Can u please describe the different types of traps with eg.
Thanks
Answer Posted / the_xxx
There are two main types of connection traps:
1. fan traps
2. chasm traps
Fan traps
A fan trap occurs when a model represents a relationship
between entity types, but the pathway between certain entity
occurrences is ambiguous. It occurs when 1:m relationships
fan out from a single entity.
Missing ALT text
Figure : Fan Trap
A single site contains many departments and employs many
staff. However, which staff work in a particular department?
The fan trap is resolved by restructuring the original ER
model to represent the correct association.
Missing ALT text
Figure : Resolved Fan Trap
Chasm traps
A chasm trap occurs when a model suggests the existence of a
relationship between entity types, but the pathway does not
exist between certain entity occurrences.
It occurs where there is a relationship with partial
participation, which forms part of the pathway between
entities that are related.
Missing ALT text
Figure : Chasm Trap
* A single branch is allocated many staff who oversee
the management of properties for rent. Not all staff oversee
property and not all property is managed by a member of staff.
* What properties are available at a branch?
* The partial participation of Staff and Property in the
oversees relation means that some properties cannot be
associated with a branch office through a member of staff.
* We need to add the missing relationship which is
called `has' between the Branch and the Property entities.
* You need to therefore be careful when you remove
relationships which you consider to be redundant.
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