erd: An entity-relationship diagram generator from a plain text description.

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erd transforms a plain text description of a relational database schema to a graphical representation of that schema. It is intended that the graph make use of common conventions when depicting entity-relationship diagrams, including modeling the cardinality of relationships between entities.

A quick example that transforms an er file to a PDF:

$ curl '' >
$ cat
# Entities are declared in '[' ... ']'. All attributes after the entity header
# up until the end of the file (or the next entity declaration) correspond
# to this entity.


# Each relationship must be between exactly two entities, which need not
# be distinct. Each entity in the relationship has exactly one of four
# possible cardinalities:
# Cardinality    Syntax
# 0 or 1         0
# exactly 1      1
# 0 or more      *
# 1 or more      +
Person *--1 Location
$ erd -i -o simple.pdf

The PDF should now contain a graph that looks like this:

See the file for more examples and instructions on how to write ER files.


Change log
Dependencies base (>=4.5 && <5), bytestring (==0.10.*), containers (==0.5.*), graphviz (==2999.*), parsec (==3.1.*), text (==1.*) [details]
License LicenseRef-PublicDomain
Author Andrew Gallant
Category Database, Development
Home page
Source repo head: git clone git://
Uploaded by mmzx at 2019-03-26T07:41:56Z


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