Database Management System (DBMS)
integrated software system that has facilities for defining the logical and
physical structure of data in a database and for accessing, entering, and
deleting data. Increasingly, formal methods are used for the description of the
data format and semantics.
The most common forms of database management system have traditionally been
separated into hierarchical (e.g. IMS),
network (e.g. CODASYL), and
relational (e.g. SQL/DS). There is an essential distinction between the first
two systems and the latter. The first two permit a 'transaction to "navigate"
through the data in the system, working through several stages, in order to
reach the required records; the records are then extracted, amended, or deleted,
as required. A relational system operates in a different way; criteria that
identify the required records are specified at the start of the transaction and
the operations are carried out on the specified records without further