即使成功构建项目，应用程序也无法与MDF文件建立连接[Visual Studio 2010 C＃]

Question

I just learned Visual Studio 2010 C# for 3 months. I added the data source call "PUBS.MDF" which is the sample database from Microsoft like "NORTHWIND.MDF". and write the code to connect the data source with the following code :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication18
{
 public partial class Form1 : Form
  {
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        string constr = @"Data Source=.\SQLEXPRESS;
                        AttachDbFilename=|DataDirectory|\PUBS.mdf;
                        Integrated Security=True;User Instance=True;";
        SqlConnection connection = new SqlConnection(constr);
        connection.Open();
        string sql = "SELECT * FROM authors";
        SqlCommand command = new SqlCommand(sql, connection);
        textBox1.Text = (string)command.ExecuteScalar();
    }

  }
}

This code is debugged successfully as the picture below :

However, after I build the project, install in my computer (window7), and click to open the application (I also click "Run as administrator"), it show the error window as the picture below :

Someone please help me.

PS.

This is how I add the PUBS.MDF file in my application

1. Click tab "Data"
2. Click "Add New Data Souce..."
3. Select "Database"
4. Select "Dataset"
5. Browse "PUBS.MDF" file

This is how I build the project

1. Click tab "File" > Add > New Project > Visual Studio Installer > Setup Project
2. Right click "Application Folder" > "Add" > "Project Output" > "Primary Output"
3. Right click "Application Folder" > "Add" > "File..." > browse "PUBS.MDF" file
4. At "Solution Explorer" window, right click the project's name > click "Build" and wait until it shows message "Build secceed"

I also upload the project, please download by this link --> http://www.4shared.com/zip/-HLqC-b_/WindowsFormsApplication18.html ?

I used to post the question almost the same with this --> Building project succeed with Access database, can search the data but cannot delete the record but in that case, the database was .accdb file and it can be solved by clicking "Run as an administrator" but this case was .MDF file and I don't know why just different type of database file but cannot solve by the same method.

Answer 1

change your connection string as below. it may work:

      string constr =@"Data Source=.\SQLEXPRESS;AttachDbFilename=" + System.Windows.Forms.Application.StartupPath + "\\PUBS.mdf;Integrated Security=True;User Instance=True";