Где и как написать этот SQL-запрос?

Это мой SQL-запрос и его выполнение, но я хочу обновить конкретный столбец таблицы с помощью этого запроса, поэтому как и где я пишу запрос на обновление?

public void Add()
{
    SqlConnection sqlcon = new SqlConnection("server =(LocalDB)\\MSSQLLocalDB; Database = Online Medical Store ; integrated security = true");
    sqlcon.Open();

    SqlCommand cmd = new SqlCommand("select LastName, FirstName, FatherName, Address, City, Contact, EmailAddress,BookSubject,BookTitle,EditionNumber,ISBN_Number,Issue_Date from IssueBooks where StudentID =@studentID and " +
        "ISBN_Number = @isbnNumber", sqlcon);

    cmd.Parameters.AddWithValue("@studentID", studentId);
    cmd.Parameters.AddWithValue("@ISbnNumber", ISbnNumber);

    SqlDataReader dr = cmd.ExecuteReader();

    if (dr.HasRows == true)
    {
        throw new Exception(" One Student Can Take Only One Book ");
    }
    else
    {
        SqlConnection con = new SqlConnection("server =(LocalDB)\\MSSQLLocalDB; Database = Online Medical Store ; integrated security = true");
        con.Open();

        SqlCommand sqlcmd = new SqlCommand("insert into IssueBooks(StudentID,LastName,FirstName,FatherName,Address, City," +
            " Contact, EmailAddress, BookSubject, BookTitle,EditionNumber, ISBN_Number,Issue_Date)values" +
            "(@studentID,@lastName,@firstName,@fatherName,@address,@city, @contact,@emailAddress,@BookSubject, @BookTitle, @EditionNumber, @ISBN_Number,@IssueDate)", con);
                                          
        sqlcmd.Parameters.AddWithValue("@studentID", studentId);
        sqlcmd.Parameters.AddWithValue("@lastName", LastName);
        sqlcmd.Parameters.AddWithValue("@firstName", FirstName);
        sqlcmd.Parameters.AddWithValue("@fatherName", FatherName);
        sqlcmd.Parameters.AddWithValue("@address", Address);
        sqlcmd.Parameters.AddWithValue("@city", City);
        sqlcmd.Parameters.AddWithValue("@contact", Contact);
        sqlcmd.Parameters.AddWithValue("@emailAddress", EmailAddress);
        sqlcmd.Parameters.AddWithValue("@BookSubject", bookSubject);
        sqlcmd.Parameters.AddWithValue("@BookTitle", bookTitle);
        sqlcmd.Parameters.AddWithValue("@EditionNumber", EditionNumber);
        sqlcmd.Parameters.AddWithValue("@ISBN_Number", isbnNumber);
        sqlcmd.Parameters.AddWithValue("@IssueDate", Issue_Date);

        sqlcmd.ExecuteNonQuery();
    }

    sqlcon.Close();
}