A database is a large structured set of persistent data. A simple database might be a single file containing many records, each of which contains the same set of fields where each field is a certain data type and length. In short, a database is an organized store of data wherein the data is accessible by named data elements. A Database Management System (DBMS) is a software package designed to create, store, and manage databases. The DBMS software enables end users or application programmers to share data. It provides a systematic method of creating, updating, retrieving and storing information in a database. DBMSs also are generally responsible for data integrity, data access control, and automated rollback, restart and recovery. It is a system, usually automated and computerized, for the management of any collection of compatible, and ideally normalized, data. A database application is computer software written to manage the data of a particular application or problem. DBMS can be an extremely complex set of software programs that controls the organization, storage and retrieval of data (fields, records and files) in a database. The basic functionalities that a DBMS must provide are:
A modeling language to define the schema of each database hosted in the DBMS, according to the DBMS data model. A database query language and report writer is used to allow users to interactively interrogate the database, analyse its data and update it according to the users privileges on data. It also controls the security of the database. Data security prevents unauthorised users from viewing or updating the database.
The DBMS accepts requests for data from the application program and instructs the operating system to transfer the appropriate data.
The main advantage of using a DBMS is to impose a logical, structured organization on the data. A DBMS delivers economy of scale for processing large amounts of data because it is optimized for such operations. A DBMS can be distinguished by the model of data upon which it is based. A data model is a collection of concepts used to describe data. There are two fundamental components of a data model: its structure, that is the way data is stored, and its operations, that is the way that data can be manipulated. There are four major DBMS data models used by major DBMS products: 1. Hierarchical 2. Network (or CODASYL) 3. Relational 4. Object-oriented A database management system may provide one, two or all the four methods. Inverted lists and other methods are also used. The most suitable structure depends on the application and on the transaction rate and the number of inquiries that will be made.
Additionally, using a DBMS provides a central store of data that can be accessed by multiple users, from multiple locations. Data can be shared among multiple applications, instead of new iterations of the same data being propagated and stored in new files for every new application. Central storage and management of data within the DBMS provides: • Data abstraction and independence. • Data security. • A locking mechanism for concurrent access with ACID properties (ACID is an acronym for atomicity, consistency, isolation, and durability). • An efficient handler to balance the needs of multiple applications using the same data. • The ability to swiftly recover from crashes and errors. • Robust data integrity capabilities. • Simple access using a standard API. • Uniform administration procedures for data.
Database Management System (DBMS) is a collection of programs that enables you to store, modify, and extract information from a database. A database can be a set of flat files stored on computer tape or disk or it could consist of database tables that are managed by a Database Management System (DBMS). There are many different types of DBMSs, ranging from small systems that run on personal computers to huge systems that run on mainframes. Some examples of database applications are computerized library systems ,flight reservation systems , nventory systems etc. From a technical standpoint, DBMSs can differ widely. The terms relational, network, flat, and hierarchical all refer to the way a DBMS organizes information internally. The internal organization can affect how quickly and flexibly you can extract information. Requests for information from a database are made in the form of a query, which is a stylized question. For example, the query SELECT * FROM EMPTABLE WHERE NAME = "RAM" AND SAL > 5000. requests all records in which the NAME field is RAM and the SAL field is greater than 5000 From EMPTABLE .The set of rules for constructing queries is known as a query language. Different DBMSs support different query languages, although there is a semi-standardized query language called SQL (structured query language). Sophisticated languages for managing database systems are called fourth-generation languages, or 4GLs for short. The information from a database can be presented in a variety of formats. Most DBMSs include a report writer program that enables you to output data in the form of a report. Many DBMSs also include a graphics component that enables you to output information in the form of graphs and charts.
One very important role of a database management system is to maintain the data definitions for each table and columns in the database. Each piece of data must be assigned a name, a data type (e.g. date, Char, numeric) and a mandatory/optional status. Most DBMS packages will enforce these rules when rows are added to the database. DBMS packages can also enforce domain rules. For example, a domains for state codes or country codes could be defined to ensure that only valid values are stored. Most DBMS software will also enforce cardinality and optionality rules that govern relationships between tables Examples of such rules are as follows: Each customer may have zero, one or many orders.(where customer and order are two diff. tables which has a relation). When rows are deleted from the database, the DBMS will ensure that all dependent rows are also deleted, leaving the database in a stable state. For example, if an customer is deleted, the DBMS would ensure that all related order items are also deleted. Enforcing referential integrity rules is an important role of database management systems. Another important role of a Database Management System is to enforce data security. Based on the assigned roles of users, a DBMS system can ensure that a given user only has read and/or update access to appropriate columns in the database. This ensure that private data such as salary information is only accessible to the appropriate parties. Data access can be restricted via database "views" that filter out sensitive data and by other means. Many DBMS applications can track changes made to tables in the database. Along with the prior version of the data, the DBMS will record the identify of the person who altered the data. Maintaining audit trails on important data is another important role for database management systems. Also see this site http://dbms.ca/concepts/audit.html…\
DBMS is as you would know DataBase Management System. Now in the present times, we use only RDBMS which is Relational DataBase Management Systems. Oracle, SQL Server all belong to RDBMS category where you store data in table format and all tables related to the other tables through one field or more.
The main thing you would have to know about DBMS is that : A DBMS is a software package for defining and managing a database. The one most important thing to know is DataBase normalization rules. These rules provide the cornerstone for developing any database. You may not adhere to all 4 rules but atleast 3 is considered important for efficient database design. Visit these link for more on this: http://databases.about.com/od/speci…http://support.microsoft.com/kb/q10…
Please visit this link for excellent intro to DBMS:
But please note that SQL queries are one way when using SQL Server and different when using Oracle or any other DBMS. There is not standard yet.
The main thing you would have to learn in SQL is select/update/delete queries, Joins (Inner , outer, left outer ), triggers and unions. There are lots and lots more if you want to be a sql developer. But the above should suffice for a programmer with limited database interaction.
I have put together some information below about DBMS and also attached a document explaining the concept.
A database management system (DBMS), sometimes just called a database manager, is a program that lets one or more computer users create and access data in a database. The DBMS manages user requests (and requests from other programs) so that users and other programs are free from having to understand where the data is physically located on storage media and, in a multi-user system, who else may also be accessing the data. In handling user requests, the DBMS ensures the integrity of the data (that is, making sure it continues to be accessible and is consistently organized as intended) and security (making sure only those with access privileges can access the data). The most typical DBMS is a relational database management system (RDBMS). A standard user and program interface is the Structured Query Language (SQL). A newer kind of DBMS is the object-oriented database management system (ODBMS). A DBMS can be thought of as a file manager that manages data in databases rather than files in file systems. In IBM's mainframe operating systems, the nonrelational data managers were (and are, because these legacy application systems are still used) known as access methods.
A DBMS is usually an inherent part of a database product. On PCs, Microsoft Access is a popular example of a single- or small-group user DBMS. Microsoft's SQL Server is an example of a DBMS that serves database requests from multiple (client) users. Other popular DBMSs (these are all RDBMSs, by the way) are IBM's DB2, Oracle's line of database management products, and Sybase's products.
IBM's Information Management System (IMS) was one of the first DBMSs. A DBMS may be used by or combined with transaction managers, such as IBM's Customer Information Control System (CICS).
A (DBMS ) database management system is a computer program (or more typically, a suite of them) designed to manage a database (a large set of structured data), and run operations on the data requested by numerous clients. Typical examples of database management system use include accounting, human resources and customer support systems. Originally found only in large organizations with the computer hardware needed to support large data sets, DBMSs have more recently emerged as a fairly standard part of any company back office. Database management system are found at the heart of most database applications. Sometimes DBMSs are built around a private multitasking kernel with built-in networking support although nowadays these functions are left to the operating system. A DBMS can be an extremely complex set of software programs that controls the organization, storage and retrieval of data (fields, records and files) in a database. The basic functionalities that a DBMS must provide are: 1.A modeling language to define the schema of each database hosted in the DBMS, according to the DBMS data model. oThe three most common organizations are the hierarchical, network and relational models. A database management system may provide one, two or all three methods. Inverted lists and other methods are also used. The most suitable structure depends on the application and on the transaction rate and the number of inquiries that will be made. The dominant model in use today is the ad hoc one embedded in SQL, a corruption of the relational model by violating several of its fundamental principles. Many DBMSs also support the Open Database Connectivity API that supports a standard way for programmers to access the DBMS. 2.Data structures optimized to deal with big amounts of data recorded to a permanent data storage device, which are very slow compared to the primary storage (volatile main memory). 3.A database query language and report writer to allow users to interactively interrogate the database, analyse its data and update it according to the users privileges on data. oIt also controls the security of the database. oData security prevents unauthorised users from viewing or updating the database. Using passwords, users are allowed access to the entire database or subsets of it called subschemas (pronounced "sub-skeema"). For example, an employee database can contain all the data about an individual employee, but one group of users may be authorized to view only payroll data, while others are allowed access to only work history and medical data. oIf the DBMS provides a way to interactively enter and update the database, as well as interrogate it, this capability allows for managing personal databases. However, it may not leave an audit trail of actions or provide the kinds of controls necessary in a multi-user organisation. These controls are only available when a set of application programs are customised for each data entry and updating function. 4.A transaction mechanism, that ideally would guarantee the ACID properties, in order to ensure data integrity despite of concurrent user access (concurrency control) and faults (fault tolerance). oIt also controls the integrity of the database. o The DBMS can maintain the integrity of the database by not allowing more than one user to update the same record at the same time. The DBMS can keep duplicate records out of the database; for example, no two customers with the same customer numbers (key fields) can be entered into the database. See ACID properties for more information (Redundancy avoidance). The DBMS accepts requests for data from the application program and instructs the operating system to transfer the appropriate data. When a DBMS is used, information systems can be changed much more easily as the organization's information requirements change. New categories of data can be added to the database without disruption to the existing system. Organizations may use one kind of DBMS for daily transaction processing and then move the detail onto another computer that uses another DBMS better suited for random inquiries and analysis. Overall systems design decisions are performed by data administrators and systems analysts. Detailed database design is performed by database administrators. Database servers are specially designed computers that hold the actual databases and run only the DBMS and related software. Database servers are usually multiprocessor computers, with RAID disk arrays used for stable storage. Connected to one or more servers via a high-speed channel, hardware database accelerators are also used in large volume transaction processing environments
Dear keerthik, Database Management Systems (DBMS) are important. They underpin all the activities of a library management system by providing the basic storage and retrieval technology. The library application software sends data to and receives data from the DBMS which, if it is working properly, is hardly noticed at all. Yet great claims are made for different types of database and their particular offerings. You should at least be able to understand the basics to understand what you might be getting - or missing when you choose a Library Management System (LMS). Database management systems have evolved fairly slowly over the last 30 years. The first commercial programming languages had file handling systems that took the responsibility from the programmer for maintaining file structures and indexes - e.g. ISAM (Indexed Sequential Access Method). A DBMS can be viewed as a more sophisticated and flexible form of file management together with a flexible tool for data extraction and often other "high level" tools. Without being too fussy about the niceties of DBMS, and ignoring those that do not figure much in library systems, these are the main types - in a rough chronological/sophistication order of their development. Note that these divisions are not completely mutually exclusive - some DBMS can be considered to fall into more than one camp - others into none. Some library system suppliers are continuing to maintain and develop their own DBMS. This may seem anachronistic but there are some advantages amongst the obvious dangers of support should the company fail. However, if the company should fail, then knowledge of the DBMS is less critical in support terms that the application knowledge - i.e. whichever DBMS a company is using, if they fail commercially, then there will be more problems with supporting the application than the DBMS. Of course a proprietary DBMS may well be Relational, Network or Hierarchical. If it uses SQL then it usually conforms to the relational model. Object orientation for a database means the capability of storing and retrieving objects in addition to mere data. As their name suggests - Database Management Systems were designed to look after data - numbers, words etc. Objects are complex and not well handled by standard Relational DBMS. Object Oriented DBMS have been emerging over the last few years and established products like Oracle with their Oracle8 have announced object capability. The implications for library systems are unclear. Most systems can handle images, video and other objects but do so in a non-standard way in many cases. The first system to announce the use of an Object Oriented DBMS is Taos from Data Research Associates.Go to site below for more on the subject: http://www.biblio-tech.com/html/dat…
A database management system (DBMS) is a computer program (or more typically, a suite of them) designed to manage a database (a large set of structured data), and run operations on the data requested by numerous clients. Typical examples of DBMS use include accounting, human resources and customer support systems. Originally found only in large organizations with the computer hardware needed to support large data sets, DBMSs have more recently emerged as a fairly standard part of any company back office.
Different Kind of DBMS : Relation DBMS Object-Oriented DBMS Object-Relational DMBS
SQL(Structured Query Language)is a language for DMBS.
Examples of RDBMS : MS-Access MSSQLServer Oracle MySQL
DBMS is Data Base management System,All Applications require DBMS as their backend on which they can store data.Most Important things are its keys like Primary Keys and Foreign Keys and much more there are 12 -13Codds rules
Hi Keerthik, For the basics of DBMS the best book to go through is: Database System Concepts,4th edition, McGraw Hill Inc by A.Silbershatz, H. Korth and S. Sudarshan
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