What is the most common design trap?

What is the most common design trap?

fan trap
The most common design trap is known as a fan trap. A fan trap occurs when you have one entity in two 1:M relationships to other entities, thus producing an association among the other entities that is not expressed in the model.

What is a fan trap?

A fan trap is a type of join path between three tables when a “one-to-many” join links a table which is in turn linked by another “one-to-many” join. The fanning out effect of “one- to-many” joins can cause incorrect results to be returned when a query includes objects based on both tables.

What is design trap?

Design trap is a problem happens when the relationship is not properly and completely identified. It happens due to the presence incomplete knowledge of process. Therefore it shows inconsistency with the real world. Fan trap is the most common design trap.

How does a fan trap occur?

Fan trap occur in a situation when a model represents relationship between entity types however a path between certain entity occurrences is ambiguous. in this model it may be impossible to determine the branch a staff belongs to, in the situation when staff belong to division having more than 1 branches.

What is the difference between fan trap and chasm trap?

The Chasm trap occurs when two “many to one” joins converge on a single table. For example a customer can place many orders/and or place many loans. The Fan trap occurs when a “one to many” join links a table which is in turn linked by another “one to many” join.

What are overlapping subtypes?

Overlapping subtypes are subtypes that contain nonunique subsets of the supertype entity set; that is, each entity instance of the supertype may appear in more than one subtype. For example, in a university environment, a person may be an employee or a student or both.

What is supertype and subtype in database?

A supertype is a generic entity type that has a relationship with one or more subtypes. A subtype is a sub-grouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroups.

What are SQL traps?

The Chasm trap occurs when two “many to one” joins converge on a single table. For example a customer can place many orders/and or place many loans. Fan trap. The Fan trap occurs when a “one to many” join links a table which is in turn linked by another “one to many” join.

What is connection trap in database?

Connection traps appear when a pathway between two or more entities is either ambiguous or false existent. Relational databases seem like something straightforward, however, correctly written query may not always lead to a correct result.

What is overlap constraint?

Overlap constraint – within an ISA hierarchy, an overlap constraint determines whether or not two subclasses can contain the same entity. An example is a single Employee entity set with a relation Reports-To that relates supervisors and subordinates.

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