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

Erd, er diagram on cosmetics.

er diagram on cosmetics.

Describe five main functions of a database administrator, Describe five mai...

Describe five main functions of a database administrator. Ans: A database administrator (DBA) is a person who is accountable for the environmental aspects of a database. Genera

Develop a java application, 1 - Serial RS232 comm port comunication 2 - ...

1 - Serial RS232 comm port comunication 2 - NanoHTTPD serving a few processed pages 3 - System tray application to indicate status and access configuration forms 4 - SQLit

The internal or physical level in dbms, The Internal or Physical Level ...

The Internal or Physical Level The collection of files permanently stored on secondary storage devices is called as the physical database. The internal or physical level is t

Strong entity set and weak entity set, Strong entity set and weak entity se...

Strong entity set and weak entity set? Strong entity set and weak entity set: A strong entity set has a primary key. All tuples in the set are distinguishable through that key.

Explain the recoverable schedule, Explain the Recoverable Schedule A r...

Explain the Recoverable Schedule A recoverable schedule is one in which for each pair of transactions Ti and Tj such that Tj reads a data item formerly written by Ti, the comm

Describe the most important classes of parallel machines, Question 1 Discu...

Question 1 Discuss the classification of DBMS based on location of database Question 2 Explain with examples different SQL commands used for creating and deleting relations.

What are aggregate functions, What are aggregate functions? And list the ag...

What are aggregate functions? And list the aggregate functions supported by SQL? Aggregate functions are functions that take a collection of values as input and return a one va

Create a entity-relationship diagrams, This project requires you to create ...

This project requires you to create a database design.  Your design will be documented in a set of Entity-Relationship diagrams.  Draw a set of Entity-Relationship diagrams to mode

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