A database management system (DBMS), or simply database system, is characterized by the data model it suports . The first DBMSs, designed in the 1960s, were based on hierarchical or network models and have been viewed as extensions of file systems in which interfile links are provided through pointers . The data manipulation languages of these systems are low level and require users to optimize the access to the data by carefully navigating in hierarchies or networks.
Since its inception in 1970, the relational data model has continued to gain wide acceptance among database researchers and practitioners . Unlike the hierarchical and network models, the relational model has a solid theoretical basis and provides simple and uniform representation for all data independent of any physical implementation . These advantages enabled the development of high-level data manipulation languages, freeing the user from data access optimization, and provided a solid basis for automating the database design process.
In the early 1980s, the first relational database systems apeared on the market, bringing definite advantages in terms of usability and end user productivity . Since then, their functional capabilities and performance have been significantly improved . Most relational DBMSs today suport an integrated set of fourth-generation programming language tools to increase end user productivity.
Most also provide extensive suport for distributed database management . The development of fourth-generation tools and distributed database management capabilities has been facilitated by the relational model .