Slide 1 Standard Grade Computing Databases

Slide 2 Standard Grade Computing Definitions DatabaseA database is a structured collection of similar information which you can search through. Eg) Police National Computer File A collection of structured data on a particular topic. A file is made up of records. Eg) Police criminal file RecordInformation held about one person or thing. A record is made up of fields. Eg) Information about a criminal FieldA single item of information. Eg) The criminals hair colour, name, eye colour etc

Slide 3 Standard Grade Computing Example Field Record File

Slide 4 Standard Grade Computing Types of Fields Textholds letters, numbers and symbols Numerichold numbers for calculations Dateholds a date Timeholds a time Graphicholds a picture

Slide 5 Standard Grade Computing Size of a Field This is the total number of characters, including spaces, needed to hold the information in a field. Eg Field sizes

Slide 6 Standard Grade Computing Field NameField Size Forename 15characters = 15 bytes Surname 15 characters = 15 bytes Date of Birth 8 characters = 8 bytes Sex 1 characters = 1 bytes Size of 1 record = = 39 bytes For 50 records storage size= 39 X 50 = 1950 bytes = = 1.9 kilobytes

Slide 7 Standard Grade Computing Create record When you create a record you must first consider – How many fields should there be. The data type for each field. What size each field should be.

Slide 8 Standard Grade Computing Add record A new record is added to the database. EgWhen a criminal has to be added to the police crime database. EgWhen a new pupil joins a school, their details need to be added to the school database.

Slide 9 Standard Grade Computing Edit record Is when details in a record need to be updated. Eg A criminal’s record will need to change when they commit another crime. (Entry in conviction field would change.) Eg A pupil’s record will need to change if they move house. (Entry in address field would change.)

Slide 10 Standard Grade Computing Create field Extra information may need to be added to each record in the database. This means adding a new field. The new field would be added to all of the records in the database.

Slide 11 Standard Grade Computing Example 1 A new field called colour has been added

Slide 12 Standard Grade Computing Example 2 Name field changed into 2 fields

Slide 13 Standard Grade Computing The search facility allows you to look for information in the database. A search may be: SimpleLook for records with a match on one field ( They have one thing in common.) Eg Hair = “Brown” ComplexLook for records with a match on more than one item in one or more fields. Eg Hair = “Brown” AND Eyes = “Blue” Searching

Slide 14 Standard Grade Computing Comparison Operators <Less than < =Less than or equal to =Equal to > =Equal to or greater than >Greater than Not equal to Eg To find all records for 1st to 3rd year in a school database you could search for: Year <= “3 rd ” EgTo find all records for criminals who do not have black hair Hair <> “Black”

Slide 15 Standard Grade Computing In a complex search we need to link the searches together using one of the following operators: ANDBoth items required in each record OROne item required in each record Eg To search a school database for all Standard Grade Computing pupils you could search for: Year = “3 rd ” OR Year = “4 th ” AND Subject = “Computing”

Slide 16 Standard Grade Computing Searching on the Internet – Simple Search This is when you search the internet for web pages that contain one keyword. E.g. Hotels

Slide 17 Standard Grade Computing Searching on the Internet – Complex Search This is when you search the internet for web pages that contain more than one keyword. E.g. Hotels + Paris

Slide 18 Standard Grade Computing Searching on CD-ROM – Simple Search This is when you search on a CD-ROM for information that contains one keyword. E.g. Music

Slide 19 Standard Grade Computing Searching CD-ROM – Complex Search This is when you search on a CD-ROM for information that contains more than one keyword. E.g. Rap + music

Slide 20 Standard Grade Computing Sorting allows you to arrange the records in a database in alphabetic or numeric order. This can be ascending (A to Z or 1 to 9) or descending (Z to A or 9 to 1) A sort may be: SimpleA sort on the contents of one field only. Eg Hair in ascending order. ComplexA sort on the contents of two or more fields. Eg Hair in ascending order AND eyes in descending order Sorting

Slide 21 Standard Grade Computing Alter record format Databases can be displayed in different ways. There are 2 different formats for organising your database – Card Format List or Table format

Slide 22 Standard Grade Computing Example of card format

Slide 23 Standard Grade Computing Example of list or table format

Slide 24 Standard Grade Computing Computed Field - Credit A calculated field allows you to carry out a calculation on another field or fields and return the answer in the calculated field. It is similar to using formulae in a spreadsheet. Eg The computed field Total Cost would contain the formula Total Cost = Cost * Number Sold

Slide 25 Standard Grade Computing Keywords - Credit This is the text used to search a file for a particular entry. Eg) If you were searching the library database and you searched for “potter” you would get books with the word “potter” in their title. For example Pottery, Harry Potter …

Slide 26 Standard Grade Computing Input and output format - Credit The user can alter the format of the input screen to make it easier to enter data. Eg) Enter all of one field before moving onto the next record. The user can customise the output from a database. Eg) Creating a report

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