Yes I need some more information with example.
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Weak and Strong Entities
Description of Weak and Strong Entities.
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Answers
Hi MajorJohn
Typical Expample of weak and strong entity
EMPLOYEE and DEPENDANTS
The entity DEPENDANTS depends of the entity EMPLOYEE
DEPENDANTS = Wife, childrens, family.
In a Company DB the DEPENDANTS entity can exist by it self. In these case we make the relation DEPENDANTS --<depends>-- EMPLOYEE
Bye Bye
Strong entity...
Table Orders
ID int Primary Key
OrderNum varchar
OrderDate datetime
Table Items
ID int Primary Key
Desc varchar
weak....
Table OrderDetail
OrderID int Foreign Key (references Order.ID)
ItemID int Foreign Key (references Item.ID)
Qty int
In this example the items and orders tables are core level or "Stong" entities. They stand alone without requiring other defined objects.
The Order detail is a "Weak" entity as it requires the existence of both an order and item to exist.
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by: pjmazePosted on 1998-11-27 at 04:03:00ID: 1026018
hi,
The existance of a weak entity depends on the existence of a strong entity; it must relate to the strong via a on-to-many relationship set.
The primary key of a weak entity is formed by the primary key of the strong entity on which the weak entity set is existence depend, plus the weak entity set’s discriminator (partial Key).
A strong entity is one that has its own primary key and dont depand on any other entitie.
If you need more info, ask ..
see ya