Database Development Lecture 4
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Total Number of Instances := Current Instance Number Goto First Property OF Action Data :=
Foreign key – a primary key of an entity that is used in another entity to identify instances of a relationship.. – A foreign key is a primary key of one entity
For instance, we want the title of each book to be included in the database, so we include a Title attribute for the Books entity class!. • Attributes are used to help
It’s also a good idea to check if any low cardinality indexes are being used, because this type of an index will make the database read a large number of data blocks into the
EER Data Modeling Object Oriented EER Class Entity type Object Entity instance Association Relationship Inheritance of attributes Inheritance of attributes Inheritance of behavior
Relational Model Concepts Degree: The total number of attributes which in the relation is called the degree of the relation.. Cardinality: Total number of rows present in the
E-R MODEL ER MODEL Entity Attribute Key Composite Multivalued Derived Relationship One to Many Many to One Many to Many Weak Entity • A basic ER model is composed of entity types
The following data were collected for each individual: height of attachment minimum and maximum in creeping species, leaf/frond number, leaf length, stem length and/or number of shoots
