Q:

c# database connection string

I'm fairly new to c# and just now started working with databases. I made a local database in my project folder, when I click properties on the database I get "Connection string" as:
Data Source="C:\Users\Documents\Visual Studio 2012\Projects\DataBaseTest\MyDatabase#1.sdf"

My question is simple, how do I create a connection string using that line? cause writing this generates an error for some reason.
SqlConnection con = new SqlConnection(Data Source="C:\Users\Documents\Visual Studio
    2012\Projects\DataBaseTest\MyDatabase#1.sdf");

A:

You are using a SQL Server Compact edition database and for that you must use SqlCeConnection instead of SqlConnection (Which is used for SQL Server).
You must also escape the back backslashes in your connection string \ becomes this \\ :
SqlCeConnection sqlConnection = new SqlCeConnection("Data Source=C:\\Users\\Documents\\Visual Studio
2012\\Projects\\DataBaseTest\\MyDatabase#1.sdf");

or use a verbatim string :
SqlCeConnection sqlConnection = new SqlCeConnection(@"Data Source=C:\Users\Documents\Visual Studio
2012\Projects\DataBaseTest\MyDatabase#1.sdf");

And if you don't have the necessary libs for using SqlCe in your projects refer to my other answer here :

Download the libs from here Microsoft SQL Server Compact 4.0

Add a reference to System.Data.SqlServerCe.dll to your project
Add this using directive using System.Data.SqlServerCe;
Use SqlCeConnection instead of SqlConnection

A:

You need to escape backslashes (replace backslashes by double backslashes) or put an @ in front of your string to tell C# to take it literally, like so:
new SqlConnection("C:\\Users\\...")

or
new SqlConnection(@"C:\Users\...")

A:

For path you can't add backslashes just like that . You need to escape backslashes . There are two ways
to escape backslash
Method #1 - Use @ in the beginning of the path string
SqlConnection con = new SqlConnection(@"Data Source=C:\Users\Documents\Visual Studio
    2012\Projects\DataBaseTest\MyDatabase#1.sdf");

Method #2 - add  double backslashes instead of one backslashes 
SqlConnection con = new SqlConnection("Data Source=C:\\Users\\Documents\\Visual Studio
    2012\\Projects\\DataBaseTest\\MyDatabase#1.sdf");

