Error de C# MySQL: palabra clave no admitida

Tengo un problema con mi escritura en la base de datos y la lectura de la base de datos.

Aquí está mi código:

MySqlConnection conn = new MySqlConnection(ConnectionString);
string ID = "";
MySqlCommand cmdRegister = new MySqlCommand("Insert into Players (username,password) values('"+"John"+"', '"+"johnisbest"+"')", conn);
cmdRegister.ExecuteNonQuery();
MySqlCommand cmdRead = new MySqlCommand("SELECT ID FROM Players WHERE username = '"+this.username+"';", conn);
MySqlDataReader reader = cmdRead.ExecuteReader();
conn.Open();

while (reader.Read())
{
    ID = (string)reader["ID"];
}
conn.Dispose();
return ID;

Siempre me da error: Palabra clave no admitida

Gracias por cada ayuda ;)

EDITAR:

public MySQL(string IPaddress, string port, string username, string password, string database)
{
    ConnectionString = "datasource=" + IPaddress + ";port=" + port + ";username=" + username + ";password=" + password + ";database=" + database + ";charse=utf_8";
}
sql = new MySQL("IP address to database", "3306", "username to database", "Here is my password to database", "name of my database");

 ConnectionString = "datasource=" + IPaddress + ";port=" + port + ";username=" + username + ";pwd=" + password + ";database=" + database + ";charse=utf_8";

Intenté reemplazar la contraseña con "pwd";

para mí esto funciona bien

Server=localhost;Database=testing;UID=root;password=testing;connect timeout=700;charset=utf8;pooling=true;Port=3306