Error in connection to retrieve data from my sql database

I suggest that you hardcode your connection string first instead of reading it from a config file to test that you can actually open a connection.

MySqlConnection clientCon = new MySqlConnection("Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword");

clientCon.Open()

Play around with different values until you get a connection. Once you have the appropriate values, you can plug them in your app config.

you can try this

in web config file.

<add name="ConnectionString" connectionString="Data Source=.;Initial Catalog=lnt;Persist Security Info=True;User ID=root;;Password=mysql" providerName="System.Data.SqlClient"/>


using System.Data.SqlClient;

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

also you can follow the path :
Tools/ConnectToDatabase and get complete connection string and use in your project .

First Create a create_connection class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace dailyNotes
{
    class create_connection
    {
        public static SqlConnection CreateConnection()
        {
            string ConnString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\Hizbul Bahar\Documents\dailynotes.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
            SqlConnection Conn = new SqlConnection(ConnString);
            Conn.Open();
            return Conn;
        }
        public void disconnect(SqlConnection conn)
        {
            conn.Close();
        }
    }
}

after that , when you want to insert, retrieve or update data you can use this class
many time. just do this.

String query="";
               SqlConnection Conn = create_connection.CreateConnection();
               SqlCommand cmd = new SqlCommand(query, Conn);
               cmd.ExecuteNonQuery();
               Conn.Close();