## Systema: The Six Relationships

For years I have been thinking that there are only four relationships in data modeling:

1. Many to Many
2. One to Many
3. One to One
4. Recursive

At least that’s what the books seemed to say. However I have been reconsidering since I began exploring the Zachman Framework on my own. It has become apparent to me through many practical applications that the textbooks are not always right. Below are the six basic data modeling relationships:

As you can see there are three cursive and three recursive relationships. The cursive relationships are between two separate entities. The recursive relationships are between an entity and itself. Restating them, they are:

1. Cursive Many to Many
2. Cursive One to Many
3. Cursive One to One
4. Recursive Many to Many
5. Recursive One to Many
6. Recursive One to One

Many to many relationships are resolved as illustrated below:

How does this fit into the Zachman Framework? Let’s examine the framework as I illustrate it below:

As you can see relationships each serve a purpose. Concepts are associations between intstances of differing entities. Contexts are one to many relationships between instances of differing entities. Logics are one to one relationships between instances of differing entities. Physics are associations between instances of the same entity. Spherics are one to many relationships between instances of the same entity. Episodics are one to one relationships between instances of the same entity.

Another way to consider this diagram is the first three relationships involve attributes, while the second three relationships involve domains.

### 4 Responses to “Systema: The Six Relationships”

1. Interesting points. I guess I’ve always looked at relationships as having two typing schemes:

1. How many-ness (cardinality & optionality)
2. How many-ntity-ness (two entities or one)

(at least with IDEX1F & IE notations).

I don’t see recursive relationships as that different than other relationships, other than graphically. Sure, there are some SQL coding nuances, but overall they are just another type of relationship to me. I have seen texts treat them as significantly different, though.

And what about cardinalities with specific numbers (one-to-six instead of one-to-many) relationships? Don’t those mean that there are really an infinite number of relationship “types”?

Personally, I almost never use relationships with specific numbers, as I almost always find exceptions or conditions where they won’t always be true.

Karen Lopez

2. grant czerepak Says:

Hi Karen,

I was concentrating on these relationships for a specific reason. I wanted to examine how the first three relationships deal with attributes while the second three deal with domains. I am still working on a full understanding for myself at this time.

Grant.

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