Database
This article describes database systems and databases from an EDP perspective. In the legal sense, non-electronic data collections are also considered databases. More on the subject can be found under database work.
A database, also called a database system, is a system for electronic data management. The essential task of a database is to store large amounts of data efficiently, without contradiction and permanently and to provide required subsets in different, demand-oriented display forms for users and application programs.
A database consists of two parts: the management software, called database management system (DBMS), and the set of data to be managed, the database (DB) in the narrower sense, sometimes also called "database". The management software organizes internally the structured storage of the data and controls all read and write accesses to the database. For querying and managing the data, a database system offers a database language.
The most common form of a database is a relational database. The structure of the data is defined by a database model.
The term database described here (consisting of DBMS and data) must be distinguished from database applications: The latter are computer programs (often belonging to application software) that manage and store their respective individually required data using a database system. Examples: Order management, purchase order management, customer and address management, invoicing.
In linguistic usage, data not managed by database systems is occasionally (and conceptually incorrectly) referred to as a "database": a set of thematically related files.
History
Based on problems with processing data in simple files, the concept of managing data through a separate software layer between the operating system (file management) and the application program was introduced in the 1960s. This concept countered the undesirable development that data storage in the form of files was usually designed for a specific application and that a significant part of the daily business was burdened with recopying, shuffling and restructuring the files.
One of the first large DBMS was IMS with the language DL/I (Data Language One). The databases managed with it were hierarchically structured. In parallel, CODASYL defined a model for network structured databases.
A major advance was made in the 1960s and 1970s by Edgar F. Codd with his research at the IBM Almaden Research Center. Codd developed the foundations of the first experimental relational database system, System R. The Berkeley Group followed with Ingres and the QUEL query language.
Oracle (then still under the company names SDL and RSI) exploited the results of System R and led SQL to commercial success. IBM followed with SQL/DS and DB2. Relational database systems replaced hierarchical and network systems in the 1980s and the majority of public authorities, corporations, institutes and medium-sized companies converted their IT to database systems.
While a few commercial database software vendors effectively dominated the market in the 1990s (namely IBM, Informix, dBASE, Microsoft SQL Server, and Oracle), open source database management systems became increasingly important in the 2000s. MySQL and PostgreSQL in particular gained significant market share. In response, the leading commercial vendors began offering royalty-free versions of their database software. Since about 2001, the importance of NoSQL systems has grown due to the lack of scalability of relational databases.
A family tree of database systems can be found as Genealogy of Relational Database Management Systems at the Hasso Plattner Institute.
Meaning
Database systems are a central part of enterprise software today. Thus, they represent a critical part of many companies and authorities. The ability of a company to take action depends on the availability, completeness and correctness of the data. Data security is therefore an important and legally required component of the IT of a company or authority.
Questions and Answers
Q: What is a database?
A: A database is a system for storing and taking care of data (any kind of information). It can be used to sort, change or serve the information stored in it.
Q: How did people store data before digital computers?
A: Before digital computers, card files, printed books and other methods were used to store data.
Q: What is a database system?
A: A database system is a computer program for managing electronic databases. It can be used to organize the data in some way.
Q: What does a "card" look like in an old-fashioned filing cabinet?
A: In an old-fashioned filing cabinet, there was usually one card for each employee with information such as their date of birth or name on it.
Q: How does the modern equivalent of this "card" look like?
A: The modern equivalent of this "card" appears on the screen rather than in physical form.
Q: What is a database model?
A: A database model refers to different ways that the information on the "card" can be stored by the computer. The most commonly used model is called the relational database model which uses relations and sets to store data.
Q: How do normal users refer to these models when talking about them? A: Normal users will typically refer to these models as 'database tables' rather than using technical terms such as relations or sets when discussing them.
