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Connect to a SQL Server database without a set file path

I am attempting to connect to a local SQL Server database in C#.
I am currently using the following connection string:
connectionString = #"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\User\source\repos\majorWork\majorWork\gameStats.mdf;Integrated Security=True";
However, I do not want to use a hardcoded file path, as I wish to be able to use the application across multiple computers, where the file path will be different. How should I go about doing this?

Best way is set this connection in Web.Config file.
<Database>
<ConnectionString name="connection">Server=servername; Initial Catalog=dbname; Persist Security Info=False; User ID=username; Password=password; MultipleActiveResultSets=False; Encrypt=True; TrustServerCertificate=False; Connection Timeout=30;;</ConnectionString>
</Database>
Then add Add System.Configuration as a reference.
in C# you can call this
string constring = ConfigurationManager.ConnectionStrings["connection"].ConnectionString;
After that you can create new connection instance by passing this to
SqlConnection con = new SqlConnection(constring)

If u install SQL server express using the default instance, then you can connect using . as your server name anyone can use it with default instance as well.
1.then in visual studio, click on solution explorer
2. Connect database, follow the instruction for SQL server
3. When it gets to server name use . to connect and choose your database name which you have created already in ms SQl, then test your connection
4. After it successful, u can now click on the database name showing under solution explorer,
5.after u click the database name, at the button right corner, there will be a connection string, copy it and use
This will be declared publicly or globally
Sqlconnection con = new sqlconnection("paste the connection string");
And to use
Sqlcommand cmd = new sqlcommand("insert into......",con);
Con.open ();
Cmd.executenonquery();
Con.close();

How to create Sql Server database users from ASP.NET code

I run an Admin site that manages client machines. Each client machine is assigned a specific Sql Server database user. Up to this point I've had to go into Management Studio and create the users. I'd like to do this automatically when I setup a client machine on the Admin site.
Any suggestions on the best way to do this? I'm using ASP.NET MVC 2(old, I know) and Entity Framework 6.

You can set up a feed that automatically imports the credentials to the existing user table in SQL if you have write-back capabilites.

create a SQL connection to the server and create the users via TSQL
Web.Config
<connectionStrings>
<add name="ConnStringDb1" connectionString="Data Source=localhost;Initial Catalog=YourDataBaseName;Integrated Security=True;" providerName="System.Data.SqlClient" />
</connectionStrings>
C#
CreateUser()
{
using(SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnStringDb1"].ConnectionString))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "tsql to create users here";
cmd.ExecuteNonQuery();
}
}
}

You could do this via SQL directly when the client machine is set up by using the CREATE USER / CREATE LOGIN statement (and assigning its privileges accordingly). You can get the SQL to guide you in doing so if you start adding the user in management studio then hit the script button at the top left of the dialog it will show you the SQL script to dynamically create the user account. Create User SQL Docs Create Login SQL Docs

Connect a C# MVC application to a remote SQL Server database

I have a SQL Server database located at http://192.168.10.3/MyDB. I have created a C# MVC application, and I need to know the steps to connect my application to the above database.
Is it only replacing the connection string in the web.config file ?
Data Source=?? ;Initial Catalog=??;Integrated Security=SSPI;
User ID=??;Password=pwd;
If so what am I to replace where I have placed the ?? sign ?

DataSource = 192.168.10.3
Initial Catalog = MyDB
User ID = whatever sql login you are using to access your SQL Server
Password = password for the sql login above

The other answers here are good. In addition, ConnectionStrings.com can be your friend, especially if you are going to connect to various types of databases in the future. Select the database that you need to connect to and then you'll see the different connection strings you can use for that database.
http://connectionstrings.com/sql-server-2012#sqlconnection

you can try this
create a new text document on your desktop - conn.txt
change file extension to udl (conn.udl)
double click to open the file in the first tab select appropriate provider
4 . in the second tab enter server name (ip address,port), username, password (check Allow saving password) and database name.
test connection
if the test reports success close the window.
open the file with notepad, copy everything but the provider name and paste it back to connectionString

Below is connection string you need for:
Data Source="192.168.10.3" ;Initial Catalog=MyDb;Integrated Security=SSPI;
User ID=sa (for example);Password=whatever you set before;

ASP.NET -Oracle-- Connection no more possible after certain amount of existing connections

We've got an ASP.NET application working with with Oracle database. To connect to the database we've used the basic ways:
OracleConnection con= new OracleConnection(....;
OracleCommand cmd=new OracleCommand();
cmd.Connection=con;
cmd.CommandText=....;
I have no idea why but after 14-15 users are logged in to the application no additional user can log in and the application refuses to log in. I don't have any clue as to where I can start investigating except for the connection string. Here's how the connection string looks like:
"User ID=SSPF_WEB_EDITION;Data Source=SSPF;Persist Security Info=False;Password=123;Validate Connection=true; Connection TimeOut=15;Pooling=False;
I thought maybe this issue is related with the "Pooling=False" option?
EDIT: We use Oracle's ODP.NET. Here's what we have in the log:
"TNS:listener could not find available handler witht matching protocol stack "

asp.net c# connect to local Db vs2008

I'm making an ASP.net with c# webapp using VS 2008, and I added a new sql database item to my project. I added tables to the databse. In the database explorer the test connection works. I guess I have two questions. One:In the application, how does one connect to the database using a connection string? or what connection string should I use? Second: How do I add a username and password to the database?
Right now I'm using this connection string in the web.config file, but when I run the app it times out and says it can't make a connection. The error is on the conn.open line.
add name="ReportsConnectionString" connectionString="Data Source=(local); Initial Catalog=REPORTS;Integrated Security=True" providerName="System.Data.SqlClient"
I have this code in one of my page's codebehind.
string sqlquery = "SELECT * FROM reportitems";
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ReportsConnectionString"].ConnectionString))
{
conn.Open();
using (SqlCommand comm = new SqlCommand(sqlquery, conn))
{
using (SqlDataAdapter adapter = new SqlDataAdapter(comm))
{
DataSet ds = new DataSet();
adapter.Fill(ds, "reportitems");
DataRowCollection dra = ds.Tables["reportitems"].Rows;
foreach (DataRow dr in dra)
{
string DRZ = dr[0].ToString();
//more stuff here
}
}
}
}

Usually SqlServer Express is reachable on your local PC using this syntax for the Data Source parameter yourpcname\SQLEXPRESS. To be sure start Management Studio and look at the Server Name request.
For the security part of your question, I suppose that you don't want the Integrated Security option (Windows User), but you want a SQLServer user. In this case you could use the User ID and Password parameters for the connection string:
Data Source=MYPC\SQLEXPRESS;Initial Catalog=REPORTS;User Id=MYNAME;Password=MYPASS;
However, this works only after you have added this user to the SQLServer.
You could use the interface of Management Studio app or you could execute a script like this
USE [master]
GO
CREATE LOGIN [MYNAME] WITH PASSWORD=N'MYPASS', DEFAULT_DATABASE=[master]
GO
USE [REPORTS]
GO
CREATE USER [MYNAME] FOR LOGIN [MYNAME]
GO

The Integrated Security=True part of the connectionstring means that the server will use the credentials of the app pool running the site, and you don't need to specify username or password. The app pool identiy will, however, need to have access to your database.

Visit http://www.connectionstrings.com/ for a good primer on various ways to set the connection string for various applications. That'll show you why (local) didn't work but .\SQLEXPRESS did and how to add username and password to it. Here's an example lifted from http://www.connectionstrings.com/sql-server-2008
Data Source=myServerAddress;Initial Catalog=myDataBase;User
Id=myUsername;Password=myPassword;

As others have said, you need a SqlExpress engine running as .mdf is not a flat file. It is a SQL server express database file and you need to connect to it.
But what have not said is that a Database in your App_Data folder needs to be attached to the SqlServer instance. This step is only done once in the first connection.
In http://www.connectionstrings.com/sql-server-2008 you will find an example in the "Attach a database file, located in the data directory, on connect to a local SQL Server Express instance" section that looks like this:
Server=.\SQLExpress;AttachDbFilename=|DataDirectory|mydbfile.mdf; Database=dbname;Trusted_Connection=Yes;
Also you can read this: http://msdn.microsoft.com/en-us/library/ms247257.aspx
I believe that you will need to run some scripts and stuff like that to create a user and assign permissions to this user in this database, and then change the connection string (once the database attached), so I don't see a point in having the database in the App_Data folder. I believe it should be better if since the beginning you create your database using the SqlServer tools and connect to it from your application.