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Standard Grade. Databases. What is a Database?. A structured collection of similar information that can be searched and sorted . A database is made up of files, records and fields. What is a Database?. A database is an organised, structured collection of similar information . - PowerPoint PPT PresentationTRANSCRIPT
Standard GradeDatabases
What is a Database?
• A database is made up of files, records and fields.
• A structured collection of similar information that can be searched and sorted.
What is a Database?
• A database can be stored on paper (manual) or on a computer (electronic).
• A program that is used for organising data on a computer is called a database package.
• Data is organised in a database as files, records and fields:
• A database is an organised, structured collection of similar information.
Files
A file is a collection of records.
Data in a database is saved on the computer as a data file and contains data on a particular topice.g. a Films data file.
Records
A record is a collection of fields.
A record is a collection of organised data on a particular person or item.
Fields
A field is a single item of information.
A field is part of a record that holds a particular piece of data e.g. Surname.
Files….Records…Fields?
Field
Record
Here is a sample record from a telephone directory data file made up of different fields:
Mr.
Title Forename Postcode Tel. No.
John Smith 101High Street
Ayr KA7 3KL 01292 262626
Sample Fields
AddressSurname Town
• Databases are used by many types of business and organisations such as:
• Telephone Directory
• Police National Computer
• Inland Revenue
• Driver and Vehicle Licensing Centre
• A personal Christmas card list
• A mailing list
• Data held in a database can be shared between other computer packages such as a word processor package – e.g. Mail Merge.
What is a Database used for?
• Records can be processed quickly.
• Records can be processed accurately.
• Information is immediately available.
All of this is impossible in a manual system !!!!
Advantages of an electronic database?
• Databases have many of the features common to a general purpose package.
• There are some special features of a database:• Create fields
• Add and alter records
• Search
• Sort
Features of a Database?
• The first step on setting up a database is deciding on the fields it requires.
• Fields hold the information you want to store.
• You can set the size and type of a field.
• Size: You can decide how many characters a field can hold e.g. a Postcode field to hold KA18 3GH would require a minimum of 8 characters as the space counts as a character!
• Type: Fields can hold different types of data:• A text field holds letters.• A number field holds only numbers.• Date and time fields hold numbers formatted into date and time.
Create Fields
• The next step is to enter records into the empty database. A new record has to
be created for each item. e.g.
Mr John Smith 1 Anytown Scotland 01929 393939
Mrs Susan Jones 5 The Town Scotland 01521 447210
Add and Alter Records
Record 1
Record 2
e.g. search for the forenames and surnames of people whose test mark was greater than 50.
• You can run a search on a database for specific information.
• You can search on a field (or fields) based on certain conditions you require.
Search Records
• Sorting allows you to organise records into a particular order:
• alphabetic• numeric
• ascending (1,2,3,4,5…)• descending (Z, Y, X, W …)
• The sort is done by choosing which field the database is to be sorted into e.g. sort alphabetically by surname.
Sort Records
Reports
• any information printed out from a database is a report.
• you can search for information, then sort it into an order, and decide what fields you wish printed out in what order.
• this is known as a report definition.
Additional features of a Database
Example:
If a database has the fields <Total Pay> and <Total Deductions>, then a third called <Net Pay> could be set up with the formula:(=Total Pay – Total Deductions).
This is a computed field.
• A computed field (also called a calculated field) can be created in a database or report.
• It carries out a calculation on a field or fields and returns an answer (similar to a spreadsheet formula in a cell).
Computed Fields
• You can decide how the information in your database is presented by altering the
format. • You can change the way the input screen looks and format a report for output.
• The position of fields can be rearranged and formatted into a particular order and layout.
• This is useful for designing input screens and producing documents such as invoices for output.
Altering Input/Output formats
Use of Keywords
• When searching for a particular record or part of it, the text that is used for the search is called a keyword.
• It is also known as a search string.
• However, care must be taken that the correct keywords are used.
Keywords