1.3.2 Databases

Question 1

relational db

Answer 1

• easy to add data
• easy to link to other applications
• easy to change format
• no redundant data/data duplication
• data integrity
• larger volume of data

Question 2

flat file db

Answer 2

• limited amount of data
• difficult to change format
• harder to update
• no specialist knowledge needed to operate

Question 3

primary key

Answer 3

• a field with a unique value
• unique identifier for every record in that table

Question 4

foreign key

Answer 4

• field that links to a primary key in another table

Question 5

capturing data

Answer 5

• manually entered via form
• magnetic ink character
• optical mark recognition
• optical character recognition

Question 6

transaction

Answer 6

a set of CRUD operations on a database

Question 7

atomic

Answer 7

the transaction is either fully processed, or it isn’t executed at all

Question 8

concistency

Answer 8

• all validation rules are followed
• helps to maintain referential integrity => all referenced (eg. foreign keys) are always valid. ensures that changes are consistent across all datbases.
• solutions: error, cascade delete

Question 9

isolation

Answer 9

the result of transactions processed concurrently is the same as if they are processed sequentially

Question 10

durability

Answer 10

• protecting/securing data from power cuts/system failures
• this can be done using secondary storage (ram is volatile), or backing up data onto cloud services

Question 11

record locking

Answer 11

• one user/process can access and modify record level data at any one time
• data that is being used elsewhere cannot be modified

Question 12

redundancy

Answer 12

having one or more copies of the data in physically different locations so if there is any damage to one copy, others can be recovered