保存：

private void btnSave_Click(object sender, System.EventArgs e)
{

FileStream stream = null;
SqlConnection conn = null;
SqlCommand cmd = null;
try
{
richTextBox1.SaveFile( "temp.rtf" );
stream = new FileStream("temp.rtf", FileMode.Open, FileAccess.Read);
int size = Convert.ToInt32(stream.Length);
Byte[] rtf = new Byte[size];
stream.Read(rtf, 0, size);

conn = new SqlConnection("Database=Northwind;Integrated Security=true;");
conn.Open();
cmd = new SqlCommand("UPDATE Employees SET Photo=@Photo WHERE EmployeeID=1", conn);

SqlParameter paramRTF =
new SqlParameter("@Photo",
SqlDbType.Image,
rtf.Length,
ParameterDirection.Input,
false,
0,0,null,
DataRowVersion.Current,
rtf);
cmd.Parameters.Add(paramRTF);

int rowsUpdated = Convert.ToInt32(cmd.ExecuteNonQuery());

MessageBox.Show(String.Format("{0} rows updated", rowsUpdated));
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if ( stream != null ) stream.Close();
if (cmd != null ) cmd.Parameters.Clear();
if (conn != null) conn.Close();
}
}

读取：

private void btnLoad_Click(object sender, System.EventArgs e)
{
richTextBox1.Clear();

SqlConnection cn = null;
SqlCommand cmd = null;
SqlDataReader reader = null;
try
{
cn = new SqlConnection("Database=Northwind;Integrated Security=true;");
cn.Open();
cmd = new SqlCommand("SELECT Photo FROM Employees WHERE EmployeeID=1", cn);
reader = cmd.ExecuteReader();
reader.Read();
if (reader.HasRows)
{
if (!reader.IsDBNull(0))
{
Byte[] rtf = new Byte[Convert.ToInt32((reader.GetBytes(0, 0, null, 0, Int32.MaxValue)))];
long bytesReceived = reader.GetBytes(0, 0, rtf, 0, rtf.Length);

ASCIIEncoding encoding = new ASCIIEncoding();
richTextBox1.Rtf = encoding.GetString(rtf, 0, Convert.ToInt32(bytesReceived));
}
}
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (reader != null ) reader.Close();
if (cn != null ) cn.Close();
}

}