ADO.NET Cookbook

3.14. Using the Shape Language to Retrieve Hierarchical Data

Problem

You want to use the Shape language with ADO.NET to retrieve hierarchical data from a SQL Server.

Solution

Execute the SHAPE command as shown in the following example using the OLE DB provider.

The sample code defines a SHAPE query to retrieve the TOP 5 Orders from Northwind and the Order Details for each of the Orders. A DataReader based on the query is created. The code iterates over the rows in the DataReader displaying the data for each Order row. If the value for the column can be cast to the IDataReader interface, it is a DataReader containing the Order Details for the Order row. The value for the column is cast to a DataReader and the collection of records is iterated over and displayed.

The C# code is shown in Example 3-14.

Example 3-14. File: ShapeForm.cs

// Namespaces, variables, and constants using System; using System.Configuration; using System.Text; using System.Data; using System.Data.OleDb; // . . . StringBuilder result = new StringBuilder( ); // SHAPE SQL to retrieve TOP five Orders and associated Order Detail records. String shapeText = "SHAPE {select TOP 5 * from Orders} AS Orders " + "APPEND ({select * from [Order Details]} AS 'Order Details' " + "RELATE OrderID TO OrderID)"; // Create the connection. OleDbConnection conn = new OleDbConnection( ConfigurationSettings.AppSettings["OleDb_Shape_ConnectString"]); // Create a command and fill a DataReader with the // SHAPE result set. OleDbCommand cmd ...