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Retrieving Hierarchical Data into a DataSet

[ Team LiB ] Recipe 2.1 Retrieving Hierarchical Data into a DataSet Problem You want to fill a DataSet with parent and related child data, even if the DataSet already has a schema that includes the relationship. Solution There are several techniques you can use to load parent and child data into a DataSet. | Team LiB Recipe 2.1 Retrieving Hierarchical Data into a DataSet Problem You want to fill a DataSet with parent and related child data even if the DataSet already has a schema that includes the relationship. Solution There are several techniques you can use to load parent and child data into a DataSet. The sample code contains three event handlers Form.Load Sets up the sample by creating a DataSet with table schemas for both the Orders table and the Order Details table from Northwind and a DataRelation object relating these two tables. The default view of the parent table Orders is bound to a data grid on the form. Load DataSet Button.Click Starts by clearing the data from the DataSet and refreshing the data grid. DataAdapter objects are created for both the parent and the child table. The Orders and Order Details are then filled using data adapters in the sequence specified and enforcing constraints during the load as specified by the user. The C code is shown in Example 2-1. Example 2-1. File HierarchicalDataSetForm.es Namespaces variables and constants using System using System.Configuration using System.Windows.Forms using System.Data using System.Data.SqlClient private DataSet ds . . . private void HierarchicalDataSetForm_Load object sender System.EventArgs e ds new DataSet Get the schema for the Orders table. DataTable parentTable new DataTable Orders SqlDataAdapter da new SqlDataAdapter SELECT FROM Orders ConfigurationSettings.AppSettings S ql_ConnectString da.FillSchema parentTable SchemaType.Source ds.Tables.Add parentTable Get the schema for the Order Details table. DataTable childTable new DataTable Order Details da new SqlDataAdapter SELECT FROM Order Details ConfigurationSettings.AppSettings S ql_ConnectString da.FillSchema childTable SchemaType.Source ds.Tables.Add childTable Add the relation between the tables. DataRelation dr new DataRelation Order_OrderDetails_Relation parentTable.Columns OrderID childTable.Columns OrderID ds.Relations.Add dr Bind