"An ER model is an abstract way of describing a database. In the case of a relational database, which stores data in tables, some of the data in these tables point to data in other tables - for instance, your entry in the database could point to several entries for each of the phone numbers that are yours. The ER model would say that you are an entity, and each phone number is an entity, and the relationship between you and the phone numbers is 'has a phone number'. Diagrams created to design these entities and relationships are called entity–relationship diagrams or ER diagrams.
Using the three schema approach to software engineering, there are three levels of ER models that may be developed. ...
Conceptual data model ... is the highest level ER model in that it contains the least granular detail but establishes the overall scope of what is to be included within the model set.
Logical ER model ... contains more detail than the conceptual ER model. In addition to master data entities, operational and transactional data entities are now defined.
The physical ER model is normally developed to be instantiated as a database. Therefore, each physical ER model must contain enough detail to produce a database and each physical ER model is technology dependent since each database management system is somewhat different.
Physical model ... is normally forward engineered to instantiate the structural metadata into a database management system as relational database objects such as database tables, database indexes such as unique key indexes, and database constraints such as a foreign key constraint or a commonality constraint." [Entity–relationship model. Wikipedia]
This crow's foot entity-relationship diagram (ERD) example "Educational data base" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park.
Using the three schema approach to software engineering, there are three levels of ER models that may be developed. ...
Conceptual data model ... is the highest level ER model in that it contains the least granular detail but establishes the overall scope of what is to be included within the model set.
Logical ER model ... contains more detail than the conceptual ER model. In addition to master data entities, operational and transactional data entities are now defined.
The physical ER model is normally developed to be instantiated as a database. Therefore, each physical ER model must contain enough detail to produce a database and each physical ER model is technology dependent since each database management system is somewhat different.
Physical model ... is normally forward engineered to instantiate the structural metadata into a database management system as relational database objects such as database tables, database indexes such as unique key indexes, and database constraints such as a foreign key constraint or a commonality constraint." [Entity–relationship model. Wikipedia]
This crow's foot entity-relationship diagram (ERD) example "Educational data base" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park.
Databases Access Objects Model with ConceptDraw PRO
ConceptDraw Basic gives the opportunity of interaction with any ODBC-compatible databases. For this the Database Access Objects Model is provided. All calls to the database are made by certain methods of objects of this model.- Er Diagram Notation For Foreign Key
- Database Management System Er Diagram
- ERD Symbols and Meanings | ConceptDraw PRO Database ...
- Er Diagram Using C
- Entity Relationship Diagram - ERD - Software for Design Crows Foot ...
- Er Diagram In Database Management System
- Er Diagram With Unique Key
- Entity Relationship Diagram Wiki
- Do You Include Foreign Key In Chen Notation
- Components of ER Diagram | Entity-Relationship Diagram (ERD ...
- Martin ERD Diagram | Crow's foot ERD - Educational data base ...
- Er Diagram For Education Sites
- Biology Illustration | Physics Diagrams | Mathematical Diagrams ...
- Design elements - ER diagram (Chen notation) | Entity Relationship ...
- Database Model Diagram
- Er Diagram Examples With Solutions In Dbms
- Entity-Relationship Diagram (ERD) | JSD - Jackson system ...
- ConceptDraw PRO ER Diagram Tool | Entity Relationship Diagram ...
- Entity-Relationship Diagram (ERD) | Components of ER Diagram ...
- Where Does A Crows Foot Point In An Erd Diagram