C#

OleDbConnection conn = new OleDbConnection( DB_STR );
OleDbDataAdapter da = new OleDbDataAdapter( "SELECT TOP 1 * FROM Guestbook", conn );
OleDbCommandBuilder cb = new OleDbCommandBuilder( da );
cb.QuotePrefix = "[";
cb.QuoteSuffix = "]";
  
DataSet ds = new DataSet();
da.Fill( ds );
  
DataTable table = ds.Tables[0];
DataRow row = table.NewRow();
  
row["Date"] = DateTime.Now;
row["Name"] = name;
row["EMail"] = email;
row["Text"] = text;
table.Rows.Add( row );
  
da.Update( ds );
  
conn.Close();

OleDbConnection conn = new OleDbConnection( DB_STR );
// do your query for a specific recordset.
// if it returns none, you must create a new, otherwise modify the existing.
OleDbDataAdapter da = new OleDbDataAdapter( "SELECT TOP 1 * FROM Guestbook WHERE ID="+ID, conn );
OleDbCommandBuilder cb = new OleDbCommandBuilder( da );
cb.QuotePrefix = "[";
cb.QuoteSuffix = "]";
    
DataSet ds = new DataSet();
da.Fill( ds );
    
DataTable table = ds.Tables[0];
    
// create new.
if ( table.Rows.Count==0 )
{
    DataRow row = table.NewRow();

    row["Date"] = DateTime.Now;
    row["Name"] = name;
    row["EMail"] = email;
    row["Text"] = text;
    
    table.Rows.Add( row );
}
// modify existing.
else
{
    DataRow row = table.Rows[0];
    
    row["Date"] = DateTime.Now;
    row["Name"] = name;
    row["EMail"] = email;
    row["Text"] = text;
}
    
da.Update( ds );
    
conn.Close();

<br />
cb.QuotePrefix = "[";<br />
cb.QuoteSuffix = "]";<br />

"In the confrontation between the stream and the rock, the stream always wins - not through strength but perseverance." (H. Jackson Brown)