dataset 关系

//设置连接字符串
string   connectString   = "server=.;password=;uid=sa;database=Northwind ";
SqlConnection   sqlConnection=new   SqlConnection(connectString);
sqlConnection.Open(); 

//   打开适配器
string   cmdText   = "SELECT   CustomerID,CompanyName   FROM   Customers   ";
SqlDataAdapter   sqlDataAdapter   =new   SqlDataAdapter(cmdText,sqlConnection); 
DataSet   dataSet=new   DataSet();
sqlDataAdapter.Fill(dataSet, "Customers "); 

cmdText   = "SELECT   CustomerID,OrderID   FROM   Orders   ";
sqlDataAdapter   =new   SqlDataAdapter(cmdText,sqlConnection); 
sqlDataAdapter.Fill(dataSet, "Orders ");

//   连接2个表
DataRelation   dataRelation   =   dataSet.Relations.Add( "CustomersOrders ",dataSet.Tables[ "Customers "].Columns[ "CustomerID "],
dataSet.Tables[ "Orders "].Columns[ "CustomerID "]);
                      
foreach(DataRow   customerDataRow   in   dataSet.Tables[ "Customers "].Rows   )
{
//   这里可以 判断条件筛选
Console.WriteLine( "CustomerID: "      customerDataRow[ "CustomerID "].ToString()      "         CompanyName: "      customerDataRow[ "CompanyName "].ToString());
foreach(DataRow   ordersDataRow   in   customerDataRow.GetChildRows(dataRelation)   )
{
//   这里可以 判断条件筛选
Console.WriteLine( "CustomerID: "    ordersDataRow[ "CustomerID "].ToString()      "       OrderID: "    ordersDataRow[ "OrderID "].ToString()); 
}
}