VS 2008 Updating SQL Database From Multiple Threads?
Oct 28, 2009
Is it safe to update an SQL database from multiple threads at the same time? I have a method which runs on up to 25 thread pool threads at the same time and it attempts to write to a text file and update an SQL database - I assumed that writing to the file would not work properly if all threads tried to write to it at the same time, so I have used SyncLock for that part of the method. Just wondering if I need to do the same thing for the part of the method that updates the SQL database? or is the framework (or SQL server) smart enough to either execute multiple update statements on the same table at the same time without a problem or queue them?
View 5 Replies
ADVERTISEMENT
Aug 25, 2010
I have an access table that I'm loading into a dataset, then I'm binding the dataset to a bindingsource. The bindingsource is the datasource for a datagridview. I can use a command builder to update the entire table, but I need to update all the rows (or changed rows) in specific columns. I have a column called "dPrint" which is Boolean. I'm not sure how to use the bindingsource as my datasource in an Update Command. I've tried this:
View 8 Replies
May 27, 2012
Been a while since I did any VB work, and have started a new project that is a Windows Service that will update a database using multiple threads. I am testing this out with a dataset that consists of a "device name" and a "device IP", pinging the device, and attempting to update the device's "status".
I have it working in a single-thread type configuration, but would like to be able to ping and update different records across multiple threads (for obvious reasons).
The problem I'm having is with the logic mainly. When the service is started, I get all the devices from the database and fill a DataSet. From there, I am looping through the dataset's rows, pinging each device and updating the record. I know how to spawn multiple threads, but I do not know how to keep track of updating the correct record and also making sure that all records are checked in some kind of order. Like, if user specifies 5 threads, I need it to get record 1, thread finishes, gets record 6 (while other threads execute), or something like that.
Note: this does no interface updating or anything like that. Only updates a database record's field value.
View 37 Replies
Oct 19, 2011
I just had a new, last-minute idea on to take on a task, so I am running to StackExchange for quick help.
What I want to do is execute a series of methods right in a row, each in their own threads. I want the application to wait until all of these threads are completed, after which the program will resume. It also has to use managed threading (thread pool).
What quick examples could you provide to help me along the way? If it's too complex, what things should I know about so that I can Google it on my own?
View 1 Replies
Jul 28, 2010
I'm testing here something, but i don't know what's the best way to do this.I have a var that tells the application the number of threads that will be started, inside the thread/function that i call i need to return/get two values i have two sub functions, each one returns an integer.Then in the end i need to sum the values.
Example:
Thread1/Function
SF1 - Returns 2
SF2 - Returns 3
Thread2/Function
SF1 - Returns 1
SF2 - Returns 5
After all threads are over, i get the
SF1Total = 2 + 1 and
SF2Total = 3 + 5.
I'm thinking in using shared vars, and inside the function/subfunctions update the values. It's this a correct way to do it? Other question, the threads are assync, but i need to know when the last one finishes. How do i control this? The order they finish doesn't need to be the order they were called....
View 4 Replies
Jul 29, 2010
In the same line of this thread Now i have a problem with the control of the ending threads. This is my
vb.net threadsEnded = 0 For j As Integer = 0 To numThreads - 1
[Code]...
Some times the application doesn't finish and if i pause the application i see that the threadEnded var doesn't have the correct value, seems like some thread doesn't update the value of the var.
View 5 Replies
Sep 4, 2010
I have a created a class, which contains a sub routine.This sub routine, should ideally be accessable by objects which are not members of the class, so I would like to make the sub, a 'shared sub' (call it Sub1).
Question: I am using many threads and there will be possibly 100s of 1000s of threads all wanting to use Sub1 (which is at present, is not shared).At present Sub1 , is not a shared sub, so every time a thread wishes to use Sub1 , I am creating a (dummy) instance of the class and then applying Sub1, to that instance.
My program works flawlessly using the above technique.Question: If I were to turn Sub1 (which is not currently shared) into a shared sub, and directly had various threads calling Sub1, would there be any issues with locking, ie. would it possible for 2 threads to enter that thread and start overwriting variables, which another thread has written to?
NOTE: there are no shared variables/properties in Sub1 and all variables used in Sub1 are declared within the sub itself.
View 7 Replies
Dec 20, 2009
I want to have multiple threads input data into the same arraylist, so they would need to share it. If this is possible how can I do this task?
View 1 Replies
Feb 19, 2009
I have an application which takes input on a local machine and sends it to a database stored on a server. I'd like to be able to deploy my application over a number of computers (all on the same network), all of them updating the same database (on the network server).First of all, will this be possible without putting together a completely new application to handle all connections to the database and sorting the entries?
View 7 Replies
Dec 30, 2009
I'm trying to learn t-sql and my reading material all say to update all the rows at once instead of processing row by row. How would I go about doing that if I'm using object data source? I can see how I would do it if I'm using a dataset/datatable, but if I'm using a List(of object) as my data source for a datagridview, how would I update all the rows in one go?
For example, let's say
Business layer - I have a Person class with generic properties (name, age, gender, occupation, etc.)
Database layer - I have a method that retreive all the rows in my Person table, and return it as a List(Of person) to be used as the data source for my grid view.
I make a bunch of changes that affects multiple records, and instead of having a button on each row in my datagrid that update that specific row, I want an "Update" button that update all the records.
View 1 Replies
Sep 15, 2011
I have a loop that creates several threads as such[code]...
View 1 Replies
Jun 29, 2011
I guess that I should preface this by saying that I am totally new to VB, but I come from the PHP/MySQL world so I can work my way through things syntactically. That being said, I have made a program that expedites a few things that I do on a routine basis at my place of work. However, because I have no idea what I'm really doing, my app logs up while the UI thread does all the background work.
What I am trying to accomplish, is a few things. Have multiple functions/subs [done]Somehow generate a generic method that executes a sub when called (one at a time, always)My already coded subs return values (for updating a progress bar for example) but have the background thread that spawns the function, update my UI threads progress bar / list box with the output.I guess I want to know if this is even doable, and secondarily, how would I go about doing this? I understand the idea of threading, but all of the tutorials that I have seen / read are pretty convoluted.
View 7 Replies
Jan 28, 2009
After making the changes or adding a record I use invoke childmethod from my toolbar to call these subs. The first table updates and adds, but the second does not. I have set all of my textboxes databindings and double checked them. I get no error, but it does not update the second table. What am I doing wrong?
Public Sub AddRecord()
'Clear out the input data fields on a new Add.
ClearInputFields()
[code].....
View 2 Replies
Mar 24, 2011
How can I do this, this what I got so far.
Dim ClassID As Integer = 1
Dim da As New SqlDataAdapter
Dim con As New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFilename=D:Database
[code].....
View 1 Replies
Apr 18, 2010
it would be best if I just copy and pasted the code (it's very trivial).
Private Sub Main() Handles MyBase.Shown
timer.Interval = 10
timer.Enabled = True
End Sub
[code]....
An exception, "The object is currently in use elsewhere", is raised during the tick event.
View 1 Replies
May 30, 2012
I am trying to get information into a database from VB 2008. I have an established connection and have pulled fields onto my form. I am able to see data already in the database on the form. Originally, I tried to use an Update button to send the data from the dataset to the database. This did not work. I then added a Save button to the Navigator on my form in hopes this would do it. This too, failed.
View 10 Replies
Mar 3, 2009
Iv created a Stock Market program and i need it to automatically download the new prices from the web on a daily basis.
It will be downloading the info from my own website - what server software should i use to manage this - simple machines forum ?? A mysql db will be on the server - how is it best way to get this whole system working ?
View 5 Replies
Apr 27, 2010
Having problem in updating an existing record. An error occurs "Data Type Mismatch in Criteria Expression"
Private Sub ToolStripButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ToolStripButton1.Click
Dim myBuilder As OleDb.OleDbCommandBuilder = New OleDb.OleDbCommandBuilder(dataAdapter)
[code].....
View 1 Replies
Jan 13, 2010
I am writing a project in Visual Basic where I need to run several instances of the same method in parallel. I can do this using BackgrooundWorker by having several (4) copies of my code module (modules 1, 2, 3 and 4) with a call to background worker in each. I then have a Main form which invoke the 4 modules which setup 4 simultaneous background threads. Seeing as the code is the same I want to simply invoke the same module 4 times.
However when I do this I get an error from Backgroounworker that it is already busy. As I understand it this means that it is being shared. However, I have specifically instantiated it as "private" (private with events worker as new backgroundworker). I have tried running the same code in a Class instead of a Module but unless I make it public I have no way of invoking it from Main. I need to be able to pass each thread data from main for it to work on and if the class is private I cant invoke it.
View 2 Replies
Nov 6, 2010
This code will show you how I started multiple threads:
For i As Integer = 0 To 10
Dim MyThread As New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf MySub))
MyThread.Start()
Next
Now I'm trying to stop the threads before closing my application but I don't know how to do that?
View 6 Replies
Jan 25, 2012
how to convert videos files using vb.net and ffmpeg. But as far as i know we cannot use multiple threads to run same exe file to convert files. Do you know how i can convert multiple videos using one external exe file (ffmpeg)?
I have not tried because my computer time was over. So iam just asking a general doubt whether if we attach it to one process then wouldn't the process get locked? Then can we multi-thread this application or not ?
View 1 Replies
May 25, 2011
I am trying to make changes to parts of an Access table but can not get the database values to change.I am able to get the datasets and things in VS to change, but the database never shows the changes.
I Have:
' Create an instance for the payrolltable
Dim dt As New MsPeachDataSet.PayrollDataTable
[code]......
View 3 Replies
Apr 8, 2011
i m having problem while updating my database... In this code when i delete records then it will deleted but it can't show updated data..for viewing new updated data i hav to again open the form ... so is there any code which i miss??? to update database @ runtime??
[Code]...
View 15 Replies
Jan 30, 2012
i'm just starting with sqlite, as apparently its quicker than access for a real time logger. i'm using this as a tutorial - i didn't install the runtime support with SQLite as it causes issues when using 2008 express.[URL]..
but it seems the data isn't being written to to the db. i can't tell exactly because i dont have a program to view the table contents, only to view the setup of the db.
View 3 Replies
Jan 22, 2010
I am working on a project that stores data on animals. I am trying to make updates to data already stored there, through inputs on a VB form. A form where all the data is populating the fields shows up and the user can change/update any field. Once they are finished, they click update and the DB is supposed to reflect those changes (Theoretically)However, I wrote the code to do that, but when it runs nothing in the database is changed and nothing gets done, as it seems. No errors appear and nothing goes wrong with the program. It just doesnt change the data in the db.
View 1 Replies
Apr 24, 2010
I am working on a project that stores data on animals. I am trying to make updates to data already stored there, through inputs on a VB form. A form where all the data is populating the fields shows up and the user can change/update any field. Once they are finished, they click update and the DB is supposed to reflect those changes (Theoretically)
However, I wrote the code to do that, but when it runs nothing in the database is changed and nothing gets done, as it seems. No errors appear and nothing goes wrong with the program. It just doesnt change the data in the db.
Here is the code updating the database.
If txtNewID.Text = "" Or cmbRegion.Text = "" Or txtWombatName.Text = "" Or cmbGender.Text = "" Or txtAge.Text = "" Or txtWeight.Text = "" Or txtLength.Text = "" Or txtCommunity.Text = "" Or txtDescription.Text = "" Then
MsgBox("Please fill in all required fields.", , "ERROR")
Else
[code]....
View 3 Replies
Apr 14, 2009
I have two forms in my program, Form1 has ListBox which contains names from the Database.Form2, has textbox and add button to get a new name from the user.but when I click on add button.. i return to Form1 to view the names in the listbox by clicking on view button: ALL NAMES ARE DISPLAYED WITHOUT THE NEW NAME.when I close my program and click on View button all names including the new name that was entered before are displayed ! is there a way to display everything in the database without closing the program??I need a way to refresh or something.
Form1:
Imports System.Data.OleDb
Public Class Form1
Dim ds As New DataSet()
[code]....
View 1 Replies
Jul 28, 2009
I have spent several hours trying to delete a row and insert a row into an Access database using the OLEDBDataadapter and dataSets without any success. I don't get any errors it just doesn't update the datatable. Here is the last version of the code I have been trying to get to work. I have done a lot of searching and have
Data save
Private Sub SaveNumDte(ByVal ltoNum As String, ByVal ltoDate As Date)
Dim numTotal, x, MaxRows As Integer
[code].....
View 4 Replies
May 31, 2012
I have this class and I have a loop that launches multiple threads from the same class. This is all done from the main form.Now I want to update the richtextbox on the main from these classes.I have tried those begininvokes etc etc and nothing worked, no error but no output as well.Here the code for launching the threads :
Private PingObjects(100000) As Account 'Account is the class and login is the sub in it...
PingObjects(I) = New Account
Threads(I) = New Threading.Thread(AddressOf PingObjects(I).login)
[code]....
And to update the rtb, im using MainForm.log.text = "....." Nothing happens, no error.I have tried using the begin invoker method as well.
View 2 Replies
Sep 28, 2010
To get pass the cross referencing error when running a thread, I use this code
[Code]...
But the AddressOf doesn't accept parameters... So how do I get pass that? Or is there another way to use delegate?
View 6 Replies
