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It520 Unit 1 Assignment

In: Computers and Technology

Submitted By dinstaardude
Words 560
Pages 3
Question 1 Define each of the following terms. In addition, provide an example of each term.

a. Entity Set - A collection of like entities. Example: If a customer is an entity, then the entity set would be a collection of two or more customers.

b. Entity Instance - Each row in the relational table. Example: A row of information beginning with the entity itself and showing the relations of that specific entity and none other.

c. Attribute - A characteristic of an entity. Example: The information used to describe the entity. If the entity is CLIENT, then the attributes would probably contain things like ‘address’, or ‘name’ or other specific bits of information.

d. Connectivity - This is the name given as a label for the different connection types, one to one, one to many, and many to many. Example: If the Relationship is between a mechanic and how many cars they can fix, then the connection would be many to many, because one mechanic can fix many cars.

e. Identifier - Is also called the Primary Key, and is an attribute, or combination of attributes, that uniquely identifies a row. Example: A student ID number, or driver’s license number is an example of a unique identifier.

f. Foreign Key - This is a primary key of one table that is present in other tables so the database has common attributes. Example: an example here is if a table identified the brand of car people buy. The foreign key would be the attribute that allows somebody to

g. Associative Entity (Composite Entity) - This is an entity that seeks to convert a many to many relationship to a 1 to many relationship by either compiling foreign keys or creating a new primary key on a new table. Example: Creating a table that tracks 2 or more foreign keys to identify a third attribute.

h. Cardinality Constraint - This a command used to restrict information based on a number value

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