How to insert code on button click in ASP.NET web application

As already noticed by a few members, your code is bad and your logic is messed up. First off, you should NOT append the values of your TextBox to your SQL statement as it could potentially leads you to SQL Injection attack. Here's an article that I wrote a while back the demonstrate how dangerous it is: [^]

Second, don't hard code your connection string and embed it in your C# code. Connection String should be put in your web.config file under connectionStrings element: Creating a Connection String and Working with SQL Server LocalDB | Microsoft Docs[^]

For example:

<connectionStrings>
  <add name="MyDBConnectionString" connectionString="Data Source=HOME-PC\\SQLEXPRESS;Initial Catalog=NoveltySystem;Integrated Security=True" providerName="System.Data.SqlClient" />
</connectionStrings>

You can then reference your Connection String value via ConfigurationManager class like this:

string dbConnectionString = ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ConnectionString;

Third, don't initialize your SqlConnection in Page_Load event since you are inserting data at Button's Click event.

Forth, make it a habit to put objects that eat resources such as SqlConnection, SqlCommand within a using block to ensure that objects will be properly disposed and after they are used.

Finally, I would recommend you to separate your code/logic for inserting data to database and keep them out from your Button click event for the ease of maintenance and separation of concerns.

Your code would now look something like this:

private void InsertRecord(string name, string language, string std, string author, string edition, string price, string stock){
      string dbConnectionString = ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ConnectionString;
	using (SqlConnection connection = new SqlConnection(dbConnectionString)) {
                string sql = "INSERT INTO addBooks(BkName,BkLanguage,BkStd,BkAuthore,BkEditions,BkPrice,BkStocks) VALUES (@BookName,@BookLanguage,@BookStd,@BookAuthor,@BookEdition,@BookPrice,@BookStock)";
                using (SqlCommand cmd = new SqlCommand(sql, connection)) {

                        connection.Open();
			cmd.Parameters.AddWithValue("@BookName", name);
	        	cmd.Parameters.AddWithValue("@BookLanguage", language);
			cmd.Parameters.AddWithValue("@BookStd", std);
			cmd.Parameters.AddWithValue("@BookAuthor", author);
			cmd.Parameters.AddWithValue("@BookEdition", edition);
                        cmd.Parameters.AddWithValue("@BookPrice", price);
                        cmd.Parameters.AddWithValue("@BookStock", stock);
			cmd.ExecuteNonQuery();
                }
 	}
}

protected void addB_Click(object sender, EventArgs e){
        InsertRecord(bname.Text,blang.Text,bstd.Text,bauthore.Text,bedition.Text, bprice.Text,bstocks);
}

Note: The may need to double check the datatype you used in your SQL Database as we passing all parameters as string datatype in this example. For example, if the BkPrice and BkStocks columns in your database is decimal and integer, then you need to change your C# code datatype as well.

Hope that helps!