1.7 Database Systems Flashcards

1
Q

What is a database?

A

An organized set of data constructed so that it can be searched, added to, deleted from or edited.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

State 6 functions a database allows you to do.

A
  1. Create and edit data structures
  2. Add, Delete and modify data
  3. Format the data
  4. Import data from other sources
  5. Use queries to search for information
  6. Produce reports about data & set security
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

State 2 types of databases.

A
  1. Flat-file database
  2. Relational database
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a flat file database?

A

A database that consists of a number of
tables with no link between them.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a relational database?

A

A database that consists of multiple tables that contain linked data, linked using relationships.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give 4 advantages for a relational database.

A
  1. Less data duplication than a flat file system.
  2. Data consistency : Less repetition so there is also less contradictory entries.
  3. Better security; Individual users can be restricted to seeing specific parts of the database.
  4. Better flexibility : adding a table is easier than making changes to a large flat file.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Give a disadvantage for a relational database.

A

For simpler sets of data, a relational database may be overkill.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are primary keys?

A

Unique identifiers of a record in a database.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are foreign keys? (2)

A
  1. A primary key from one table included in another table.
  2. A field that allows a link between two tables.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an entity relationship diagram? (2)

A
  1. A real world thing (entity) is described
    using a database table.
  2. Links are used to show the type of relationship between the entities.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is entity-relationship modelling?

A

Taking a real world situation and representing it using an entity-relationship diagram.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the three types of relationships?

A
  1. One-to-one
  2. One-to-many
  3. Many-to-many
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Give an example of a 1-to-1 relationship.

A

Each driver has one vehicle and each vehicle is driven by only one driver.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give an example of a 1-to-many relationship.

A

A teacher teaches multiple classes, but each class is only ever taught by one teacher.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give an example of a many-to-many relationship.

A

A student can sit any number of exams, and several students sit each exam.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State 3 advantages of providing different views in a database system.

A
  1. Restricts what someone can view in the database.
  2. This improves privacy of the database.
  3. Can stop people from changing data in a table.
17
Q

What is data normalisation?

A

Ensuring that the database has no data redundancy and no data inconsistencies.

18
Q

What problems occurs when data isn’t normalised?

A

Data duplication (e.g. data redundancy)

19
Q

State 3 problems with a paper based system (1).

A
  1. Time consuming to find client details.
  2. Difficult to back up as each piece of paper will have to be copied.
  3. Time consuming to amend or create client records.
20
Q

State 3 problems with a paper based system (2).

A
  1. Time consuming to search for client details.
  2. Can be difficult to read due to poor handwriting.
  3. Can take up a lot of physical storage space.