VS2010 function that truncates a table

Question

This is my Sql functions class created in c#.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data;
using System.Windows.Forms;

namespace DatabaseTest
{
   static class SQLFunctions
{

   static private SqlConnection dbconnect = new SqlConnection(@"Data Source=sourcecode_guy-pc\sqlexpress;Initial Catalog=test;Integrated Security=True");



   static public void Delete(object button) // This is the *Delete Function*
   {
       try
       {
           dbconnect.Open();

           int IsDeleted;

           SqlCommand DeleteAllQuery = new SqlCommand("DELETE FROM users", dbconnect);
           DeleteAllQuery.ExecuteNonQuery();
           IsDeleted = (int)DeleteAllQuery.ExecuteScalar();

           if (IsDeleted == 0)
           {
               MessageBox.Show("Database has been truntcated.");
           }
           else if(IsDeleted == 1)
           {
               MessageBox.Show("An error has occured and your database table was not deleted.");
           }
       }
       catch (Exception ex)
       {
           MessageBox.Show(ex.ToString());
       }
       finally
       {
            dbconnect.Close();
           }
       }

   }
}

This is the delete button in my form

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace DatabaseTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            SQLFunctions.Delete(button: btnDelete);
        }
    }
}

When I run the program, it gives me a System.NullReferenceException: Object reference not set to an instance of an object. at DatabaseTest.SQLFunctions.Delete(Object button) in C:\my path :)

I'm trying to pass that function to my btn_delete but I get that error that I mentioned above!! — sourcecode_guy, Apr 21 '15 at 02:16
Oh, I see. Anyway, where should I place that break point?? :) — sourcecode_guy, Apr 21 '15 at 02:28

score 0 · Answer 1 · answered Apr 20 '15 at 23:23

0

Your code Executes the Command twice.

DeleteAllQuery.ExecuteNonQuery();
IsDeleted = (int)DeleteAllQuery.ExecuteScalar();

Remove one or the other.

answered Apr 20 '15 at 23:23

Jon Tirjan

3,556
2
16
24

VS2010 function that truncates a table

1 Answers1