Entity-relationship Model
Unit 3 Assignment 1 Define.
1. Logic Design -The entity relation design without regard to what RDBMS or system it will be on.
2. Physical Design-The design adapted to the RDBMS and system constraints and features.
3. Naming Convention – A set of rules or suggestions that promote consistency in the naming of database objects.
4. ERDs- (Entity Relation Diagram) One common method of depicting entities and relations in a diagram.
5. Crow’s Feet Notation - crow’s feet notation actually conveys more information about a relationship than the arrow notation.
6. One-to-One Relationship - . A one-to-one relationship specifies that for each row in the primary entity, there can be one and no more than one related record in the secondary entity. In a one-to-one relationship, the primary key of the first entity is often the primary key of the second entity.
7. One-to Many Relationship - A one too many relationship means that for each record in the primary entity there can be many associated records in the secondary or child entity.
8. Many-to-Many Relationship - A many-to-many relationship means that each record in the pri- mary entity can have many related records in a second entity and each record in the second entity can have many related records in the primary entity
9. Cardinality- Cardinality refers to the number of allowed related rows between entities. The usual one-to-many relationship assumes that for each one record in the primary key entity, there can be any number of related rows in the foreign key entity.
10. Maximum Cardinality - The highest number permitted.
11. Minimum Cardinality - The smallest number permitted.
12. Linking Entities- Linking entities are used to resolve many-to-many relationships into two one-to-many relationships.
13. Domain Entities- Domain entities are the entities that relate directly to the business of the database. In a database to track customer orders, for instance, domain entities would probably include ones like
1. Logic Design -The entity relation design without regard to what RDBMS or system it will be on.
2. Physical Design-The design adapted to the RDBMS and system constraints and features.
3. Naming Convention – A set of rules or suggestions that promote consistency in the naming of database objects.
4. ERDs- (Entity Relation Diagram) One common method of depicting entities and relations in a diagram.
5. Crow’s Feet Notation - crow’s feet notation actually conveys more information about a relationship than the arrow notation.
6. One-to-One Relationship - . A one-to-one relationship specifies that for each row in the primary entity, there can be one and no more than one related record in the secondary entity. In a one-to-one relationship, the primary key of the first entity is often the primary key of the second entity.
7. One-to Many Relationship - A one too many relationship means that for each record in the primary entity there can be many associated records in the secondary or child entity.
8. Many-to-Many Relationship - A many-to-many relationship means that each record in the pri- mary entity can have many related records in a second entity and each record in the second entity can have many related records in the primary entity
9. Cardinality- Cardinality refers to the number of allowed related rows between entities. The usual one-to-many relationship assumes that for each one record in the primary key entity, there can be any number of related rows in the foreign key entity.
10. Maximum Cardinality - The highest number permitted.
11. Minimum Cardinality - The smallest number permitted.
12. Linking Entities- Linking entities are used to resolve many-to-many relationships into two one-to-many relationships.
13. Domain Entities- Domain entities are the entities that relate directly to the business of the database. In a database to track customer orders, for instance, domain entities would probably include ones like