EntityException was unhandled by the user code, Underlying provider failed an open

Question

In my mvc 4 project I have installed entity framework through nuget package manager
Then added EmployeeContext.cs class file to the models folder then added the following code in to that

public class EmployeeContext : DbContext
{
public DbSet Employees {get; set;}
}

and I added namespace using System.Data.Entity;
3. Now I added a connection string in to the web.config file, in the root directory:

<connectionStrings>
  <add name="EmployeeContext" 
        connectionString="server=.; database=Sample; integrated security=SSPI"
        providerName="System.Data.SqlClient"/>
</connectionStrings>

4. Mapped "Employee" model class to the database table, tblEmployee using "Table" attribute as shown below.

    [Table("tblEmployee")]  
    public class Employee  
    {  
        public int EmployeeId { get; set; }  
        public string Name { get; set; }  
        public string Gender { get; set; }  
        public string City { get; set; }   
    }

and added the namespace "System.ComponentModel.DataAnnotations.Schema" for the table attribute.
5. I created EmployeeController.cs in which the ActionMethod Details() is shown below:

public ActionResult Details(int id) 
{  
    EmployeeContext employeeContext = new EmployeeContext();  
    Employee employee = employeeContext.Employees.Single(x => x.EmployeeId == id);  

    return View(employee);  
}

6. Finally, the following code in Application_Start() function, in Global.asax file.
Database.SetInitializer<MVCDemo.Models.EmployeeContext>(null);
and added the namespace using System.Data.Entity;

when I build this project it is showing build succeeded and run this program http://localhost/MVC4Demo/Employee/Details/1
I am getting error in this particular line saying that

Employee employee = employeeContext.Employees.Single(x => x.EmployeeId == id);    

EntityException was unhandled by the user code  
Underlying provider failed an open

When I install the entity framework from nugget it has the latest version 6.0.2 what is that I am doing wrong so that I am not able to run this project.

upto my knowledge whatever I presented in my code that connectionString only I have used. — kool kims
Is server=. correct? Shouldn't you be using the server name instead of .? — kvothe
actually I have checked the sql server it is not in the local I have changed the server=QUTED004/SQLEXPRESS actual in which my db is there. — kool kims

Md Firdaus Alam Md Firdaus Alam · Accepted Answer · 2017-08-07T18:12:29

Use exact name of your Server in ConnectionString section. Copy it from SQL Server login page. Server Details

<connectionStrings>
  <add name="EmployeeContext"
        connectionString="server=LAPTOP-J1IQQE3F\SQLEXPRESS; Database=sample; integrated security=True"
        providerName="System.Data.SqlClient"/>
</connectionStrings>

Change code in "Employee" Model class as following.

using System;  

using System.Collections.Generic;  

using System.Linq;  

using System.Web;  

using System.ComponentModel.DataAnnotations.Schema; 
using System.ComponentModel.DataAnnotations;  

namespace MVCDemo.Models


{
        [Table("tblEmployees")]  /* to map tablename with our Modelclass*/


      public class EmployeeModel


        {
            [Key] //If the property is named something other than Id, 
                  //you need to add the [Key] attribute to it.
                  //Otherwise give error "Entity type has no key defined".
            public int EmployeeId { get; set; }
            public string Name { get; set; }
            public string Gender { get; set; }
            public string City { get; set; }
        }
    }

EntityException was unhandled by the user code, Underlying provider failed an open

1 Answers