[an error occurred while processing this directive]
Database Management Systems Glossary
- Concurrency-control manager
- The program module that is responsible to control the interaction among the concurrent transactions and protect the database consistency.
- consistency constraints
- Requirements that apply to the data. For instance, in a student database, all students must have a Social Security number. Also known as business rules or integrity constraints.
- data
- A collection of known facts that can be recorded and have implicit meaning.
- datum
- data abstraction
- Views of the data of differing complexity, physical level, logical level, and view level.
- database
- A collection of related data.
- database administrator
- The person(s) assigned overall responsibility for the correct operation of the DBMS.
- database management system
-
Consists of a collection of interrelated data and a set of programs to access those data.
- Data Definition Language (DDL)
- A database schema is specified by a set of definitions expressed by a special language called a Data Definition Language.
- Data Dictionary
- A database schema is specified by a set of definitions expressed by a special language called a Data Definition Language. The schema is compiled and the results are stored in the data dictionary. The date dictionary contains metadata about the database and is used before before the actual data is read or modified in the DBMS.
- data independency
- The ability to modify a schema definition in one level without affecting a schema definition in the next higher level, i.e., logical data independence and physical data independence.
- Data Manipulation Language
- A language that enables users to access or manipulate data as organized by the appropriate data model.
- data model
- A collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints.
- data redundancy
- Data is repeated in different locations, files, or formats
- data inconsistency
- Various copies of the data no longer agrees, such as different files having different addresses for the same student.
- data isolation
- Data is in different locations and different formats.
- entity
- A person, place or thing. Includes the attributes that provide additional information about the person, place or thing.
- Entity-Relationship model
- The entity-relationship (E-R) data model is based on a perception of a real world that consists of a collection of basic objects (entities) and of relationships among these things.
- file processing system
- A system where each user defines and implements the specific files needed for each application.
- Hierarchical model
- Data is represented as collections of tree of data and links to represent relationships.
- metadata
- Network model
- Data are represented by collections of records and relationships are represented by arbitrary graphs.
- Object-oriented model
- The object-oriented (O-O) model is based on a collection of objects, where the object contains the instance variable and the bodies of code that operate on that object.
- physical data model
- Physical data models are used to describe how the data is stored at the lowest level.
- Record-based model
- Record-based models describe the data at the logical or view level, where the database is structured in fixed-format records of several types.
- Relational model
- The Relational model uses a collection of tables to represent both data and the relationships among those data.
- schema
- A database schema is similar to a record in Pascal or a struct in C. It describes the data and its logical format.
- storage manager
- Program module that is the interface between the low-level data stored in the database and the application porgrams.
[an error occurred while processing this directive]
last modified on Tuesday, 08-Jun-1999 11:59:41 EDT