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

What is stored procedure, What is Stored Procedure? A stored procedure ...

What is Stored Procedure? A stored procedure is a named group of SQL statements that have been previously formed and kept in the server database. Stored procedures accept input

What is identity, What is Identity? Identity (or AutoNumber) is a colum...

What is Identity? Identity (or AutoNumber) is a column that automatically produces numeric values. A start and increment value can be set, but most DBA leave these at 1. A GUID

What are the time stamps associated with each data item, What are the time ...

What are the time stamps associated with each data item? W-timestamp (Q) denotes the largest time stamp if any transaction that implemented WRITE (Q) successfully. R-timesta

What are advantages of object models, What are advantages of object models?...

What are advantages of object models? Object models are efficient for communicating with the application experts and reaching a consensus about the significant aspects of the p

Define outer union operation of the relational algebra, Define outer union ...

Define outer union operation of the relational algebra. Compute the outer union for the relations R and S given below. Outer Join - If there are any values in one tabl

Differences between a file processing system and a dbms, List any two signi...

List any two significant differences between a file processing system and a DBMS. File Processing System vs. DBMS Data Independence - Data independence is the capacity t

Why are cursors necessary in embedded sql, Why are cursors necessary in emb...

Why are cursors necessary in embedded SQL? A cursor is an object used to store the output of a query for row-by-row processing through the application programs. SQL statements

Describe specialsation and generalization, Describe Specialsation and gener...

Describe Specialsation and generalization? Specialisation /generalization: This is a top down and bottom up approach to the design of database. It displays the IS_A relation

Explain the dependency relationship of object oriented, Explain the depende...

Explain the dependency relationship of object oriented A dependency is a relationship which states that a change in specification of one thing can affect another thing, but n

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