DataRelation manipulation in Asp.net

Question

Hi All I am trying to establish the relationship between two tables but its showing the following error Object reference not set to an instance of an object. the code is as followsDataRelation oDR = new DataRelation(Dept_Emp oDS.Tables[tbl_Department].Columns[DNo] oDS.Tables[tbl_EmpDept].Columns[DNo] false);

SIVA · Answer

Hi Satyapriya nice sharing.. its displaying the parent records in Gridview but my requirement is i need to make primary key column in parent table as link button. when i click that button it have to display all the related child records in another gridview can you send me the code please

Satyapriya Nayak · Answer

Data relation example using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data.OleDb; namespace Data_relation { public partial class Form1 : Form { string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings[dsn]; OleDbCommand com; OleDbDataAdapter oda; DataSet ds; DataRelation dr; string str; public Form1() { InitializeComponent(); } private void btndisplay_Click(object sender EventArgs e) { OleDbConnection con = new OleDbConnection(ConnectionString); con.Open(); str = select * from product; com = new OleDbCommand(str con); oda = new OleDbDataAdapter(com); ds = new DataSet(); oda.Fill(ds product); str = select * from customer; com = new OleDbCommand(str con); oda = new OleDbDataAdapter(com); oda.Fill(ds customer); con.Close(); DataColumn dc1 = new DataColumn(); DataColumn dc2 = new DataColumn(); dc1 = ds.Tables[product].Columns[prodid]; dc2 = ds.Tables[customer].Columns[prodid]; dr = new DataRelation(Customers taking this product are dc1 dc2); ds.Relations.Add(dr); dataGrid1.DataSource = ds; dataGrid1.DataMember = product; } } } Thanks

SIVA · Answer

i have established the relationship directly please check properly the relation ship thank you i resolved that problem now

Datta Kharad · Answer

Hi You can refer this code.. // Get the DataColumn objects from two DataTable objects // in a DataSet. Code to get the DataSet not shown here. DataColumn parentColumn = DataSet1.Tables[Customers].Columns[CustID]; DataColumn childColumn = DataSet1.Tables[Orders].Columns[CustID]; // Create DataRelation. DataRelation relCustOrder; relCustOrder = new DataRelation(CustomersOrders parentColumn childColumn); // Add the relation to the DataSet. DataSet1.Relations.Add(relCustOrder);