Notations - borkdominik/bigER GitHub Wiki

📖 Table of Contents

1. Changing the Notation
2. Overview of ER Notations
3. UML Notation

The notation can be changed in the header of .erd files:

erdiagram Example

notation = default // change the notation

entity A {}
entity B {}

relationship Rel {
   A[1] -> B[N] // specify cardinality and participation constraint
}

The currently supported notations are:

• Default: default (used if the notation is not specified)
• Bachman: bachman
• Chen: chen
• Crow's Foot: crowsfoot
• UML: uml

Syntax	Description	Bachman	Chen	Crow's Foot
[0..1]	Zero or One
[0..N]	Zero or Many
[1] or [1..1]	One and only One
[N] or [1..N]	One or Many

UML is often used for data modeling and its concepts are similar to ER modeling with slight variations. In bigER, the UML notation has the following differences:

• Binary relationships are rendered as direct connections with no connecting diamond node
• Visibility of attributes can be specified
• Aggregation and Composition relationships can be specified

Binary without labels	Binary with labels

Ternary without labels	Ternary with labels

The UML Notation allows specifying the visibility of attributes. The visibility is shown in the diagram, and it has no effect on the output of the generators.

entity Example1 {
    + attr1: INT key
    - attr2: VARCHAR
    # attr3: VARCHAR
    ~ attr4: DATE
}

entity Example2 {
    public attr1: INT key
    private attr2: VARCHAR
    protected attr3: VARCHAR
    package attr4: DATE
}

Name	Syntax	Diagram
Aggregation (right)	A -* B
Aggregation (left)	A *- B
Composition (right)	A -o B
Composition (left)	A o- B