edrdo / dbdia

Diagram generator for Entity-Relationship models and relational schemas.

dbdia

Author: Eduardo R. B. Marques

dbdia is open-source software under the terms of the Apache License 2.0.

Summary

dbdia is a diagram generator for database Entity-Relationship (ER) models and relational schemas.

Diagrams are expressed using a domain-specific language that is translated to image format (PNG, PDF, SVG, ...) using the dot tool from Graphviz .

The visual syntax employed by dbdia in ER and relational diagrams mostly follows the conventions of the Fundamentals of Database Systems, 7th edition textbook by Ramez Elmasri and Shamkant B. Navathe.

Run dbdia online using a Colab notebook

DSL used for ER models and relational schemas

Check here for a description of the DSL used by dbdia.

Examples

Check the examples directory in this repository or in the dbdia release archive. The examples can be also be tested directly in the Colab notebook.

Entity definitions

EntityName 
(
  _ KeyField _,
  OptionalField ?,
  . DerivedField ., 
  { MultiValueField },
  CompositeField ( SubField1, { SubField2 }, SubField3 ?, . SubField4 .),
  { ComplexField(SubField1, SubField2(SubField21, SubField22)) } 
)

Relationship definitions

EntityA ( ) // with no attributes (just for convenience)
EntityB ( ) // you can in any case ommit attributes in diagrams
EntityC ( ) // using the 'rel' diagram type generation

// Relationship: Rel1 
// Entities involved: EntityA and EntityB
// Cardinality: 1 to N
// Participation: partial for EntityA, total for EntityB
// Relationship attributes: none

EntityA --- 1 --- < Rel1 > === N === EntityB

// Relationship: Rel2
// Entities involved: EntityA and EntityB
// Cardinality: M to N
// Participation: partial for both entities
// Relationship attributes: none

EntityA --- M --- < Rel2 > --- N --- EntityB

// Relationship: Rel3
// Entities involved: EntityA and EntityC
// Cardinality: 1 to 1
// Participation: total for EntityA, partial for EntityC
// Relationship attributes: Rattr1, { RAttr2 } as shown.

EntityA === 1 === < Rel3( RAttr1, { RAttr2 } )> --- 1 --- EntityC

Relational schema definitions

table A
(
  _ PrimaryKey _,
  PlainField, 
  OptionalField ?, 
  ForeignKey1 --> A.PrimaryKey,
  ForeignKey2 --> B.PrimaryKey
)

// Type info is optional - this table has type annotations per each field
// Any identifier is accepted for the type designation.
table B
(
  _ PrimaryKey _ int, 
  PlainField varchar
) 

Download, install, and use

Dependencies

• A Java runtime environment, version 8 or higher.
• Graphviz

The following should work with recent versions of Ubuntu:

sudo apt install default-jre
sudo apt intall graphviz

Install

• Download the ZIP of the latest release here.
• Unzip the release archive to some folder <DBDIA_PATH>
• The dbdia script (for Linux/MacOS/POSIX) and the dbdia.bat variant for Windows can be found in <DBDIA_PATH>/bin. It may be convenient to add <DBDIA_PATH>/bin to your PATH environment.

Usage

dbdia [-option1=value1 ... -optionk=valuek] <typeOfDiagram> inputFile outputFile

Diagram types

• er: full ER diagram including entities, entity attributes, and relationships;
• ent: ER diagram including entities and their attributes only;
• rel: ER diagram excluding entity attributes;
• sch: relational schema diagram.

Options

• Type dbdia help for a list of options.

Compiling from scratch

Requirements:

• Java JDK (OracleJDK or OpenJDK) for Java 8 or higher
• Maven 3.x

Commands:

git clone [email protected]:edrdo/dbdia.git
cd dbdia
mvn package 

dbdia's Issues

Bug - parsing stops before EOF

Parser is failing for sequences such as:

a())
b()

(in this case no error is indicated after a() due to the incorrect parenthesis)

Hexadecimal being displayed in .svg file instead of UTF-8 (dbdia 0.3)

When saving the database schema/ER model into a .svg file, this is what I get:

It looks like instead of displaying the UTF-8 characters, dbdia is displaying the hexadecimal representation of them. I don't know whether this is an error with my setup or with the tool itself though. I tried saving with other formats (png and jpg) and they are working fine. Have you encounter something like this before?

Thanks in advance.

Line color is always black in the case of total participation

Web app for project

Hey! Wouldn't it be a good extension to the project to create a basic web application that based on the user input in the front end generates the ER model images in the back end and then displays it to the user? Maybe something similar to what already exists for markdown processing (https://dillinger.io/ for example), but using the dbdia syntax to create them.

Thanks!