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- What is a ER diagram with example?
- Which software is used to draw ER diagram?
- What are the components of ER diagram?
- What is the example of ER model?
- How cardinality is calculated in ER diagram?
- How is primary key represented in ER diagram?
- How do I create an ER diagram in Word?
- What is ER model in Rdbms?
- What is the ER diagram and its rules?
- What is assumption in ER diagram?
What is a ER diagram with example?
An entity is an object or component of data. An entity is represented as rectangle in an ER diagram. For example: In the following ER diagram we have two entities Student and College and these two entities have many to one relationship as many students study in a single college.
Which software is used to draw ER diagram?
Adobe Illustrator. Adobe Illustrator is an excellent tool for creating ER diagrams although most users utilize it to create icons, logos, illustrators, and other graphic design elements. Creating an ER diagram is Illustrator is as simple as a walk in the park.
What are the components of ER diagram?
ER diagrams or ERD's are composed of three main elements: entities, attributes, and relationships.
What is the example of ER model?
Examples: an employee entity might have a Social Security Number (SSN) attribute, while a proved relationship may have a date attribute. All entities except weak entities must have a minimal set of uniquely identifying attributes which may be used as a unique/primary key.
How cardinality is calculated in ER diagram?
Crowsfeet is one of the most popular methods for creating E-R diagrams. With crowsfeet notation, cardinality is represented by decorations on the ends of lines. A cardinality of one is represented by a straight line perpendicular to the relationship line.
How is primary key represented in ER diagram?
The primary key is indicated in the ER model by underlining the attribute. A candidate key is selected by the designer to uniquely identify tuples in a table. It must not be null. A key is chosen by the database designer to be used as an identifying mechanism for the whole entity set.
How do I create an ER diagram in Word?
Go to the File menu, find Database, choose an ER diagram type and start. The ER diagram symbols library will open automatically on the left, providing a defined set of symbols commonly used in ER diagram. Drag a suitable shape for each entity or primary business concept relevant to your model.
What is ER model in Rdbms?
An ER model is a design or blueprint of a database that can later be implemented as a database. ... In terms of DBMS, an entity is a table or attribute of a table in database, so by showing relationship among tables and their attributes, ER diagram shows the complete logical structure of a database.
What is the ER diagram and its rules?
Entity relationship diagrams are used in software engineering during the planning stages of the software project. They help to identify different system elements and their relationships with each other. It is often used as the basis for data flow diagrams or DFD's as they are commonly known.
What is assumption in ER diagram?
Assumptions. A supplier can exist without providing components. A component does not have to be associated with a supplier. A component does not have to be associated with a product.
