Read or Write connection strings in web.config file using asp.net

Introduction:

In this article I will explain how to read or write connection strings in web.config file using asp.net.

Description:

In Previous article I explained clearly about Encrypt or Decrypt connection strings in web.config file using asp.net. Now I will explain how to write connection strings in web.config file and how to read connection strings from web.config file using asp.net. 

I have one web application that contains many pages and each page contains relationship with database connection to get data from database and display it on page because of that I need to write database connections for each page to interact with database. Now the server name or credentials of database server has changed in that situation it will create problem because we need to modify the database connections of each page using asp.net. 

To avoid this situation it would be better if we place connection string in one place and reuse it in every page wherever we need to connect to SQL Server. Web.config is the best place to store the connection strings in asp.net and it would be safer place to store the connection strings instead of writing connection strings in every web page.

Now we want to add connection string in web.config file for that first create new website using visual studio after that create new website open web.config file and search for “connectionStrings” and add new item in connectionStrings section

After open web.config file in application and add sample db connection in connectionStrings section like this 

<connectionStrings> <add name="yourconnectinstringName" connectionString="Data Source= DatabaseServerName; Integrated Security=true;Initial Catalog= YourDatabaseName; uid=YourUserName; Password=yourpassword; " providerName="System.Data.SqlClient"/> </connectionStrings >

Example of declaring connectionStrings in web.config file like this

<connectionStrings> <add name="dbconnection" connectionString="Data Source=SureshDasari;Integrated Security=true;Initial Catalog=MySampleDB" providerName="System.Data.SqlClient"/> </connectionStrings >

Here to access my database server there is no need of username and password for that reason I didn’t enter username and password in connection string.

After add dbconnection in connectionString we need to write the some code in our codebehind file to get connection string from web.config file for that add following namespace in codebehind file and write the following code

using System.Configuration;

 This namespace is used to get configuration section details from web.config file.

After add namespaces write the following code in code behind

C# code

using System; using System.Data.SqlClient; using System.Configuration; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) {    //Get connection string from web.config file string strcon = ConfigurationManager.ConnectionStrings["dbconnection"].ConnectionString; //create new sqlconnection and connection to database by using connection string from web.config file SqlConnection con = new SqlConnection(strcon); con.Open(); } }

VB.NET

Imports System.Data.SqlClient Imports System.Configuration Partial Public Class _Default Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) 'Get connection string from web.config file Dim strcon As String = ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString 'create new sqlconnection and connection to database by using connection string from web.config file Dim con As New SqlConnection(strcon) con.Open() End Sub End Class

Here we stored our database connection string in web.config file it was not secured if we want to encrypt the connection string in web.config file check this post encrypt or decrypt connection string in web.config file.

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