![]() Now, let’s see how to draw ER diagrams and EER diagrams. If you want to separate words use underscore mark.Write all attributes in the singular form.Write all relationships in a singular form.Write all entities in the singular form.Here are some rules for drawing ER and EER diagrams In the Physical design, we specify internal storage structure and paths, assign one or more indexes and tune indexes.Īt the conceptual design stage, we design the ER or EER diagrams. In the Logical design, we transform the conceptual design into relational, transform entities as tables, transform entity attributes into table column, and normalization. In the Conceptual design, we identify all entities, we define attributes and their properties and we define relationships between entities. The following are the types of entities, attributes, and relationships. If the same entity participates more than once in a relationship it is known as a recursive relationship. RelationshipsĪ relationship is an association that describes the interaction between entities. If an attribute can have more than one value it is called a multi-valued attribute.Īn attribute-based on another attribute. In the ER diagram, the attribute is represented by an oval. For example, Roll_No, Name, DOB, Age, Address, Mobile_No are the attributes that define entity type Student. AttributesĪttributes are the properties that define the entity type. In more technical terms it can be defined as an entity that cannot be identified by its own attributes. In the ER diagram, the entity is represented by a rectangle.Ī weak entity is an entity that depends on the existence of another entity. For example, People, Property, Organizations, Agreements and, etc. It refers to individuals, organizations, systems, bits of data or even distinct system components that are considered significant in and of themselves. EntityĪn entity is any singular, identifiable and separate object. ![]() ”Entity, Attribute, Relationship, Cardinality, and Participation”.□ Okay, Let’s see what are these. When you read this article you will find these words. ![]()
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