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Deletion of Fields/Records

You can prevent the deletion of fields/records by backing up the database so that you can restore the database back to the last back up if a deletion occurs which many companies do although some data may not be retrievable if it was added after the last backup most backups are stored elsewhere so that they can’t be deleted. A cause of a deletion is normally human error where they have hit the delete key by accident that is why many databases ask you if you’re sure you want to delete this field.

Incorrect Data Types

To prevent incorrect Data Types many database’s use multiple choice questions so that the wrong data can’t be entered into the database and the data inputted is relevant and forms can be completed quicker and more accurately than if it was just a text box and people may put irrelevant data.

Validation

A Validation rule limits and controls what users can controls what users can enter in a table field or a control .Data types provide the first layer of validation. When you design a database table, you choose a data type for each field in the table, and that data type controls what you can enter.

 Field sizes provide another layer of validation, you can set a character limit on a field so you can prevent a user from spamming text into the field, or it can prevent an inexperienced user from mistakenly entering the wrong data.

Null values

Null values are shown when data isn’t entered at all or incorrectly similar to validation as it is there so that information is entered correctly this happens when information that the database needs isn’t entered and it comes up telling you what you have missed the question normally has a * to show that the information is needed to complete the form