This page is for data modellers or application designers. It explains how to use a relationship diagram to understand how your system's data is interconnectedconnected.
TODO: Check for info in these links
- https://www.sisense.com/en-gb/glossary/entity-relationship-diagram/
- https://www.smartdraw.com/entity-relationship-diagram/
- https://www.guru99.com/er-diagram-tutorial-dbms.html
Overview
Use an a relationship diagram to visualise how your system's information represent the information that your application will use and how it is connected. PhixFlow's relationship diagrams are similar to simplified version of an entity-releationship diagrams relationship diagram (ERDs). An ERD shows the relationship between an entities and their attributes. You can find a good explanation of ERDs in this article: ER Diagram Tutorial in DBMS. In PhixFlow, :
- entities are represented by streams
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- attributes are represented by stream attributes
- a stream must have a unique identifier - its primary key
- a relationship is usually between a primary key in one stream, and the same data being used in another stream, where it is a foreign key
- a relationship can be either one-to-one or one-to-many.
In PhixFlow, you can create a relationship diagram
- either by dragging in existing streams and then adding relationships
- or, as you add streams to the diagram, you can create the streams and their attributes.
For example, a simple relationship diagram can represent a company and its employees. A company has attributes, such as a name, address, turnover. In a PhixFlow stream, a company must also have an attribute that identifies the company uniquely. A company also has employees. In a relationship diagram this looks like:
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