entity-relationship - 文本中的实体关系符号

Question

实体关系是否有标准(非图形)表示法？

现在我正在使用我自己的 janky 符号:

用户 >> 照片, (1-many)

用户 > 个人资料，(1-1 hasOne)

个人资料 < 用户 ，(1-1 属于)

照片 << 用户，(多 1 属于)

照片 <> 标签，(多对多)

Answer 1

差不多 10 年后，我也很难找到明文标准。这是我到目前为止所发现的(尽管有公平的警告，它主要是碰巧在文本中运行良好的图形标准)。

首先，描述对象之间关系的基数的常用术语是“多重性”。

This association relationship indicates that (at least) one of the two related classes make reference to the other. This relationship is usually described as "A has a B" (a mother cat has kittens, kittens have a mother cat).

• Wikipedia

尽管相当多的资料来源也使用“基数”一词。
关于 Multiplicity vs Cardinality 的这个 SO question 上的差异有一些很好的答案。我发现这个非常简洁:

...a multiplicity is made up of a lower and an upper cardinality. A cardinality is how many elements are in a set. Thus, a multiplicity tells you the minimum and maximum allowed members of the set.

• Jim L.

UML 的多重表示法

UML 的 multiplicity notation 在文本中运行良好。

+--------------+--------+-----------------------------------------+
| Multiplicity | Option |               Cardinality               |
+--------------+--------+-----------------------------------------+
| 0..0         | 0      | Collection must be empty                |
| 0..1         |        | No instances or one instance            |
| 1..1         | 1      | Exactly one instance                    |
| 0..*         | *      | Zero or more instances                  |
| 1..*         |        | At least one instance                   |
| 5..5         | 5      | Exactly 5 instances                     |
| m..n         |        | At least m but no more than n instances |
+--------------+--------+-----------------------------------------+

这似乎有一些变化:

微软的 Relational Notation

+---------------------------------+---------------------+
|          Multiplicity           |     Cardinality     |
+---------------------------------+---------------------+
| *                               | One to zero or more |
| 1..*                            | One to one or more  |
| 0..1                            | One to zero or one  |
| 1                               | Exactly one         |
| Two numbers separated by a dash | a range             |
+---------------------------------+---------------------+

IBM's

+------+--------------------+-------------------------------+
| Rose | Software Architect |          Description          |
+------+--------------------+-------------------------------+
| n    | *                  | Unlimited number of instances |
| 1    | 1                  | Exactly 1 instance            |
| 0..n | *                  | 0 or more instances           |
| 1..n | 1,,*               | 1 or more instances           |
| 0..1 | 0..1               | 0 or 1 instances              |
+------+--------------------+-------------------------------+

Smartdraw 的 Martin Style

陈风

来自 what I've read Chen的风格是“原始格式”。我 commonly see this expressed in text 为:

+----------+--------------+
| Notation | Description  |
+----------+--------------+
| 1:1      | One to One   |
| 1:N      | One to Many  |
| N:1      | Many to One  |
| M:N      | Many to Many |
+----------+--------------+

IDEF1X 等

有 IDEF1x(NIST 标准):

IDEF1X is a method for designing relational databases with a syntax designed to support the semantic constructs necessary in developing a conceptual schema.

这似乎描述了维基百科 Min-Max / ISO notation 引用的 here's a German article (英文链接目前已断开，但 Entity–relationship model article )，其中还列出了一些其他样式的图形符号，其中一些是文本友好的。



德语 article on (min,max) notation 也有一个比较 UML, Chen, (min,max) 和 MC (Modified Chen) 的有用表格:

+----------------------+-----------------+---------------------------------+-------------+-----------------+----------------------+
| (min,max) [Entity 1] | [UML, Entity 1] |          Chen-Notation          | MC-Notation | [UML, Entity 2] | (min,max) [Entity 2] |
+----------------------+-----------------+---------------------------------+-------------+-----------------+----------------------+
| (0,1)                | 0..1            | 1:1                             | c:c         | 0..1            | (0,1)                |
| (0,N)                | 0..1            | 1:N                             | c:mc        | 0..*            | (0,1)                |
| (0,N)                | 1..1            | 1:N + total participation       | 1:mc        | 0..*            | (1,1)                |
| (0,N)                | 0..*            | M:N                             | mc:mc       | 0..*            | (0,N)                |
| (1,1)                | 0..1            | total participation + 1:1       | c:1         | 1..1            | (0,1)                |
| (1,N)                | 0..1            | total participation + 1:N       | c:m         | 1..*            | (0,1)                |
| (1,1)                | 1..1            | total part. + 1:1 + total part. | 1:1         | 1..1            | (1,1)                |
| (1,N)                | 1..1            | total part. + 1:N + total part. | 1:m         | 1..*            | (1,1)                |
| (1,N)                | 0..*            | total participation + M:N       | mc:m        | 1..*            | (0,N)                |
| (1,N)                | 1..*            | total part. + M:N + total part. | m:m         | 1..*            | (1,N)                |
+----------------------+-----------------+---------------------------------+-------------+-----------------+----------------------+