无法访问数据库(SQL Server CE/Windows Mobile 6.5) [英] Unable to access database (SQL Server CE / Windows Mobile 6.5)

问题描述

我正在为 Windows Mobile 6.5 设备创建一个应用程序，其中的一部分应该在设备插入时复制 SQL 数据库，在拔下时有一个本地副本(因为没有连接).

I'm creating an application for a Windows Mobile 6.5 device, part of which is supposed to replicate a SQL database when the device plugged in, to have a local copy when unplugged (because no connection).

因此，为了拥有一个本地数据库，我遵循了Northwind"教程SQL Server CE(使用我自己的测试数据库)，但经常遇到设备无法连接到数据库的问题.我无法调试(因为我每次都必须将程序传输到设备进行测试)但我收到此错误消息(无论我尝试使用什么连接字符串):

So, to have a local database I followed the "Northwind" tutorial for SQL Server CE (with my own test database), but constantly run into the issue that the device can't connect to the database. I can't debug (because I have to transfer the program to the device to test it every time) but I get this error message (whatever the connection string I try to use):

SQL 数据库错误:未指定的错误 [.\userdb.sdf]

SQL database error: Unspecified error [.\userdb.sdf]

我尝试了多个连接字符串，如果我使用设计器将数据源绑定到表单，我可以看到可以访问数据库.但是我需要手动设置一些查询，因为它们比填写表格要复杂得多.

I tried multiple connection strings, and I can see the database can be accessed if I bind the data sources to the forms using the designer. But I need to manually set up some query as they will be a lot more complicated than just filling forms.

这是我的代码，它只是用来填写表格，但下一步是登录/密码检查:

Here's my code, it's just supposed to fill a form but the next step would be a login/password check:

public partial class UserLogin : Form
{
    private SqlCeConnection _conn;

    public UserLogin()
    {
        InitializeComponent();

        _conn = new SqlCeConnection(@"Data Source=.\userdb.sdf;Password=PASSWORD;Persist Security Info=True");  
    }

    private void buttonCancel1_Click(object sender, EventArgs e)
    {
        this.Close();
    }

    private void buttonLoad1_Click(object sender, EventArgs e)
    {
        try
        {
            SqlCeCommand cmd = new SqlCeCommand();
            cmd.Connection = _conn;
            cmd.CommandText = "SELECT userid, username, password FROM Users";

            _conn.Open();
            SqlCeResultSet resultSet = cmd.ExecuteResultSet(ResultSetOptions.Scrollable | ResultSetOptions.Updatable);
            this.bindingSource1.DataSource = resultSet;

        }
        catch (SqlCeException sql_ex)
        {
            MessageBox.Show("SQL database error: " + sql_ex.Message);
        }
    }

我也尝试了一些不同的东西，其中表单填充了来自设计器的数据集，但我仍然无法手动访问数据库:https://pastebin.com/10P3wGeP

Also something different I tried, where the forms are filled with a DataSet from designer but I still can't manually access the database: https://pastebin.com/10P3wGeP

推荐答案

Windows Mobile 既不知道驱动器号，也不知道当前"目录.这就是Data Source=.\userdb.sdf"总是失败的原因.

Windows Mobile neither knows about drive letters nor a 'current' directory. That is why "Data Source=.\userdb.sdf" will always fail.

在 windows mobile 上，您始终必须使用完全限定的路径名​​来访问文件.

On windows mobile you always have to use a full qualified path name to access a file.

你可以使用

 string path = System.IO.Path.GetDirectoryName( 
  System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase );

获取可执行文件启动目录的路径.

to get the path to the directory of where the executable is started.

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