I am attempting to modify DBaseIV files using ADO in .NET I am able to open and read the data with no problem but everything is showing as read only and there is no way (at least that I can find) to perform Updates/Inserts/Deletes to the underlying Database table.
There seems to be almost no documentation that I have been able to find dealing with DBASE files. I have found a few references that BDE (Bordland Database Engine) needs to be installed and used for changing DBASE database files. However, it appears that BDE must be purchased. I found one reference that indicated ADO Jet 3.5 would work but 4.0 would not. Then I found another that said 4.0 had been updated to include Update/Insert/delete SQL interfaces.
Can anyone point me in the right direction for being able to modify a DBASE IV database table using ADO (or some other method within .NET) It is currently not possible to change from DBASE to another database structure this may be coming in the next year or so but will still need to perform modification to DBASE files for the forseable future.
I have a dictionary of key=string and value=datatable. I use a key to retrieve a datatable and assign that datatable to a new variable. Then I make some updates to the variable. However, I find that the dictionary itself is being updated even though I'm only updating the variable. This causes significant issues when I try to reference the dictionary later. How can I set up my dictionary so that it won't update when I use a value?
dim dt1 as datatable
dt1=dictionary(key)
For row=0 to dt1.rows.count dt1.Rows(row)(4)=dt1.rows(row)(4)/2 Next row
'at this point, when I look up dictionary(key), the value I get shows all of the original values divided by 2.
I'm not sure of the syntax necessary to access a class's attributes inside of a Dictionary declaration.
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So if I want to test it and use MsgBox() how do I trickle down to pull, say, name in food > cheese1 > info > attributes2 > name?
EDIT:I just realized that Array in info needs to be a Dictionary for an associative array, so please ignore that error and just assume it is a Dictionary for this question's sake.
I have created a structure with some variables that I'm trying to update during the course of a sub routine but they are not updating, when I cycle though them at the end all the variables are still set to 0.
Imports System.Data Imports System.Collections Structure Team
I am trying to populate some fields in Word document using DocVariable:[code]The proplem that I am facing is when I open the document after running the program the fields won't be updated, so I have to go each field and highlight it then > right click > update field to get the new value!I need a way to update them or my work will be meaningless.I forgot to say that the DocVariables are inside textboxes.
I'm not sure exactly how to describe this. In VB6, there was a Timer command. I could create a variable of type Timer and loop until the current value for Timer exceeded the initial plus a given amount of time. This allowed me to update form variables while the timing loop was executing. How can I do something similar in .NET?
Here is a sample of the VB6 code:
Code: Dim StartTimer As Double StartTimer = Timer Do
I have a Public Sub I am using to enumerate running processes and then display them in a ListView.I want to be able to update the list automatically each second. I've thought of doing this in two different ways, but the method that I want to use is checking if the process has exited or not.
When reading up on the Process Properties, I ran into .HasExited and .Refresh.I thought that I could use a timer and have it tick at 1 second intervals. I would then check, each second, if the Process has exited. If it has, remove it from the list.The problem with this, is that I don't want to put the sub in the timer because it would just constantly flicker the control. I need to figure out a way to access the variables inside of the Sub while inside of the Timer's .Tick event.The other issue is being able to add processes that aren't there. Which I can within another sub. I was thinking I could create a sub that grabbed the Processes by ID, compare them to the list, and them add them if they aren't there. If I did this, I could also remove Processes by ID that aren't in the list.
I want to group items from a linq query under a header, so that for each header I have a list of objects that match the header title. I assumed the solution would be to use ToDictionary to convert the objects, but this allows only one object per "group" (or dictionary key). I assumed I could create the dictionary of type (String, List Of()), but I can't figure out how to write it. As an example I have written a simplified version below.
I have created a class with a function in it. I have a collection of data I want to pass back. I tried an arraylist first. Now I am trying to use a dictionary. My problem is that it creates the dictionary ok, but I am only get the last row of data from my
Function GetWeldAuditInfo(ByVal ResourceId As String, ByVal VendorId
countDictionary As Dictionary(of Category, Dictionary(of Date, Integer))
The Class has a Enumeration Property. For the purposes of demonstration, I'll call it MasterCategory.I have been trying to get out an object that looks like the following:
groupedCountDictionary As Dictionary(of MasterCategory, Dictionary(of Date, Integer)
Which results in a IEnumerable (Of Dictionary(of Date, Integer)) for each MasterCategory value.However, I need that IEnumerable of Dictionary flattened to one dictionary with all the integers summed (total counts) for each date. I then tried to use various selects and group bys (from numerous stackoverflow posts) to "flatten" it, but my efforts have fallen short.
Current Code
[Category Class] - MasterCategory As Enum - Name As String etc
I have created a Dictionary class (MyDictionary for the example). I am currently trying to pass MyDictionary into a function, filter it into a new instance of MyDictionary and pass this new instance into another method. When I am attempting to create the second instance from the filtered first instance of MyDictionary via Lambda Expressions and the ToDictionary Method, I am getting the following error:
Unable to cast object of type 'System.Collections.Generic.Dictionary`2[System.Int32,System.String]' to type 'MyDictionary'. I have simplified the example and recreated it in LINQPad and am getting the same error.
I use VS2005 and I have just started working with the dictionary in particular the Dictionary.ContainsKey method. At the bottom of the page in the msdn library it says the following in the community content How to make sure that Contains functions properly.
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):
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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.
Last year (2010) I came across a FANTASTIC command that allowed me to take a string of variables with a common delimiter and break it all back out into separate variables (possibly an array) with one statement.
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As long as the delimiter was a unique specifiable character, this one-statement command could break it out into elements. my memory and point me in the right direction.
I have code, shown below, that works all except for 1 thing: The variables being passed byRef get passed, but once modified in the else section of the "if me.invokerequired" code of RecordData, the variables are never updated in the calling function. To reiterate, the calling function does not receive the updated data that is in the variables custid and amt.When debugging, I see the data change in the else section of "if me.invokerequired", but once it returns from the callback the data is missing.[code]
I define some global variables of a class as follows:
Private Class MyClass Private var1 as Decimal Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
Does the memory used in declaring variables are reclaimed by the OS when these variables go out of scope?Does the memory used be released by setting thier value to nothing? if not, then how can I force the garbage collector to run or excecute at a certain/desired time..How about in Windows Forms..How can we make sure that the memory used in initializing and showing forms be released if those forms were closed?
Question 1: What is the difference between "Background Worker" and "Worker Pool" as indicated within the MSDN samples provided.
Question 2: I noticed while using, AddressOf _Function_, variables cannot be passed; what would be an efficient solution to this?
Question 3: While using multithreading is it required to invoke before setting variables, or only form properties?
Question 4: While using System.Net.Sockets is it safe/efficient to use Application.DoEvents while waiting for new data; or would be using a Do While loop be fine without DoEvents since the action would be multithreaded? Note: there can be up to 2000-3000 sockets in use at a time.
I'm new in .NET programming.I have a class Form1 that includes Button1_Click event.Button1_Click creates a multiple Text Boxies at run time)Here is the class:
Public Class Form1 Dim shiftDown As Integer Dim counter As Integer
i've been doing ADO.NET for a while but I would like to know if its posssible to use dao recordsets in VB.Net 2010 and where I can get tutorials and code samples to do database stuff like insert etc. I've tried to google but most of the code available is for vb6 I was going through some stuff on this link [URL]../bb243801%28v=office.12%29.aspx and i'd like to know if it works for vb.net 2010 or maybe theres something i'm missing. because the moment I put "Dim dbmyDB As dao.database" its been giving me the wavy blue line and i am now doubting if it works or maybe i'm missing some other code
If you are using an sql database with a vb.net application, does the user need to have anything extra other than the .net framework installed for the program to run? Meaning, if I simply compile the application, are there any extra steps I need to take to make this work?
Ok, so I am on my last book of course material for college and this weekend I started making my own personal applications, stuff I can really use in everyday life, these projects also serve as a port folio for future employers
I recently moved over to a Windows 7 computer and I can't get databases to work with VB.net.Before I moved I used to do an Access database and connect it to VB through the ODBC thing. However, I don't have Access on this computer (open office) so I'm not sure how to create a database and connect it.I have tried to use the SQL Compact Edition that comes with Visual Studio but I not sure how to get it to work. Also would something like mySQL work with VB? I have looked at the mySQL workbench and like it, what else would I need to download to be able to use the databases created with it in Visual Studio?
I am trying to carry out a synchronisation of two databases: one on the server and the other on a local machine. So that even when they are not connected on the network, the local database can carry on accepting data but when the network is back on, the local database can update the server and the server can also update the local machine with data it accepted during the time when the network was off. by first comparing two tables in two databases and then if they are any differences the updating begins and i've since been stuck.
Private Sub btnCompareTables_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompareTables.Click 'dont know which arguments to put when calling this function 'How do i tell the computer which databases to compare Comparing()
I have two dataset , each with with table . each datasets is connected to a separate dataadapter to get data from sql server database file (two different tables SQLtableOrders & SQLtableCustomerA))
datasetOrders.Tables("Orders") >>> the first column "orderID" is a primary unique key. Its structure is details below : OrderID----OrderName----OrderCost--------Date 1----------A---------------54------------11/11/2010
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note that I had already made this by getting the data by SQL Statement "Select SQLtableOrders.* , SQLtableCustomerA.orderID FROM SQLtableOrders, SQLtableCustomerA WHERE SQLtableOrders.orderID = SQLtableCustomerA.orderID" It is really working fine , but the problem that it takes time to get data from the SQL server each time I disply orders. I already have the datasetOrders.Tables("Orders") data on the client PC , I need only to make the client PC extract which orders are assinged to a ceratin customers. I can do it by For... Next , but I guess it will take time , specially if "orders" data contains many data .
