Optional Non-Identifying Relationships in the Logical Model
In an optional non-identifying relationship, the attributes that are migrated into the non-key area of the child entity are not required in the child entity. Therefore, nulls are allowed in the foreign key.
You can set the default null option in the Model Editor. If you assign a non-identifying relationship, either a mandatory or optional non-identifying relationship is automatically assigned based on your default null setting. However, you can change the null option in the Relationships editor to override the default setting.
An optional non-identifying relationship is drawn differently depending on the notation for your model:
- IDEF1X notation draws a dashed line with a solid dot on the child end and a diamond on the parent end.
- IE notation draws a dashed line with a cross and a circle on the parent end. The child end indicates the cardinality with:
- Crows feet with a cross and a circle (Zero, One or more)
- Crows feet with a cross (One or more)
- A cross and a circle (Zero or one)
- A dashed line (Exactly n)
You can create an optional non-identifying relationship when you add a relationship using the Relationships editor, on the diagram window, or using the Model Explorer.
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