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);

DataRelation manipulation in Asp.net

Answers (4)