9.2. Starting with a Relational Database
A common Web service scenario occurs when you have a relational database and you want to expose some of it to applications over the Web. So you create a Web service with some Web methods that return DataSets. If you are going to allow clients to update your database, you might also create some Web methods that take in a DataSet and use it to update the database. Listing 9.1 shows an example Web method called GetCustomersDataSet that returns a DataSet from the Customers table in the Northwind database.
Listing 9.1. A Web method that returns a DataSet (VBWSBook\Chapter9\CustomerOrders.asmx.vb)
<WebMethod()> _ Public Function GetCustomersDataSet() As DataSet Dim Sql As String = _ "SELECT CustomerID, CompanyName ...