Checking Existence Of List Item In Sql Database?
Jun 16, 2011
I am trying to check where an item in my array list exists in the database.The list would have already been created at an earlier stage.Now that some items may have been removed from the database, I wish to check the list against that database before removing the items, from the list, which are no longer in the database.The following code removes all items from the list rather than just each one which doesnt exist.[code]....
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Jan 6, 2010
I am trying to have my program check for the existence of a registry key so I do not get a null reference exception error. The key may or may not exist depending on the computer. How can I check to see if it exists and then change its value if it does exist or skip over it to the next one if it does not exist? (I already know how to change the value part of it) Im just not sure how to check for the existence of it for example would be trying to set the value of a key that does not exist called test below... this obviously would throw a null exception error so how do I check for the existence of the key before executing these instructions and then if it does not exist it skips this and keeps going to the next code ?
Dim testkey As RegistryKey = Registry.LocalMachine.OpenSubKey("SystemCurrentControlSetTEST", True)
Dim keyval As Int32
' Set to ON
keyval = 1
testkey.SetValue("ON", keyval)
I also check the status of the registry entry on form load
Dim Test As RegistryKey = Registry.LocalMachine.OpenSubKey("SystemCurrentControlSetMYTEST", False)
'Get the reg value.
Dim Testflag As Integer = CInt(Test.GetValue("ON"))
[code]....
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Mar 5, 2009
The application I'm writing requires the user to select a certain directory on their hard-drive (a game directory), which is saved to the Settings. If the directory is not selected, my application can't work. So, when the program starts for the first time, the directory setting will not be present, and I want my application to ask the user to select the correct directory before the application starts (the main form is shown). I used the following code in the Form_Load event of my main form:
vb.net
If My.Settings.WolfPath = String.Empty Then
MessageBox.Show("Please select your root 'Wolfenstein - Enemy Territoryetmain' mapping installation.", "Select W:ET Path", MessageBoxButtons.OK, MessageBoxIcon.Information)
[code]....
It looks pretty complicated (probably too complicated) but I wanted to make sure that the user cannot continue until a valid directory has been selected. So when the user cancels the folder selection, my application should end. If the user selects an invalid directory (it should end in "etmain") it should display a messagebox and show the folder browser dialog again. It should keep doing this until the correct path has been chosen.The problem occurs when an invalid directory is first chosen. The messagebox does show, but it shows behind all other applications! It took me a minute to figure that out, because I could not find my application anywhere, but Visual Studio still said it was running... After finally finding the messagebox behind everything else, it seems that now everything comes up behind everything else! When I click OK on the messagebox, the new folder browser dialog also shows up in the background, etc, etc. If I then choose a valid directory, the application loads the main form in the background...
I thought at first the problem would be the fact that I am running this code in the Form_Load event. A better place perhaps would be a Sub Main() from which the main form would be loaded explicitly (Application.Run(mainForm)). However, I can only select Forms as the Startup Form. If I disable the "Enable application framework" checkbox I can select the Sub Main() as Startup Object, but all the visual styles are lost...?
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Jun 2, 2010
is there is any direct method or function in array class that can check if any given byte array is a subarray of other array?or should i loop through the each byte of main array to see if smaller array exists in that or not?
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Jan 24, 2007
I wish to 'record' sound into a wma,wav,midi or mp3 file, not external sound say from a microphone etc but sound played through the computer speakers on your own system however I don't know of any COM components that allows this. Is there any way to do this?
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Jan 1, 2012
I have a list box on the form which functions as a copy/paste. When you copy something, it is automatically added to the list box as a "clipboard helper". Here is the problem,however: if the text is more than 1 line, the list box does not show all the text.It ends up looking messy.So getting back to my question, is it possible to make the list box item height for an item depending on the amount of lines that item contains?This is a one line sentence in the list box and should take up one line.This is a multi line sentence in the list box and should take up two lines for item height.
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Aug 10, 2009
My code follows. I have six items (indices 0-6) and I'm trying to check if one has been selected or not. If not, then messagebox yells at you to select one. If it does, it tells you what you have selected. I'm having a horrible brain fart and contemplated coming here for about 45 minutes as I couldn't get it.
If ListBox1.SelectedItem.ToString <> "" Then
MessageBox.Show("You selected " + ListBox1.SelectedItem.ToString)
Else
MessageBox.Show("Please select an item.")
End If
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Feb 24, 2009
Case: I have one ComboBox which i fill up by using DisplayMember, DataSource with DataTable.
[Code]....
When user key-in in ComboBox (not select from the list), I check with above all possible but still got nothing. According to my knowledge, .Contains(cboStudent.Text) should work. Right?
I out of idea to check this checking.
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Feb 12, 2011
I'm having some difficulty with a sorted & grouped listbox in WPF vb.net 3.5 that has an items source bound to an ObservableCollection.
What I want to be able to do is to retrieve a piece of data from the ObservableCollection items source depending on what item in the listbox the user has selected.I've almost got it working but because the listbox is sorted it does not match the index of the items source.
[code]...
As I previously mentioned, because the lstBox is sorted and also grouped the index's don't match up.Does anyone know how I can get the correct information I want from the List Source depending on the selected item in the list box?
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Oct 13, 2011
How someone would select an item from a list box and click a button and have that item go into another listbox with it's price? I seem to be stuck on this part.
Here's my code:
I want to select the first option from the first listbox and I want to put it into another listbox along with the price of that item on the same line in the listbox. I can't seem to figure out how to that.
Public Class Form1
Const dcmPRICE_STRESS As Decimal = CDec(595.0)
Const dcmPRICE_TIME_MANAGMENT As Decimal = 695
[CODE]...
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Feb 13, 2011
my program downloads into a combobox every item(line) that is in a text file located on a server.
Every line in the text file ends with "a)" or with "g)".
Now I just want to make 3 radio buttons:
- one that will allow the download in the combobox only the item ending with "g)"
- one that will allow the download in the combobox only the item ending with "a)"
- one that will allow the download in the combobox of both (I already know how to do).
How can I do so?
To download the entire list in the combobox I do:
Dim List As String = client.DownloadString("http://mywebsite.com/mytextfile.txt)Dim lines As String() = List.Split(New String() {ControlChars.CrLf}, StringSplitOptions.RemoveEmptyEntries)ComboBox1.Items.Clear()
ComboBox1.Items.AddRange(lines)
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Apr 21, 2011
I'm trying to add a string to a listbox if there is none exact string existed inside, but it turns out a very weird error. Look at this.
On form_load, I have this:
AddHandler Server1.OnUserLoggedIn, AddressOf HandleUser
And then,
Public Sub HandleUser(ByVal username As String)
'Here, you handle adding the text to a text box.
Me.Invoke(New PrintMessageDelegate(AddressOf AddUser), username)
End Sub
[Code] .....
The output is when I connect the first client, it works fine. But, when I try to connect the second client, it prints out three times both the listbox1 item and the txtDisplay. It's like get caught in loop, but I have tried other kind of loops like for each and other string comparison too, still work that way.
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Sep 8, 2011
How would one go about checking a listbox's items for duplicates? Basically I need to write a program that displays the teams from a text file provided by my instructor, in alphabetical order. I can do that, but what I can't figure out is how to prevent the For loop from adding a duplicate team. What I'm envisioning is:
If teams(i).name is not in lstTeams.Items Then
lstTeams.Items.Add(teams(i).name)
End If
I have a program that compiles and works so far, except for the above problem and my alphabetical order (which I can probably figure out on my own:
Public Class danbrockteams
Structure team
Dim name As String
[Code]....
This works except that my listbox is filled with the team every player is in rather than just listing all possible teams. Not exactly looking for someone to just give me the answer, as I understand things best when figuring them out on my own, so I suppose a hint is what I'm really after.
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May 14, 2012
how whould I go about deleteing an item from a listbox and it will select the next available item.you know like the treeview control selects the next node if you delete one.
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Mar 23, 2011
Public Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
[code]....
When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row" I want to the Validate function to know it is in MyContacts. How do I do this?
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Jan 6, 2010
I've been trying to fix this for a while now and have yet to find a solution that works, I want it so that when an item is added another of the same name cannot be added. Here's what I have
Dim i As Integer
For i = 0 To ComboBox1.Items.Count() - 1
If ComboBox1.Items.Item(i) = TextBox1.Text Then
'do nothing
Else
[Code]...
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Jun 18, 2009
i want to stop accepting form drop down listbox if certrain criteria is not met [code]how i can cancel the selection of drop down list?
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May 5, 2010
i want to search item A (from a list of X items) in list B but i want to get the item not found example Search ITEM A in LIST B if not found then return a print....if found continue with ITEM B..and so on.
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Mar 13, 2012
I have a checkedlistbox with numbers in it and I'm trying to load a list of numbers from a database and check all of them (they should all be in the checkedlistbox).
I was trying to do this by loading all the values into a separate listbox using my own subroutine (I know that part works) and then finding the corresponding item on the checkedlistbox, like this:
Dim ItemName As String
For Each item In ListBox1.Items
ItemName = ListBox1.GetItemText(item)
If CheckedListBox1.Items.Contains(ItemName) = true Then
CheckedListBox1.SetItemChecked(CheckedListBox1.Items.IndexOf(ItemName), True)
End If
Next
End If
But this doesn't work: It never returns a match, even when the item is definitely on the list. How do I make this work?
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Jan 24, 2012
I am working on a program that gathers test scores from the user in the form of a list box (array preferably). I need to be able to check the user's entries to validate they are between 0-100. I have tried using If statements with a messagebox.show() error message.When the user enters an invalid entry the error messagebox pops up but after selecting ok the program moves on to the next test score.
The GetTestScores procedure gathers the students test scores from the user
Sub GetTestScores(ByRef intTestScores() As Integer)
Dim intCounter As Integer = 0
[code].....
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Jul 6, 2011
I want my program to check the pagerank of all string list items, and than add it do a listbox. Now this is my code to open a list and add it to a string list ( itemlist as list(of string)
Dim stream_reader As New IO.StreamReader(OpenFileDialog1.FileName)
Dim line As String
line = stream_reader.ReadLine()
Do While Not (line Is Nothing)
line = line.Trim()
[Code] .....
I'm using the DLL from this website: [URL]. The problem is that it only checks the first website and the other websites will be 0/10 automatically while they might be 3/10 or something else.
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Dec 15, 2010
[code]Now how can I check if a certain employee is in the list? ie. I want to know if "John Smith" is in Employees. I see there is a .Contains method but I can't figure out how to use it on a ListIf Employees.Contains(???) Then (need to check for "John Smith" here)
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Jan 11, 2011
I have a List myList of MyObjects. Is it possible to check if myList contains a particular myObject based on a property of myObject in VB.NET? In C#, you'd something similar to this right:
myList.Exists(myObject => myObject.property1 == 3)
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May 30, 2011
I have a List(Of MyObj), and I want to iterate through that list and compare each element to all other elements in the same list, excluding (if possible) the same element. I have a solution that works, but it's slow and uses double For loops. It may possibly have also summoned Cthulhu from his sleep. This below is a sanitized version of what I have:
Dim MyList As New List(Of MyObj)({Obj1, Obj2, Obj3, Obj4, Obj5, Obj6})
If MyList.Count > 0 Then
For i = 0 To (MyList.Count - 1) Step 1
[code]....
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Nov 15, 2011
I want to know how to test the 1st list box if it has items more than the other list box but by one item, here is what i have: If lstInvisibleTv. Items.Count > lstInvisiblePc.Items.Count Then it works good if the lstInvisibleTv list box is greater than the other list box by one but it also works if it is greater the other one by one or more which I do not want. I want it to work just by one.
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Apr 16, 2012
I have an invoice that lists several items that one person has ordered. I want to take this invoice and every time I check the item it removes one of those from another list i created called item details. I added items to this list using the item collection in the listbox.. I have invoice one that has a pink sock ordered. when i clicked this box next to it I want my total pink socks of 12 to move down to 11... the detail page and the invoice are two separate pages.
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Feb 17, 2010
if i pressed the RadioButton .. ENGLISH.. only Teacher's which teach English will be displayed in the listbox and so on. there is in access table called TEACHER which has all these information. i used the following code for displaying the TEACHERS' name in listbox and it worked pefectly but what i want is displaying according to radiobutton checked.
Sub conxn1()
Connection.Open()
Dim da As New OleDb.OleDbDataAdapter("select * from Teacher ", Connection)
[Code]....
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Dec 26, 2011
Basically I have a form which has 2 drop downs. In the 1st drop down I am selecting City category. When the city is selected I want to update the 2nd drop down values in correspondence to 1st value choosen in 1st drop down. I have done like this,This adds the value in the 1st Drop Down:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim s As String = "connection String"
sqlconn = New SqlConnection(s)
[code]....
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Oct 31, 2011
I've never really used the Check List Box in the past, however, for the recent program I am developing, I am using this control rather than individual check boxes scattered across the form.Anyway, I want to be able to program through code which items get checked in this checked list box. Specifically, I have a variable that contains the text of each check box that I want checked.With a normal check box, I can simply say:
Dim strNames As String
strNames = "John Doe, Mark Johnson, Mike Brown, Cindy Smith"
If strNames.ToString.Contains("Mike Brown") Then[code]....
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Aug 3, 2009
I have the following code:
' The yearNode does not exist.
Dim yearNode = From y In App.Data.<year>
Where y.@id = xlParams.Year
[code].....
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