Read connection string from web.config

How can I read a connection string from a web.config file into a public class contained within a class library?

I’ve tried:



But these classes are not recognized within my class library.


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Method 1

You need to add a reference to System.Configuration and then use:


Method 2

Add System.Configuration as a reference.

For some bizarre reason it’s not included by default.

Method 3


// Add a using directive at the top of your code file    
using System.Configuration;

// Within the code body set your variable    
string cs = ConfigurationManager.ConnectionStrings["connectionStringName"].ConnectionString;


' Add an Imports statement at the top of your code file    
Imports System.Configuration

' Within the code body set your variable    
Dim cs as String = ConfigurationManager.ConnectionStrings("connectionStringName").ConnectionString

Method 4

Add System.Configuration as a reference then:

 using System.Configuration;


 string conn = 

Method 5

I guess you need to add a reference to the System.Configuration assembly if that have not already been added.

Also, you may need to insert the following line at the top of your code file:

using System.Configuration;

Method 6

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.DataVisualization.Charting;
using System.Web.UI.WebControls;


string constring = ConfigurationManager.ConnectionStrings["ABCD"].ConnectionString;
                using (SqlConnection con = new SqlConnection(constring))


    <add name="ABCD" connectionString="Data Source=DESKTOP-SU3NKUUMSSQLSERVER2016;Initial Catalog=TESTKISWRMIP;Integrated Security=True" providerName="System.Data.SqlClient"/>

In the above Code ABCD is the Connection Name

Method 7

In VB : This should work


In C# it would be (as per comment of Ala)


Method 8

You have to invoke this class on the top of your page or class :

using System.Configuration;

Then you can use this Method that returns the connection string to be ready to passed to the sqlconnection object to continue your work as follows:

    private string ReturnConnectionString()
       // Put the name the Sqlconnection from WebConfig..
        return ConfigurationManager.ConnectionStrings["DBWebConfigString"].ConnectionString;

Just to make a clear clarification this is the value in the web Config:

  <add name="DBWebConfigString" connectionString="....." />   </connectionStrings>

Method 9

using System.Configuration;

string conn = ConfigurationManager.ConnectionStrings["ConStringName"].ToString();

Method 10

using System.Configuration;

string connString = ConfigurationManager.ConnectionStrings["ConStringName"].ToString();

Remember don’t Use ConnectionStrings[index] because you might of Global machine Config and Portability

Method 11

First add this:

using System.Configuration;

Method 12

Everybody seems to be suggesting that adding

using System.Configuration;

which is true.

But might I suggest that you think about installing ReSharper’s Visual Studio extension?

With it installed, instead of seeing an error that a class isn’t defined, you’ll see a prompt that tells you which assembly it is in, asking you if you want it to add the needed using statement.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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