Re: Removal Of Row By Listbox Troubles - Visual Basic Discussion Boards

Re: Removal Of Row By Listbox Troubles

Dave Kreskowiak4-Jun-09 1:30

Dave Kreskowiak

4-Jun-09 1:30

Your SQL statement is wrong. You may want to lookup the syntax for the DELETE statement. It should be:

DELETE FROM Team WHERE ID = ...

I highly discourage using string concatenation to build an SQL query like this. Google for "SQL Injection Attack" to see why and for example on using a parameterized query that is safer and easier to debug.

By the way, thank you very much for exposing one of your SQL Server's usernames and passwords to everyone on the ENTIRE INTERNET!

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Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Re: Removal Of Row By Listbox Troubles

EliottA4-Jun-09 2:50

EliottA

4-Jun-09 2:50

Dave Kreskowiak wrote:
thank you very much for exposing one of your SQL Server's usernames and passwords to everyone on the ENTIRE INTERNET!

Ha!

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Re: Removal Of Row By Listbox Troubles

eginteractive4-Jun-09 3:07

eginteractive

4-Jun-09 3:07

I'm not concerned about it, as it's public anyway, not much you can really do to somehow affect my server.

The password is changed frequently also.

Also, I'm not really worried about SQL Injection as only my trusted friends are going to be able to have access to this application.

Re: Removal Of Row By Listbox Troubles

Oakman4-Jun-09 4:10

Oakman

4-Jun-09 4:10

eginteractive wrote:
Also, I'm not really worried about SQL Injection as only my trusted friends are going to be able to have access to this application.

You are a trusting soul. That's so nice to see these days.

Jon
Smith & Wesson: The original point and click interface

Both democrats and republicans are playing for the same team and it's not us. - Chris Austin

Re: Removal Of Row By Listbox Troubles

dan!sh 4-Jun-09 5:20

dan!sh

4-Jun-09 5:20

IMO you are underestimating the skills of a lot of folks out there.

जय हिंद

Re: Removal Of Row By Listbox Troubles

dan!sh 4-Jun-09 2:07

dan!sh

4-Jun-09 2:07

You have mixed SQL insert and delete statements. Check the syntax for delete.

जय हिंद

Re: Removal Of Row By Listbox Troubles

Jon_Boy4-Jun-09 7:24

Jon_Boy

4-Jun-09 7:24

Confused on what's borked with your SQL command?

1. Run profiler and see what's being sent to the server. Copy and paste that command into a query window in SQL Management Studio. Fix it until its right and reflect the changes in VB.

2. OR get the command.commandtext and paste that into the query window.

Easy to find and easy to fix. If your statement doesn't work in SQL natively, it will never work from VB.

"There's no such thing as a stupid question, only stupid people." - Mr. Garrison

Re: Removal Of Row By Listbox Troubles

eginteractive4-Jun-09 16:49

eginteractive

4-Jun-09 16:49

     sqlconn.Open()
 Catch ex As Exception
     MsgBox("Could not connect!", MsgBoxStyle.Critical, "Connection Error!")
 End Try
 If sqlconn.State = 1 Then
     Dim sqlremovedata As New SqlCommand( _
"DELETE FROM [Team] WHERE ([ID]) = "(ListBox1.SelectedItem))
     sqlremovedata.ExecuteNonQuery()
     MsgBox("Deleted successfully!", MsgBoxStyle.Information, "Record Deleted!")
     sqlconn.Close()
 End If

OH WONDERFUL. Now I've got a new error.

Conversion from type 'DataRowView' to type 'Integer' is not valid.

How to check if a file exists then delete it in vb.net 2005?

Striker.dbz3-Jun-09 23:45

Striker.dbz

3-Jun-09 23:45

I am stuck on a problem.
i need to delete a file by click a button in but before i need to check if the file exists.

Please reply.

Re: How to check if a file exists then delete it in vb.net 2005?

Johan Hakkesteegt3-Jun-09 23:59

Johan Hakkesteegt

3-Jun-09 23:59

Imports System.IO

If File.Exist("YourFileName.txt") Then

End If

My advice is free, and you may get what you paid for.

Re: How to check if a file exists then delete it in vb.net 2005?

Striker.dbz4-Jun-09 0:20

Striker.dbz

4-Jun-09 0:20

Where should i write Imports.Sytem.IO ?

Re: How to check if a file exists then delete it in vb.net 2005?

Johan Hakkesteegt4-Jun-09 0:22

Johan Hakkesteegt

4-Jun-09 0:22

Write Imports System.IO all the way at the top of your code, before all other code.

The rest goes in the click event of your button

My advice is free, and you may get what you paid for.

Re: How to check if a file exists then delete it in vb.net 2005?

Striker.dbz4-Jun-09 0:32

Striker.dbz

4-Jun-09 0:32

Thanks Problem solved.

Re: How to check if a file exists then delete it in vb.net 2005?

Dave Kreskowiak4-Jun-09 1:25

Dave Kreskowiak

4-Jun-09 1:25

The rest goes in a seperate method and the button click event calls. Big Grin | :-D

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Re: How to check if a file exists then delete it in vb.net 2005?

Johan Hakkesteegt4-Jun-09 1:32

Johan Hakkesteegt

4-Jun-09 1:32

Considering the question I figured I'd keep it simple Smile | :)

Have a look at the next post above this one, the code in it is soooo wrong I am afraid to even answer anything.

My advice is free, and you may get what you paid for.

Re: How to check if a file exists then delete it in vb.net 2005?

Dave Kreskowiak4-Jun-09 3:30

Dave Kreskowiak

4-Jun-09 3:30

Yeah, I saw a bunch of things wrong with it, but only pointed out a couple of issues. Since he's bent on writing bad code and practicing bad habits, why bother saying anything...

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Re: How to check if a file exists then delete it in vb.net 2005?

Ashfield4-Jun-09 1:40

Ashfield

4-Jun-09 1:40

Having seen all your recent posts, why not try buying a book and using that? These are very simple, basic questions you are asking and it seems as if you have no real idea what you are doing.

Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP

Re: How to check if a file exists then delete it in vb.net 2005?

Striker.dbz4-Jun-09 4:03

Striker.dbz

4-Jun-09 4:03

I already have many books , but the information is very confusing Confused | :confused:

please suggest a good one for begginners like me?

Re: How to check if a file exists then delete it in vb.net 2005?

Jon_Boy4-Jun-09 7:31

Jon_Boy

4-Jun-09 7:31

If you wanted to be really lazy, you could use the My.Computer.FileSystem methods as well.

Check this. Get you pointed in the right direction with the basics.

You could always search code sites for tutorials (ahem, CodeProject anyone?) or press F1 and search the MSDN library. For most topics, its really not that hard to find examples in the MSDN with minimal searching.

Is it beer thirty yet?

"There's no such thing as a stupid question, only stupid people." - Mr. Garrison

Re: How to check if a file exists then delete it in vb.net 2005?

Ashfield4-Jun-09 8:53

Ashfield

4-Jun-09 8:53

I have no idea what book would be suitable for a beginner as I haven't looked at that level f information for many years, but there are hundreds to choose from. Go to a good book shop or Amazon and browse a few until you find one you can understand. In the meantime, press F1 for help or use google, there are thousands of examples and code snippets out there, it just takes a little initiative to look for yourself rather than expecting other people to do your research for you.

I just had a quick look on Amazon and thsi sounds about your level:

Microsoft Visual Basic.NET Programming for the Absolute Beginner (Absolute Beginners) (Paperback)
by Jonathan Harbour

If that one is too complex then change career, t can't be much simpler than this.

Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP

Re: How to check if a file exists then delete it in vb.net 2005?

Jon_Boy5-Jun-09 2:05

Jon_Boy

5-Jun-09 2:05

Ashfield wrote:

If that one is too complex then change career, t can't be much simpler than this.

Honesty is the best policy. I think people who attempt to pick up programming for the first time tend to pick projects that are nearly impossible to start with. Start with the basics and then move on.

"There's no such thing as a stupid question, only stupid people." - Mr. Garrison

Insert Values Into Database By Textbox Issues

eginteractive3-Jun-09 15:25

eginteractive

3-Jun-09 15:25

Hey all, I've been working with making a client to insert / delete ect. from a database, and I can't get text fields to insert values into a database for some strange reason.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button1.Click
    Dim sqlconn As New SqlClient.SqlConnection
    sqlconn.ConnectionString = "Server=[removed];Database=erik_asp;Uid=asp;Pwd=[removed for security purposes];"
    Try
        sqlconn.Open()
    Catch ex As Exception
        MsgBox("Could not connect!", MsgBoxStyle.Critical, "Connection Error!")
    End Try
    If sqlconn.State = 1 Then
        Dim sqlconnecter As New SqlCommand( _
   "INSERT INTO [Team] ([position], [name], [email]) VALUES (" & positionbx.Text & ", " & usernamebx.Text & ", " & emailbx.Text & "))", sqlconn)
        sqlconnecter.ExecuteNonQuery()
        sqlconn.Close()
    End If
End Sub

It returns this error:

The name 'blahblahblahtext' is not permitted in this context. Only constants, expressions, or variables allowed here. Column names are not permitted.

This happens with all the text boxes.

Please note I am able to easily connect and view current data in the grid, I just can't insert this data and it's starting to irritate me.

Re: Insert Values Into Database By Textbox Issues

Luc Pattyn3-Jun-09 15:36

Luc Pattyn

3-Jun-09 15:36

Hi,

1.
when presenting string literals SQL expects them to be in quotes (so they can include keywords, spaces, some special symbols, etc. without confusing the SQL parser).

2.
your code is vulnerable to "SQL injection" where the user could make your command do entirely different things simply by entering well chosen text into your textboxes. Use parameterized queries instead.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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Re: Insert Values Into Database By Textbox Issues

eginteractive3-Jun-09 15:44

eginteractive

3-Jun-09 15:44

Can you explain to me how to fix this if you would? I am newer at using databases in Visual Basic, and I have experience in PHP (not much though) and SQL injection on MySQL databases, but MS SQL is different for me. I am not too worried about other users having this because I am the only one that will have this, I'm programming it for my convenience down the road.

Re: Insert Values Into Database By Textbox Issues

Luc Pattyn3-Jun-09 15:52

Luc Pattyn

3-Jun-09 15:52

AFAIK the same is true for PHP+MySQL, you need single quotes (be careful not to include extraneous spaces!)

Example:
...VALUES (" & positionbx.Text & ", " & usernamebx.Text & ", ... should be changed to
...VALUES ('" & positionbx.Text & "', '" & usernamebx.Text & "', ...

When in doubt, print the final SQL statement (e.g. using Console.WriteLine) so you can have a real look.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

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