All data entered into a system is validated. Data validation is performed by a computer program. There are a variety of validation methods used on data to ensure accurate entry of data. Let’s look at some of the validation methods used:
- Length Checks
In this validation technique, data entered is checked to make sure it is a particular length, for example 4 characters, if it’s greater or less than 4 characters it is detected as an error.
- Range Checks
Here data is checked to lie within a specified range as in if integers (numerical values) were entered a range of 10 – 1000 may be specified in which case all entered data must be in between 10 & 1000.
- Presence Checks
This is a simple check performed to check if data has been entered into a field, it makes sure required fields are not left blank.
- Character Checks (or Character Type Check)
This checks if data entered is a particular character type, for example it may check that a ‘name’ field has only letters.
- Check Digit
A check digit is a single digit generated from a complete number, for example an ISBN contains a check digit, the last digit of the ISBN is a check digit. It is calculated using the rest of the numbers in the ISBN, when checked, the check digit is recalculated, if it produces a different value an error has occurred during data transmission or entry.
- Hash Totals
Hash totals are meaningless totals calculated using a series of entered records, for example if you find the totals of all the record numbers of a collection of records it is a meaningless total. It could be used as a hash total to validate the records.
- Control Totals
This is similar to a hash total except the total is a meaningful one, i.e. instead of totaling record numbers you might total the salaries of the employees in an employee database, this total provides some meaning and it can be used to validate data.
Well the above are some of the checks made when you enter data. So the next time you register for a service online remember most of these checks and maybe even a few more are made on each of the fields you fill in!
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May 10, 2008 at 06:27:56
Hi,
Once a data validation has been done and errors found, how does one correct them?
Links to relevant sites or articles would be mush appreciated
Thank you
[Reply]
luq reply on May 10th, 2008 11:53 am:
the computer program which validates the data detects the errors and prevents the entered data being processed and requests the user to enter correct values for the incorrect data notifying the user of the errors, the user then corrects the errors and enters the data into the system, hope that helps, thanks for the comment!
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