Avoiding Referential Integrity While Updating
Jul 4, 2009
I have an MS Access database and an MS Visual Basic 2008 front end.I get this error when trying to update a record that has related records:The record cannot be deleted or changed because table 'X' includes related records.I only want to update one field in the row in the 'parent' table which is not the primary key field of either record but the 'Update' command seems to want to rewrite the whole datarow. Rewriting the whole row causes the error (as this updates the primary key). If I switch off refrential integrity checking in the underlying database this solves the problem except that I want to maintain referential integrity so its not really a solution. I have tried beginEdit and EndEdit with no success - same error.Is there a way to update just one field in a row and write that back to the database?
View 2 Replies
ADVERTISEMENT
Sep 8, 2009
I've seen a good bit written on avoiding updating a form from a thread.However,I was wondering if that was a problem if the thread exists in an object that programatically builds the form?Thus the form and associated logic exist within the same "thread space." Seems on the face of it like it would work since everything in the form should be in a single dispatch queue.
View 8 Replies
Sep 3, 2010
If I was to upload one or more file(s) to a server, is there anyway to check that / those file(s) against the file(s) stored on my computer without downloading the file(s) to check against the original file(s)using VB.Net?This would need to be done in a recursive fashion from a parent folder downwards, the folder being of the end-users choosing.
View 6 Replies
Sep 17, 2011
Is it possible for my application to check if its been modified?
e.g. Could i compile the app and use a 3rd party tool to calculate the MD5 checksum of the compiled exe - and inside the app, code it so that if the MD5 checksum doesnt match then run the deactivation process?
I know its not foolproof but if it makes it slightly more hassle to crack my app i'd rather have it
View 1 Replies
Aug 5, 2008
I would like to determine which DataGridViewRow causes an SQLException to occur.A typical scenario follows:1) Using LinQ, I select a set of 'StockItems' as a datasource for a datagridview, and all works fine.2) I insert a new object and (purposely) leave a primary key value blank.3) I attempt to save using MyDBContext.SubmitChanges(Data.Linq.ConflictMode.FailOnFirstConflict)4) An SQLException is received.How do I tell which row has caused a violation, particularly when one or several changes have been made. I would like to advise the user that a specific row in the datagrid caused the error to occur.
View 2 Replies
Sep 23, 2010
How to ensure data integrity in multiple table update (which have relationship like reference of a column)[code]Now when I update the tables in datagridview in win form .and update it using dataadapter .update then how to make sure that all the data is updated correctly.
View 1 Replies
Jan 19, 2009
Im adding listviewitems and want to avoid duplication. Now currently, I have resorted to looping through the listview and comparing each items text property against what Im adding. But for a big table this is very slow. The ListView has a .Contains Method but this does not seem to do what I would have assumed; for example [code]Is there a way of doing this so I dont have to loop through all the items?
View 6 Replies
Sep 14, 2010
I have the following code block. I'm tired of typing the same IF statement to check if the string has any lenght before assignning them to the class properties of Employee.
Is there any better to accomplish this?
Dim title = txtTitle.Text.Trim
Dim firstName = txtFirstName.Text.Trim
[code].....
View 6 Replies
Oct 13, 2010
I'm working on a new DAL for my latest project. As the performance is essential I'm avoiding late binding/reflection as much as possible. One central part is the DAL function for populating Business Objects.One class is called in order to connect to the database with the given SQL (stored procedures can't be used in this environment) and the given Business Object or List is populated. As different Business Object types will be populated by the same function I made an Interface that all of the Business Objects implements with the Sub called "Fill". The question is - will reflection be used in this scenario? My thought was as I'm "describing" the objects trought the interface the compiler doesn't need to use Reflection.
[Code]...
View 3 Replies
Feb 15, 2012
I'm writing the following bits of code for a SaveFile Dialog box in Visual Basic 2010.NET. The code works well as the XLSX file is created and opens in Microsoft Excel. However, the problem that I am having is that if the program overwrites a file, the user is getting two prompts. One prompt is from the program's own SaveFile dialog confirming the choice. The other is from Microsoft Excel asking you the same. It's as if the program is running in the background.[code]
View 1 Replies
Sep 26, 2011
I want to avoid the creation of SQL queries inside the dataset. Here's the screenshot:
Dim search_by_dateofcanvass = sqlcomm.CommandText = "SELECT [#], Material_Name, Brand, Unit, Discount, Supplier, Category, Date_of_Canvass, City, ListPrice, Material_Description, NetPrice, Area FROM CanvassTable WHERE (Date_of_Canvass = " & DTPcanvass.Text & ")"
Me.CanvasstableTableAdapter.search_by_dateofcanvass(Me.FinalDatabaseDataSet.CanvassTable, datepick)
By the way that query can be use to search for date.
View 3 Replies
Sep 16, 2011
If dr("iname").ToString = DataGridView1.item(0).cells.item(0).valueThen Then
MsgBox("Similar items are not allowed.", MsgBoxStyle.Critical)
Exit Sub
End If
I need to avoid displaying similar data from my mysql database table iname to the gridview, but I can't identify the right syntax/code for that?
View 1 Replies
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.
View 4 Replies
Sep 25, 2009
One feature of C# compiler is that namespace declaration by default follows the folder name structure in the project. By e.g. you have MyProject1MyDrawing and inside you create a class MyPoint the namespace for MyPoint will be MyProject1.MyDrawing
In VB I cant see any namespace declaration(apparently it implicitly 'inherits' the project(MyProject1) namespace). If I create a MyPoint and MyLine clases in the MyDrawing folder I need to surround each of created classes with "Namespace MyProject1.MyDrawing"..."End Namespace".
Is it possible to automatically name the namespaces like in C# by the folder name?
View 10 Replies
May 17, 2012
I need the Logitech HD Webcam C310 to be preselected.When the Main Form opens the Webcam must be running allready, withoute having to select it from the Video Source Window.
View 1 Replies
Jul 26, 2010
This particular function is used to save the returned results for a ping sent across the internet. Unfortunately the code won't let me Use the streamwriter method or the fileopen method, because it says:"The process cannot access the file 'C:UsersChrisDocumentsPinging DataFilesave2.txt' because it is being used by another process."
Private Sub SaveToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SaveToolStripMenuItem.Click
FileOpen(1, "C:UsersChrisDocumentsPinging Datacount.txt", OpenMode.Input, OpenAccess.Read)
[code].....
View 1 Replies
Jan 31, 2009
i get a lots of errors with my application because users doesn't have the .Net Framework installed so i was thinking, can't i take every .net framework resource that my application uses and needs, and add it as a reference in my application so that the user does not need to install .Net Framework?
View 6 Replies
Feb 25, 2011
I am creating an application that parses an XML and retrieves some data. Each xml node specifies the data (const), a recordset's column-name to get the data from (var), a subset of possible data values depending on some condition (enum) and others. It may also specify, alongside the data, the format in which the data must be shown to the user.
The thing is that for each node type I need to process the values differently and perform some actinons so, for each node, I need to store the return value in a temp variable in order to later format it... I know I could format it right there and return it but that would mean to repeat myself and I hate doing so. So, the question: How can I store the value to return, in a temp variable, while avoiding boxing/unboxing when the type is unknown and I can't use generics? P.S.: I'm designing the parser, the XML Schema and the view that will fill the recordset so changes to all are plausible.
[Code]...
View 1 Replies
Aug 22, 2011
If a booking is present in database on 12/27/2011 at 5:00 pm for 2 hours and i try to make a new booking on 12/27/2011 between 5 to 7 pm then my code generates an error message. Even if i try to book at 4:00 pm for 2 hours it generates an error message as the 2nd hour will be overlapped here with already made booking from 5:00 to 7:00.
Now here comes the problem part. When day changes it doesn't generate error message i.e. IF a booking is there on 12/27/2011 at 11:00 pm for 3 hours then it should not allow new booking till 12/28/2011 2:00 am but when i try to book 12/28/2011 at 1:00 am it saves it in the database and doesn't generate an error message. I want an error message generated in such a case.
I am using two separate fields in database one for time and one for date. Both of them have DateTime datatype.
newtime refers to time on which i'm trying to make new booking addednewtime refers to time after adding the duration to time on which i'm trying to make new booking
[Code]...
View 1 Replies
Apr 16, 2009
Does the absolute value protect the following code from the Environment.TickCount wrap?
[code...]
View 5 Replies
Oct 5, 2010
I've got a Word Addin in VB.net and VSTO that exposes a COM compatible object via Word.COMAddins.Object, so that the addin functionality can be called External to Word, without accesses to Word itself being cross-process.The technique worked in VB6, but with VB.net, it still works, but it's much slower than the same code running directly from the addin via a task pane, as if the calls are all cross process when they shouldn't be.Anyone who's ever done Word automation knows that code that runs perfectly acceptably INPROC with Word (in this case the instance of the ADDIN that Word itself loads), will generally run unacceptably slowly out of process (or cross process).[code]And slow as in a factor of about 10 to 1; what takes 3 seconds to run when run directly from the ADDIN via the task pane, takes ~30seconds to run when called from external code through the COMADDIN.object object. I'm guessing that I'm running into some sort of issue with .net APPDOMAINS or something and what +really+ constitutes cross proc calls in .net, but I've found nothing so far that would even hint about this sort of thing.My next step, barring some mystical insight, will be to code up a repro, which could get tricky because of the shear number of elements in play.
View 1 Replies
May 2, 2012
If the parameter variable is not passed then this code throws an exception of "Conversion from string "" to type 'Date' is not valid."
This is my code.
Public Shared ReadOnly Property Request_projectStartDate() As Date
Get
Dim _value As String = Nothing
[Code] .....
View 2 Replies
Jun 17, 2011
loading of form when I experiment with Debug.Write code?I deleted the form,placed code in a standard module before running the program but am getting an error message.With the form existing I get what I want but I just don't need to wait for the form to load and then to click cancel to close it.Is it not possible to have just a standard module in a VB 2010 Express project? If not can't I place the code in form1.vb but stop it from loading every time I test something?
View 10 Replies
Feb 7, 2012
I'm writing the following bits of code for a SaveFile Dialog box in Visual Basic 2010.NET. The code works well as the XLSX file is created and opens in Microsoft Excel. However, the problem that I am having is that if the program overwrites a file, the user is getting two prompts. One prompt is from the program's own SaveFile dialog confirming the choice. The other is from Microsoft Excel asking you the same. It's as if the program is running in the background. Does anyone know how I can write this code to save the file as an Excel file? [Code]
View 1 Replies
Mar 4, 2011
I am using Printdialog() to get my report printed (.rdlc)I want to avoid this dialogue and send the report directly to the printer without user interference.
View 1 Replies
Oct 14, 2010
I have code in an ASP.NET form that needs to, depending on user entry create messages in the database. We are speaking of potentially thousands of db entries. How do I protect against deadlocks, I mean apart from using Transactions and setting IsolationLevel to Serializable, as well as using WITH(NOLOCK) statement on my select statements since I don't mind a dirty read.
[Code]...
View 1 Replies
Mar 15, 2011
I need to draw a bitmap background with one or more moving bitmaps in the foreground; something like a chessboard where pieces move across it. I use a timer-tick event to redraw the background and then draw the relocated foreground image like the code below. But I get flicker, even though I set the form to use double-buffering. The culprit seems to be redrawing the background to refresh where the foreground images used to be; no flicker if I replace the background DrawImage with a simple Graphics.Clear. I think what I want to do is draw the background, and the foreground bitmap(s), in memory and then render it all. I used to do this with double-buffering, BitBlt, and .Refresh in VB6 but I haven't found the equivalent in VB2010. This must be a pretty common graphics requirement; what's the trick to it?
Dim Gfx As Graphics
Me.SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.UserPaint Or ControlStyles.OptimizedDoubleBuffer, True)
Dim rectBrd As Rectangle 'use as clipping region for drawing
[Code].....
View 11 Replies
Jan 13, 2011
I am trying to implement a solution for updating form controls without using a delegate.
Imports System.ComponentModel
Imports System.Runtime.CompilerServices
Public Module MyInvoke
[code]....
I get a cross threading error as though i didnt even use this method:Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on.
View 3 Replies
Jan 25, 2012
I have a webpage with a form that is used to edit some object. This object contains a Collection of other objects defined like this: Public Overridable Property Employees As List(Of Employee)
On a form I can delete an employee, add a new one or modify existing one. When I click save new values are sent to the server. On a server I check if the user exists. If exists then I modify its values, if it does not exist then I add it. All employees that exist on the server and were not sent are marked as deleted (State changed to EntityState.Deleted). I try to use the following code (dbCollection = database entities, newCollection = collection sent from the form):
[Code]...
This code does not work, because changing to EntityState.Deleted removes the object from collection, and for each loop breaks, since the collection is modified...I know that I can overcome this problem by using a for loop or adding objects to delete to some other list first, but I hope maybe there is a pattern that would make my code nicer.
View 1 Replies
Apr 15, 2010
I realize this has been covered a million times before but with threading sometimes a problem is app specific. I have a multithreaded app that assigns a url to a thread which it then fetches and crawls. Now the function where I collect each threads items I have added synclocks assuming this would avoid alterations. But I get the "collection was modified, enumeration operation may not execute" error. look at my code:
For Each landingPage As String In landingPages
'logger.constructLog("Working on landingPage link: " & landingPage & " at " & DateTime.Now.ToString, True)
[Code]....
View 2 Replies
