Overview of Database Management System Long Answer Type Questions Part 2
Explain the differences between File Based System and DBMS.
The following are the differences between file system and DBMS.
|1. A file management system is an abstraction to store, retrieve, management and update a set of files.||1. DBMS is a collection of inter-related data and a set of programs to access those data.|
|2. In file system approach, each user defines and implements the needed files for a specific application to run.||The fundamental characteristic of database approach is that the database system not only contains data’s but it contains complete definition or description of the database structure and constraints.|
|3. File system doesn’t allow sharing of data or data sharing is very complex.||In DBMS data can be shared very easily due to centralized system.|
|4. When data is redundant, it is difficult to update.||In DBMS, as there is no or less data redundancy, data remains consistent.|
|5. In conventional file system, if we want to search, retrieve, access some data item, it becomes very difficult because in file system for every operation we have to make different programs.||In DBMS searching/ retrieval/accessing of data item is very easy and user- friendly because searching and querying operations are already available in the system.|
|6. In file system there is no standard format of data or we can say data is scattered in various formats or files which also make data retrieval difficult.||6. In DBMS, due to centralized system the format of similar type of data remains same.|
|7. The value of data in database must follow or satisfy some rules or consistency constraints.||7. DBMS maintains the data integrity by enforcing the constraints by adding appropriate code.|
|8. In file system there is no or very less security. General security provided by file system are locks, guards etc.||8. DBMS have high level security like encryption, passwords, biometric security (finger print matching, face and voice detection etc) etc.|
|9. Automatically means a transaction must be all- or-nothing i.e., the transaction must either fully happen, or not happen at all. It must not complete partially.||9. Transaction atomicity is a special feature of DBMS. In DBMS either a transaction completed fully or none of the action is performed, For this, DBMS maintains the transaction log in which intermediate values are stored.|
|10. Any multi-user database application has to have some method for dealing with concurrent access to. data-when more than one user is accessing the same data at the same time.||10. DBMS along with an appropriate application provides safety towards concurrent access.|
Explain the advantages and disadvantages of DBMS?
DBMS is a collection of programs that enables user to create and maintain a database. In other words it is general- purpose software that provides the users with the processes of defining, constructing and manipulating the database for various applications.
Advantages of DBMS:
1. Controlling Data Redundancy: If database have more than one records of same type then it is called data redundancy. In DBMS, all data is stored in one single database file and that recorded data is placed in the database.
2. Data Sharing: Data can be shared by authorized users of the organization among multiple users. Many users can be authorized to access the same data simultaneously. The remote users also can share the same data.
3. Enforcing Data Integrity: In database approach, data integrity is much easier. In database, data is stored in the tables. A single database contains multiple tables which is easy to retrieve and update the data.
4. Data Security: Data security is the protection of the database from unauthorized access. The DBMS ensures access of the database through authorized channel. To ensure security, DBMS provides security such as by giving user name and passwords.
5. Ease of application development: The programmer needs to develop applications according to user specification. The other issues such as data integrity, security etc are handled by DBMS itself which makes application development easier.
6. Multiple user interfaces’ DBMS provides different types of user interfaces such as application program interfaces, graphical user interfaces which includes form style and menu driven interfaces. Form style interface provides user interaction with forms and menu driven interface provides user interaction with list of options called as menus.
7. Backup and recovery: Most of the DBMS’s provide backup and recovery subsystems which creates automatically backup Of data from hardware and software failures and restores the data if required.
8. Data Independence: Data Independence keeps data separated from all programs that make use of it. In DBMS, database and application programs are separated from each other and we can easily change the database structure without modifying the application program.
9. Reduced Maintenance: It can be easily maintainable due to centralized nature of the system.
Disadvantages of DBMS
1. Cost of Data Conversion: When computer file based system replaced with database system, it must be converted to database file. It’s difficult to convert data file into database, so for this we have to take help of database designers along with application programmers and also we should take help of software which costs lot of money for developing the software.
2. Complexity: Database system creates additional complexity and requirements. DBMS is extremely complex piece of software. The operation of database system with sev, eral users and databases is quite costly and demanding.
3. Cost of Hardware and Software: To run DBMS software, we need high speed of data processor and large memory size and DBMS software also too
4. Size: DBMS is large piece of software due to its complexity and breadth functionality. It occupies large space of disk and large memory to run the efficiently.
5. Cost of staff training: DBMS is complex database system which is required to train the users all levels including programming, application development etc for which organization has to pay lot of amount for training staff to run the DBMS.
6. Higher impact of failure: In most of the organizations, all data stored in a single database. Since all users and applications rely on the availability of the DBMS. If database is damaged due to electric failure or database corruption data may lost forever.
What is DBMS? What are the objectives of DBMS?
Database management system has made a revolution in all the industries .that handles lots of data. All these organizations are making a huge profit just because of database management system. This is why because DBMS provides a lot benefits to all these companies and there are lots of objectives of using a database management system.
1) Mass Storage: DBMS can store a lot of data in it. So for all the big firms, DBMS is really the ideal technology to use.
It can store thousands of records in it and one can fetch all that data whenever it is needed.
2) Removes Duplicity: If you have lots of data then t 4ata duplicity will occur for sure at any instance. DBMS guarantt -e it that there will be no data duplicity among all the records. While storing new records, DBMS makes sure that same data was not inserted before.
3) Multiple Users Access: No one handles the whole database alone. There are lots of users who are able to access database. So this situation may happen that two or more users are accessing database. They can change whatever they want, at that time DBMS makes it sure that they can work concurrently.
4) Data Protection: Information such as bank details, employee’s salary details and sale purchase details should always be kept secured. Also all the companies need their data secured from unauthorized use. DBMS gives a master level security to their data. No one can alter or modify the information without the privilege of using that data.
5) Data Backup and recovery: Sometimes database failure occurs so there is no option like one can say that all the data has been lost. There should be a backup of database so that on database failure it can be recovered. DBMS has the ability to backup and recover all the data in database.
6) Everyone can work on DBMS: There is no need to be a master of programming language if you want to work on. DBMS. Any accountant who is having less technical knowledge can work on DBMS. All the definitions and descriptions are given in it so that even a non-technical background work person can work on it.
7) Integrity: Integrity means your data is authentic and consistent- DBMS has various validity checks that make your data completely accurate and consistence.
8) Platform Independent: One can run ubms at any platform. No particular platform is required to work on database management system.
Explain the functions of DBMS
DBMS performs several important functions that guarantee the integrity and consistency of the data in the database. The most important functions of Database Management System are
1. Data Dictionary Management: Data Dictionary Management is the one of the most important function in database management system. DBMS stores definitions of the data elements and their relationships (metadata) in a data dictionary. So, all programs that access the data in the database work through the DBMS.
2. Data Storage Management: The DBMS creates and manages the complex structures required for data storage, thus relieving you from the difficult task of defining and programming the physical data characteristics. A modem DBMS system provides storage not only for the data, but also for related data entry forms or screen definitions, report definitions, data validation rules, procedural code, structures to handle video and picture formats, and so on.
3. Data transformation and presentation: The DBMS transforms entered data in to required data structures. The DBMS relieves you of the chore of making a distinction between the logical data format and the physical data format.
That is, the DBMS formats the physically retrieves \ data to make it conform to the user’s logical expectations.
4. Security Management: Security Management is another important function of DBMS. The DBMS creates a security system that enforces user security and data privacy. Security rules determine which users can access the database, which data items each user can access, and which data operations (read, add, delete, or modify) the user can perform. This is especially important in multiuser database systems.
5. Multi User Access Control: To provide data integrity and data consistency, the DBMS uses sophisticated algorithms to ensure that multiple users can access the database concurrently without compromising the integrity of the database.
6. Backup and Recovery Management: The DBMS provides backup and data recovery to ensure data safety and integrity. Current DBMS systems provide special utilities that allow the DBA to perform routine and special backup and restore procedures. Recovery management deals with the recovery of the database after a failure, such as a bad sector in the disk or a power failure. Such capability is critical to preserving the database’s integrity.
7. Data Integrity Management: Data integrity management is another important function of DBMS. The DBMS promotes and enforces integrity rules, thus minimizing data redundancy and maximizing data consistency. The data relationships stored in the data dictionary are used to enforce data integrity. Ensuring data integrity is especially important in transaction-oriented database systems.
8. Database Access Languages and Application Programming Interfaces: The DBMS provides data access through a query language. A query language is a non-procedural language—one that lets the user specify what must be done without having to specify how it is to be done. Structured Query Language (SQL) is the defacto query language and data access standard supported by the majority of DBMS vendors.
9. Database Communication Interfaces: Current- generation DBMSs accept end-user requests via multiple, different network environments. For example, the DBMS might provide access to the database via the Internet through the use of Web browsers such as Mozilla Firefox or Microsoft Internet Explorer.
Write about the evolution of Database Management Systems.
A Database Management System allows a person to organize, store, and retrieve data from a computer. It is a way of communicating with a computer’s “stored memory.” In the I very early years of computers, “punch cards” were used for input, output, and Jata storage. Punch cards offered a fast way to enter data, and to retrieve it. Herman Hollerith is given credit for adapting the punch cards used for weaving looms to act as the memory for a mechanical tabulating machine, in 1890. Much later, databases came along.
Databases (or DBs) have played a very important part in the recent evolution of computers. The first computer programs were developed in the early 1950s, and focused almost completely on coding languages and algorithms. At the time, computers were basically giant calculators and data (names, phone numbers) was considered the leftovers of processing information. Computers were just starting to become commercially available, and when business people started using them for real-world purposes, this leftover data suddenly became important.
Enter the Database Management System (DBMS). A database, as a collection of information, can be organized so -a Database Management System can access and pull specific information. In 1960, Charles W. Bachman designed the Integrated Database System, the “first” DBMS. IBM, not wanting to be left out, created a database system of their own, known as IMS. Both database systems are described as the forerunners of navigational databases.
By the mid-1960s, as computers developed speed and flexibility, and started becoming popular, many kinds of general-use database systems became available. As a result, customers demanded a standard be developed, in turn leading to Bachman forming the Database Task Group. This group took responsibility for the design and standardization of a language called Common Business Oriented Language (COBOL). The Database Task Group presented this standard in 1971, which also came to be known as the “CODASYL approach.”
The CODASYL approach was a very complicated system and required substantial training. It depended on a “manual” navigation technique using a linked data set, which formed a large network. Searching for records could be accomplished by one of three techniques:
- Using the primary key (also known as the CALC key)
- Moving relationships (also called sets) to one record from another
- Scanning all records in sequential order
Eventually, the CODASYL approach lost its popularity as simpler, easier-to-work-with systems came on the market.
Edgar Codd worked for IBM in the development of hard disk systems, and he was not happy with the lack of a search engine in the CODASYL approach, and the IMS model. He wrote a series of papers, in 1970, outlining novel ways to construct databases. His ideas eventually evolved into a paper titled, A Relational Model of Data for Large Shared Data Banks, which described new method for storing data and processing large databases. Records would not be stored in a free-form list of linked records, as in CODASYL navigational model, but instead used a “table with fixed-length records.” IBM had invested heavily in the IMS model, and wasn’t terribly interested in Codd’s ideas. Fortunately, some people who didn’t work for IBM “were” interested. In 1973, Michael I Stonebraker and Eugene Wong (both then at UC Berkeley) made the decision to research relational database systems. The project was called INGRES (Interactive Graphics and Retrieval System), and successfully demonstrated a relational model could be efficient and practical. INGRES worked with a query language known as QUEL, in turn, pressuring IBM to develop SQL in 1974, which was more advanced (SQL became ANSI and OSI standards in 1986 lnd 1987). SQL quickly replaced QUEL as the more functional query language.
RDBM Systems were an efficient way to store and process structured data. Then, processing speeds got faster, and “unstructured” data (art, photographs, music, etc.) became much more common place. Unstructured data is both non-relational and schema-less, and Relational Database Management Systems simply were not designed to handle this kind of data.