What are the various symbols used to draw an e-r diagram, Database Management System

Assignment Help:

What are the various symbols used to draw an E-R diagram? Explain with the help of an example how weak entity sets are represented in an E-R diagram.

Various symbols used to draw an E-R diagram

13_Symbol ER Diagram.png


Weak Entity Sets - An entity set that does not have a key attribute is called weak entity set. A weak entity must participate in an identifying relationship type with an owner or identifying entity type Entities are identified by the combination of:
• A partial key of the weak entity type
• The primary key of the identifying entity type

Example:
Suppose that a DEPENDENT entity is identified by the dependent's first name and birhtdate, and the specific EMPLOYEE that the dependent is related to. DEPENDENT is a weak entity type with EMPLOYEE as its identifying entity type via the identifying relationship type DEPENDENT_OF

1958_Dependents.png


Related Discussions:- What are the various symbols used to draw an e-r diagram

Client server databases, Client Server Databases- The concept behind the C...

Client Server Databases- The concept behind the Client/Server systems is simultaneous, cooperative processing. It is an approach that presents a one systems view from a user's vie

Design and prototype, This assignment is worth 45% of your final grade for ...

This assignment is worth 45% of your final grade for this module.  Marks will be awarded as follows: Prototypes (wireframe and web based prototype) You are expected

Define serializable schedule, Define Serializable schedule Serializable...

Define Serializable schedule Serializable schedule: An interleaved schedule of much more than one transaction is known as a serializable schedule, if it is equal to some serial

What is class diagram, Class Diagram A class diagram is required to su...

Class Diagram A class diagram is required to support functional necessity of system. In a static design view, class diagram is used to model vocabulary of the system, simple c

Explain difference between volatile, Explain the difference between the thr...

Explain the difference between the three storage types - volatile, non volatile and stable.             Ans: Volatile storage: if storage media loses data while power goes off,

What is asterisk in sql, What is Asterisk in SQL? Asterisk (*): In SQL,...

What is Asterisk in SQL? Asterisk (*): In SQL, the columns for all the tables and views in the FROM clause will be displayed.

What is the meaning of recovery, What is the meaning of Recovery? In d...

What is the meaning of Recovery? In deferred update methods, if a transaction fails before arriving its commit point, it will not have altered the database in any way, so UNDO

Define hot backup, Hot Backup: Some sites cannot terminate the database wh...

Hot Backup: Some sites cannot terminate the database while creating a backup copy of the files. The cold backup is not a reliable option. So different kinds of backing up database

Database Models, Benefits and Limitations od Data Models?

Benefits and Limitations od Data Models?

Built online transaction processing, Question: A DBMS built for Online ...

Question: A DBMS built for Online Transaction Processing (OLTP) is generally regarded as unsuitable for data warehousing. Each system is designed with a different set of requir

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