Difference between a weak and a strong entity

A strong entity set has a primary key. All tuples in the set are distinguishable

by that key. A weak entity set has no primary key unless attributes of

the strong entity set on which it depends are included. Tuples in a weak entity

set are partitioned according to their relationship with tuples in a strong entity

set. Tuples within each partition are distinguishable by a discriminator, which is a set of attributes.



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