an entity set may not have sufficient attribute 2 form a primary key is called weak entity set.ex entity set payment has 3 attribute pay-no,pay-date, pay-amount.pay-no is a sequential no generated 4 each loan.each payment entity is distinct,payments 4 different loans may share the same payment no.thus entity set doent have a primary key,so it is a weak entity set.
Placid04
bakhra,muzaffarpur,bihar.
weak entity
bonds
public
The concept of corporate entity is main purpose why it exists.
Any business that does not have another legal form of organization. For example- Joe Smith trading as Joes Plumbimg is taxed and has the legal liabilities of the individual. Joe Plumbing, LLC is a separate entity from Joe Smith and is treated as such for legal and tax.
why do we need weak entity in database when we can make it strong entity?
A weak entity set can always be make into strong entity set by adding to its attribute of its identifying entity set. For a weak entity set, we add columns to the table corresponding to the primary key of the strong entity set on which the weak set is dependent.
the enitity which is set primary key is said to be strong entity and the entity which does not set primary key is said to be weak entity.
An entity set that does not possess sufficient attributes to form a primary key is called a weak entity set. One that does have a primary key is called a strong entity set. The discriminator (or partial key) of a weak entity set is the set of attributes that distinguishes among all the entities of a weak entity set The existence of a weak entity set depends on the existence of a identifying entity set. It must relate to the identifying entity set via a total, one-to-many relationship set from the identifying to the weak entity set We depict a weak entity set by double rectangles in E-R diagram. We underline the discriminator of a weak entity set with a dashed line in E-R diagram.
The primary key of a weak entity set is formed by taking the primary key of the strong entity set on which its existence depends (see Mapping Constraints) plus its discriminator. 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 (a particular row) 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.
A weak entity can be identified uniquely only by considering the primary key of another (owner) entity.
weak entity
An entity set may not have sufficient attributes to form a primary key is called weak entity set. One with primary key is called strong entity set.
The table that has primary key is strong entity and the table that has no primary key is weak entity
In contrast to the strong or regular entity, a weak entity is one that meets two conditions: 1. The entity is existence-dependent; that is, it cannot exist without the entity with which it has a relationship. 2. The entity has a primary key that is partially or totally derived from the parent entity in the relationship.
dependents in an organization
an entity set may not have sufficient attribute 2 form a primary key is called weak entity set.ex entity set payment has 3 attribute pay-no,pay-date, pay-amount.pay-no is a sequential no generated 4 each loan.each payment entity is distinct,payments 4 different loans may share the same payment no.thus entity set doent have a primary key,so it is a weak entity set. Placid04 bakhra,muzaffarpur,bihar.