急急急，listView 的问题

Question

        private void Search()
        {
            string sql = string.Format("SELECT QuestionId,Question,Answer,Difficulty FROM dbo.Question WHERE Difficulty ='{0}'",textBox1.Text);
            listView1.Items.Clear();
            try
            {
                SqlCommand command = new SqlCommand(sql, DBHelper.connection);                DBHelper.connection.Open();
                SqlDataReader dataReader = command.ExecuteReader();
                while (dataReader.Read())
                {
                    ListViewItem item = new ListViewItem(dataReader["Question"].ToString());
                    item.SubItems.AddRange(new string[]{
                    dataReader["Answer"].ToString(),
                    dataReader["Difficulty"].ToString()
                });
                    listView1.Items.Add(item);
                    
                    
                }
                dataReader.Close();
                
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                DBHelper.connection.Close();
            }
        }        private void button1_Click(object sender, EventArgs e)
        {
            Search();
        }
        private void DeleteQusetion()
        {
            int result = 0;
            string sql = string.Format("DELETE FROM dbo.Question WHERE QuestionId='{0}'",listView1.SelectedItems[0].Tag);
            listView1.Items.Clear();
            try
            {
                SqlCommand command = new SqlCommand(sql, DBHelper.connection);                DBHelper.connection.Open();
                result = command.ExecuteNonQuery();
                          }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                DBHelper.connection.Close();
            }
            if (result > 0)
            {
                MessageBox.Show("删除成功");
            }
            else {
                MessageBox.Show("删除失败");
            }
        }        private void 删除ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DeleteQusetion();
        }这段代码我要在Search方法里面加句代码Tag记录 然后在Delete方法里的SQL语句里删除，那句代码怎么写，忘了。急急急
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