Question

Here is my code:

    private void textBox1_TextChanged(object sender, EventArgs e)
    {
        //**************************************
        int aa = textBox1.Text.Length;

        var qry = (from p in dc.Products
                   where p.ProductName.Substring(aa) == textBox1.Text.Trim()
                   select p).ToList();
        productDataGridView.DataSource = qry;
    }

When I enter a letter in the textbox the datagrid become empty

Answer 1

private void textBox1_TextChanged(object sender, EventArgs e)
    {
        var searchValue = textBox1.Text.Trim();//you can add a ToUpper();
        var qry = (from p in dc.Products
                   where p.ProductName.StartsWith(searchValue);//you can add a ToUpper() to p.ProductName
                   select p).ToList();
        productDataGridView.DataSource = qry;
    }