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Connect to database in network drive

I am a newbie to SQL Server and .net. Please let me know if my question is not clear before down voting.
I am working on a Windows application with C#. I should give option to users to connect to a .mdf file on a network drive. On my machine, I have Windows and SQL Server authentication. Users have SQL authentication hence I should use userid and pwd. Myself and users work on that network drive, read/write/modify. We pretty much share documents, add and delete docs from network drive.
Here is the designer
I will choose the SQL Server database .mdf file which is located in network drive and then do test connection. For Test Connection this is the code
string sTemp = System.Configuration.ConfigurationManager.AppSettings["connectionStringShare"];
string connectionString = sTemp.Replace("{AppDir}", txtDB.Text.Trim());
using (SqlConnection objSqlConnection = new SqlConnection(connectionString))
{
try
{
objSqlConnection.Open();
objSqlConnection.Close();
MessageBox.Show("Connection is successfull");
}
catch (Exception ex)
{
MessageBox.Show("Error : " + ex.Message.ToString());
}
}
This is the connection string
<add key="connectionStringShare"
value="Data Source=.\SQLEXPRESS;Initial Catalog=TableSQLExpress;AttachDBFilename={AppDir};Integrated Security=SSPI;user id=sa;password=pwd;" />
Here is the error message I got
Directory lookup for the file "S:\zrep\TableSQLExpress.mdf" failed with the operating system error 3(The system cannot find the path specified.).
Cannot attach the file 'S:\zrep\TableSQLExpress.mdf' as database 'TableSQLExpress'.
I changed connection string and tried also tired using windows authentication. No luck. Let me know if I need to provide any additional details. Since I am newbie to this field please give me detailed answer. I am glad to find this group. Thanks for everyone who looked into this.

When you use server-based SQL Server (i.e. Microsoft SQL Server Express) you are unable to share database file via network drive, it is by design. Even if you override default SQL Server behavior with a switch and enable UNC paths for databases, your data will be corrupted by multiple server instances trying to use single database MDF file. If you need to host database in serverless environment (using only a network drive), you may opt to Microsoft SQL Server Compact (SQL Server CE) edition. But be aware that in such case only one user will be able to access database file at the same time (exclusive locking -> low performance). Plus SQL Server CE does not have stored procs.

C# Database Connection Stored in DLL to Call

I am New to the more enhanced features of the C# and .NET coding practices
I have been trying to Find A solution to using a particular method in C# for Winforms, Windows Services And ASP.NET web Applications where you program your connection to SQL and Convert the C# Code file to a dll to be used in your project.
The idea is to Create the Connection and Convert it to a dll so that every time you start a function and need to make a database connection you will just write it where you say
Function ABC
{
//VB Version would be like this as i have seen this
Dim DCDLL as New Dataconn
//Where 'DCDLL' is the DLL file which is being declared as a new dataconnection
//C# Version would be Alon these Lines
SQLConnection DataConn = New SQLConnection(DCDLL)
}
I have only seen the VB Code version of the Call so I am not keen on the C# Method that this would be done
Meanwhile The DLL Holds all the other code like
string ConnectionString =
"Data Source=Datasource; UID=User; PWD=Pass; Persist Security
Info=True; Initial Catalog= Catalog";
Dataconn = new SqlConnection(ConnectionString);
Dataconn.Open();
the purpose of the DLL would be to handle the connection to the database, Open it catch errors if dataconnection is not successfull and close the connection if needed so that you dont have to programatically do this every time. Also it is only responsible for the connection therefore you can use a function to call the connection execute the procedure and whatever else is required.
The idea of using a DLL is just to make the Connection settings to the Database a little more secure, the Connection obviously wont become super secure but it adds more security than having the Code in you code pages etc.
i have spoken to and seen people use this type of method but my research on how to achieve this via google and other sources does not seem to understand what i am searching for.
I am trying to understand that when i code this file how it must be done as to ensure that it handles the database connection correctly without issues and doesnt break.
If anyone can Give me Examples in C# of how to do this it would be appreciated or if you know of any pages that have explained how to achieve this i would be most grateful for your assistance

You should put your connection strings in app.config / web.config, and use c# to get the values...
Get ConnectionString from app.config in c#
You can also encrypt the connection string...
http://msdn.microsoft.com/en-us/library/89211k9b(v=vs.80).aspx

Writing to MySQL

I've some some light database programming in school, before, but I'm trying to learn best practices now that I'm writing more sophisticated applications. Writing to a MySQL database isn't hard, but I'm wondering what a best practice is for having distributed applications write to a remote database on Amazon EC2.
As of right now, I'll have a MySQL database hosted in the cloud that's able to receive incoming connections. I questioned this as by default, it only enabled the local host to connect to it.
Is there a more secure or professional way to write to a MySQL instance in the cloud than just doing some kind of DbConnect, hard coding my server's online host name, root username and password? I just don't want to make a production application that's not accessing the database in the best fashion.
Thanks! You guys are always awesome.

the most viable to date option for database work is to use something like entity framework
your model is the model, your database connection sits on its own and you can easily port the application to another database provider if need... I.E mysql to msSQL without really having to do much in the way of work.
Entity framework code first is the easiest i think to port over. Also for mysql you just need the mysql.net connector from the provider themselves, this works with entity framework.
also by working with models and using linq you further help reduce prodlems with SQL injection as you wont actually be writing or sending any SQL.
Given that, should you have a massive database, EF is a pain in the butt and is really slow and for this a simple database class would do, you can have a few functions like this:
private readonly MySqlConnection _conn = new MySqlConnection();
private MySqlCommand _myCommand = new MySqlCommand();
private readonly string _dbConn = ConfigurationManager.AppSettings["dbConn"];
public void Closedb()
{
try
{
_conn.Dispose();
_conn.Close();
}
catch (Exception ex)
{
}
}
public void UpdateDatabaseWithSql(string mysql)
{
Closedb();
_conn.ConnectionString = _dbConn;
_conn.Open();
_myCommand= new MySqlCommand(mysql,_conn);
_myCommand.ExecuteNonQuery();
Closedb();
}
a DB connection for mysql looks like this, in the web.config file:
<add name="MvcCustomContext"
connectionString="server=[ip];User Id=[user];password=[pass];Persist Security Info=True;database=[dbname]"
providerName="MySql.Data.MySqlClient" />
hope this helps

The best way is to have another application running on the server and listening a port on TCP to make the actions on the database. You can encrypt the message and decrypt on server application, having a safe username/password and data traveling.

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.

Connecting to a database from the beginning

I have been working in a business writing advanced software apps, and obviously im provided with access to our SQL server and all the connection strings needed.This is fine for my job now - but what if i wanted to do this for a new (very small) business... If i wanted to purchase a small database server and set up a piece of software that talks to the databases on this server, how would i go about a) Talking and connecting to the server in code (c#) and b)What would i need regarding things like internet/phone connections etc to make this possible.
Edit: the reason it would need a server is because it would need to be accessed from 2 or 3 different computers in different locations?

Actually there are quite a few ways to create a database connection, but I would say one of the easiest ways is to utilize the methods and classes found in System.Data.SQLClient. A basic connection would look something like the following:
using System.Data.SQLClient;
namespace YourNamespace
{
public class DatabaseConnect
{
public DataType getData()
{
DataType dataObj = new DataType();
SqlConnection testConn = new SqlConnection("connection string here");
SqlCommand testCommand = new SqlCommand("select * from dataTable", testConn);
testConn.Open()
using (SqlDataReader reader = testCommand.ExecuteReader())
{
while (reader.Read())
{
//Get data from reader and set into DataType object
}
}
return dataObj;
}
}
}
Keep in mind, this is a very, very simple version of a connection for reading data, but it should give you an idea of what you need to do. Make sure to use a "using" or "try/catch" statement to ensure that the connection is closed and resources are freed after each use (whether it successfully gets data or not).
As for your other question about what equipment you may require. In the beginning I would suggest just creating the database on your local machine and running tests from there. Once you are confident with trading data back and forth, feel free to move the database to another box or an online server. Any internet connection type should suffice, though I can't vouch for dial-up, haven't used it in years.
One final note, if you do happen to decide to move to an online server system, make sure that the service you use allows for outside connections. Certain services use shared server systems, and force users to use their internal database interfaces to manage and write to the database.
--- EDIT ---
As for the server system itself, build up a separate box on your local network that you can see, and load up the database software of your choice. Since you are using C#, it would probably be easiest to go with Microsoft SQL Server 2005 / 2008. The installation is rather straightforward, and it will prompt you to automatically create your first database while installing.
After installation it will be up to you to add in the tables, stored procedures, custom functions, etc... Once your base structure is created, go ahead and use the above code to make some simple connections. Since you are familiar with the above practices then I'm sure you know that all you really need to do is target the server machine and database in the connection string to be on your way.

In case your application is small (by small I mean the usage of resources like CPU and memory) then your SQL Server can reside on the same box.
Else you need to have a separate server box for your database and connect to that from your application. In this case, preferably your database box and application box would be on the local area network.
Check this link for having a connection to SQL Server from C# code - http://www.codeproject.com/KB/database/sql_in_csharp.aspx
cheers

You should probably expose your database with an xml web services layer, so that your architecture will be scalable. The general idea is host your sql server and webservices, using Native SQL Server XML Web Services you can make this available to your remote clients. When in your clients you simply add a service reference in Visual Studio and your data will now be available in your client app.
Hope this helps some.
Cheers

You may find the connectionstrings website useful - worth bookmarking.