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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 else can I help you with?
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.
Can an identifying relationship of a weak entity type will be of a degree greater than two give example?
Sure thing, honey. An identifying relationship of a weak entity type can definitely have a degree greater than two. For example, let's say we have a weak entity type called "Order Item" that depends on both "Order" and "Product" entities to uniquely identify it. In this case, the identifying relationship would have a degree of two (connecting "Order" and "Product") but the weak entity type itself would have a degree of three. Hope that clears things up for ya!
What is the difference between a required attributes and optional attributes?
strong entity : in this the attributes must have values for instance . weak entity : in this the attributes may or may not have values for instance .
What is aggregation in ER diagram?
-Used when we have to model a relationship involving (entitity sets and) a relationship set.-Aggregationallows us to treat a relationship set as an entity set for purposes of participation in (other) relationships.
Primary and secondary key in DBMS?
key is nothing but a attribute and attribute is the aspect of a member in an entity entity is represented by set of attributes. primary key is the one which is selected by the database designer to identify a entity in a entity set super key is one or more attributes which is used to identify the entity in an entity set uniquely candidate key minimal number of super keys... in some context super key and secondary key are equal. foreign key is the relational constraint between tables or entities A secondary key is made on a field that you would like to be indexed for faster searches! For any Further detail,you visit this website:http://www.iyogibusiness.com
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.
What is strong and weak entity set?
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.
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.
Could you have an example of a weak entity?
dependents in an organization
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.
Why do we need weak entity sets?
why do we need weak entity in database when we can make it strong entity?
Can an identifying relationship of a weak entity type will be of a degree greater than two give example?
Sure thing, honey. An identifying relationship of a weak entity type can definitely have a degree greater than two. For example, let's say we have a weak entity type called "Order Item" that depends on both "Order" and "Product" entities to uniquely identify it. In this case, the identifying relationship would have a degree of two (connecting "Order" and "Product") but the weak entity type itself would have a degree of three. Hope that clears things up for ya!
What is weak entity type?
Weak entity means an entity which doesnt uniquely exist and requires another foreign entity for its complete representation. For example, we have a University database and we have a table of departments having dept_id as its primary key. Now, a department cannot exist independently unless there is a university, so this entity needs university id as well to represent it.
When is the concept of weak entity used in data modelling?
A weak entity can be identified uniquely only by considering the primary key of another (owner) entity.
