Databases

HideShow resource information

Data structures and specific features

Data: these are facts about a specific person, place or thing

Information: data that has been processed into a form that is useful to the user

Field: item of data, a fact

Record: detail relating to a single thing or person, consists of fields

File: collection of related records

Table: used to store data with each row in the table being a record and the whole table being a file

Relational database: a database where the data is held in two or more tables with relationships (links) established between them. The software is used to set up and hold the data as well as to extract and manipulate the stored data

Key field: a field in a database that is unique to a particular record

 

1 of 7

Continued

Flatfile databases

  • for storing data where a single card is used to store one record
  • only contain one table of data
  • this limits their use to simple data storage and retrieval systems
  • unsuited to business applications where much more flexibility is needed
  • Problems: data redundancy, there is often a lot of duplicate data needed in the table. Time is wasted re-typing the same data and more data is stored than needs to be making the whole database larger. When a record is deleted a lot of data that is still useful, may be deleted

Relational databases

  • data is stored in several tables with links between the tables to enable the data in the separate tables to be combined together if needed

Records are always rows. Fields are always columns.

To link two tables together there needs to be the same field in each table.

2 of 7

Collect/enter data and everyday tasks

Input forms:

  • electronic version of paper forms and they enable data to be entered directly into the computer
  • can be used to: enter new records, view records, browse records, add new records, delete records, edit records

Amending data means altering the set of data in some way. Amending data can involve updating, deleting redundant data, modifying existing data

Updating:

  • bringing data up-to-date because of changes that may have occurred since the data was originally input

Deleting:

  • some of the data in a database will become redundant, this means the data is no longer needed and therefore should be deleted
  • removing some of the data from a database
  • examples: when personal info is wrong, when a person dies
3 of 7

Continued

  • it is important to delete data because you can waste money sending mail shots and other correspondence to people who have moved, it is a requirement under the Data Protection Act that personal information that is incorrect should be either corrected or deleted

Sorting means putting the data in order. Can be sorted in ascending or descending order

  • ascending order: smallest number is first and largest number is last
  • descending order: largest number is first and the smallest number is last
  • reasons for sorting data: if lists are printed, then it is easier to find a particular person if they are ordered according to surname, you can identify who your best customers are by the amount they have spent in a year. To do this you can sort them according to the total amount they have spent

Searching/selecting/filtering

  • in order to narrow down information we can restrict it by asking only for data satisfying certain criteria
  • filtering is used where only specific information is obtained
4 of 7

Continued

Merging:

  • combining two files to form the one file
  • could be what happens if two people are inputting data into a database and need to combine both files at the end of the day
5 of 7

Outputs from a database and mail merging

Outputs:

  • Reports - the output from a database in which the results are presented in a way that is controlled by the user
  • Reports are used to present the output from a database system
  • reports should have a relevant title
  • report should contain a date, information changes so the person looking at the information needs to know that it is latest version
  • only data or information that is important should be included
  • the details of the report should be clearly laid out
  • pages in report should be numbered

HEADERS AND FOOTERS

What is involved in mail merging?

  • involves combining a list of anmes and addresses with a standard letter so that a series of similar letters is produced, each addressed to a different person.
6 of 7

Continued

  • steps involved: create a letter to be sent to different people, create a name and address list for the recipients of the letter, insert the variable fields into the letter, merge the names and address details with the letter to produce the personalised letters
  • mail merging not confined to letters: invoice, payslip, membership card, name badge
7 of 7

Comments

No comments have yet been made

Similar Design & Technology: Systems & Control Technology resources:

See all Design & Technology: Systems & Control Technology resources »See all resources »