Section 2 Flashcards

1
Q

Have you ever had trouble finding a document in a filing cabinet or folder that someone else organized?
The files may have been organized to meet that person’s needs, but not your own.

A

Data modeling attempts to capture the needs of the business users so that the resulting database is one that everyone can use.

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2
Q

When you are able to recognize and analyze information, you can better ………… how things work and potentially make them ……….

A

understand / better

For example:
−How to make the line at the food counter go faster
−How to successfully exchange an item at the store
−How to organize and keep track of your growing CD collection

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3
Q

Also, recognizing and analyzing information helps prevent …………. and ………….

A

mistakes / misunderstanding

For a business, this is important because it saves time and money

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4
Q

A conceptual model Is the result of completing the ………. ………. ……….

A

Data Modeling process

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5
Q

A conceptual model Addresses the needs of a business (what is …………. ………….), but does not address its implementation (what is ………… …………)

A

conceptually ideal / physically possible

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6
Q

A conceptual model:

  1. Is based on current needs but it may reflect future needs
  2. Captures the …………. and ……….. ………… of a business
A
  1. FYI
  2. functional / informational needs
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7
Q

A conceptual model: −Identifies :

  1. important ………… (objects that become ……… in database)
  2. ………… among …………
A
  1. entities / tables
  2. relationships / entities
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8
Q

A conceptual model: −Does not specify :

  1. ………….. (objects that become ………… or ………. in database)
  2. ………… …………. (attribute that becomes ………. ………. in database)
A
  1. attributes / columns / fields
  2. unique identifiers / primary key
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9
Q

A conceptual model is important to a business because it:

  1. Describes exactly the ………. ……….. of the business
  2. Facilitates …………..
A
  1. information needs
  2. discussion
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10
Q

A conceptual model is important to a business because it:

  1. Prevents ………… and …………..
  2. Forms important “ideal system” …………..
A
  1. mistakes / misunderstandings
  2. documentation
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11
Q

A conceptual model is important to a business because it:

  1. Forms a sound basis for ……… …….. ……….
  2. Documents the ………. (also known as the “business rules”) of the business
A
  1. physical database design
  2. processes
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12
Q

A conceptual model is important to a business because it:

Takes into account ……………… and …………. governing this industry

A

regulations and laws

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13
Q

A logical model is called an ……….. ……….. ………. and is illustrated in an …………

A

entity relationship model (ERM) / ERD

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14
Q

A logical model Includes all entities and relationships among them

A

R 2

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15
Q

A logical model

  1. Specifies all ………… and …….. for each entity
  2. Determines …………. …………
  3. Determines relationship ……….. and ………….
A
  1. attributes / UIDs
  2. attribute optionality
  3. optionality / cardinality

cardinality: the number of elements (= separate items) in a mathematical set

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16
Q

A physical model:

Is an extension to a logical data model

  • Defines (3)
  • Identifies ……….., …………., and other database objects
A
  1. table definitions, data types, and precision
  2. views, indexes
17
Q

A physical model

  1. Describes how the objects should be implemented in ………. ………..
  2. Shows all ………… structures, including (3)
A
  1. specific database
  2. table / columns, primary keys, and foreign keys
18
Q
A
19
Q

Entities can be: (3)

A
  1. Tangible, like PERSON or PRODUCT
  2. Intangible, like SKILL LEVEL
  3. An event, like CONCERT
20
Q

It would not make sense to have an entity with only one ………………

A

instance

21
Q

Both the entity and the attribute represents something of ………….. to the business

A

significance

22
Q

An attribute is a specific piece of information that
helps:

…………. an entity

………….. an entity

………… an entity

………….. an entity

…………. an entity

A
  1. Describe
  2. Quantify
  3. Qualify
  4. Classify
  5. Specify
23
Q

An attribute has a ……….. ………..

A

single value

24
Q

Attributes have values. An attribute value can be a number, a character string, a date, an image, a sound, etc. These are called “…………” or “…………..”

A

data types / formats

25
Q

Data type: A classification:

  1. identifying one of various types of data,
  2. stating the possible values for that type,
  3. the …………… that can be done on that type, and
  4. the way the values of that type are ………….
A
  1. FYI
  2. FYI
  3. operations
  4. stored

Single-valued: Can only have one value at any point for each instance in the entity

26
Q

An attribute for an entity must be single-valued. In more precise terms, an instance of an entity can
have only one value for each attribute at any point in time. This is the most important characteristic of
an attribute. The attribute value, however, may change over time.

A

For example: The entity CAR may have attributes “model” and “color.” There can be only one value for
these (for example, “Beetle” and “green”) at one time, for each instance (i.e. for each individual car).
Although the model remains the same over the lifetime of the car, its color can change.

27
Q

Some attributes (such as age) have values that constantly change These are called …………. attributes

A

volatile

28
Q

Other attributes (such as order date) will rarely change, if ever, these are ………….. attributes

A

nonvolatile

29
Q

If given a choice, select the ………….. attribute

A

nonvolatile

For example, use birth date instead of age

30
Q

A good conceptual data model stays the same regardless of the type of database the system is eventually built—or implemented—on. This is what we mean when we say that the model is “……………………”

A

implementation-free

31
Q

There are four goals of ER modeling:

  1. Capture all ……….. ………..
  2. Ensure that data appears ……… ……….
  3. Model no data that is ……….. from other data already modeled
  4. Locate data in a …………, ………. ………..
A
  1. required data
  2. only once
  3. derivable
  4. predictable / logical place