Thursday, 22 September 2011

Brief History of Database and DBMS

Due to the advancement in the electronic industry, the increased processing and storage capacity of computer has opened the doors for computer scientists to develop various techniques to store large amount of related data in an efficient and compact manner. The concept of database was introduced by IBM in 1960s. A brief description about the development of DBMS and database models is given below:

  • Hierarchical DBMS
A large  amount of search was conducted during 1960s. As a result NAA (North American Aviation) developed a software known as GUAM (Generalize Update Access Method). GUAM was based on the concept that smaller components come together a part of larger components and so on, until the final product is assembled. This is like a hierarchical structure and thus known as hierarchical structure.

  • Network DBMS
In the mid-1960s, another development was made known as IDS (Integrated Data Store) by General Eletric. This work was headed by CHARLES Bachman. This development led to a new type of database system known as network DBMS. This network database system was developed partly to address the need to represent more complex  data relationships that could be modeled with hierarchical structures, and partly to impose a database standard. To establish such standards, the Conference on Data System Languages (CODASYL), comprising representatives of the US Government and the world of business and commerce, formed a List Processing Task Force in 1965. It was renamed ad Data Base Task Group (DBTG) in 1967. The terms of reference for the DBTG were to define standard specifications for an environment that would allow database creation and data manipulation. A draft report was issued in 1969 and the initial report describing a network database implementation was issued in 1971. The DBTG proposal identified three components:
  • The network schema, which represents the logical organization of the entire database  as seen by the DBA. It includes a definition of the database name, the type of each record, and the components of each record type.
  • The sub-schema, which represents the part of the database as seen by the user or application program.
  • A Data Management Languages, which is used to define the data structure, and the to manipulate etc.
For standardization, the DBTG specified three distinct languages
  1. A schema Data Definition Language (DDL), which enables DBA to define the schema.
  2. A sub-schema DDL, which allows the application programmers to define the parts to the database they require.
  3. A Data Manipulation Language (DML), to manipulate the data of database.

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