Databases Standard Grade

Databases A large amount of information must be stored in some sort of order so that it can be accessed easily and quickly. Examples of manual databases are: Filing cabinets in classrooms Filing cabinets in classrooms Telephone Directory Telephone Directory

Databases Most businesses use databases: Schools Schools Local Authority Local Authority DVLA DVLA Police National Computer Police National Computer Doctors & Dentists Doctors & Dentists Hospitals Hospitals The list is endless The list is endless

Database Structure Databases are a structured way of storing information. Databases consist of: Fields - which hold a single piece of information. Records - which hold all the fields about one particular thing. Files - a collection of related records.

Database Structure MakeModelRegMilesEngine FordKa PA08 RAB AudiA3 SE03 BOB FiatPunto FP52 UNT SeatIbiza W565 WHS FordFocus ME09 AGS RECORDS FIELDS

Database Features Databases can be used in two main ways: Search - where you tell the computer what you want to find and the computer searches for it. Sort - where you get the computer to put the information into a different order

Searching There are two types of searching: 1.Simple Search 2.Complex Search

Simple Search A simple search is when you search on one field. Eg 1.Make = “Ford” 2.Colour = “Blue” 3.Top Speed > Age <18

Complex Search Examples 1.Make = “Ford” AND Colour = “Blue” 2.Colour = “Blue” OR Colour = “Green” 3.Sex = “Male” AND Age > 18 4.NOT Top Speed <100 5.Make = “Ford” AND NOT Model = “Ka” 6.Model = “Focus” OR Model = “Fiesta”

Sorting Sorting is when you organise the information into a different order. The two basic orders are: 1.Ascending (a to z, 1 to 10) 2.Descending (z to a, 10 to 1) (Down) (Down)

Simple Sort Sorting by one field: Eg. 1.Ascending order by height 2.Descending by age 3.Descending by points 4.Ascending by surname

Complex Sort Sorting on more than one field at the same time Eg 1.Ascending by Surname THEN Ascending by Forename (register) 2.Descending by points THEN descending by goal diff. THEN descending by goals scored (league table)

Field Types There are several different types which are used to define fields: Text - hold characters (letters/numbers/symbols) Number - holds only numbers Date/Time - holds VALID dates and times only Radio Buttons - restricts choice Pop-up Menu - holds a list of choices

Layouts / Formats We can create different layouts / formats for different uses of a database. Not all layouts need to contain all the fields. For Example An input layout may include all the fields. An input layout may include all the fields. An output layout (such as a school report) may only include relevant fields. An output layout (such as a school report) may only include relevant fields.

Calculated / Computed Fields A field where the computer uses a formula to calculate the information. The formula usually refers to another field in that record. Eg Total= ‘WPMark’ + ‘SSMark’ + ‘DBMark’ Average= Total / 3

Calculating Sizes In a database each character takes up 1 byte of space in memory / storage. Field NameField TypeField Length SurnameText25 AgeNumber3 PostcodeText8 Tel No.Text20 For this example one record would need 56 bytes of memory records would need 112,000 bytes of memory which is approx. 109 kb (112,000 / 1024 )