Exception when trying to connect to .sdf database

Question

I have database in file C:\Users\Pawel\Documents\DB.sdf. How can I connect to it?

Simple code below does not work and generates exception.

Code:

[WebMethod]
public String TestCon()
{
    SqlConnection sql = new System.Data.SqlClient.SqlConnection(
        @"Data Source=C:\Users\Pawel\Documents\DB.sdf");

    string str = "OK";

    try
    {
        sql.Open();
        sql.Close();
    }
    catch (Exception ex)
    {
        str = ex.Message;
    }

    return str;
}

Result:
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

What am I missing? What I should do to open connection correctly?

EDIT:
System.NotSupportedException: SQL Server Compact is not intended for ASP.NET development.
Great :P

Answer 1

Consider using System.Data.SqlServerCe.SqlCeConnection:

System.Data.SqlServerCe.SqlCeConnection con = 
   new System.Data.SqlServerCe.SqlCeConnection(@"Data Source=C:\Users\Pawel\Documents\DB.sdf");

(Add a reference to System.Data.SqlServerCe, if necessary)

Also, to use it with ASP.NET, add:

AppDomain.CurrentDomain.SetData("SQLServerCompactEditionUnderWebHosting", true);

Answer 2

Apparently, you are using a SQL Compact Edition (sdf file). Have you tried using SqlCeConnection instead of SqlConnection ?

As a bonus: if you dont want to mess with connectionstrings anymore, please try this.

Do do so, you have to add a reference to System.Data.SqlServerCe assembly.