Beautify README
[erdiag.git] / README.md
1 # erdiag: Entity-Relationship Diagrams Generator
2
3 Inspired by [this repository](https://code.google.com/archive/p/merisier/).
4
5 This parser reads ER diagrams definition files, and produces two types of diagrams + SQL code.
6 [Graphviz](https://www.graphviz.org/) is used on server side to translate parsed graph descriptions into SVG objects.
7
8 **TODO** list:
9
10 - functional integrity constraints (CIF),
11 - inter-relations constraints (or, and, xor...),
12 - inheritance with the right symbol (triangle).
13
14 *Note:* temporary dependency to [underscore](http://underscorejs.org/); good library but used so far only for its shuffle() method.
15
16 -----
17
18 An entity is defined as follow
19
20 [Entity]
21 #attr1 (*)
22 attr2 (*)
23
24 with (\*) = optional SQL indications, and # denoting a (part of) a key.
25
26 A relationship is defined in this way
27
28 {Relation}
29 Entity C1
30 Entity2 C2
31 --
32 attr1 (*)
33 attr2 (*)
34
35 where attributes are optional, and C1 (resp. C2) = cardinality for entity 1 (resp. 2).
36 Defining relationships with more than two attributes is easy: just add entities.
37 Cardinality dictionary:
38 * \* = 0..n
39 * \+ = 1..n
40 * 1 = 1..1
41 * ? = 0..1
42
43 Special cardinalities are also available to indicate relative identification: `?R` and `1R`.
44
45 To mark a weak entity, just surround its name by extra-brackets
46
47 [[WeakEntity]]
48
49 In the same way, a weak relation can be written
50
51 {{WeakRelation}}
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53 The syntax for these two last is then the same as in the non-weak versions.
54
55 To indicate an inheritance relation, proceed as follow
56
57 is_a
58 Animal Cat Fish
59 Planet Mars Venus
60
61 Finally, blocks must be separated by new lines. For a usage example, see example.html (it should render as seen in example\_\*.svg)
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63 Note that the "drawMcd" method can take a second argument, which indicates the type of graph.
64 * "bubble" draws the standard graph, as seen [here](https://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model#/media/File:ER_Diagram_MMORPG.png) for example
65 * "compact" (default) use the same box for an entity and its attributes