CODEWITHSUNDEEP
databaseentity-relationshipdiagramcardinality
android.replay
android.replay

Reputation: 31

Which is the right cardinality notation?

I am learning er diagrams, and I am at the point where I got really confused about cardinality notation, I now how is working but different examples on internet show how to write cardinality.

So in some of the examles the say ardinality is: max/min ---- min/max and in others is min/max----min/max which is the right one cause I am getting really confused about.

emloyes*/1--------have-------1/*departments o cardinality is external and partecipation internal max/min ---- min/max

But in this image example(0/1---1/10) and as well in some youtube videos is rappresented like min/max------min/max cause I see first the 0 so it cannot be max/min----min/max, so which is the right one?

If you want me to update the subject with any images or more information I will.

Upvotes: 0

Views: 366

Answers (1)

muszeo
muszeo

Reputation: 2352

'min .. max', so 0..1 for example would mean zero or 1. You can use any positive integers in the ranges, 1..10 for example, or 23 .. 2051. * is the wildcard meaning "any", i.e. 0..* means zero or many.

Upvotes: 1

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