SQL Server MVP Deep Dives- P6: Each year Microsoft invites all the MVPs from every technology and country to Redmond for an MVP Summit—all top secret—“don’t tweet what you see!” During the MVP Summit, each product team holds a series of presentations where they explain their technologies, share their vision, and listen to some honest feedback. | 156 Chapter 12 Using XML to transport relational data entities the XML Schema. Again the subject of XML and XML Schema exceeds the scope of this article therefore let s emphasize one principal benefit of using the XML Schema. In SQL Server the XML standard is implemented as a data type and because all data types typically represent implement a specific data domain the purpose of the XML Schema in regards to the XML data type is to enforce its domain. The XML Schema will provide us with a guarantee that the discography data coming in or going out of our database is valid that it complies with the business rules. Data domain A data domain defines which values are allowed in a specific data element such as a variable a column and so on . For instance a data element of a numerical type can only contain numerical data numbers it can t for instance contain letters or punctuation marks with the obvious exception of the decimal point . A data element of the integer numerical type can only contain numbers and no other characters. The XML data domain is similar to the two examples in the previous paragraph but is governed by a much more complex set of rules defined by an XML Schema. ENTITIES OF PRINCIPAL IMPORTANCE Let s take another look at the physical model. We can see two entities that stand out as being more significant to the business compared to the rest. The first such entity is the Album even from Joe s narrative it should be quite clear that the Album represents a principal business entity. It contains all the information vital to the discography business all the data about the Tracks and about the Album itself. The other principal entity also verifiable both in the logical and the physical models as well as in Joe s statements is the Band. Bands represent at least in our particular model the groups of Persons collectively responsible for the existence of the discography business. This means that we ll require two XML Schemas one to represent the Albums and one to
