Bachman diagram
Encyclopedia
Bachman diagrams are diagram
s which are used to design the data
using a network or relational "logical" model, separating the data model
from the way the data is stored in the system. The model is named after database pioneer Charles Bachman
, and mostly used in computer software design
. A Bachman diagram is another name for a data structure diagram
.
In a relational model a relation is the cohesion of attributes that are fully and not transitive functional dependent of every key in that relation. The coupling between the relations is based on accordant attributes. For every relation a rectangle has to be drawn and every coupling is illustrated by a line that connects the relations. On the edge of each line arrows indicate the cardinality. We have 1-to-n, 1-to-1 and n-to-n. The latter has to be avoided and must be replaced by two 1-to-n couplings.
Diagram
A diagram is a two-dimensional geometric symbolic representation of information according to some visualization technique. Sometimes, the technique uses a three-dimensional visualization which is then projected onto the two-dimensional surface...
s which are used to design the data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
using a network or relational "logical" model, separating the data model
Data model
A data model in software engineering is an abstract model, that documents and organizes the business data for communication between team members and is used as a plan for developing applications, specifically how data is stored and accessed....
from the way the data is stored in the system. The model is named after database pioneer Charles Bachman
Charles Bachman
Charles William "Charlie" Bachman is an American computer scientist, who spent his entire career as an industrial researcher rather than in academia...
, and mostly used in computer software design
Software design
Software design is a process of problem solving and planning for a software solution. After the purpose and specifications of software are determined, software developers will design or employ designers to develop a plan for a solution...
. A Bachman diagram is another name for a data structure diagram
Data structure diagram
A Data Structure Diagram is a data model used to describe conceptual data models by providing graphical notations which document entities and their relationships, and the constraints that binds them....
.
In a relational model a relation is the cohesion of attributes that are fully and not transitive functional dependent of every key in that relation. The coupling between the relations is based on accordant attributes. For every relation a rectangle has to be drawn and every coupling is illustrated by a line that connects the relations. On the edge of each line arrows indicate the cardinality. We have 1-to-n, 1-to-1 and n-to-n. The latter has to be avoided and must be replaced by two 1-to-n couplings.