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Local DB in Visual Studio 2015

After a few years, I have returned to writing in C# and I am really struggling here - I would like to have my app to have a local SQL database. I have added Service-based database and "Database1.mdf" was added to my project. I created a table and added some data just to see if it is working but I cannot connect to it. I tried numerous connection strings with no success (Server not accessible).
Do I need to run something else in the background? I thought that I might have a local database and with .NET client I can access it, and I hoped it would work whenever I bring my application (also not requiring any SQL server running). Is that wrong?

If you don't require any SQL server, take a look at SQLite. This is lite SQL database engine. Database is just one file. C# has a great library to SQLite on NuGet: https://www.nuget.org/profiles/mistachkin
SQLite is widely used, event in Android (as a native db engine).

here is what i use to connect. it appears as a Data Connection in Server Explorer.
string con2 = #"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=" + Application.StartupPath + "\\jobfile_2017.mdf;Integrated Security=True;Connect Timeout=30";
when i first started working with these, i used this source 1
it works on PC's that i have nothing installed (not even office) but as i said i'd be interested to know of any shortcomings of this method

I experiencing same problem and decided to move mdf file to static c:\db directory. Connection string was changed to incorporate new file location (AttachDbFile).
But AttachDbFile has some issues also (by some reason one table in db is inaccesible and error is access denied).
So I decided to move to Sqlite. LocalDb has many issues to work with. I read good note to resolve problem: in command line stop/remove/start name of instance. But it nuissance.
Wish you good luck to work with these db files.

Why is entity framework giving this error on web server?

I'm trying to use Entity Framework to add records to a database from a webform input that go into a database on sqlserver.
Everything works fine locally.
I used webmatrix to publish my site to my remote server, the website and my local version of the database is successfully recreated on the remote server with all the data.
However when it comes time to add records to the database, it gives an error on the remote server which i managed to trace to the ctx.Students.Add line.
using (var ctx = new HDPS_SchoolDataEntities())
{
SchoolDataModel.Student temp = new SchoolDataModel.Student();
temp.Name = this.FirstName;
temp.Surname = this.Surname;
temp.Parents = this.Parents;
ctx.Students.Add(temp);
ctx.SaveChanges();
}
I can't find any difference between my local version that works and the one on the remote server that doesn't work. The web.config seems to be configured as expected and all the necessary dll's are in my bin folder but it just won't work on the remote server... any ideas what could be wrong?
Oops forgot the error message!
edit
after Installing .net 4.5 and changing the connection mode from windows authentication to SQL authentication the error now becomes:
Code generated using the T4 templates for Database First and Model First development may not work correctly if used in Code First mode. To continue using Database First or Model First ensure that the Entity Framework connection string is specified in the config file of executing application. To use these classes, that were generated from Database First or Model First, with Code First add any additional configuration using attributes or the DbModelBuilder API and then remove the code that throws this exception.
Everything should be the same on the webserver as the entire website is being copied across but it works fine locally so not sure what the problem is...
OKay I solved the issue with the help of this webpage
http://blog.oneunicorn.com/2012/02/26/dont-use-code-first-by-mistake/
In short It seems webmatrix was does not include the metadata part of the connection string on upload to the server thus the EDMX file containing all the information mapping the classes to the database tables was not being referenced causing any queries to the framework to fail.
Once i pasted the original connection string generated by the Entity Framework wizard onto the server everything worked fine.

Based on the error given in your comment, it sounds like you are failing to connect to the database. Check your connection string, username and password. If those are correct, make sure your database settings allows connections from your server ip address.

OKay I solved the issue with the help of this webpage
http://blog.oneunicorn.com/2012/02/26/dont-use-code-first-by-mistake/
It seems webmatrix was does not include the metadata part of the connection string on upload to the server thus the EDMX file containing all the information mapping the classes to the database tables was not being referenced causing any queries to the framework to fail.
Once i pasted the original connection string generated by the Entity Framework wizard onto the server everything worked fine.

I want to run C# program without changing SQL Server instance or without changing SQL Server installed PC name

I have C# application which uses SQL Server R2 as its database. That database is on a separate PC by the name of SERVER. SQL Server's instance name also server.
My windows application uses DataSet to communicate with the database. Now my SQL installed PC name is change to another name, ex SERVERHP. Now all my coding works want to change my connection string. Are there any other easy way to do it ?
I am to tried to edit hosts file, but it does not work for me.
This is my coding style (http://goo.gl/FQrkp). I am using DataSet with DataAdapter with IDE designers.
I have 100 ~ 150 forms. Now I cannot compile all codings. I want to easy method to connect that SQL Server database.
I want to have a way to hide the change of the hostname of the computer

You have a couple of options:
Globally replace all server names with IP address in connection strings in the app
Globally replace all server names with the new server name in the app
Add a CNAME record to the DNS table on the server (assuming of course you're in the same network, which you are if you're using computer names)
Add an entry to the LMHOSTS file (you can add as many names as you'd like that point to the same IP)

As I understand, it is SqlConnection used to connect to database, or something like that. Why don't you use SqlConnectionStringBuilder? Then you can dinamically construct connection string you need. Also, to get list of servers, you can use SqlDataSourceEnumerator, from namespace System.Data.Sql.

It sounds like you want to have a way to hide the change of the hostname of the computer (Server/Desktop/Virtualized instance of Windows, whatever) that is running your SQL Server.
This isn't my area of expertise, but I can't think of a way to do it that only involves your application code and just the computer.
If you control the local DNS you can create a CNAME entry with the old name that "points" at the new one. Depending on how your connection strings are stored, you might have to edit them or you might not. But you won't have to worry about the location of your SQL Server changing again because you can always edit your CNAME to point at the new location.
Note for the future - not your current problem: If you continue to use MS SQL Server in particular you'll want to be careful about moving it to a computer where it isn't the default instance because then you need to put the instance name in the connection string as well, which might force you to edit all of your application web.configs and app.configs again.

Are you using Visual Studio 2012 with your development efforts? I ran into a conflict with the mini SQL db VS installs (Using Premium version) and had to modify the ConnectionStrings section of my Machine.config file to point to my SQL database. For whatever reason, VS will write references to the mini db in the Machine.Config file (for whatever version of .Net you are leveraging) throwing potetial conflicts.
The file can be found in %systemroot%\Microsoft.Net\Framework64\dot net version\Config
If you're using an x86 processor the Framework64 folder is just called 'Framework'.

connect to .mdf file in vs2010 , wpf application

I am using VS2010 , and I built a .mdf file using SQL server 2008
I want to use this database file in my wpf application so that I can add rows to it and delete rows from it
the problem is , I can't access this file , and all the insertion and deleting is actually hapening to the datacontexct i created .
I used myDataContexct.Submitchanges() but it didn't work either
I tried to add a connection string when I define the datacontexct that holds the url of my .mdf file and this it gave me a runtime error when trying to access this file and the error messege says :
An attempt to attach an auto-named database for file Trial.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
please help me because I searched alot but I couldn't find any help

If the application is not going to be installed in a manner that many clients are accessing the same server, you would want to consider using SQL Server Compact Edition.
Are you sure the connection string in your app.config refers to the local mdf file? perhaps it refers to the server instance?
What technology do you use, is it LinqToSql or Entity Framework (I think you have t call SaveChanges, not AcceptChanges)?
If you do intend to access the server instance, then the problem seems to be a security restriction.
Please add more details on statement no. 1, and I'll write further info.

Local database, I need some examples

I'm making an app that will be installed and run on multiple computers, my target is to make an empty local database file that is installed with the app and when user uses the app his database to be filled with the data from the app .
can you provide me with the following examples :
what do I need to do so my app can connect to its local database
how to execute a query with variables from the app for example how would you add to the database the following thing
String abc = "ABC";
String BBB = "Something longer than abc";
and etc
Edit ::
I am using a "local database" created from " add > new item > Local database" so how would i connect to that ? Sorry for the dumb question .. i have never used databases in .net

Depending on the needs you could also consider Sql CE. I'm sure that if you specified the database you're thinking of using, or your requirements if you're usure you would get proper and real examples of connection strings etc.
Edit: Here's code for SqlCe / Sql Compact
public void ConnectListAndSaveSQLCompactExample()
{
// Create a connection to the file datafile.sdf in the program folder
string dbfile = new System.IO.FileInfo(System.Reflection.Assembly.GetExecutingAssembly().Location).DirectoryName + "\\datafile.sdf";
SqlCeConnection connection = new SqlCeConnection("datasource=" + dbfile);
// Read all rows from the table test_table into a dataset (note, the adapter automatically opens the connection)
SqlCeDataAdapter adapter = new SqlCeDataAdapter("select * from test_table", connection);
DataSet data = new DataSet();
adapter.Fill(data);
// Add a row to the test_table (assume that table consists of a text column)
data.Tables[0].Rows.Add(new object[] { "New row added by code" });
// Save data back to the databasefile
adapter.Update(data);
// Close
connection.Close();
}
Remember to add a reference to System.Data.SqlServerCe

I'm not seeing anybody suggesting SQL Compact; it's similar to SQLite in that it doesn't require installation and tailors to the low-end database. It grew out of SQL Mobile and as such has a small footprint and limited feature-set, but if you're familiar with Microsoft's SQL offerings it should have some familiarity.
SQL Express is another option, but be aware that it requires a standalone installation and is a bit beefier than you might need for an applciation's local cache. That said it's also quite a bit more powerful than SQL Compact or SQLite.

Seems like you're:
-Making a C# app that will be installed and run on multiple
computers
-That needs a local database (I'm assuming an RDBMS)
-You need to generate a blank database at installation
-You then need to be able to connect to the database and populate it when
the app runs.
In general, it seems that you need to read up on using a small database engine for applications. I'd start by checking out SQLite, especially if you need multi-OS capability (eg., your C# program will run on Microsoft's .NET Framework and Novell's Mono). There are C# wrappers for accessing the SQLite database.

I believe this question is about the "Local Database" item template in Visual Studio:

What are you considering as a database? From what little you've provided in your question, I'd suggest SQLite.
You can get sample code from their site Sqlite.NET

Not sure I fully understand what you're asking but Sqlite is a good option for lightweight, locally deployed database persistence. Have a look here:
http://www.sqlite.org/
and here for an ADO.NET provider..
http://sqlite.phxsoftware.com/

For 1)
The easiest way to provide this functionality is through SQL Server Express User Instances. SQL Server Express is free, so your user does not have to pay additional license for SQL Server, and the User Instance is file-based, which suits your requirement.
For 2)
This is a big topic. You may want to go through some of the tutorials from Microsoft to get the feeling of how to connect to DB, etc.