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Flashcards in Midterm Deck (15)
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1

How does a deletion anomaly occur?

the unintended loss of data due to deletion of other data

2

How does an insertion anomaly occur?

The inability to add data to the database due to absence of other data

3

How does a modification anomaly occur?

unexpected side effect from trying to insert, update, or delete a row

4

Define a database

A self-describing collection of related records or, for relational databases, of related tables.

5

What is a foreign key?

Attribute that points to a primary key

6

What is the purpose of metadata within a database?

Data that is about the data.
example: description of an attribute

7

In order to implement a many-to-many relationship within a database, what type of entity needs to be placed between the entities that form the many-to-many relationship?

associative entity

8

What type of relationship is formed when an associative entity is placed between it?

many-to-many relationship

9

Describe a non-ID dependent weak entity

A weak entity is an entity that cannot exist by itself and a non-ID dependent entity is when a foreign key is not part of a primary key

10

(essn, pno) -> hours

essn and pno are the determinant

11

What is the purpose of a primary key?

To identify a row in a table

12

what is a transitive dependency?

a non-prime attribute that points to another non-prime attribute

13

3NF has to have ______

2 non-prime attributes

14

What is a composite key?

Two primary keys

15

Purpose of a referential integrity constraint

To insure that a foreign key points to a primary key