我正在尝试从表 1 中选择然后插入日期时间到表 2。我已成功插入数据。但是，表 2 中显示的日期时间是 0000-00-00 00:00:00。 Idk错误在哪里。有人请帮我解决这个问题。我正在为此苦苦挣扎。这是 SELECT 然后 insert 的正确方法吗？ (从表 1 中选择，然后插入到表 2 中)

 try
    {
        string myConnectionString;
        myConnectionString= "server=localhost;uid=root;pwd=root;database=medicloud;SslMode=None;charset=utf8";

        MySqlConnection connection = new MySqlConnection(myConnectionString);
        MySqlCommand cmd = new MySqlCommand();

        cmd.CommandType = CommandType.Text;

        EncodingProvider ppp;
        ppp = CodePagesEncodingProvider.Instance;
        Encoding.RegisterProvider(ppp);

        connection.Open();   

        string select = "Select time from assign where userId=@name";
        cmd.Parameters.AddWithValue("@name", txtValue.Text);                           
        cmd.CommandText = select;
        cmd.Connection = connection;


        MySqlDataReader selectAssign = cmd.ExecuteReader();
        selectAssign.Read();
        string assign = (selectAssign["time"].ToString());
        selectAssign.Close();


        cmd.CommandType = CommandType.Text;
        cmd.CommandText = "INSERT into bluetooth (userId,arm,armNumberDone,armNumber,comDate,assignDate,status) VALUES (@name, @stupid0, @stupid1, @stupid2, @stupid3, @stupid4, @stupid5)";
        cmd.Parameters.AddWithValue("@stupid0", databaseLine);
        cmd.Parameters.AddWithValue("@stupid1", counter);
        cmd.Parameters.AddWithValue("@stupid2", databaseValue);
        cmd.Parameters.AddWithValue("@stupid3", DateTime.Now);
        cmd.Parameters.AddWithValue("@stupid4", assign);
        cmd.Parameters.AddWithValue("@stupid5", complete);
        cmd.Connection = connection;


        cmd.ExecuteNonQuery();
        connection.Close();

    }

    catch (MySqlException ex)
    {
        txtExercise.Text = ex.ToString();
    }

最佳答案

请试试这个

try
{
      string myConnectionString;
      myConnectionString = "server=localhost;uid=root;pwd=root;database=medicloud;SslMode=None;charset=utf8";

      MySqlConnection connection = new 
           MySqlConnection(myConnectionString);
      MySqlCommand cmd = new MySqlCommand();

      cmd.CommandType = CommandType.Text;

      EncodingProvider ppp;
      ppp = CodePagesEncodingProvider.Instance;
      Encoding.RegisterProvider(ppp);

      connection.Open();

      string select = "Select time from assign where userId=@name";
      cmd.Parameters.AddWithValue("@name", txtValue.Text);
      cmd.CommandText = select;
      cmd.Connection = connection;

      MySqlDataReader selectAssign = cmd.ExecuteReader();
      selectAssign.Read();
      string assign = (selectAssign["time"].ToString());
      selectAssign.Close();

      DateTime assignDate = DateTime.Now;
      DateTime.TryParseExact(assign, out assignDate);

      cmd.CommandType = CommandType.Text;
      cmd.CommandText = "INSERT into bluetooth 
(userId,arm,armNumberDone,armNumber,comDate,assignDate,status) VALUES (@name, 
@stupid0, @stupid1, @stupid2, @stupid3, @stupid4, @stupid5)";
      cmd.Parameters.AddWithValue("@stupid0", databaseLine);
      cmd.Parameters.AddWithValue("@stupid1", counter);
      cmd.Parameters.AddWithValue("@stupid2", databaseValue);
      cmd.Parameters.AddWithValue("@stupid3", DateTime.Now);
      cmd.Parameters.AddWithValue("@stupid4", assignDate);
      cmd.Parameters.AddWithValue("@stupid5", complete);
      cmd.Connection = connection;

      cmd.ExecuteNonQuery();
      connection.Close();
   }
  catch (MySqlException ex)
  {
      txtExercise.Text = ex.ToString();
  }
}

关于c#数据库选择然后插入。但是值为0，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51549480/