Hi,
What is Weak Entity set?
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Arjun PanwarPosted Jan 28, 2012, 3:55 AM
Satyapriya NayakPosted Jan 25, 2012, 12:56 PM
An entity set that does not have a primary key is referred to as a weak entity set.
The existance of a weak entity set depends on the existence of a strong entity set; it must relate to the strong set via a on-to-many relationship set.
A distriminator of a weak entity set is the set of attributes that distinguishes among all the entities of a weak entity set.
The primary key of a weak entity set is formed by the primary key of the strong entity set on which the weak entity set is existence depend, plus the weak entity set's discriminator.
Refer
http://www.cs.sfu.ca/CourseCentral/354/zaiane/material/slides/Chapter2/tsld024.htm
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VulpesPosted Jan 25, 2012, 11:17 AM
In contrast, an entity set which does have sufficient attributes to uniquely identify its members and to form a primary key is said to be 'strong'.