Data Flow Diagram of Information System Development and Management

In the test, the data flow chart is a big test site. Both small questions and big questions appear. How can we draw a data flow chart? Here, I sorted it out.

A Data Flow Chart consists of four basic symbols: data flow, processing (or processing), files, data source points, or endpoints. Frankly speaking, these four symbols are not in the form of a recognized image, but we must follow the painting in this teaching material during the examination.

Data Flow. Data streams are represented by arrows with names. However, you do not need to name the data streams of the streaming or outflow files. Other data streams must be marked. Data streams are named by nouns or phrases.

Processing (or processing ). It is also called data processing. It is represented by an ellipse. In a hierarchy, numbers must be written to identify its position in the hierarchy. For example, if the top layer is called the 0 layer and the parent graph of the 1st layer, the first layer is the subgraph, and so on. When the number is specified, the first layer is processed as 1, 2, 3 ...... (In the data flow diagram, we usually use P1, P2, P3 ...... The second layer of its subgraph is 1.1, 1.2, 1.3 ...... And so on. The name must contain a verb.

File. It is also called a data storage or data storage file, which is represented by an open strip. If it is a read file, the data flow direction should flow out of the file; if it is a write file, it is the opposite; if it is a read and write, the data flow is bidirectional. General files also need numbers: 1, 2, 3 ...... In the data flow diagram, F1, F2, F3 ...... Format

Data Source or end point. It is also called an external entity. It is represented by a box.

Line crossover is not allowed in a data flow diagram, so the same external entity or file sometimes needs to appear multiple times. At this time, we need to draw a diagonal line at the bottom right of the external entity symbol or draw a vertical line on the left of the file symbol to indicate repetition.

Steps for drawing a data flow diagram:

(1) first, draw the input and output of the system, that is, first draw the top layer, because it only needs to be processed. You only need to consider its input and output data.

(2) then draw the internal system, that is, draw the bottom layer data flow diagram on the top layer. It cannot be further decomposed. This is basic processing. The serial number starts from 0 (the serial number method has been mentioned in the previous processing), from top to bottom, from external to internal.

The data flow diagram is also described in detail in the soft engineer. It may be okay if you cannot read the book and watch the video. Finally, we hope we can all take the questions of the data flow chart and pass the "Information System Development and Management" exam!

Data Flow Diagram of Information System Development and Management