Use connectionstring from web.config in source code file

Question

I know this might be a very basic question, but maybe thats why I'm having problems finding the answer. Right now I'm creating database connections in my source files by doing something like this:

SqlConnection con = new SqlConnection("Data Source=...Password=...);
SqlCommand cmd = new SqlCommand(String.Format("SELECT * FROM Table;"), con);
con.Open();
SqlDataReader reader = cmd.ExecuteReader();

But this means that if I choose to change databases it will be a major pain. Do you guys know how to use the connection string from a web.config file instead?

Thank you!

Just out of curiosity, are you closing / disposing your connections / commands / readers? If you're not using the 'using' keyword, start! — RQDQ, Mar 15 '11 at 19:39

score 48 · Accepted Answer · edited Aug 14 '15 at 10:13

48

SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionStringNameFromWebConfig"].ConnectionString);

Make sure that your website has a reference to System.Configuration or it won't work.

The documentation can be found as How to: Read Connection Strings from the Web.config File, with code sample

edited Aug 14 '15 at 10:13

chridam

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answered Mar 15 '11 at 19:34

David

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How about for OLEDB connection? – Si8 May 09 '14 at 17:33
You should be able to find that info at connection strings.com. – David May 09 '14 at 18:15

Bala R · Answer 2 · 2011-03-15T19:39:50.383

7

You can try

var conString = System.Configuration.
                ConfigurationManager.ConnectionStrings["connectionStringName"];
string strConnString = conString.ConnectionString;
SqlConnection con = new SqlConnection(strConnString);

edited Mar 15 '11 at 19:39

answered Mar 15 '11 at 19:34

Bala R

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1

+1: Note that the OP may have to manually add the System.Configuration reference to his project. – NotMe Mar 15 '11 at 19:36

score 5 · Answer 3 · answered Mar 15 '11 at 19:35

In your app.config (or web.config):

<configuration>
       <connectionStrings>
           <add name="MainConnectString" connectionString="yourConnectionString" providerName="providerName" />
       </connectionStrings>
</configuration>

And in code:

string connectionString = ConfigurationManager.ConnectionStrings["MainConnectString"];

score 2 · Answer 4 · answered Mar 15 '11 at 19:38

2

along with StackOverflowException's response, make sure to add using System.Configuration; to your code behind page

answered Mar 15 '11 at 19:38

user279521

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score 1 · Answer 5 · answered Nov 05 '12 at 15:38

1

If you get "cannot implicitly convert type 'system.configuration.connectionstringsettings' to 'string'", do:

string connectionString = ConfigurationManager.ConnectionStrings["MainConnectString"].ConnectionString;

answered Nov 05 '12 at 15:38

user1431356

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score 1 · Answer 6 · answered Mar 15 '11 at 19:39

You can use EnterpriseLibrary.

using Microsoft.Practices.EnterpriseLibrary.Data;

Then you create a method to get connection string:

 public static string GetConnectionString()
    {
        Database YourData = DatabaseFactory.CreateDatabase("someconnectionname");
        return YourData .ConnectionString;
    }

In your web.config you will have following:

 <connectionStrings>   
   <add name="someconnectionname" connectionstring=..... />
 </connectionString>

Use connectionstring from web.config in source code file

6 Answers6

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