why do we need weak entity in database when we can make it strong entity?
To convert a weak entity to a strong entity, you can assign it a primary key that uniquely identifies each instance of the weak entity, rather than relying on the primary key of its associated strong entity. This often involves creating a new attribute or a combination of attributes within the weak entity itself to serve as the primary key. Additionally, you may need to remove the dependency on the strong entity's key, ensuring the weak entity can exist independently. Lastly, update the database schema to reflect these changes.
The table that has primary key is strong entity and the table that has no primary key is weak entity
viable entity
Economic entity assumption is an assumption under the Generally Accepted Accounting Principles that separates the stakeholders from the business itself. The business is its own entity. Economic entity assumption is an assumption under the Generally Accepted Accounting Principles that separates the stakeholders from the business itself. The business is its own entity.
Which states limit the foreclosing entity to the proceeds from the auction?
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.
In a relational database, a weak entity is an entity that cannot be uniquely identified by its attributes alone; therefore, it must use a foreign key in conjunction with its attributes to create a primary key.Wikipedia
To convert weak entities to relations in a database schema, you first need to identify the weak entity's identifying relationship with its owner entity. This involves including a foreign key in the weak entity that references the primary key of the owner entity. Additionally, the weak entity should have its own primary key, typically created by combining its partial key with the primary key of the owner entity. Finally, this new relation can be established in the relational schema, ensuring that the weak entity can now be uniquely identified.
To convert a weak entity to a strong entity, you can assign it a primary key that uniquely identifies each instance of the weak entity, rather than relying on the primary key of its associated strong entity. This often involves creating a new attribute or a combination of attributes within the weak entity itself to serve as the primary key. Additionally, you may need to remove the dependency on the strong entity's key, ensuring the weak entity can exist independently. Lastly, update the database schema to reflect these changes.
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.
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 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.
the entity set departure which has only one attribute date is a weak entity set. this is because if each departure entity is distinct, different flights may have departure on same day, so different flights may share the same date valuebbye
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
When a weak entity lacks a candidate key and its instances cannot be uniquely identified without a relationship to another entity, it relies on that relationship to establish its identity. This typically occurs in a one-to-many relationship where the weak entity’s existence is dependent on the strong entity, which provides the necessary identifying attributes. As a result, the weak entity will often include a foreign key from the related strong entity as part of its primary key. Without this relationship, instances of the weak entity would be indistinguishable and cannot be adequately represented in the database.