ADO.NET Concurrency Single User
Jan 16, 2009
I've got a problem with my latest project, I get concurrency error but I'm the only one working on the database.It's an sql server 2005 express database, and i'm making a remote connection. I have a related database or how do I say it, it's with relations. But the strange thing is that I can update the first table but the 2nd one not. Well here is my code, don't really know how to explain it better but I get an error when updating my orderinformation table but when only changing values in orders that table updates perfectly. [code]
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Mar 2, 2009
give me some example code to insert rows of datagridview into a sql express database table? Also, how do I manage concurrency as it is a multi user application?
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Oct 19, 2009
Suppose i have made a single user program that receives its data from a database on a SQL server. What things do I have to change to the program to make it a multi user program while preserving data integrity?
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Jun 9, 2011
How can I prevent a single user from logging in to my asp.net website from more than one computer at the same time?I have tried using the application server side state managenment but it is not work properly.
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Nov 20, 2010
Is it possible to show more than one user interface at a single time in order to show how to show how all relate in real time?
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Oct 16, 2009
I am using help of SqlServer.Management.Smo to rename an attached MS-SQL database.
Dim db As New Database = ActiveSQLServer.Databases(OLD_NAME)
db.ExecuteNonQuery("ALTER DATABASE " & OLD_NAME & " SET SINGLE_USER WITH ROLLBACK IMMEDIATE")
db.ExecuteNonQuery("ALTER DATABASE " & OLD_NAME & " MODIFY NAME = " & NEW_NAME)
The problem is that after renaming the database is set as a Single User.So what am i doing wrong?
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Mar 19, 2012
i have an access 2007 database in wich i have a table named abc_PersonalLog, wich also has three columns: Id (auto number), StarDate (text) and LogEntry (Memo). It is a Diary application. So, when the user makes a log entry, the StarDate column receives a string formed of concatenated year, month and day, i.e. if date is 20th march 2012, the string will be 120320, and the Log entry column, the text entered by user in a textbox.My problem is that, somehow, i have to retrieve that data, when the user will want to read log entries he made. I managed to assign the text property of a label to the LogEntry text for a given date.But, if the user makes multiple entries in a single day, the table will have several rows containing the same string in the StarDate field, but different text in the LogEntry fields. How can i display ALL the LogEntry texts for all the rows containing the same StarDate value? Here is my code so far:
[Code]...
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Jan 8, 2012
I have been assigned a task to create a basic hangman program and I need help to figure out how to show the letters that the user has guessed correctly without displaying any of the other Characters.The word that the user will be guessing is in a label the user will be guessing letters by clicking buttons This is a piece of the code for one of the buttons the user can click to guess the letter "C":
btnc.Visible = False
Guessletter = "C"
If lblword.Text.Contains("C") Then
*this is the part where I become stuck*
End If
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Nov 13, 2010
I have a Search form where the user can click a Button that opens up a rtb with every single word (12,800+) used in the King James Bible. Every word is Capitalized ("Thankful, Grateful", etc), so in my code, the user selects a word, then right-clicks and sends the word to the TextBoxSearch in lowercase. Now, if the RTBDisplay (where all search results go) is empty, then a msgbox pops up asking if the user would like to re-search the same word in Uppercase. If they click OK then the word in the TextBoxSearch (lets says: "thankful") is supposed to become "Thankful". But instead, the TextBoxSearch goes blank. I have tried many variations of code, and here is my latest (doesn't work):
If Me.RichTextBoxSearch.Text = "" Then
MsgBox("Would you like to search the same word but in Uppercase?", CType(1, MsgBoxStyle), "Re-Search?")
If CBool(MsgBoxResult.Ok) Then[code]....
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Aug 3, 2009
I am new to VB and seeking to create a visual basic program which controls the display of several on-screen elements depending on a single value input by a user. The user can enter anyone of 2500 values and depending on the value entered, five different display elements on the screen will change color or text. The program's response to a given input value never changes, in other words if the user enters 279, the five different display items will always be the same. However, there is no real pattern to the display items that would allow for programming an anticipated response to the input value.
My thinking is to create a large and ponderous "lookup table" in visual basic - I am assuming this an be done but perhaps there is a different or better method. I plan on creating the lookup file in Excel but was assuming I'd need to export it to something that VB could easily read. Any suggestions on the best way to do this? Does the lookup table reside as a separate .txt files someplace or something like that? [Code]
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Aug 15, 2011
In my application, the user clicks a single button and the program displays each network adapter description into a message box and then gets all the ip info for the workstation and places it into a text file and opens that text for reading. What I would really like for it to do would be to display all the network adapters into a single messagebox instead of messagebox for every adapter like it is currently doing. Here is the code I have on that button. Let me know if anyone needs more info or has any questions:
[Code]...
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Apr 9, 2010
The way I'm doing this is performing multiple reads on different tables to extract data. In this case I'm reading 2 different MS Access 2003 tables. I then dump the data into a "Row" variable that I have Publicly defined for each Class (each Access table is defined as a Class containing all the fields, Add, Change, Delete, and Select functions).For example, my first read extracts all the fields from the "tblClients" table and loads them into the form fields via the "clientROW" object. My second read extracts all the records from the "tblClientAddr" table associated with the selected Client and loads them into their form fields respectfully via the "addressROW" object.
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Jul 5, 2011
what is the different writing code application vbnet 2005 application for single user and multiuser?
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Jun 13, 2012
How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface
Public Economic as EconomicClass
Public Sub New()
MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
interface.Economic.MyMethod
interface.Currency.MyMethod
etc
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
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Jan 28, 2011
My users are getting this error when trying to update the database:
"Concurrency violation: UpdateCommand affected 0 of the expected 1 records"
All the users are doing is clicking a button which updates a record.No two users are updating the same record or even within the same column. They could be updating within the same row but still not the same record.It seems to be happening when the program is open for a little while and they come back and try to update the database through the program. I have read a little bit about this error but none seem to lead to a clear solution.It seems like the database connection is timing out due to inactivity?Here is my update command:
vb.net
Private Sub btnComplete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnComplete.Click
Me.txtComplete.Text = Date.Today[code].....
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Dec 15, 2011
I'm having an issue with a concurrency violation when I save my data(only on one form). All other data forms are working fine. This form has a lot of code, so to isolate the problem I added a new form to the project and dragged the table from my datasource, in detail, to the form. this is the only code in the form,
[Code]....
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Dec 23, 2009
Say I have a code with 3 methods that do some pretty intensive work. Would executing these methods on 3 seperate threads be faster then executing them one after the other on a single core cpu? And what if it's a dual core or HT?
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Sep 5, 2010
I am trying to make a list, separated by a comma, of entries from a single column in a SQL database. I have been spending the last several days searching for a way to do this, but every thing I found either didn't work, or wasn't exactly what I was looking for.
The query will pull all the email address that are not null. What I need to know is how to take the result of that query and make it look like this:
email0@address.com, email1@address.com, email2@address.com, etc, etc, ...
I feel like I should know this, but for the life of me, I can't remember nor can I find it in any of the textbooks I have.
I am using Visual Basic 2010 and SQL Server 2005. I also have access to Visual Basic 2005 if needed.
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Oct 23, 2009
I use SqlParameters when executing database statements. I know that I can replace a single quote with two single quotes... but in the past SqlParameters took care of this for me. I have two projects.. in one, the SqlParameter does this and it handles single quotes fine, in another, it does not and I'm at a loss why (I even copied and pasted the code):
[Code]...
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May 7, 2010
I am trying to use the DGV to view various properties from a variety of different class instances. Is it possible to bind each cell individually?
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Mar 19, 2011
In our database we have gigantic tables (it was initially built 20 years ago). We are on the process of developing it.
Some tables contain rowversion and optimistic concurrency. We were wondering if there is a way to just correspond rowversion to the modification of some specific columns, but not all of them. In Normal Case, T-SQL which is generated then would be huge.
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Jan 28, 2009
I get an error when updating a related table, the main table can be updated but the related gives me a concurrency error but I don't know why. Btw I'm the only one using the program and it's connecting to sql server 2005 express.Inserting works like a charm.My piece of code, I hope you get it. The concurrency error is given on Me._objtblOrderinformatieA.Update(Me.objdtsOrders.orderInformatie)
If MessageBox.Show("Bent u zeker dat u deze record wilt wijzigen?", "Orderbeheer", MessageBoxButtons.YesNo) = 6 Then
update_dataset()
Me._objtblOrdersA.Update(Me.objdtsOrders.orders)
[code]....
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Jan 21, 2011
We got an old system here in .NET 4.0 using an Oracle DB. At some point, some calculus are made and the system "locks" that register in the table using the following command: "SELECT [the registry that will be update by the calculus] FOR UPDATE NOWAIT". So if anyone tries to calculate or update the registry with that ID it won't work. After calculating, the system connects to the DB again and then "releases" the registry by simply executing a Rollback command.
Theoretically, this is correct for the system(although I don't like it). Anyway, here is the thing: if something is being calculated(and these calculous take like 5 minutes to finish) and in the middle of the calculous I close the browser, the registry will still be "locked", only being unlocked when IIS restarts(actually I dunno if it's released first, I forced IIS restart 'cause it was taking too long). [Code]
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Jun 18, 2012
I am doing a small project and I am using vb.net with MS access database. I am facing a Concurrency issue sometimes when I try to save data in the datagried view. I have added the datagried view by dragding and drop the table from the data source. Only one user is using the form to save data at one time. I think it works properly unless I moved from record to record then it gives me an error. "Concurrency, 0 records updated from expected 1....."
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Apr 14, 2010
i understand that web service creates its own sessions so thats no problem to multi-thread. but i am writing my results into the database and files. how to do i do my concurrency control for writing into file and database here, can i do it on my calling app which is a console app or i will have to do it in my web service. i am not returning anything to the calling app.
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Apr 30, 2009
I'm new to vb.net and its database methods so I'm a bit confused by these datasets and grids and table adapters.
I'm getting:Concurrency violation: the UpdateCommand affected 0 of the expected 1 records.
On this line:frmMain.AccountsTableAdapter.Update(frmMain.DsAccounts)
I have a datagridview attached to a dataset. I also have a button that the user can press to update information in the datagrid based on a website. But I often get that error when it comes to actually updating the table.
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Jun 12, 2009
I am trying to make a simple demo of a DataGridView bound to a database table. I want to add a row, delete a row, and save the table. I used the IDE to do just about everything. It created the BindingSource when I set the datasource of the DataGridView to a table of a DataSource I added to the project.
Now the only code looks like this:
Public Class Form1
Private Sub DataGridView1_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[Code] .....
I set the AutoIncrementStep to 1 in my Key field in the dataset (the .xsd). I left the Key field visible in the DataGridView and it seems to be adding the correct Key when a row is added. However, I still occasionally get the "concurrency violation" error if I just mess around with these 3 buttons. Any idea why/how to prevent that?
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Mar 17, 2009
get around the following problem please?I have an Access database which can be accessed by more than one instance of my application (which is) a Form with a DataGridView on it.I populate the DGV with
Form1.Validate()Form1.CHECKLISTBindingSource.EndEdit()Form1.CHECKLISTTableAdapter.Update(Form1.chkDataSet.CHECKLIST) The Access Database can then be updated via the DGV by a button click (which runs the code above (to copy across the latest copy of the DB) and then runs the code below to copy your changes to the DB)
Form1.CHECKLISTTableAdapter.Fill(Form1.chkDataSet.CHECKLIST)
Form1.DataGridView4.DataSource = Form1.CHECKLISTBindingSource
Form1.DataGridView4.Refresh()
The Access table is basicaly a 'Time' Column and a 'Name' Column.
[Code]...
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Aug 24, 2011
I'm trying to update a Access database. I'm new to this and I've reviewed an Ado tutorial early today. I'm trying to apply what is taught but I'm getting an error message and I can't seem to get passed it.
In my code I have an Add, Update, and Delete process. The Add and Delete processes work just fine. It is only when I go to update the database that I get the following message."Concurrency violation: the UpdateCommand affected 0 of the expected 1 records."
[Code]...
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Feb 8, 2011
I cannot for the life of me work out why I get a concurrency error on the second update Here is my
[Code]....
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