This utility translates a plain text description of a relational database schema to a graphical entity-relationship diagram. The visualization is produced by using Dot with GraphViz. The output graph is a png image.

Here is an example of the output:

🎉 New: erd-dotnet can now automatically create the .er and png files when connecting to your postgress database.

erd-dotnet requires:

• GraphViz
• .Net 8 Runtime

All of these are available for Windows, Mac and Linux. Dot must be in your path.

For linux, you should also install the font "Noto Color Emoji". For example (Debian / Ubuntu):

sudo apt install fonts-noto-color-emoji

erd-dotnet ERD_FILE OUTPUT_FILE [OPTION]

Where:

• ERD_FILE is the path of the erd file (.er format)
• OUTPUT_FILE is the path of the output file (.png or .txt)

Options:

DB is a database connection string like: Host=192.168.XXX.XXX:5432;Username=user;Password=pwd;Database=my_database;, see Npgsql doc

🚨 By default, the output will be a png file. This requires Dot to be installed.

🌐 Alternatively you can use the dot option and use an online tool: Copy and paste the contents of the .dot file into an online graphviz viewer

The er format is a text file that can easily be updated. The name of the table is enclosed in [ ], followed by the names of the columns in the following rows. A primary key is preceded by *, a foreign key by +. Note that a column may be both a primary key and a foreign key.

The relationships between the tables are expressed as follows:

table1 *--1 table2

The cardinality is expressed as:

[Person]
*name
height
weight
birth
+location_id

You need .net 8 SDK.

Build:

dotnet build

Run:

dotnet run

docker run --rm -it -v $(pwd):/data mochsenbein/erd /data/simple.er /data/simple.png

docker build -t erd . &&  docker run --rm -it erd

This work is based on the work of:

• https://github.com/BurntSushi/erd
• https://github.com/kaishuu0123/erd-go