Connection error -SQL to ASP.net

using System;
using System.Data.SqlClient;
using System.Web.UI;

namespace gridview1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string StrCon = "Data Source=DESKTOP-Rajeev;Initial Catalog=SqlPractice;Integrated Security=SSPI";

            using (SqlConnection con = new SqlConnection(StrCon))
            {
                con.Open();
                string query = "SELECT * FROM Tbl_Employee";
                SqlCommand cmd = new SqlCommand(query, con);
                SqlDataReader reader = cmd.ExecuteReader();
                GridView1.DataSource = reader;
                GridView1.DataBind();
            }
        }
    }
}

using System;
using System.Data.SqlClient;
using System.Web.UI;

namespace gridview1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string StrCon = "Data Source=DESKTOP-Rajeev;Initial Catalog=SqlPractice;Integrated Security=SSPI";
            
            using (SqlConnection con = new SqlConnection(StrCon))
            {
                con.Open();
                string query = "SELECT * FROM Tbl_Employee";
                SqlCommand cmd = new SqlCommand(query, con);
                SqlDataReader reader = cmd.ExecuteReader();
                GridView1.DataSource = reader;
                GridView1.DataBind();
            }
        }
    }
}

The code you've provided seems mostly correct for connecting to an SQL database and binding the data to a GridView in an ASP.NET web application. However, there's a minor issue in your connection string. Instead of "datasource," it should be "Data Source." Also, there's a typo in "initial catalog"; it should be "Initial Catalog."

Here's the corrected code:

using System;
using System.Data.SqlClient;
using System.Web.UI;

namespace gridview1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string connectionString = "Data Source=DESKTOP-66R7QLC;Initial Catalog=SqlPractice;Integrated Security=SSPI";
            SqlConnection connection = new SqlConnection(connectionString);

            try
            {
                connection.Open();
                string query = "SELECT * FROM Tbl_Employee";
                SqlCommand cmd = new SqlCommand(query, connection);
                SqlDataReader reader = cmd.ExecuteReader();
                GridView1.DataSource = reader;
                GridView1.DataBind();
            }
            catch (Exception ex)
            {
                // Handle exceptions here
                // You can log the error or display an error message
            }
            finally
            {
                connection.Close();
            }
        }
    }
}

Make sure that:

1. Your SQL Server instance is running and accessible from your application.
2. The "SqlPractice" database exists.
3. The "Tbl_Employee" table exists in the "SqlPractice" database.

Also, consider adding error handling to the code to properly handle exceptions that may occur during database operations.

string connectionString = "Data Source=DESKTOP-66R7QLC;Initial Catalog=SqlPractice;Integrated Security=SSPI";
SqlConnection connection = new SqlConnection(connectionString);
connection.Open();
string query = "SELECT * FROM Tbl_Employee";
SqlCommand cmd = new SqlCommand(query, connection);
SqlDataReader reader = cmd.ExecuteReader();
GridView1.DataSource = reader;
GridView1.DataBind();
connection.Close();

I think there might be an issue with your connection string. Try this:

string connectionString = "Data Source=DESKTOP-66R7QLC;Initial Catalog=SqlPractice;Integrated Security=SSPI";

Full Code:

using System;
using System.Data.SqlClient;
using System.Web.UI;

namespace gridview1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string connectionString = "Data Source=DESKTOP-66R7QLC;Initial Catalog=SqlPractice;Integrated Security=SSPI";
            
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                connection.Open();
                string query = "SELECT * FROM Tbl_Employee";
                SqlCommand cmd = new SqlCommand(query, connection);
                SqlDataReader reader = cmd.ExecuteReader();
                GridView1.DataSource = reader;
                GridView1.DataBind();
            }
        }
    }
}

It looks like you have commented out some code and made some minor mistakes in your C# code for connecting to a SQL database and populating a GridView. Here's a corrected version of your code:

using System;
using System.Data.SqlClient;
using System.Web.UI;

namespace gridview1
{
    public partial class WebForm1 : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string connectionString = "Data Source=DESKTOP-66R7QLC;Initial Catalog=SqlPractice;Integrated Security=True";
            SqlConnection connection = new SqlConnection(connectionString);

            try
            {
                connection.Open();
                string query = "SELECT * FROM Tbl_Employee";
                SqlCommand cmd = new SqlCommand(query, connection);
                SqlDataReader reader = cmd.ExecuteReader();

                GridView1.DataSource = reader;
                GridView1.DataBind();
            }
            catch (Exception ex)
            {
                // Handle any exceptions here, e.g., display an error message.
                Response.Write("Error: " + ex.Message);
            }
            finally
            {
                connection.Close();
            }
        }
    }
}

Here are the changes made:

1. The connection string should include Integrated Security=True to use Windows Authentication.

2. We added a try-catch block to handle any exceptions that might occur during database operations.

3. In the catch block, you can handle exceptions by displaying an error message or logging the error.

With these changes, your code should now work correctly to connect to the SQL database, fetch data from the Tbl_Employee table, and bind it to the GridView. Make sure your SQL Server instance is running and that the database and table names are correct.