled less then all of a failure to maintain the perfection of the data.
• Consistency
DBMS will ensure that this consistency with the transaction data stored will be in accordance with the main reference data, and avoid duplication of data. For example: if there is a process that is being added data not found in the reference data, then the DBMS will reject the consistency of this process.
• Isolation
Data will be safer with this isolation function, at which time the data is opened in serial data remains safe despite the changes. Clearer reference to go to the link isolation.
• Durability
Given this function, then the resistance of the stored data will be ensured. Although the data is stored in the database a lot, but the DBMS to guarantee that data will not be damaged.

Some of the functions provided by the DBMS are:
• Manage and control large amounts of data.
• Perform backup, recovery, and logging to the database.
• Simplify and expand the security database.
• Conduct an examination of data integrity.

Level Abstraction in a DBMS
Data in the DBMS can be described in three levels of abstraction, namely conceptual, physical, and external. Data definition language (DDL) is used to define an external schema and conceptual. All DBMS vendors include SQL command to describe the physical aspects of the scheme. Information about the scheme conceptual, external and physically stored in the system catalog.

Has several reviews (views), a single conceptual scheme (logical) and physical schema.

    Describe how users see the data
    Conceptual schema defines the structure of logic
    Physical schema describes the files and indexes used

The scheme is defined using the DDL (Data Definition Language), data modified using DML (Data Management Language).

Description : DEFINITION of DATABASE MANAGEMENT SYSTEM
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