将具有相同主键的2个表SQL Server连接到C#

怎么了，伙计们，我对这个代码有一些问题，我希望你们能弄清楚

我有两个表（客户和注册）使用SQL Server

客户

1. Id
2. 名称
3. 等等

注册

1. Id
2. 日期

我正在处理我的C#程序，我想将它们显示为listview，但我有错误，这是我的代码：

public void listdata()
    {
        SqlDataReader reader = null;
        listView1.Items.Clear();
        listView1.Columns.Clear();
        listView1.Columns.Add("ID", 55, HorizontalAlignment.Center);
        listView1.Columns.Add("Tanggal Registrasi", 150, HorizontalAlignment.Center);
        listView1.Columns.Add("Nama Pemohon", 150, HorizontalAlignment.Center);
        System.Data.SqlClient.SqlConnection conn = konn.GetConn();
        try
        {
            conn.Open();
            string sql = "select*from Ms_Register a join Ms_Coba b on a.id = b.id where id='" + textBox1.Text + "'";
            SqlCommand command = new SqlCommand(sql, conn); 
            command.ExecuteNonQuery();
            conn.Close();
            //Check
            reader = command.ExecuteReader();

            while (reader.Read())
            {
                ListViewItem item1 = new     ListViewItem(reader["id"].ToString(), 0);
                item1.SubItems.Add(reader["tanggal"].ToString());
                item1.SubItems.Add(reader["nama"].ToString());
                listView1.Items.Add(item1);
            }
        }
        catch (Exception e)
        {
            MessageBox.Show(e.ToString());
        }
        finally
        {
            conn.Close();
        }
    }

两个表都有相同的id，错误显示"列名"id"不明确"有人能解决这个问题吗？感谢

select * from Ms_Register a join Ms_Coba b on a.id = b.id where id='" + textBox1.Text + "'"

string sql = "select * from Ms_Register a join Ms_Coba b on a.id = b.id where a.id='" + textBox1.Text + "'";