Relationship cardinality

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Cardinality is when you define a relationship, and you specify whether one or more configuration items can be in the source classification and target classification.

The following list describes the possible values of cardinality are:
  • 1:n - one to many
  • 1:1 - one to one
  • n:n - many to many
The following table describes the cardinality values:
Cardinality Relationship rules
1:n
  • A configuration item that belongs to the source classification can have the relationship with multiple configuration items that belong to the target classification.
  • A configuration item that belongs to the target classification can have the relationship with only one configuration item that belongs to the source classification.
  • For example, you specify a 1:n cardinality for an installed with relationship between computer systems and operating systems. Therefore, a computer system instance can be installed with many operating system instances. This 1:n value also implies that an operating system instance can have an installed with relationship with only one computer system instance.
1:1
  • A configuration item that belongs to the source classification can have the relationship with only one configuration item that belongs to the target classification.
  • A configuration item that belongs to the target classification can have the relationship with only one configuration item that belongs to the source classification.
  • For example, you specify a 1:1 cardinality for a runs on relationship between operating systems and computer systems. Therefore, an operating system instance can run on only one computer system instance.
n:1
  • Multiple configuration items that belong to the source classification can have the relationship with only one configuration item that belongs to the target classification.
  • A configuration item that belongs to the target classification can have the relationship with multiple configuration items that belong to the source classification.
  • For example, you specify an n:1 cardinality for an installed on relationship between operating systems and computer systems. Therefore, multiple operating system instances can be installed on one computer system instance. This n:1 value also implies that an operating system instance can be installed on only one computer system instance.
n:n
  • Multiple configuration items that belong to the source classification can have the relationship with multiple configuration items that belong to the target classification.