我希望 MS Access 中最后一条记录的相应 ID 出现在消息框内 [重复]

Posted 2023-05-07

【中文标题】我希望 MS Access 中最后一条记录的相应 ID 出现在消息框内 [重复]

【英文标题】：I want the corresponding ID of last record in MS Access to appear inside a Message Box [duplicate]

【发布时间】：2021-02-23 13:40:04

【问题描述】：

我正在使用 C# (Visual Studio 15) 中的 Access 作为数据库。我想将表单条目（添加记录）保存到 Access 数据库中，并希望记录的相应 ID 在成功保存后显示在 MsgBox 中。我尝试了以下方法：

 private void Form21_Load(object sender, EventArgs e)
      
          try
          
              connection.Open();
              checkConnection.Text = "Server Connection, Successful";
              connection.Close();
          
          catch (Exception ex)
          
              MessageBox.Show("Error, Server not connected " + ex);
          
      
    

    private void Button6_Click(object sender, EventArgs e)
    
        connection.Open();
        OleDbCommand command = new OleDbCommand();
        command.Connection = connection;
        command.CommandText = "insert into Students_File ([YourNames],[Nationality],[StateOfOrigin],[PlaceOfBirth],[DoB],[HomeAddress],[LastSchools1],[LastClass1],[LastSchools2],[LastClass2],[LastSchools3],[LastClass3],[AdmClass],[CurrentClass],[Guidian],[GuardianContact],[UserName],[PassWord],[Gender],[RegistrationDate]) values('" + YourNames.Text + "','" + Nationality.Text + "','" + StateOfOrigin.Text + "','" + PlaceOfBirth.Text + "','" + DoB.Text + "','" + HomeAddress.Text + "','" + LastSchools1.Text + "','" + LastClass1.Text + "','" + LastSchools2.Text + "','" + LastClass2.Text + "','" + LastSchools3.Text + "','" + LastClass3.Text + "','" + AdmClass.Text + "','" + CurrentClass.Text + "','" + Guidian.Text + "','" + GuardianContact.Text + "','" + UserName.Text + "','" + PassWord.Text + "','" + Gender.Text + "','" + RegistrationDate.Text + "')";
        command.ExecuteNonQuery();
        //MessageBox.Show("Congrats! Your registration, is successful. You may now click close button, then proceed to login");

        command.CommandText = "Select * from Students_File where UserName='" + UserName.Text + "' and PassWord='" + PassWord.Text + "'";
        OleDbDataReader reader = command.ExecuteReader();
        int count = 0;
        while (reader.Read())
        
            count = count + 1;
        
        if (count == 1)
        
            MessageBox.Show("Congrats! Your registration, is successful. You may now click close button, then proceed to login");
            this.Close();
        
        else if (count > 1)
        
            MessageBox.Show("Sorry, the chosen username or password is currently existing or picked by another user. Consequently, your registration was not successful. Do please, decide another but a unique one. Thank you");
        
        connection.Close();
    

【问题讨论】：

它没有回答我的问题。如果新记录添加成功，我需要 ID 出现在 MessageBox 中！

我想如果你能得到 id 然后你可以做任何你需要做的事。

对不起，我如何操作上面代码的给定链接中的答案。我想这是我的弱点。

为什么用户需要查看记录 ID？这对他们有任何意义吗？

虽然它将作为帐户所有者的学生 ID，但在忘记密码表单中也需要它来恢复忘记的登录详细信息。

【参考方案1】：

你可以这样做：

using (OleDbCommand Command = new OleDbCommand("", conn))

    Command.CommandText = "Your big ugly mess - need to change this to parmaters!)";
    Command.Connection.Open();
    Command.ExecuteNonQuery();

    Command.CommandText = "Select @@Identity";
    var intLastID = Command.ExecuteScalar;

    MsgBox("Last id into database = " + intLastID);

如前所述，您确实希望更改该插入命令 - 它太长、太难维护，并且容易出现代码错误甚至 sql 注入。

但是，现在，您可以使用上述方法来获取/提取最后一个 ID 插入。

【讨论】：

谢谢。这解决了我的问题

【参考方案2】：

在解决我的询问时，我有以下代码（来自 Kevin）：

     string query = "Insert Into Categories (CategoryName) Values (?)";
        string query2 = "Select @@Identity";
        int ID;
        string connect = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|Northwind.mdb";
        using (OleDbConnection conn = new OleDbConnection(connect))
        
            using (OleDbCommand cmd = new OleDbCommand(query, conn))

            
                cmd.Parameters.AddWithValue("@CategoryName", OleDbType.Integer);
                conn.Open();
                cmd.ExecuteNonQuery();
                cmd.CommandText = query2;
                ID = (int)cmd.ExecuteScalar();
            
        

现在，我的挑战是如何在成功创建记录后让 ID 出现在消息框中。请考虑我在这篇文章中最早的代码。