The purpose of an Entity Relationship Diagram (ERD) is to plan out the relationships between entities in your data model. An ERD uses special symbols to demonstrate a kind of relationship between two entities: one-to-many, many-to-many, one-to-one. It can even get more specialized in showing the number of required records in a table (0 or more, 1 or more, 1 only, etc).
The ERD might end up resembling a spider web, a confusing-seeming diagram of boxes and lines, but after studying the diagram, one can clearly see the relationships.
Here are some tools that people have used to create an ERD:
|Free ER Diagram Tool||Web|
|FileMaker||macOS and Windows||FM Buttons and Lines|
|OmniGraffle||macOS||AppleScript'able and good for lots of things|
|Yed||Mac, Win, Linux, Java, Web||https://www.yworks.com/products/yed|
Inspiration Software, Inc. - The Leader in Visual Thinking and Learning | inspiration.com Fairly simple. Originally designed for teachers and students. Works well. Much less bloat than OmniGraffle or other such tools. Simple. Fast.
|Gliffy||Web, Chrome extension||Gliffy Online Extras|
|Pen and Paper / Whiteboard||N/A|
When I architect an ERD I will typically do it on a piece of paper and / or a whiteboard.
When I need to document an ERD I typically use Gliffy
|MySQL Workbench||Mac, Win, Linux|
Can create ER Models ( and of course able to connect to MySQL database and edit data / schema)
|Microsoft Visio||Windows (maybe iOS too?)||Has many built in useful drawing types.|
|Sparx Systems Enterprise Architect||Windows||Full blown database engineering management system for SQL but has lots of functionality that can be used for FM.|