L'inserimento di valori in un database MySQL non funziona come previsto

Con MysqlDataAdapter è necessario impostare solo selectCommand. Genererà automaticamente insertCommand da MySqlCommandBuilder

Il tuo codice è quasi corretto sono necessarie solo 2 modifiche.

1. Aggiungi la riga seguente prima di dataAdapterCurrentTest.Update(ds.Tables["currentTest"])

new MySqlCommandBuilder(dataAdapterCurrentTest);

2. Commenta seguendo la riga del codice

dataAdapterCurrentTest.InsertCommand=insertCmd

Quindi il codice finale è

 class Program
    {
        static void Main(string[] args)
        {
            MySqlConnectionStringBuilder connBuilder = new MySqlConnectionStringBuilder();

            connBuilder.Server = "ds2";
            connBuilder.Database = "fhem";
            connBuilder.UserID = "fhemdbuser";
            connBuilder.Port = 3307;
            connBuilder.Password = "!2345Abcde";
            //connBuilder.DefaultCommandTimeout = 120;
            //connBuilder.UseDefaultCommandTimeoutForEF = true;
            //connBuilder.AllowUserVariables = true;

            MySqlConnection conn = new MySqlConnection(connBuilder.ConnectionString);
            conn.Open();
            MySqlCommand selectCmdCurrent = new MySqlCommand("select `TIMESTAMP`, `DEVICE`, `TYPE`, `EVENT`, `READING`, `VALUE`, `UNIT` from current;", conn);
            MySqlCommand selectCmdCurrentTest = new MySqlCommand("select `TIMESTAMP`, `DEVICE`, `TYPE`, `EVENT`, `READING`, `VALUE`, `UNIT` from currentTest;", conn);
            MySqlCommand updateCmd = new MySqlCommand("update `currentTest` set `TIMESTAMP`[email protected],`DEVICE`[email protected],`TYPE`[email protected],`EVENT`[email protected],`READING`[email protected],`VALUE`[email protected],`UNIT`[email protected]", conn);
            updateCmd.Parameters.Add("@p1", MySql.Data.MySqlClient.MySqlDbType.DateTime);
            updateCmd.Parameters.Add("@p2", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            updateCmd.Parameters.Add("@p3", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            updateCmd.Parameters.Add("@p4", MySql.Data.MySqlClient.MySqlDbType.VarString, 512);
            updateCmd.Parameters.Add("@p5", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            updateCmd.Parameters.Add("@p6", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            updateCmd.Parameters.Add("@p7", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);

            MySqlCommand insertCmd = new MySqlCommand("insert into `currentTest` values(@p1, @p2, @p3, @p4, @p5, @p6, @p7)", conn);
            insertCmd.Parameters.Add("@p1", MySql.Data.MySqlClient.MySqlDbType.DateTime);
            insertCmd.Parameters.Add("@p2", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            insertCmd.Parameters.Add("@p3", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            insertCmd.Parameters.Add("@p4", MySql.Data.MySqlClient.MySqlDbType.VarString, 512);
            insertCmd.Parameters.Add("@p5", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            insertCmd.Parameters.Add("@p6", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            insertCmd.Parameters.Add("@p7", MySql.Data.MySqlClient.MySqlDbType.VarString, 128);
            MySqlDataAdapter dataAdapterCurrent = new MySqlDataAdapter(selectCmdCurrent);
            MySqlDataAdapter dataAdapterCurrentTest = new MySqlDataAdapter(selectCmdCurrentTest);
            // MySqlCommandBuilder builder = new MySqlCommandBuilder(dataAdapterCurrent);
           // dataAdapterCurrentTest.InsertCommand = insertCmd;
            dataAdapterCurrentTest.UpdateCommand = updateCmd;
            DataSet ds = new DataSet();
            MySqlCommand prepareCmd = new MySqlCommand("truncate currentTest;", conn);
            prepareCmd.ExecuteNonQuery();
            //prepareCmd = new MySqlCommand("insert into currentTest select * from current;", conn);
            //prepareCmd.ExecuteNonQuery();
            prepareCmd = new MySqlCommand("INSERT INTO `currentTest` VALUES(\"2020-06-06 12:45:23\",\"DEVICE\", \"TYPE\", \"EVENT\", \"READING\", \"VALUE\", \"UNIT\")", conn);
            for (int i = 0; i < 10; i++)
                prepareCmd.ExecuteNonQuery();
            dataAdapterCurrentTest.Fill(ds, "currentTest");
            dataAdapterCurrent.Fill(ds, "current");
            int row = 0;

            Stopwatch sw = new Stopwatch();
            for (int i = 0; i < 10; i++)
            {

                DataRow newrow = ds.Tables["currentTest"].NewRow();
                newrow["Timestamp"] = DateTime.Now;
                newrow["Device"] = "Device";
                newrow["TYPE"] = "Type";
                newrow["EVENT"] = "Event";
                newrow["READING"] = "Reading";
                newrow["VALUE"] = "Value";
                newrow["UNIT"] = "Unit";
                ds.Tables["currentTest"].Rows.Add(newrow);
            }

            new MySqlCommandBuilder(dataAdapterCurrentTest);

            dataAdapterCurrentTest.Update(ds.Tables["currentTest"]);
            ds.Tables["currentTest"].AcceptChanges();
        }
    }