Recursing through a directory/filesystem using C#
This will teach you how to recurse through a directory/filesystem using C#..
The problem comes from not knowing how many folders/files exist.
One folder can have many folders inside it, those folders can each have many folders inside it.
I will show you how to recurse through the filesystem and explain it so that you UNDERSTAND it. This isnt for copy-paste.
We will start with a C# console application and pick a path, we'll use C: for this.
First of all, we're going to need the IO namespace. The IO namespace has access to File and Directory methods.
At the top add these lines:
using System; //Just so we can use the shortcut Console instead of System.Console using System.IO; //Gives us access to file, directory objects
Now, in our "main" method, we are going to write the following:
string path="C:/"; //set the root path we want to recurse through.
//check if the directory exists
if(Directory.Exists(path)){
DirectoryInfo di=new DirectoryInfo(path);
//based on a path, this object will give you directory information about that directory
printDirectories(di);
//this method will actually go through our directories and print out information
}else{
Console.WriteLine("Directory does not exist. Press Enter to exit");
Console.ReadLine(); //when you hit return the program will terminate.
}
Now we will write the print directories method. It takes a DirectoryInfo object as a parameter and will use that to recurse through the file system.
//declared as static because were a console app, this can be private in your application if it a utility method.
2 Important methods we're going to be looking at are in the DirectoryInfo object. They are
public FileInfo[] directoryInfoObject.GetFiles() //returns an array of FileInfo objects
public DirectoryInfo[] directoryInfoObject.GetDirectories() //returns an array of DirectoryInfo objects
static void printDirectories(DirectoryInfo di){
foreach(FileInfo fi in di.GetFiles()){
//we are going to run code for each file
Console.WriteLine(fi.FullName); //this prints out the full file name including the path
}
//now that we process this directory for files, we do the same for every subdirectory in this directory
foreach(DirectoryInfo subDir in di.GetDirectories()){
//we are going to call the printDirectories method, with the subdirectory as the root.
//its files will be processed, then its subdirectories will be checked
//this happens foreach Directory in the current directory
printDirectories(subDir); //recurse
}
}
Thats simple recursion. The most common use of this is for populating a treeview and another use that comes to mind is file searching. Keep an eye out for the next tutorial: Populating a Treeview from a file system!
Creating/Retrieving a GUID object from a string C#
GUIDS are great to use if you ever may need to merge data.
The chances of collision (duplicates) are extremely low.
To generate a new guid, use this code:
Guid g=Guid.NewGuid(); //this generates a GUID object
Guid g2=Guid.NewGuid().ToString(); //this generates a GUID string
There may be a time where in a stored procedure, you have a GUID as a parameter.
In C# you may have to pass this paramater to the procedure.
This is actually very simple.
Given a string that you know is a GUID, you can retrieve a guid object like so:
Guid g=new Guid(myStringGUID);
And thats all folks 
Installing and Configuring MySql/Connecting with C#
Recently, I was asked to do some C# development with MySQL as the backend.
Having C# with SQL Server 2005 development under my belt setting up a connection to a MySQL Server was pretty easy, however, I will walk you through the setup.
Two packages you will need are the MySQL Essentials Installer(this installs the server)
and the MySQL Connecter/.NET Installer(this installs the bridge between MySQL and .NET)
The third package, the GUI tools, is optional, but it is a lot easier to work with. (Think of it as a Management Studio Express, for those of you who have used SQL 2005)
MySQL Essentials Package: http://dev.mysql.com/downloads/mysql/5.1.html#downloads
MySqlConnector/NET: http://www.mysql.com/products/connector/net/
MySQL Gui Tools: http://dev.mysql.com/downloads/gui-tools/5.0.html
Run the Essentials Package first, this package actually contains the server instance.
Follow the prompts, they are pretty much straight forward.
When you receive the prompt about your root password, pick a password.
Next install the MySQL Connector.
Follow the prompts, they are pretty much straight forward as well, and should install pretty quickly.
From here, you can use the command line client located in Start>Program Files>MySql Version>MySql Command Line Client, however, I choose to use the GUI tools instead.
If you have not already, launch the GUI tools installer.
Once this is done, go to Start>Program Files>MySql Version#>MySQL query browser
Click the ... button next to Stored Connection.
Click New Connection.
Fill out the properties
Connection: Name the connection
Username: root
Password: password used during setup
Hostname: localhost
Port: default is 3306
Schema: specify the default database, you can leave this blank.
Click apply and close.
In the connection screen, from the dropdown, pick the connection we just created.
Type your password.
If given a warning about a default schema, type test or default in the Default Schema field, this will create
a database named test or default. You can always delete this dummy database afterwards.
To create tables right click your database in the Schemata and click Create New Table.
Most of the GUI is intuitive and should be picked up quite easy.
Connecting to MySQL using C#
Start a C# Application project (I'm using a Console App in my example)
Right click your project and click Add Reference.
Navigate to the Connector DLL.
By default this dll is located at C:/Program Files/MySql/MySql Connector .NET Version#/Binaries/.NET 2.0/MySql.Data.dll
Once this is added add the line:
using MySql.Data.MySqlClient;
using System.Data; //for the ConnectionState enum
to the top of your code.
Add this code to your main/load method:
//sets up the connection string
string connString = "Server = localhost; Database = databaseName; Uid = root; Pwd = pass;";
//creates a new MySqlConnection object
MySqlConnection conn = new MySqlConnection(connString);
try{
//try to open the connection, catch any exceptions
conn.Open();
//if the connection succeeds, print a msg
Console.WriteLine("Connection Succeeded");
}catch(Exception ex){
//print that the connection failed, and the associated Message
Console.WriteLine("Connection Failed: "+ex.Message);
}finally{
//if the connection is currently open, close it
if(conn.State==ConnectionState.Open)
conn.Close();
}
Troubleshooting:
- If you are having trouble connecting, check your username and password.
- Double check the connection string.
- If you are sure the above is correct, make sure the MySql server instance is running. You can do this by
- going to Start>Run. Type services.msc and hit Ok. Scroll down the list to MySql, it should say started. If it does not, right click and hit Start.
- Try to connect with the MySql GUI tools.
Just about everything you can do with SQL Server you can do with MySql using the familiarly named classes:
MySqlConnection, MySqlCommand, MySqlDataReader
Hope this gets you started on using MySql and C#.
Any questions or comments, feel free to ask.