Spread Sheets

Spread Sheets

1. Data base Concepts

   • Table/Flat file.
     • When data is organised into files which consists of rows and columns.
   • Record.
     • Is represented as a row in a table.
   • Field
     • Part of a record that stores in a single data item and is represented by a column.
   • Key field / Primary Key
     • Field used to identify a Record
   • Query
     • A way of searching and extracting data from a data base to answer a question.
   • Form
     • A common way to collect data from people.
   • Report
     • Allows Tables and results from queries to be presented in a user friendly way.
   • Macro
     • A small program written to perform repetive tasks automatically
   • Relationship
     • A way to link two tables in a database.
   • Foreign Key
     • The key field from one table that is stored in another table.

2. Data types

   • Text
     • A mixture of numbers and letters such as a postcode.
     • Short Text
       • Used for small number of characters.
     • Long text
       • Large number of characters.
   • Number
     • Data that requires a calculation.
   • Currency
     • Monetary data
   • Autonumber
     • To create a key field that the computer generates sequential numbers automatically for each new record.
   • Yes/No
     • Two possible options, like true/false. Also known as Boolean value.
   • OLE object
     • Object Linking And Embedding, Has been created using something other than the spreadsheet software.
   • Hyperlink
     • Link to a website.
   • Attachment
     • Files that are attached to a record, I.E a photo
   • Lookup Wizard
     • To create a list of values, i.e a drop down list.

3. Data Validation

   • Guarantees that data is present and correct.
   • Presence check
     • Ensures that data is present and cannot be left blank.
   • Length Check
     • Ensures that data is the correct number of characters, I.E a password must be 8 letters long.
   • Type Check
     • Ensures that the correct data type in entered I.E Currency for price
   • Format Check
     • Ensures that data entered matches a predetermined postcode, I.E postcode BtXX XXX
   • Range Check
     • Makes sure a value within a limit is entered, ie between 1-10

4. Logical Operators

   • Comparing a value against other data is a typical operation when data is queried into a database
   • < and >
     • Less than and greater than
   • <=
     • Less than or equal to
   • >=
     • Greater than or equal to
   • Equal to
     • =
   • <>
     • Not equal.