How to create a connection string programmatically

The code snippet for creating a connection string programmatically in .NET C# follows:

/*
// Opening the configuration file for a DLL, i.e. %ProgramFiles%\Memba\Velodoc\Management Console\Memba.Console.dll.config
ExeConfigurationFileMap objExeConfigurationFileMap = new ExeConfigurationFileMap();
objExeConfigurationFileMap.ExeConfigFilename = System.Reflection.Assembly.GetExecutingAssembly().Location + ".config";
Configuration objExeConfiguration = ConfigurationManager.OpenMappedExeConfiguration(objExeConfigurationFileMap, ConfigurationUserLevel.None);
*/

// Opening the configuration file for an executable, i.e. C:\Windows\System32\mmc.config
Configuration objExeConfiguration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

// Creating a connection string element from the connection string in web.config
ConnectionStringSettings objConnectionStringSettings = new
ConnectionStringSettings(
"MyDatabase",
"Data Source=.;Initial Catalog=MyDatabase;Integrated Security=True;Connect Timeout=30",
"System.Data.SqlClient"
);

// Get the connection strings section
ConnectionStringsSection objConnectionStringsSection = objExeConfiguration.ConnectionStrings;

// Add the new element
objConnectionStringsSection.ConnectionStrings.Clear();
objConnectionStringsSection.ConnectionStrings.Add(objConnectionStringSettings);

// Save the configuration file
objExeConfiguration.Save(ConfigurationSaveMode.Modified);

// Refresh and check
ConfigurationManager.RefreshSection(objConnectionStringsSection.SectionInformation.Name); // IMPORTANT!
Debug.Assert(ConfigurationManager.ConnectionStrings.Count == 1);
Debug.Assert(ConfigurationManager.ConnectionStrings[0].Name == objConnectionStringSettings.Name);
Debug.Assert(ConfigurationManager.ConnectionStrings[0].ConnectionString == objConnectionStringSettings.ConnectionString);
Debug.Assert(ConfigurationManager.ConnectionStrings[0].ProviderName == objConnectionStringSettings.ProviderName);

Note that this code assumes you have the following statements in your .cs file:

using System.Configuration;
using System.Diagnostics;