.net - Linq2sql Synchronized Rapid Deletes?
May 7, 2011
I set up a test harness by checking for and then deleting records added to the db in the previous testing session, and then I test my recording adding code by adding back the same records.Interestingly this code works fine when there is a break in the debugger, but fails with a "duplicate key" exception when I let it run with no breaks, which leads me to believe there is some kind of concurrency issue.The basic metacode is as follows:
DoTest()
dim j as datacontext
dim recs = from myrecs in j.mythings select myrecs where myrecs.key="key1" or
myrecs.key = "key2"
[code]....
I've confirmed that I'm properly deleted the previous added records, and this works fine as does adding the new records when I have a break in the code before I hit the add records step. but without the break, it throws duplicate key exceptions in the "addrecordestomytable" method suggesting that it hasn't grabbed the current version of the table when it creates the new data context in addrecordstomytable, even though the records should have already been deleted.I've tried refreshing the table, but this doesn't seem to work either.Note backing database is ms sql server 10?
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Oct 4, 2011
I set up a test harness by checking for and then deleting records added to the db in the previous testing session, and then I test my recording adding code by adding back the same records.Interestingly this code works fine when there is a break in the debugger, but fails with a "duplicate key" exception when I let it run with no breaks, which leads me to believe there is some kind of concurrency issue
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Apr 22, 2010
I have a data bound datagridview where I am allowed to add and delete rows.So a new row is the last row in the grid with the '*'. When a user starts to type in the new row, that row no longer is considered the new row. It is then inserted into a row above the new row (*). The user, however, can press 'Esc' key and this row gets deleted.If the user does not pressed 'Esc' but move the cursor along that row, this row will be permanently there. I have tested this scenario and check the underlying dataset and it registers no changes as in the myDataset.hasChanges=FALSE.If I call myDataAdapter.Update(myDataSet), nothing gets updated. How do I save this row to the database?
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Jan 13, 2009
how to make linq2sql behave like my custom code used to, I want to check to make sure that it isn't already "built" in behavior that I can just use by setting up the relationships right in the designer...
Very simple example: I have two tables: Person and Notes, with a 1 to many relationship (1 Person, many notes), linked by Person.ID->Note.PersonID.
I have a stored procedure (all data access is done via SP's and I plan on continuing that) which makes the Link2SQL a bit more work for me.
sp_PersonGet(@ID int) which returns the person record and sp_PersonNotesGet(@PersonID) which returns a set of related notes for this person.So far so good, I have an object:
Dim myPerson As Person = db.PersonGet(pnID).Single
and I can access my fields: myPerson.Name, myPerson.Phone etc.and I can also do a
Dim myNotes As Notes = db.PersonNotesGet(pnID)
to get a set of notes and I can iterate thru this list like:
For Each N As Note In myNotes
( do something)
Next[code].....
Basically, Linq2SQl would need to call 2 stored procedures each time a Person record is created...Is this doable "out of the box", or is this something I need to code around for myself?
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Dec 22, 2009
I have this one line property
Public ReadOnly Property DateToUniversal(ByVal dt As Nullable(Of Date)) As String
Get
Return If(dt.HasValue, dt.Value.ToString("u").Substring(0, 10), "")
[code].....
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Feb 25, 2010
I want to use Linq2Sql as the data source for my Crystal reports. I have all my data in my domain objects in the form of Lists. The problem is all my domain model resides in a different namespace in the form of a .dll. And when i try to assign a data source for my report in Database Expert window, under .NET Objects, i can only see classes that are available in the current project and not from other projects in my solution, nor from other namespaces.
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Jul 30, 2009
I have a timer that I've established that I have set to run at a 20ms interval.Within that timer code, I have some code that is performing a visual display, moving a graphic incrementally.This all works great on a nice fast machine, when I can be sure that the "work" is actually being completed before it's "called" again by the timer.It does not behave well on a slower machine, when I suspect that the timer is being called again before the work is being done from the previous call(s).
I've tried establishing a global boolean variable called "Timer1Active". I set this variable when I enter the code to TRUE, and to FALSE as I exit the procedure. I also check, using an IF statement if it is true at the beginning of the procedure, skipping all of the procedure if it's not yet been set back to false.This approach seems to stop the visual portion from happening altogether. I think, anyway. That or it's now way faster and I can't see it at all (but I doubt it).
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Sep 23, 2009
I've got a very simple data structure. I'm using SQLExpress with Linq2SQL and vb.net
**ParentClass**
parentId
name
[code].....
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Jul 3, 2010
I have tried to set up combo boxes in the gridview but all the combo boxes have the same value in them instead of the value from the database. I am using entity framework and WPF. There is a parent child relationship between two tables but the source for the combo box is a separate table with names and IDs for tags. I have been looking all day. Hopefully this won't be too easy to solve.
The "Tag" Column displays the combo box. The Column "Tag ID" displays the value from the database. When I display the data the TagID Changes in diffrent rows but the Tag column is the same (the first choice) in all the rows. When I change one combo box they all change. I can't see where they are hooked together.
Here is the XAML
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="372" Width="675" mc:Ignorable="d"
[Code].....
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Jun 9, 2011
What I can do: Display an image (e.g. a bitmap) by loading it into a control (e.g. picture box), showing that picture box (visible equals true / refresh) and then hiding it (visible equals false / refresh).The onset of the image onto the screen is not necessarily synchronized with the raster scan (needs to run on CRT monitor) meaning the lower portion of the image may appear one (partial) frame before the upper portion. Though I can specify (roughly) how long the image is on the screen I cannot specify the number of frames and there is enough variability in the timing that I will not get the same number of frames every time.
What I'd like to do: I'd like to be able to have my display wait until the beginning of the next frame before showing my image. I'd also like to tell it exactly how many frames to show the image before removing it. Ideally I'd like to be able to cue up multiple images to be shown for one frame each in order (animation).
I've found a lot of information on the web about DirectX but the few tutorials I've tried are overly complicated for my needs and invariably fail to start for unspecified reasons.I don't need 3D.What I want to display would work just fine in a picture box if the timing were cleaner and predictable.
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Apr 22, 2010
I am using an activeX control to read data from an external source. This data is processed in 5 second increments. Each piece of data is passed through an event. When the event triggers I call a "decision" procedure from the event to process the data and make decisions on what to do, i.e. call other procedures, store the data, etc... This works fine when I have a small number of samples (around 10), however, when the number of samples increases to say 100, that is I am recieving 100 pieces of data every 5 seconds, the "decision" procedure does not fully run. Is it possible that the event trigger is causing the code to exit the "decision" procedure prematurely? I know that the "Decision" procedure starts since I have written data from the beginning of the procedure but not the end of it. how to handle the rapid event triggers?
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Jul 9, 2011
The code I have is meant to be used during possible rapid mouse movement by the user. It is supposed to get the current location (works), move to specified location (works), mouse down(works), mouse up (works), then return the mouse to the old position. I added the delay because it seemed that it was having trouble registering the click if done too quickly. The problem I am having is that if the user is moving their mouse during the time the code is activated, their movement can throw the location of the mouse down or mouse up events off even with the added check routine I added.
'Get current mouse position
Dim MousePosX As Integer = Windows.Forms.Cursor.Position.X
Dim MousePosY As Integer = Windows.Forms.Cursor.Position.Y
Q = True
'Move mouse to Q Location and click
[Code] .....
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Jun 20, 2012
[Code]...
How to create a LINQ query that allows the end user to choose a few months?
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May 5, 2011
I want to filter the SQL Compact Database to get rows that as been synchronized to the SQL SEVER Using sync framework can any one give me an hint on how to get this done. I will prefer a sample code in VB.NET
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Sep 28, 2011
what is the most robust method for adding a empty row (to select "nothing") to a ListBox?
Dim List = Enumerable.Repeat(New TABLE With {.Text = "", .ID = -1}, 1).AsQueryable().Union(From t In mainctx.TABLEs)
ddlMangelKategorie.DisplayMember = "Text"
ddlMangelKategorie.ValueMember = "ID"
ddlMangelKategorie.DataSource = List.ToList
But this has some drawbacks:wordy must explicit write the Type (TABLE in this case), so i cant wrap this in a function have not found an solution, which works with anonymous types I.e. if I add a From t In mainctx.TABLEs Select Text=col1, id=col2 to the query, this method does not work anymore.
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Aug 10, 2011
(Currently using VB.NET 2010 Express) I'm trying to make a program, the main of which is file transfer. I'm trying to create a program that will keep files and folders synchronized across multiple client computers. I'm using a File system watcher to trigger events, and Using a simple System.Net.Sockets UDP client transfer (found via google) to transfer commands between it and itself on other computers.
Here's that code (this just sends from one textbox to another over the internet)
Imports System.Net.Sockets
Imports System.Net
Imports System.Text
Dim udpClient As New UdpClient(1024)
Dim RemoteIpEndPoint As New IPEndPoint(IPAddress.Any, 0)
[Code] .....
By this method, I can rename, move, or delete files. I want to implement file transfer, so that whenever a new file is created, or updated, my program will automatically transfer the file to the other computers and update them there.
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Dec 28, 2011
Im trying to debug a troublesome Project. I downloaded and installed the Symbols from MS, set my Project to use the Folder where I installed them, etc. When I start Debugging, I can see at the bottom of my IDE window that it is loading Symbols at a rapid clip, until it gets to It stops, and I have tried waiting 15 minutes to no avail.
The file exists - D:Symbols
asapi32.pdb90DF78A27042428D99A8021F064506472
asapi32.pdb - 1.40 MB (1,469,440 bytes) - Created Wednesday, November 24, 2010, 12:25:44 PM
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Apr 29, 2010
I just made a rapid file transfer form for my photos.In which I drag photos into a listview with my destination folder set.I assign each individual file transfer to a new thread. This works very fast as compared to the standard drag n' drop.
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Apr 29, 2011
I have to develop an exe, which should remove my application folder
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Jan 24, 2012
I have two (2) variables in a textbox (L7B) and (D2B).
TextBox3.Text = (L7B) &
" " & (D2B)
I want to write over (L7B) without changing " " & (D2B).I have been using the TextBox3.Text.remove command with success however in this case there are just too many scenarios. (D2B) isn't the same number of characters so I would have to determine the number of characters to remove in each scenario.
To write over (L7B) I thought I would try TextBox3.Text.remove ((L7B)). To my amazement VB accepted this command but when I run it it removes " " & (D2B). How is it removing the wrong variable? I could understand if it didn't work at all, after all that's what I expected to start but to delete the wrong variable !! why?
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Dec 16, 2009
Just looking to keep application looking neat, One Form Parent / Child relation, set to cascade updates / and deletes. What I'm looking for is when the form loads the user enters some information for the parent (about 2 column out of 5), then I create a datarow with the information that I have. At this point before I actually send and update command, I would like to get the next scope identity for that datarow.
The reason is I also use that Identity as an Id number in this case a receipt number, and the user will enter detail data that is stored in the child, then calls the save function, this is when I intend to actually call the update to the database.
So the question is, Can I retrieve the scope identity for a datarow that only exist in the dataset without calling the update command and actually storing the data in the database? Or in my case creating my own auto index sub a better choice?
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Oct 10, 2009
I want to make a program that deletes file(s) i ''Trash'' in VB08. If you know some codes just reply.
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Aug 4, 2009
I need to write a program which deletes itself while running...How to do in vb.net and what is the concept to do it..
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May 15, 2011
I try to do a very simple job which is: Delete a row in dgv AND database! But now after three days I'm running out of steam
The problem is: I select on or more rows in dgv and push the del button. The sub zDelete starts working and at the end the selected row is gone and the row after my selection is gone too!?!? The deletion of the selected row was well done in dgv and database. But why is the next row in dgv only also disappeared??? After a restart of the form the missing row is back up again. And when I try to delete the last row it trows an exception error: System.IndexOutOfRangeException was unhandled
The code fragment is this:
'Delete all selected rows in dgv AND database!
Private Sub zDelete()
If MessageBox.Show("Do you really want to delete the selected rows?", "Delete", MessageBoxButtons.YesNo) = DialogResult.Yes Then
[Code].....
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Feb 24, 2012
So I have been working on this small project for a little while now Basically I need this program to be able to delete a single folder or multiple folder depending on the text in the textbox.So far, I can do the single file just fine, this is the code for that.[code]Simple as it sounds...I haven't figured it out...then again I am pretty new to VB, being I started programming in it literally 2 weeks ago.I am guessing that I have to set a variable for the textbox...which leads me to believe I need to use something other than a textbox to do this...I was thinking of using a DataGridView...I not sure how I would make it check if there is anything in a cell then delete it if there is.
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Aug 28, 2010
Frontend: Visual Basic.Net VS: VS 2010 .net Framework: 4.0 Backend: MySQL 5.0. Everything is working well, add/edit/save. I am using datasets to manipulate the database the forms are created by wizard and i drag and drop the details over the form. The Problem: I delete a record on the form, it disappears (it deletes it from dataset i think) but i go to the database it is still there also if i close the form and re-open it the records re-appear.
There is something i do but it raises an error, after deleting the records i hit the save button,the following comes up. Transaction has already been rolled back or is not pending after that the records are really deleted.
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Apr 2, 2009
We were working with a VB.Net app that contains something like 2200 VB modules/forms/classes and got a not-uncommon error message when we went to compile it. (Didn't write down the exact message, but it's basically unable to copy an image file that's in use.)Problem, of course, is that not everybody got out of the app when we told them to. Like I said, not uncommon. (It's a shared app that runs from a server.)Now, the weird thing. After kicking the offenders out, when we recompiled the program the image, which we use on search buttons, was gone. The file was still there but all of the property settings that referenced it were gone. Looked into the Designer code & they were gone from there, too. Seems to me that a compiler should *mark* the code that won't compile, not delete it.Anyway, I only see two courses. Either we restore our app from a backup, losing all our changes, or we go thru all the forms (like I said, there are 2200 modules-not sure how many are forms, but it's a bunch) and manually replace the properties on all the search buttons. Either way it's going to cost us at least a day's work.
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Jul 27, 2009
I have a manually created a dataset (dsPickingList) that I add data too as the user inputs data on a form. There is a datagridview on my form of which it's datasource is set to dsPickingList.What I would like to do is spot if a user deleteds a row from the datagridview and update the dataset (dsPickingList) as it is ultimatly this dataset that is stored to the db and printed, not the DataGridView.[code]This is why I need the action from the DataGridView to update the dataset
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Jul 22, 2011
Which one of these two do you suggest for writing simple windows form applications?Visual C++ is too complicated for my small to medium applications and the proccess of creating seems to be longer when compared with C# or VB.NET.
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Apr 9, 2011
I have a delete method for a binary search tree that only deletes the last two values that were entered in, and when it tries to delete anything to the left of the root or even the root itself it returns a null pointer exception.
Public Function Delete(ByVal key As Integer) As Boolean
Dim current As Node = root
Dim parent As Node = root
Dim isLeftChild As Boolean = True
[Code]...
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