The Design Classic Of Databases

DESIGN classic diagram of flow of data before that creation of UML (the current paradigm of diagrams to convert them into programming code) engineers used workflow diagrams, to visually represent the flow of data through systems for the treatment of information. They were the diagrams in computing cominezos. Flow charts describe what operations and are required to solve a given problem in that sequence.A flowchart or organizational chart is a representation that illustrates the sequence of operations to be carried out to achieve the solution of a problem.Diagram of streams of data (DFD) is one of the most important tools used by systems analysts. The use of the data flowcharts as modeling tool was popuralizado by De Marco (1978) and Gane and Sarson (1979), through its methodologies of structured analysis of systems. They suggested that data flow diagram is used as the first tool by system analysts to model components of the System. These components are the processes of the system, the data used for these processes, any external entity that interacts with the system and system information flows. Now we will describe each of the four parties that form a DFD to)-processes show which makes the system.

Each process has one or more inputs data and produces one or more outputs data. They are represented with circles. (b) – a file or data store is a repository of data. Processes can enter or retrieve them. Each data store is represented by a thin line and has a unique name.

c-external entities are outside the system, but provide or use data from it. They are entities over which the designer has no control. (d) – and the most important are data flows that model the movements of information in the system and are depicted by lines connecting the components. The flow direction is indicated by an arrow, and the line with the name of the data flow. It is recognized that the classical charts or DFD were a little abstract, and thank goodness for the sake of designers who have evolved in a more clear and concise way so that they should not give errors when translating them to a programming language. As a preview to the next type of diagrams you dire that are called entity-relationship model and it is what has been used now for designing applications, also called diagrams e-r, and was a key concept when it comes to the classes and objects appear but this breakthrough I’ll leave for a next installment.

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