如何编写外部连接字符串配置文件并使我的C＃应用​​程序识别并读取它？

Question

My current c# windows form application is using the following code to connect to a database to retrieve information and the it is stored at Setting.cs

public static String connectionString ="Data Source=####; Initial Catalog=###; User ID=####; Password='####'";

I have written out an external Connection.config file and the content would be :

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="Connection" providerName="System.Data.providername" 
         connectionString="Data Source=####; Initial Catalog=###; User ID=###;                      Password='####!';" />
  </connectionStrings>
</configuration>

is the above code written correctly? as I sort of just copied and paste online and editted the connection string part as i do not know what does the "add name" and providerName part does.

what i would like to ask is where should i write the code in my forms to read the connection string from my external config file so i can remove the one in my setting.cs file.

thank you.

don mind the ### as it is just replaced by me to represent the information.

Answer 1

You can use config source to split your config files. Example App/web.config:

<connectionStrings configSource="myExternalConfigSource.xml" />

External Config:

<connectionStrings>          
  <add name="Connection" providerName="System.Data.providername" 
     connectionString="Data Source=####; Initial Catalog=###; User ID=###; />
</connectionStrings>  

More info: http://www.nikhilk.net/Entry.aspx?id=158

If you use this method, you can reference your config as normal and still have your configuration split out into seperate files.

Answer 2

we use:

<configuration>
    <appSettings>
        <add key="connection.string" value="Initial Catalog=XXX;server=localhost;User=YYY;Password=ZZZ;" />
    </appSettings>
</configuration>

and then just:

ConfigurationManager.AppSettings["connection.string"];

Answer 3

Add the following in your web.config file right at the bottom above the closing config tag.

   <connectionStrings>
      <add connectionString="Data Source=Servernamegoeshere;Initial Catalog=databasenamehere;Persist Security Info=True;User ID=***;Password=***" name="nameyouwanttogivethisconnection" providerName="System.Data.SqlClient" />
   </connectionStrings>
</configuration>

To reference the connection on the page load of the main form use this:

public void Page_Load(object sender, EventArgs e)
{
        string connectionString = ConfigurationManager.ConnectionStrings["nameyouwanttogivethisconnection"].ConnectionString;
        SqlConnection SqlConnection = new SqlConnection(connectionString);
        SqlCommand SqlCommand = new SqlCommand("update table etc etc....",SqlConnection);
        SqlConnection.Open();
        SqlCommand.ExecuteNonQuery(); //This line is for updates and inserts, use SqlCommand.ExecuteReader(CommandBehavior.CloseConnection); for select statments
        SqlConnection.Close();
}

Make sure you add these references to the top of the page you are using this code on:

using System.Data;
using System.Configuration;
using System.Data.SqlClient;

You may then use that connection to create a Sqlcommand to run against your database.

Answer 4

You could also use ApplicationSettings, and forget about writing information in config files manually (It will be done automatically)

1. Right click on your project in solution explorer and select Properties.
2. Go to Settings tab.
3. Click on the link to create the settings file. (It will be called Settings.settings)
4. For Name, type the name you want to use for the connection string. (ie ConnectionString)
5. For Type, select Connection String
6. For Scope, select Application
7. For Value paste your connection string.

When you want to use it, just type

Application.Settings.Default.ConnectionString

ie

SqlConnection connection = new SqlConnection(Application.Settings.Default.ConnectionString);