Databases

Question 1

Hierarchy of passwords

Answer 1

Limits users to various parts of the program. A receptionist would only have access to basic patient details whilst a doctor would see all information on the patient.

Question 2

Access rights

Answer 2

Only certain users can access and change data. A nurse would see all the information on a patient but be unable to alter the drug dose details whilst a doctor could.

Question 3

Data redundancy

Answer 3

Is where you store an item of data more than once. A company may hold its data in different files. This is wasteful because some data may need to be input twice. Data which is repeated unnecessarily is called redundant data. It refers to the unnecessary duplication of data. In a flat-file database details about such information as customer details will be duplicated. In a well designed relational database there should be no ‘repeating attributes’, no piece of data should be unnecessarily repeated

Question 4

Data integrity

Answer 4

The integrity of data is the correctness, i.e. the extent to which it truthfully represents the original information. Truthful, Accuracy. One of the problems of maintaining integrity arises when updating occurs, and every record has to be changed in a flat-file database, if one record was left unchanged the data would no longer be wholly correct. In a relational database you only have to change data in one table and all other references in any other application will automatically be changed

Question 5

Data consistency

Answer 5

Data being inconsistent in a flat file due to possibility of different formats, etc, and being consistent in a RDBMS as each record is only stored once so cannot have different attributes. A date field could be stored in file as a text field but in another field as a date/time field and the data would be incompatible. In a relational database because the attributes of any one entity are contained within one file, there is no risk of the same attribute being stored in a different format in a different file (Spelling mistakes in names).

Question 6

Data Normalisation

Answer 6

A staged (mathematical) process (1) which removes repeated groups of data and inconsistencies.

Question 7

Data Independence

Answer 7

Being kept separate from the database, so if the database becomes corrupted, the data will still be fine.

Question 8

Data Warehouse

Answer 8

Large, Archive of data, which is used for Decision Making.

Question 9

Data Mining Advantages

Answer 9

—Predictions for future sales

—Comparisons with competitors

—Analysis of best sites for shops

—The company with a list of customers likely to buy a certain product, which they can use to target with a mail shot

Question 10

Data Mining

Answer 10

Data mining is interrogating the data to find patterns in the data which is stored in the warehouse.

Question 11

Data Warehouse Advantages

Answer 11

—Allows the company to store information about every sale

—Can use it to plan future changes or developments in their business

—Allows the company to use data mining

—Allows the company to find the most popular product and buy more

Question 12

Relational Database

Answer 12

A series of tables linked together using primary and foreign keys.

Question 13

Primary key

Answer 13

A unique key to identify a record.

Question 14

Foreign Key

Answer 14

A key from another table, which is used to identify a record uniquely. It’s used to link tables together.