Weak entity, Database Management System

Assignment Help:

Entity types that do not have any key attribute, and therefore cannot be identified independently, are known as weak entity types. A weak entity can be recognized uniquely only by considering some of its attributes in conjunction with the primary key attributes of another entity, which is known as the identifying owner entity.

Usually a partial key is attached to a weak entity type that is used for unique identification of weak entities associated to a particular owner entity type. The following restrictions must hold:

  • The weak entity set and the owner entity set must participate in one to many relationship set. This relationship set is known as the identifying relationship set of the weak entity set.
  • The weak entity set necessary to have total participation in the recognized relationship.

 


Related Discussions:- Weak entity

Database, How many physical thing?

How many physical thing?

Database ass1, #quCreate a database design specification (Enhanced Entity R...

#quCreate a database design specification (Enhanced Entity Relationship Diagram (EERD) and Relational Data Model (RDM)) from the given business description. The RDM must be in 3rd

RAID technology, what characterizes the levels in RAID technology

what characterizes the levels in RAID technology

What is rdbms terminology for a row, What is RDBMS terminology for a row? ...

What is RDBMS terminology for a row? A tuple is a RDBMS terminology for a row

What is the use of keyword isa, What is the use of keyword ISA? The use...

What is the use of keyword ISA? The use of keyword ISA is to show that a class is a specialization of another class.

Express the subsequent query in sql assumes, Express the subsequent query i...

Express the subsequent query in SQL assumes which the data is stored within EMPLOYEE table with relevant fields (i) Display name, job, salary, and hire date of employee who are

User error-database errors, User error :  This contains errors in the progr...

User error :  This contains errors in the program (e.g., Logical errors) with errors made by online users of database.  These types of errors can be avoided by applying some check

Define granularity and hierarchy of granularity of locks, Define granularit...

Define granularity, hierarchy of granularity of locks & multiple granularity locking. Explain the modified two phase locking along with multiple granularity locking. Ans: The s

Tuples-attributes , Consider a relation s over the attributes A and B wit...

Consider a relation s over the attributes A and B with the following characteristics: 5,000 tuples with 10 tuples per page A 2-level B+ tree index on attribute

Hardware failure-database recovery and security, Hardware failure :  Hardwa...

Hardware failure :  Hardware failures are the failures when some disk or hardware chip fails. This may result in loss of data. One such trouble can be that a disk gets damaged and

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd