Creating a single connection file for my C# .NET Winform Application

Question

I want to make a single connection file , using which , all the Forms of my winform application should connect to the online mysql database and select,update & insert data.

I have named the connection file as CONNECTION.CS, connection string is :

OdbcConnection conn = new OdbcConnection("Driver={MySQL ODBC 5.1 Driver};uid=ab ; password=pass;server=www.myweb.com;database=mydb;port=3306");

Now , how do I use it in the Form1.cs,Form2.cs ..........to establish connection to the database and start inserting and retreiving data? Please help.

Do i need to inherit this Connection.cs in all the Forms? Please help with code

Don't leave the connection open for the whole program's lifetime. This is a bad design. Open it when you need it and close it when you don't — the_drow
– the_drow, Commented Jun 26, 2011 at 8:23

Mahmoud Gamal · Accepted Answer · 2011-06-26 16:35:02Z

2

I think it will be easer if you define it in the app.config file

<appSettings>
  <add key="ConnectionString" value="Driver={MySQL ODBC 5.1 Driver};uid=ab ; password=pass;server=www.myweb.com;database=mydb;port=3306" />
   </appSettings>
</configuration>

so whenever you want to get a connectionstring you can get it :

string strConn = ConfigurationManager.AppSettings["ConnectionString"];

or you can use a class as a data access layer :

class Connection
{
     OleDbConnection conn;
     OleDbCommand cmd;
     public Connection()
     {
          string connnstr = "Driver={MySQL ODBC 5.1 Driver};uid=ab ; password=pass;server=www.myweb.com;database=mydb;port=3306";
          conn = new OleDbConnection(connstr);
          cmd = new OleDbCommand();
          cmd.Connection = conn;
     }
     public OleDbDataReader GetData()
     {
        ....
     }
}

then whenever you want to getdata just

Connection conn = new Connection();
OleDbDataReader dr = conn.getData();

by this way you just define a single connection file.

edited Jun 26, 2011 at 16:35

answered Jun 26, 2011 at 8:02

Mahmoud Gamal

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4 Comments

sqlchild Over a year ago

ok sir, but if this file is visible when i install my application on my customer's pcs , then if he / she deletes it OR changes some code in it by mistake then it would be a big problem? so how do i deal with this?

Mahmoud Gamal Over a year ago

ok i edited the answer and i added an alternative way to define a single connection string in a class that represents the data access layer.

Waleed Al-Balooshi Over a year ago

@sqlchild the following blog post shows you how to encrypt specific sections of the app.config, so that your customers wouldn't be able to read the connection string. This is a best practice for any connection strings in the web.config too. dotnetprofessional.com/blog/post/2008/03/…

Waleed Al-Balooshi Over a year ago

I believe it is best to keep it in the app.config and encrypt the connectionstring section. Compiled code can be easily decompiled, especially with tools like .Net reflector.

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