Databases+-+Data+Validation

Databases - Data Validation by Daniel Flowers

Data Validation
 * A validation check is an automatic check made by a computer to ensure that any data entered into the computer is sensible. **A validation check does not make sure that data has been entered correctly. It only ensures that the data is sensible. For this reason validation checks are not usually as effective as verification checks. They can however be carried out automatically by a computer and therefore require less work by computer operators making them cheaper to use
 * A data type ** is a data storage format that can contain a specific type or range of values. Some common data types include integers, floating point numbers, characters, strings, and arrays. They may also be more specific types, such as dates, times and Boolean values.
 * A range check **is a method of checking the validity of input data by determining whether the values fall within an expected range.

A check digit  is a particularly important method of validation. It is used to ensure that code numbers that are originally produced by a computer are re-entered into another computer correctly. The check digit is a single digit added onto the end of a code number by the computer. The check digit is calculated from the other digits in the number. Check digits are included in [Code Readers|bar code] numbers.

This procedure is used to generate a check digit to add to the end of a number. It uses the Modulo-11 weighted check digit calculation. This calculation is used for ISBN numbers on books. 1) Start with the original product number e.g. 185813415. 2) Weight each digit by its position in the string and add up the results : 3) Divide the total by 11 and then subtract the remainder from 11. The check digit is the result of this operation : 228 / 11 = 20 remainder 8 => Check digit is 11-8 = 3. If the remainder is 10 then the check digit is set to X. If it is 11 then the check digit is 0 4) Add the check digit to the end of the original number to get the complete product number : 1858134143 <span style="color: #00b050; font-family: "Arial Rounded MT Bold","sans-serif";">Input Mask
 * <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">Digit || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">1 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">8 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">5 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">8 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">1 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">3 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">4 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">1 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">5 ||  ||
 * <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">Weightings || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*10 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*9 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*8 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*7 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*6 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*5 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*4 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*3 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">*2 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">Total ||
 * <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">Result || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">10 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">72 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">40 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">56 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">6 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">15 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">16 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">3 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">10 || <span style="color: #3c3c3c; font-family: "Arial Rounded MT Bold","sans-serif";">228 ||

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