# Cardinality vs multiplicity?

### Question

• Hi,

I need to know the difference between cardinality and multiplicity. I tried to find answers on the internet, but mostly I got answers related to UML. But I need to know the difference between them in the context of a database or data modeling. Can anybody please tell me the difference ( if possible with the help of an ER Diagram)?

Thanking You,

Abhilash D K

Tuesday, March 11, 2014 6:54 AM

### Answers

• Abhilash,

As per Rambaugh, Multiplicity is the specification of the range of cardinality values for a particular set. They are actually one and the same except that we choose one of these terms in UML and Data modeling respectively.

You might wanna check this:

http://martinfowler.com/bliki/MultiplicityNotCardinality.html

Thanks,
Jay
<If the post was helpful mark as 'Helpful' and if the post answered your query, mark as 'Answered'>

• Marked as answer by Tuesday, March 11, 2014 8:33 AM
Tuesday, March 11, 2014 7:36 AM
• Hi Abhilash,

UML uses the term Multiplicity, whereas Data Modelling uses the term Cardinality. They are for all intents and purposes, the same.

Cardinality (sometimes referred to as Ordinality) is what is used in ER modelling to "describe" a relationship between two Entities.

Take a look at the following reference for a good simple explanation of terms and their use.

ER Diagram Tutorial

John Sansom | SQL Server MCM

• Edited by Tuesday, March 11, 2014 7:41 AM
• Marked as answer by Tuesday, March 11, 2014 8:33 AM
Tuesday, March 11, 2014 7:05 AM

### All replies

• Hi Abhilash,

UML uses the term Multiplicity, whereas Data Modelling uses the term Cardinality. They are for all intents and purposes, the same.

Cardinality (sometimes referred to as Ordinality) is what is used in ER modelling to "describe" a relationship between two Entities.

Take a look at the following reference for a good simple explanation of terms and their use.

ER Diagram Tutorial

John Sansom | SQL Server MCM

• Edited by Tuesday, March 11, 2014 7:41 AM
• Marked as answer by Tuesday, March 11, 2014 8:33 AM
Tuesday, March 11, 2014 7:05 AM
• Abhilash,

As per Rambaugh, Multiplicity is the specification of the range of cardinality values for a particular set. They are actually one and the same except that we choose one of these terms in UML and Data modeling respectively.

You might wanna check this:

http://martinfowler.com/bliki/MultiplicityNotCardinality.html

Thanks,
Jay
<If the post was helpful mark as 'Helpful' and if the post answered your query, mark as 'Answered'>

• Marked as answer by Tuesday, March 11, 2014 8:33 AM
Tuesday, March 11, 2014 7:36 AM
• Hi Sansom,

Thank you for the reply

Abhilash

Tuesday, March 11, 2014 8:33 AM
• Hi,

Thank you for the reply

Abhilash

Tuesday, March 11, 2014 8:33 AM