Data Handling

Data Handling

1. Data Validation: Checks that data entered is reasonable but cannot check it is correct.

   • Range check: It checks the length of the data entered is within a certain range.
   • Presence check: Makes sure data has been entered in a cell.
   • Format check: Makes sure data has been entered in the correct format e.g. date of birth.
   • Length check: It checks the data isn't to short or long.
   • Check Digit: It puts digits into a calculation to check they are valid commonly used on barcodes.
   • Lookup Check: It checks the data is correct from a table stored else where.

2. Data Types

   • Text: stores both letters and numbers.
   • Integer: Stores whole numbers that don't begin with zero.
   • Real Number: Stores only decimal numbers however they cant start with zero.
   • Date: Is used to store date in the correct format however their is a format choice. Short date e.g. 03/09/2020 or long date e.g. 3rd September 2020
   • Boolean: offers a choice of one or the other. Yes/no.
   • List: Offers a few select items on a list reducing mistake.

3. Databases

   • Relational database
     • It links several tables together saving on data duplication saving on mistakes but also time
     • Can be used to enforce rules by brining up error messages when certain rules are broken.
     • Easy to run a query.
   • Flat file database
     • One large database holding all the information means some data may be keyed twice
     • Difficult to read and use day to day
     • Difficult to run a query on a large table.
     • More prone to mistakes due to confusing layout.