Oracle数据库中LONG类型字段的存取

CREATE TABLE TEST 
(
AGREEMENT_ID  CHAR(3) NOT NULL,
AGREEMENT_CONTENT LONGNULL
      )

protected void Button1_Click(object sender, EventArgs e)
{
OracleConnection conn = new OracleConnection
(@"Password=XXXXXX;User ID=hk;
Data Source=wealth;Persist Security Info=True");
conn.Open();
OracleCommand cmd = new OracleCommand("Select * From TEST", conn);
string sql = "Insert Into TEST (AGREEMENT_ID, AGREEMENT_CONTENT)   
Values(:P_ID,   :P_Value)";
cmd.CommandText = sql;
cmd.Parameters.Add("P_ID", this.TextBox2.Text);
cmd.Parameters.Add("P_Value", this.TextBox1.Text);
cmd.ExecuteNonQuery();
conn.Close();
      }

protected void Button2_Click(object sender, EventArgs e)
{
OracleConnection conn = new OracleConnection
(@"Password=XXXXXX;User ID=hk;Data Source=wealth;
Persist Security Info=True");
conn.Open();
string sql = "Select   *   From   TEST where AGREEMENT_ID = :P_ID";
OracleDataAdapter da = new OracleDataAdapter(sql, conn);
da.SelectCommand.Parameters.Add("P_ID", this.TextBox2.Text);
DataSet ds = new DataSet();
da.Fill(ds);
this.TextBox1.Text = ds.Tables[0].Rows.Count.ToString();
this.TextBox1.Text = ds.Tables[0].Rows[0]["AGREEMENT_CONTENT"].ToString();
conn.Close();
      }