Ytukyg

Basically i want to see foreign key data in another datagridview. Parent data show in 1st datagridview and show child data in 2nd datagridview. when 1st gridview row click then 2nd gridview show child data table show.
i have two table , student and subject.
student==stu_id, name, roll.
subject==sub_id, name, subject_code, stu_id.
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First of all you haven't provided us with any code.

Now i will just explain you how to do it (without actual code since i do not have code of yours).

It is quiet easy and doesn't require much setup. Only thing you need to do is decide WHEN you want to change data in child datagridview. When you decide when to do it (example is on cell click), simply create event in first datagridview and use RowFiltering on second one. It would look like this:

private void DataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)

{

    DataGridViewRow row = dataGridView1.SelectedRows[0]; //Selecting only first selected row.



    //Above code of getting row will not work if you have not set datagridview mode to full selection.

    //If you do not want to you could get row like this



     DataGridViewRow row = dataGridView1.Rows[e.RowIndex];



     int CategoryIdOfSelectedOne = Convert.ToInt32(row["CategoryID"].Value);

     (secondDGV.DataSource as DataTable).DefaultView.RowFilter = string.Format("CategoryID= '{0}'", CategoryIdOfSelectedOne);

}