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Databases > Chapter 1 > Flashcards

Chapter 1 Flashcards

1
Q

What is a database and what is it from the beginning?

A

A database is a collection of data, it is just a table. Once you put it in the table, a database is created.

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2
Q

What do you need in order to control a database?

A

In order to get it controlled, we need DBMS. DBMS is a software.

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3
Q

What is an example of a manually maintained database?

A

Shopping list

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4
Q

What is an example of a computerized database?

A

Bank account data

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5
Q

What are the tasks of DBMS?

A

*Data Definition Language (DDL), when creating a database, need to decide how many rows and columns that are needed for the table. Can add/delete from the table itself. (Table)

*Data Manipulation Language (DML), for example adding/remove/modifying the data. It is about the data. (Data)

*Database Querying, retrieving required data from the database. Required means based on condition. Ex. “attendance >5”.

Database Control, how to control the database. Who sees what/who has access to it?

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6
Q

What are the purposes of database languages?

A

Communicate.
Retrieve data from the database.
Add data to the database.
Modify data in the database.
Delete data from the database.

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7
Q

What is data?

A

Raw facts. Ex. “How many students in the class?”

Have not yet been processed to reveal their meaning to the end user

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8
Q

What is data management?

A

Generation, storage, and retrieval of data

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9
Q

What is information?

A

Produced by processing raw data to reveal its meaning.
Requires context.
Should be accurate, relevant, and timely to enable good decision making.

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10
Q

What does database definition mean?

A

*Creating new database and tables
*Alter existing tables in the database
*Drop existing database and tables

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11
Q

What does database manipulation mean?

A

*Adding new data to the database
*Modifying existing data in the database
*Deleting existing data from the database

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12
Q

What is Database Querying?

A

Querying means retrieving required data from the database.

For example, you may want to retrieve “name and ID number of students” from the database.

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13
Q

What is Database Control?

A

*Limiting access to data only to authorized users
*Sharing data among the users in such a way that database integrity is maintained

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14
Q

What are the elements of the database approach?

A

Entities, Relationships,Data models

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15
Q

What is an entity?

A

Noun form describing a person, place, object, event, or concept

Composed of attributes

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16
Q

What are Relationships?

A

Between entities

Usually one-to-many (1:M) or many-to-many (M:N), or one-to-one (1:1)

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17
Q

What are the Main data models used by most of the DBMS?

A

Network Data Model

Hierarchical Data Model

Relational Data Model

18
Q

How can the relationship in the Network Data model be?

A

Binary type or Many to one

19
Q

How can the relationship in the Hierarchical Data model be?

A

Data is in collections of records. Relationships are represented as sets. A restricted type of Network Data Model.

Each Record Type can have only one Parent and thus hierarchy.

20
Q

How can the relationship in the Relational Data model be?

A

Data and relationships are represented using tables. Data items are represented as columns of tables. A relational data model based database consists of one or more tables.

A relationship between every table. Will get information from the other table, through the relationship.

21
Q

What is Metadata?

A

Describes the data characteristics and the set of relationship that links the data found within the database. For example, the type of values (numeric, text…) stored on each data element, and whether the data element can be left empty.

22
Q

What are the roles of DBMS?

A

Might be written using: Visual Basic, Java, or C#.

Intermediary between the user and the database.

Enables data to be shared.

Presents the end user with an integrated view of the data.

Receives and translates application requests into operations required to fulfill the requests.

Hides database’s internal complexity from the application programs and users.

23
Q

What are the advantages of DBMS?

A

DBMS helps make data management more efficient and effective.

  • Better data integration and less data inconsistency (inconsistency = Different versions of the same data appear indifferent places).
  • Improved Data Sharing: end users have better access to more managed data.
  • Improved Data Security: More users access the data, greater the risks of data security breaches.
  • Improved Data Access
  • Improved Decision Making. Important: Data Quality (accuracy, validity, and timeliness of data).
24
Q

What are the types of databases?

A

Single user supports only one user at a time.

Multiuser supports multiple users at the same time.

Workgroup databases: Supports a small number of users or a specific department.

Enterprise database: Supports many users across many departments.

25
Q

What is a General-purpose database?

A

Everyone can have access to it. Contains a wide variety of data used in multiple disciplines.

26
Q

What is a Discipline-specific database?

A

Contains data focused on specific subject areas.

27
Q

What is an Operational database?

A

Designed to support a company’s day-to-day operations.

28
Q

What is Unstructured data?

A

Data that exists in its original (raw) state, i.e., the format it was collected. The data exists in a format that does not lend itself to the processing that yields information.

29
Q

What is Structured data?

A

The result of formatting unstructured data to facilitate storage, and generation of information. Structure is applied based on type of processing to be performed.

30
Q

What is Semistructured data?

A

Data that been processed to some extent.

31
Q

What is row in databases?

A

Record

32
Q

What is column in databases?

A

Field

33
Q

What is everything in the cell in databases?

A

Data in Access

34
Q

What is Analytical database?

A

Stores historical data and business metrics used exclusively for tactical or strategic decision making

35
Q

What is Data warehouse?

A

Stores data in a format optimized for decision support

36
Q

What is Online analytical processing (OLAP)?

A

Tools for retrieving, processing, and modeling data from the data warehouse

37
Q

What can be some problems with file system data processing?

A

Lengthy development times
Difficult of getting quick answers
Complex administration system
Lack of security and limited data sharing = everyone can have access to it
Extensive programming (read, edit, write)

38
Q

What is Data dependence?

A

Data access changes when data storage characteristics change.

39
Q

What is Data independence?

A

Data storage characteristics is changed without affecting the program’s ability to access the data.

40
Q

What is Data Redundancy?

A

Having a lot of same data. The data has been duplicated/repeated many times.

41
Q

What are the problems with data redundancy?

A

Storage consuming

Money consuming because you have to pay for a storage location

Poor data security

Data inconsistency

Increased likelihood of data-entry errors when complex entries are made in different files

Data anomaly: Develops when not all of the required changes in the redundant data are made successfully, for example an employee address changed, but is not corrected in all files in the database

Databases (6 decks)

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