tailieunhanh - Retrieving Hierarchical Data into a DataSet

[ Team LiB ] Recipe 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 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 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 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 Namespaces variables and constants using System using using using using private DataSet ds . . . private void HierarchicalDataSetForm_Load object sender e ds new DataSet Get the schema for the Orders table. DataTable parentTable new DataTable Orders SqlDataAdapter da new SqlDataAdapter SELECT FROM Orders S ql_ConnectString parentTable parentTable Get the schema for the Order Details table. DataTable childTable new DataTable Order Details da new SqlDataAdapter SELECT FROM Order Details S ql_ConnectString childTable childTable Add the relation between the tables. DataRelation dr new DataRelation Order_OrderDetails_Relation OrderID OrderID dr Bind