C#

DateTime myDateTime = .....
string sql = "UPDATE People SET BirthDate = @Date WHERE ID_person = 1";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add("@Date", myDateTime);
cmd.ExecuteNonQuery();

void DataGrid1MouseDown(object sender,
                        System.Windows.Forms.MouseEventArgs e)
{
    //Determine where we clicked the DataGrid
    Point pt = new Point(e.X, e.Y);
    DataGrid.HitTestInfo hti = dataGrid1.HitTest(pt);

    if(e.Button == MouseButtons.Left)
    {
        // If it was a LeftClick on a Column Header...
        if (hti.Type == DataGrid.HitTestType.ColumnHeader)
        {
            // Determine the column name
            DataColumn dc;
            dc = dt.Columns[hti.Column];

            // Save the data in column1 of any selected row in an array.
            al = new ArrayList();
            for(int i = 0; i < dt.Rows.Count; i++)
            {
                if (dataGrid1.IsSelected(i))
                {
                    listBox1.Items.Add(dt.Rows[i][0].ToString());
                    al.Add(dt.Rows[i][0].ToString());
                }
            }
            SortData(dc.ColumnName);
        }
    }
}

private void SortData(string colname)
{
    // Sort the DataTable into an array
    DataRow[] drarray;
    drarray = dt.Select(null, colname,
                        DataViewRowState.CurrentRows);

    int len = drarray.Length;

    // Add the rows from the sorted array to the end of the table
    for (int i = 0 ; i < drarray.Length ; i++)
    {
        DataRow dr = dt.NewRow();
        for (int j = 0; j < dt.Columns.Count; j++)
        {
            dr[j] = drarray[i][j];
        }
        dt.Rows.Add(dr);
    }

    // Remove the original rows
    for (int i = len - 1 ; i >=0  ; i--)
    {
        dt.Rows.RemoveAt(i);
    }

    // If the data in column1 of any row is in the ArrayList,
    // then Select the corresponding DataGrid row.
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        if (al.Contains(dt.Rows[i][0].ToString()))
        {
            dataGrid1.Select(i);
        }
    }
}

AnotherClass myClass = new AnotherClass();
myClass.userName = this.text1.text;

//Assuming that you have overloaded its constructor properly
AnotherClass myClass = new AnotherClass(this.text1.text);