1.3.2 Databases

Question 1

1.3.2 A)
What is a database

Answer 1

organised collection of data. That allows for easy adding, modifying, deletion and searching of the data.

Question 2

1.3.2 A)
Inside a database a table is also known as
Inside a table a row is also known as
Inside a table a column is also known as

Answer 2

1) an entity or file
2) a row or tuple
3) a field or attribute

Question 3

1.3.2 A)
What is the advantages and disadvantages of a flat file

Answer 3

A) simple and quick to set up, do not need a specialised to maintain, good for storing small amount of data
D) When lots of data inputted likely to have repeating data which is inefficient as it takes up unnecessary space, it becomes slow to query and is difficult to maintain.

Question 3

1.3.2 A)
What is a flat file

Answer 3

single file, with comma separated values (csv)

Question 4

1.3.2 A)
What is a relational data base

Answer 4

Splits information into multiple tables. links tables with one another using relationships for 1:M , M:M , 1:1.

Question 5

1.3.2 A)
What is the advantages and disadvantages of a relational data base

Answer 5

A) structured and efficient way to store and retrieve data , reduce redundancy.
D) Expert needed , costs , performance

Question 6

1.3.2 A)
What is a primary key

Answer 6

A field that has a unique value / a
unique identifier (1) for every record in
that table (1)

Question 7

1.3.2 A)
What is a foreign key

Answer 7

attribute that links to tables together, foreign key has to be a primary key in another table

Question 8

1.3.2 A)
What is a composite key

Answer 8

candidate key that consists of two or more attributes that together create a unique identifier. values of comp key must be diff across all records

Question 9

1.3.2 A)
What is a secondary key

Answer 9

Can also specify one or more secondary keys to be indexed. Helped files be searched quickly and easily (instead of typing a unique id something easy to remember like a last name )

Question 10

1.3.2 A)
What is indexing

Answer 10

Held for primary keys so it can be easily located quickly. so that sequential searching is not needed.

Question 11

1.3.2 A)
What is normalisation ? ( in terms of data bases )

Answer 11

Process of coming up with the best possible layout for relational databases.

Question 12

1.3.2 A)
Properties of normalisation in terms of databases

Answer 12

no redundancy
consistent data in linked tables
easy to add / remove records

Question 13

1.3.2 C)
What is first normal form

Answer 13

• No Repeating fields/data
• Data is atomic
• Has a primary Key

Question 14

1.3.2 C)
What is second normal form

Answer 14

• Is in First Normal Form
• Every field is dependent on the
  primary key

Question 15

1.3.2 C)
What is third normal form

Answer 15

Has a transitive relationship/ A non-key field depends on another non-key field

Question 17

1.3.2 E)
What is referential integrity

Answer 17

The process that ensures consistency. Ensure that information is not removed if it is required elsewhere in a linked data base. If 2 db are linked cannot detect

Ensuring that changes are consistent
across a database
– if a record is removed all references to
it are removed
– A foreign key value must have a
corresponding Primary key value in
another table

Question 18

1.3.2 F)
Transaction processing

Answer 18

ensuring that interdependent operations on the system are either all completed successfully or all canceled successfully

Makes sure operation happens.

Question 19

1.3.2 F)
What acronym can be used for transaction processing

Answer 19

A- Atomicity
C-consistency
I-isolation
D -durability

Question 20

1.3.2 F)
ACID -Atomicity

Answer 20

Transaction must be procession in it entirety or not at all

Question 21

1.3.2 F)
ACID -consistency

Answer 21

Transaction must maintain the integrity laws between linked lists

Question 22

1.3.2 F)
ACID -Isolation

Answer 22

Simultaneous execution of transactions should lead to same result as if it was one after the another.

Question 23

1.3.2 F)
ACID -Durability

Answer 23

Once a transition has been executed it will remain so regardless of env. such as a power cut.

Question 24

1.3.2 F)
What is record locking
and what is the use

Answer 24

The process of preventing simulations access to record in a db. Used to prevent inconsistency or a loss of update. while one person edits a record it lock .

Question 25

1.3.2 F)
What is the con’s record locking

Answer 25

Deadlock - people waiting for access while already looking at a record causing no one moving

Question 26

1.3.2 F)
What is redundancy

Answer 26

Some info important and cannot be lost.
redundancy is the process of having copies of data in physically diff locations .