Professor Materials Week 2 Flashcards

1
Q

What are the advantages of databases?

A

program/data independence
reduced data duplication
data consistency
data sharing
faster application development
standards enforcement
better data quality
improved accessibility
less maintenance

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2
Q

What are the disadvantages of databases?

A

Database adminstrator and other specialized personnel needed
Installation and management costs
Conversion costs
need for explicit backup and recovery
organizational conflict

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3
Q

What are the three types of database relationships?

A

One-to-one (rare)
one-to-many
many-to-many

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4
Q

What is a weak entity?

A

An entity that cannot exist in a database i.e. an order that has no customer.

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5
Q

What is a mandatory relationship?

A

A relationship that must exist, i.e. an order must have a customer.

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6
Q

What is a composite entity?
E

A

Entities that exist to represent the relationship between two or more entitites.

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7
Q

What are the two development approaches?

A

top-down (Start at general and drill down)
bottom-up (start with details and work up)

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8
Q

What is the database development lifecycle?

A
  1. Create a data model (E-R model)
  2. Transpose data into relationships
  3. Normalize relations
  4. Implement the relational schema within a DBMS
  5. Define forms, queries, reports, menus
  6. Populate data
  7. Maintenance
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9
Q

What is the UoD?

A

Universe of Discourse, a short description of the subset or mdoel of reality that we are interested in implementing

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10
Q

What is data modeling?

A

The process of determining what items are of importance to the users, rules that users need to be enforced and creating a model to capture that

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11
Q

What is the schema?

A

Design for the database , including its tables, relationships, domains and constraints.

Syntax: RELATION_NAME(primary_key(underlined), attribute1, attribute2)

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12
Q
A
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