Database Connection issue

Question

Sir I am in a windows application project. My problem is of database connection could not be established. Please help to solve this issue. ConfigurationManager.ConnectionString[ ].ToString() is not working in my form. Here the screenshot:-

Mukesh Sagar · Answer

define the connection string in the App.config file as : Now with in the code  include the namespaces: System.Data.SqlClient; System.Configuration; Now to read the connection string : String strCon = ConfigurationManager.AppSettings[cn].ToString(); Then use this for creating the SqlConnection object.

Upendra Pratap Shahi · Answer

Check the configuration class is there or not.

Bineesh VP · Answer

I finded out the issue. The cause for this error was of not added reference of System.Configuration.dll. Thank you all for the help

Raja T · Answer

Hi Please refer bellow code. It is working fine. Form1.Cs ----------------- using System; using System.Windows.Forms; using System.Data; using System.Data.SqlClient; using System.Configuration; namespace DemoWindowsFormsApplication { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender EventArgs e) { try { string str = ConfigurationSettings.AppSettings[ConnectionString].ToString(); SqlConnection con = new SqlConnection(str); con.Open(); MessageBox.Show(Connection Open); con.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } } } App.config --------------

Nilesh Jadav · Answer

hey there ! Check out the given below links: https://www.connectionstrings.com/store-connection-string-in-webconfig/ http://www.c-sharpcorner.com/UploadFile/1a81c5/configuring-connection-string-in-app-config-file-during-runt/