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Can weak entity be converted into strong entity in DBMS?
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.
Explain the difference between a weak and a strong entity set?
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.
Can weak entity be converted into strong entity?
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.
What is weak entity sets in dbms?
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.
Why do we need weak entity sets?
why do we need weak entity in database when we can make it strong entity?
What is strong entities vs weak entities?
The table that has primary key is strong entity and the table that has no primary key is weak entity
How can you convert weak entity to 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.
Example of weak entity set?
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.
What occurs when a weak entity does not have a candidate key and its instances are indistinguishable without a relationship with another 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.
Why do you need weak entity set?
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
Examples of weak entity?
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.
What is the difference between a regular and a weak and a regular entity?
A regular entity, also known as a strong entity, has a primary key that uniquely identifies each instance and can exist independently of other entities. In contrast, a weak entity does not have a sufficient primary key and relies on a "strong" or "regular" entity for its identification; it is dependent on the strong entity for its existence and typically has a partial key. Weak entities are often used to represent a relationship that requires more context, while regular entities stand alone as distinct objects in a database.
