commercial data processing lesson 3: data validation
TRANSCRIPT
Commercial Data Processing
Commercial Data Processing
Lesson 3: Data Validation
Commercial Data Processing
By the end of this lesson you will be aware of:
By the end of this lesson you will be aware of:
GIGO
Validation
Verification
Check Digit
Range Check
Commercial Data Processing
data collection & preparation
data input
data processing & storage
output of data
Data must be collected before it can be input. It can be collected in from a source document, such as an order form.
Data has to be entered into the computer for processing. Inputting data directly ie automatically, reduces the mistakes made by people and makes this stage quicker.
Data is processed, ie fed into the program and manipulated. There are 2 types of processing: interactive and batch. Data is then stored on some form of backing store.
Processed data is either displayed on a monitor, printed onto paper (often as a turnaround document) or output to a file.
The Data Processing The Data Processing CycleCycle
The Data Processing The Data Processing CycleCycle
The Data Processing CycleThe Data Processing Cycle
Commercial Data Processing
Error CheckingError Checking
Data entered into a CDP processing system must be correct.
Data however entered, manually or automatically, cannot be assumed to be correct.
Data has to be checked for errors.
There is a well known adage: Garbage In Garbage Out (GIGO).
The Data Processing CycleThe Data Processing Cycle
Commercial Data Processing
VerificationVerification
Verification is needed for passwords and pin numbers.
Data to be verified is entered twice.
The data is then compared if it is exactly the same both times then it is correct, any difference it is wrong.
Verification is the process of checking the data for complete accuracy.
Commercial Data Processing
ValidationValidation
Validated data cannot be guaranteed to be correct.
There are several methods of validating data from check digit, range checks, length checks and more.
Validation is the process of checking that the data should be correct and accurate.
Commercial Data Processing
Validation Using Check Digit Validation Using Check Digit
The last number of a bar code is a Check Digit. Check digit
It is a computer check digit which help to makes sure the bar code read by the reader is correct and accurate.
A check digit is calculated using the other numbers in the bar code.
Eg 3+2+0+0+0+0+0+0+0+3+7+7=22 divide by 5 = 4.4 so check digit 4
So 4 is added to the end of the bar code 3200000003774.
Calculating the Check Digit
Commercial Data Processing
Validation Using Check Digit Validation Using Check Digit
1. Scan the bar code.
2. Perform the calculation on the numbers scanned in.
3. Compare the check digit scanned and the check digit calculated
IF check digit: scanned = calculated THEN
Bar Code is correct, ie it has been validated
OTHERWISE
Bar Code is wrong, and error sounded usually BEEP!
Validating The Bar Code
Commercial Data Processing
Validation Using Other MethodsValidation Using Other Methods
Type of Check How They Work
Range Check
Checks a number entered is within a specific range.
Examples
Enter a number between 0 and 100.
Enter a month, must be between 1 and 12.
Field Length
Checks the number of characters entered to see if there are enough.
Examples
Passwords that must be between 6 and 8 characters.
Commercial Data Processing
Answer the following questions in your jotter.
1. Explain that it is important that data must be correct.
2. Explain what is meant by GIGO.
3. Explain the difference between validation and verification.
4. Give an example of when verification is needed and suggest how it can be done.
5. Explain how a check digit can be used in validating data.
6. Explain how a range check can be used in validating data.
Commercial Data Processing
Extension Tasks
Read the through information contain in http://www.teach-ict.com/as_a2/topics/validation_verification/verification_validation/validation1.htm
Past Paper Question