試圖附加自動命名的數據庫文件失敗

Question

嘗試登錄到我的asp.net網站的管理部分時，我得到以下錯誤：

試圖附加自動命名的數據庫文件C：\ Users \ joshy \ Documents \ Visual Studio 2015 \ WebSites \ nas2 \ App_Data \ nas.mdf失敗。具有相同名稱的數據庫存在，或指定的文件無法打開，或位於UNC共享上。

**它突出反映了以下幾行代碼在我connectionclass.cs

文件：**

Line 113:  try 
Line 114:  { 
Line 115:   conn.Open(); 
Line 116:   int amountOfUsers = (int)command.ExecuteScalar(); 

這裏是連接class.cs文件的用戶部分的代碼：

#region Users 
    public static User LoginUser(string name, string password) 
    { 
     //Check if user exists 
     string query = string.Format("SELECT COUNT(*) FROM nas.dbo.users WHERE name = '{0}'", name); 
     command.CommandText = query; 

     try 
     { 
      conn.Open(); 
      int amountOfUsers = (int)command.ExecuteScalar(); 

      if (amountOfUsers == 1) 
      { 
       //User exists, check if the passwords match 
       query = string.Format("SELECT password FROM users WHERE name = '{0}'", name); 
       command.CommandText = query; 
       string dbPassword = command.ExecuteScalar().ToString(); 

       if (dbPassword == password) 
       { 
        //Passwords match. Login and password data are known to us. 
        //Retrieve further user data from the database 
        query = string.Format("SELECT email, user_type FROM users WHERE name = '{0}'", name); 
        command.CommandText = query; 

        SqlDataReader reader = command.ExecuteReader(); 
        User user = null; 

        while (reader.Read()) 
        { 
         string email = reader.GetString(0); 
         string type = reader.GetString(1); 

         user = new User(name, password, email, type); 
        } 
        return user; 
       } 
       else 
       { 
        //Passwords do not match 
        return null; 
       } 
      } 
      else 
      { 
       //User does not exist 
       return null; 
      } 
     } 
     finally 
     { 

      conn.Close(); 
     } 
    } 

    public static string RegisterUser(User user) 
    { 
     //Check if user exists 
     string query = string.Format("SELECT COUNT(*) FROM users WHERE name = '{0}'", user.Name); 
     command.CommandText = query; 

     try 
     { 
      conn.Open(); 
      int amountOfUsers = (int)command.ExecuteScalar(); 

      if (amountOfUsers < 1) 
      { 
       //User does not exist, create a new user 
       query = string.Format("INSERT INTO users VALUES ('{0}', '{1}', '{2}', '{3}')", user.Name, user.Password, 
             user.Email, user.Type); 
       command.CommandText = query; 
       command.ExecuteNonQuery(); 
       return "User registered!"; 
      } 
      else 
      { 
       //User exists 
       return "A user with this name already exists"; 
      } 
     } 
     finally 
     { 
      conn.Close(); 
     } 
    } 
    #endregion 

更多的connectionclass.cs代碼：

using System.Collections; 
using System.Configuration; 
using System.Data.SqlClient; 
using Entities; 

public static class ConnectionClass 
{ 
    private static SqlConnection conn; 
    private static SqlCommand command; 
    private static object toursdate; 

    static ConnectionClass() 
    { 
     string connectionString = ConfigurationManager.ConnectionStrings["nas_connect"].ToString(); 
     conn = new SqlConnection(connectionString); 
     command = new SqlCommand("", conn); 

任何幫助將不勝感激。

謝謝。

Answer 1

首先請分享全部代碼或請檢查您是否嘗試打開一個已關閉的連接。