Data validation
In the first chapter, we defined APEX to be a data-centric development tool. The data is our most valuable resource, and as such, we should take special measures to ensure it has the following:
Quality: There are many ways to define data quality. For me, it's the ability of the data to serve the purposes for which we are gathering it. For example, if we maintain a customer file in order to be able to send our prospective customers some commercial information, and if our data doesn't include all the options to contact the customer, then the quality of the data is not good enough. If the data should meet certain standards and it does not, then we need to be able to spot it and take corrective measures.
Accuracy: The data must be accurate in order to serve its purpose. It's not enough that we have the customer's credit details. They must be the correct ones, e.g. the correct length of the credit card number, the card is not out of date, etc.
Consistency and Integrity: The...
