Checking For Duplicate Values Before Attempting Insert?
Apr 14, 2011
I have a form where two fields on the first page of the form make up the primary key. I want to check for duplicate values before attempting to insert the record, since I don't want the user to go all the way through the form only to find out they can't submit it. So I'm trying to check for duplicate values when the user tries to go to the next page of the form. I wasn't quite sure how to do it, and sure enough I'm getting an error. ("Object reference not set to an instance of an object.") The problem is apparently in my if statement, "If myValue.Length > 0 Then", but I'm not sure what needs to be in place of that.
Protected Sub CustomValidator1_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles CustomValidator1.ServerValidate
'get values
[code].....
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Aug 5, 2009
am new to VB.NET and i was wondering if anyone here knows how to check for duplicate values in strings?
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May 16, 2012
How do i read through a textfile line by line checking for and removing duplicate values?
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Feb 7, 2012
I am using the DataSet to test for data errors on a DataGridView (to give the user feedback before they save changes back to the database). RowChanging event has the code at the bottom and this manages error messages on the DGV via an ErrorProvider. I want to add something to this code that esnures there are no duplicate rows (it's a 2 column table and one of those is the autoincrement PK). However I cannot work out how to do this and since the column in the database is set to Indexed (No Duplicates) it will throw an Ole error if I don't handle it, I could manage it in a Try block around TableAdapter.Adapter.Update but would prefer not to add needless round trips to the DB when it really ought to be simple to do it in the code (and preferably in the DataSet, not the form).
I found the following code (Forum Post) and try as I might I can't make it work since I can't get access to a DataTable within the RowChanging event that allows me to run DataTable.Rows.Find().
Dim expression as String
Dim matchingRow as DataRow
matchingRow = Mytable.Rows.Find(expression)
In my case:Mytable would be some kind of reference to the table / dataset etc.
'expression' would be e.Row.compclass.ToString
* a reference to the database table the form works with (bearing in mind that this code is in the DataSet not in the form). I've tried properties/methods of the DataSet itself; creating a new DataTable and linking it to the DataSet Table (or DB Table); creating
a new DataTable and loading it with the table contents - Searching MSDN and the forums hasn't popped anything up yet.I'm currently experimenting around this code:
Dim strCompClass As String = e.Row.compclass.ToString
strCompClass.Trim()
Dim foundRow As DataRow = ???.Rows.Find(strCompClass)
[code]....
This is the current code in the RowChanging event. The new code would be inserted after the last End If in the code below.
Private Sub ref_compclassDataTable_ref_compclassRowChanging(ByVal sender As System.Object, ByVal e As ref_compclassRowChangeEvent) Handles Me.ref_compclassRowChanging
If e.Row.HasErrors Then
[code]....
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Sep 10, 2009
I've read through all the search results for this and haven't quite got it yet. I often get given Excel spreadsheets of file names and have to check through them for duplicate names.I am making an app to do this for me. I've extracted the data from Excel I'm just having issues with checking for the duplicate. I've tried 2 different ways I found online and neither are working for me,
[Code]...
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Apr 1, 2012
I have this line of codes here to check if the records exist.
Try
If StudentInfoBindingSource.Find("StudentNumber", StudentNumberTextBox.Text) = -1 Then
ToolStripLabel4.Visible = True
[Code].....
This codes works perfectly but there is a problem, if I close that certain form and reopen it and try to input the same student number, the ex.Message for the Try appears and still the progressbar() command executes although the data will not be saved. I want to ged rid of the execution of progressbar() how can I make it work? And as much as possible I want the message box in Else to be executed and not the msgbox in try catch.
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Dec 22, 2009
I need to check if a Commodity entered into (TextBox1.Text) already exists on my table before i insert it. I'm having issues checking if the number of rows returned from my Select is equal 0? Also i'm wondering should i be checking for an exception and open/closing my connections each time i make a call to my DB or is the way i have it coded below OK?
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
Try
myConnection = New SqlConnection("server=localSQLEXPRESS;uid=sa;password=12345;database=My DB")
myConnection.Open()
[code]....
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Apr 13, 2011
I am being forced to us Option Strict in my class and this is a new feature to me. Right now my code is having trouble comparing the current time to be added (A Date) with the list of times (Object). Here is my complete code
Option Strict On
Public Class schedulebookForm
' handles Add button user event
Private Sub addButton_Click(ByVal sender As System.Object, _
[Code]....
Problem is inside TimeTaken Function, inside the For.. Until. Basically the If... Then Statement. I tried. .contains, Select Case, and a few other alternatives.
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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 9, 2012
I have script like this :
Private Sub cmd_save_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmd_save.Click
If txt_kdbrg.Text <> "" Then
[Code]....
give me alternative script, if object is duplicate script give alert or message "already exist"
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Nov 5, 2011
i'm using below code to save data to sql but i need to save the new data only not all data
table name :
CHECKINOUT
key :
CHECKTIME
[Code]...
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Nov 3, 2009
Is there an easier way to prevent a duplicate insert after refresh? The way I do it now is to select everything with the all fields except ID as parameters; if a record exists i don't insert. Is there a way to possible detect refresh?
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Aug 9, 2011
I have two table, src_table and dest_table src_table contain multiple rows including duplicates I want to copy rows from src_table to dest_table without duplicates.
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May 3, 2012
How to make only one record at a time get inserted in the database table and also delete from the other table?
Once the details are filled ,I insert it in table1 as the new record and I delete the same record from table2.[code]...
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Apr 2, 2010
Is there any reason to favor one of these approaches over the other when inserting into a generic dictionary with the possibility of a key conflict? I'm building an in-memory version of a static collection so in the case of a conflict it doesn't matter whether the old or new value is used.
If Not mySettings.ContainsKey(key) Then
mySettings.Add(key, Value)
End If
[code].....
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Feb 26, 2012
I'm using an unbound data grid in Visual Basic. I made the following loop for the purpose of searching each cell and each column for a duplicate value. But for some reason I get a "InvalidCastException" when I try to add a second row.
Private Sub AddJudgeBtn_Click(sender As System.Object, e As System.EventArgs) Handles AddJudgeBtn.Click
Dim exists As Boolean
' ToDo: If the value entered is already on the list, don't add again.
If JudgeList.Rows.Count() > 0 Then
[code]...
EDIT: Adding the entire click event.
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Dec 14, 2011
I am trying to get duplicate values from dgv into a combo:
[Code]...
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Oct 20, 2011
m_ListOfsAllFields.OrderBy(Function(x) x.DisplayOrder)
here I have DisplayOrder = 0 for 2 fields, so orderby is messing up and not ordering properly. How can I use orderby to order this collection?
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Jan 29, 2011
How can i avoid the duplicate values in the Access Database?? I am working in VB.NET, to create DataEntry Form. I have Combobox. When enter the value on Combobox and press OK button then the value should check on the database , if the value is not there then it should save on the db. else the Missage will give "It is Saved".
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Jun 21, 2010
I want to insert number for City_Id and City_name , i wrote a query for auto generate number for City_Id,working fine but in the city name i want to avoid inserting duplicate value like if Mumbai is a City ihave already saved then system should not allow that name again. neither in small or in capital or mixed letter.
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Dec 15, 2011
I need to validate a particular coloumn in datagrid for duplicate values before inserting into database. I am using datatable.
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Mar 9, 2010
Get Random value with no duplicate
[Code]...
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Jan 20, 2009
I have a fairly large Drop down menu:
<asp:DropDownList ID="DropDownList8" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList8_SelectedIndexChanged">
<asp:ListItem Value="" Selected="True"></asp:ListItem>
[code]......
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Apr 1, 2012
I am currently trying to make an insert statement that will first check for exceptions before it is sent to the SQL server, I am new to this and would like to know what errors I should be looking out for and also what code should I use to ensure the errors will be caught. [code]This is a continuation of a previous thread...it was getting kind of long and the initial issue was resolved so i decided to open a new thread..
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Apr 1, 2012
I am currently trying to make an insert statement that will first check for exceptions before it is sent to the SQL server, I am new to this and would like to know what errors I should be looking out for and also what code should I use to ensure the error will be caught.
[Code]...
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Nov 7, 2010
How can I avoid Duplicate values in Datagrideview. When I am putting Product Id in Invoice which is adding in datagrideview if it is exist in datagrideview it will Highlight with deferent color and give me massage that this Id is existent in datagrideview
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Jul 5, 2011
I am trying to create a .Net application to edit a excel file by deleting some columns and keeping the columns which we need and then removing the duplicate values based on the first column which is going to be the Serial no. which should have a check to have 6 digits by default like 2563 should be displayed as 002563.
Code:
Public Function GetAllFileContents(ByVal path As String, ByRef errorMessage As String) As IList(Of String)
Dim contents = New List(Of String)
Try
Dim files = Directory.GetFiles(path, "*.xls")
If (files.Length = 0) Then errorMessage = "Please select the files"
For Each file In files
[Code] .....
I am trying to create something different by not only letting me do it for excel files but for say txt and csv files along with it. Removing all the values which I dont want and removing the duplicates and then if possible putting a check on the first column of data that the serial number number should have minimum of 6 characters and then The output file should have all the details in Uppercase
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Feb 10, 2012
How do I prevent users from a inserting a duplicate value using SQL Query
datatype is VarChar(50)
e.g. the name field has already been defined as "Josh", I don't want it to be able to add another "Josh"
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Feb 9, 2010
I am using a MS Access database as the backend of my VB.NET application. I am entering users details into the database using an INSERT INTO statement:
cn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & config("DatabasePath") & ";")
cn.Open()cmd = New OleDbCommand("INSERT INTO blah blah blah...", cn)
dr = cmd.ExecuteReader
[Code]...
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