Data+Validation

**__Data validation__**
There are many different types of this data validation, for example:
 * Data validation ensures that all the information in your database is accurate and correct. **
 * ** Data type validation ** – This is simply verifying that the type of data is in the right form i.e. that the names in the data base are correctly in text format //or// that the dates in the database are in the date/time data type.


 * ** Range checking ** – This is a type of validation that ensures that all the data that is inputted into a certain field, is within the correct limits. You can change the settings on your database that means when users are inputting data it will only enable them to put in data within a certain range. An example of this would be a date of birth field which will only let you put in DOB’s that are over a certain age i.e. 18, it would be used maybe when people are getting a driving license because you have to be over a certain age.


 * ** Check digits – ** this is a more complex type of data validation, but is also a form of redundancy check for checking if there are any errors in the data. Check digits usually use algorithms to validate human input errors. These can include different levels of errors such as:
 * Single digit errors – 1 >> 2
 * Position errors – 32 >> 23
 * Twin errors – 11>>22


 * ** Field size – ** this is a simple validation check to check whether the data is within the Field size limits. Such as if you are only able to input 25 characters for a field, it will not allow you to input 30 characters.


 * ** Input mask – ** This makes sure that you can only input data into a certain format so the data is generically inputted throughout the database. An example of this would be a date field where they need to input it into this format.[[image:itgs2010-jess/date_format.png]]
 * ** Drop down list – ** this validation means that the user to only select an option from a set drop down list of values or items and this again is so the information is generic throughout the database but also stops people putting their own values in.[[image:itgs2010-jess/dropdown.png width="544" height="177"]]