I am interested in the pros and cons of data tables and arrays in VB 2010. I programmed decades ago in FORTRAN and used arrays extensively.However, I frequently see data tables in code snippets and don't know when they should be used in lieu of an array.
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Can I know which is better when retrieving data?
View 3 RepliesI prefer having total control for data access, populating recordsets (now datasets) precisely via a connection string and SQL select (or stored procedure call), etc.Now I wonder whether I really should be using the Data Sources option which just popped up on my radar? From the little I've seen so far, it seems to bind an entire table to a control, whereas most of the time I only need a small number of records from large tables.Before I spend a lot of time investigating, I hope a quick word from you might help me feel happier continuing as I am, or whether I need a kick up the backside towards a Better Way.
View 12 RepliesI have 1 access database with 3 tables How do I make the combobox get data from one table and input it to another table?ex.I have a table with all my Carriers and another table with jobs that are assigned to Carriers?
View 3 RepliesI have about 100 strings that depend on an integer value. There is potential for the list to grow to 255. What is the faster/preferred method of assigning the string based on the passed integer, a hash table or a switch statement. I googled around and can't seem to find anything that compares the speed of the hash table lookup vs. the speed of the switch statement. Is there an easy way I could measure the speed myself or any links to articles describing the performace of each method?
View 4 RepliesIs an ArrayList the same thing as a Structure (i.e. 'array of records')? If they're not the same think, what't the difference?
View 3 Repliesi have used in vba 3 dimensional jagged arrays where i had up to 10000 rows. i am now transferring this to vb.net and learnt that it would be better to work with lists. the dimensions are such as (30, 10000, 30). how would i structure this by using lists?
View 8 Repliesi need to copy all the rows with data from a existing table to other existing table through button click
View 13 RepliesI have been working on a number of card games. Important, of course, is shuffling the deck.I have come up with a few different ways to do this. Currently I do not shuffle, but to deal a card, I lay out the deck in order, selecting a random number between 1 and the number of cards remaining and selecting that card. I then remove that card from the deck so that another card can be picked.There are two main ways to do this, and I am trying to figure out which one is optimal.The first is to have an array of cards. When one card is dealt, a new array is formed with that card missing. I kind of like keeping the array size exactly the size of the deck, but perhaps this is not efficient. So, the first array has length n and the new array after the card is dealt has length n-1. VB.Net makes it simple to change array sizes around like this.
View 1 RepliesHas anybody ran into this error before?
View 2 RepliesThis should be an easy one, looks like I got myself too confused.I get a table from a database, data ranges from varchar to int to Null values. Cheap and dirty way of converting this into a tab-delimited file that I already have is this (shrunken to preserve space, ugliness is kept on par with original):
da.Fill(dt)
' da - DataAdapter '
' dt - DataTable '
[code].....
I have an array which originally was a Variant array in VB6. Example code in VB6:
ListBoxDrawings.List(X1, Y1) = myArray(X2, Y2)
myArray(A, B) = ListBoxDrawings.List(I, C)
After running it through ArtinSoft's VBUC, its values are handled using GetValue & SetValue.Example code in VB.NET: (ignore conversion to ListView)
ListViewDrawings.Items(X1).SubItems(Y1).Text = CStr(myArray.GetValue(X2, Y2))
myArray.SetValue(ListViewDrawings.Items(I).SubItems(C).Text, A, B)
Since VB.NET doesn't do Variants, I figured out that the array should be typed as a 2D String Array. It seems like there's no reason to use GetValue/SetValue, as the former returns an Object and the latter takes one. This means that I'd have to cast the returned object as a String (Cstr) if I wanted to assign it to a variable, which seems like a pointless extra step that might introduce errors. Also, since the method has lots of overloads, the code might not be as clear. Is there any advantage to using SetValue / GetValue, or should I just consider that an artifact of VBUC converting a Variant, and access the array directly like the original code did?
VB.NET without Get/Set methods:
ListViewDrawings.Items(X1).SubItems(Y1).Text = myArray(X2, Y2)
myArray(A, B) = ListViewDrawings.Items(I).SubItems(C).Text
just want to know what is the difference between these date values?Once some one told me that its difference is server date and client date but not sure which one he meant.Below is 3 type of date currently I'm using and don't know what is the difference between them.
DateTime.Now is from System.DateTime.Now
Now is from Microsoft.VisualBasic.DateAndTime
Today.date is also from System.DateTime
I had a .chm file I used in VB2008 and I'm having trouble getting it to work for VB2010. I use the code below to reference the file.
vb
Module HTMPHelpAPI Public Const HH_DISPLAY_TOPIC As Short = &H0 Public Const HH_DISPLAY_TOC As Short = &H1 Public Const HH_DISPLAY_INDEX As Short = &H2 Public Const HH_DISPLAY_SEARCH As Short = &H3 Public Const HH_HELP_CONTEXT As Short = &HF Declare Function HTMLHelp Lib "hhctrl.ocx" Alias "HtmlHelpA" (ByVal hwnd As IntPtr, ByVal lpHelpFile As String, ByVal uCommand As Int32, ByVal dwData As Int32) As Int32End Module
I then call it from my menu using this:
vb
Private Sub HelpToolStripMenuItem1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles HelpToolStripMenuItem1.Click HTMLHelp(IntPtr.Zero, "PE Files Help.chm", HH_DISPLAY_TOC, 0) 'Dim sHelpFile As String 'Dim sStartupPath As String 'sStartupPath = Application.StartupPath.ToString 'sHelpFile = Replace(sStartupPath, "in", "hlp") & "PE Files Help.chm" 'Me.hlpHtmlLocal.HelpNamespace = sHelpFile End Sub
I had found the commented out portion online and tried to get it to work, but nothing will bring up the file. Do I need to have it loaded into VB.Net somehow or point to it or does it need to be in a certain location?
I've been fiddling with this for ages and can't get it right. If you have this in C#:
videoSource1.NewFrame +=new NewFrameEventHandler(videoSource1_NewFrame);
void videoSource1_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
// stuff to do in here
}
How would write it in VB? My head is spinning with AddHandler and AddressOf and I can't seem to get it right.
I make a lot of programs that require an internet connection to download things from the web.At the very beginning, I used WebClient, as I didn't know Socket & how it worked.But now, I use Socket all the time, altough it's more lines of code. It seems to work faster then WebClient.I am interested if this is really true & why WebClient is slower (so is HttpWebRequest) then just a Socket.I've setup 2 threads which starts on the click of a button (WebClient thread starts first), the Socket beats the WebClient by just some milliseconds, but still.Each way has it's advantages & disadvantages, e.g.: if you use Socket, you need to write the header yourself & parse the response header.My question is, which one do you prefer & why ?Do you know why WebClient & HttpWebRequest are slower then Socket, as I assume, WebClient & HttpWebRequest both use tcp to download the things.
View 2 RepliesI have a program that backs-up remote locations to a centralized FTP server. Upon successful completion, a record is written to a SQL database with the following information:
GUID (uniqueidentifier)
StoreID (varchar(5))
DateStamp (sqldatetime)
ProgramAndVersion(varchar(50))
I am currently managing the program by running a report on who has written a record to the database. If the record is not written, I manually go in and backup the necessary files.The problem with this, is that it can take up to 30 minutes/day to do this task. While that's not a long time, it's getting somebody to be dedicated when I'm off and that has proven to be difficult.
I want the program to automatically search for missing records, but I'm not sure how to do this. I was thinking about bringing in the last 30 days with a SELECT statement and then comparing the information that I have in the SQL database versus a calendar control (or something). I need to make this process completely automated and not very intensive on the SQL server. I only have the following
2010
Sub FindMissingBackups(ByVal DaysToCheck As Integer, ByVal StoreNumber As String)
Dim TodaysDate As SqlDateTime = Now()
Dim PastDate As SqlDateTime = DateAdd(DateInterval.Day, -DaysToCheck, Now())
[code]....
I am in the process of migrating from VB6 to VB 2008. In a pixel grid system I have thousands of cells with about 15 properties each. In VB6 I employed the user-defined datatype "udtCell()" as my array structure. Is this still a good approach - or should I perhaps make Cell a class?
View 2 RepliesI found a sample of how to display data from a table in to a datagrid using VB.
con.Open()
Dim reader As SqlDataReader = _
cmd.ExecuteReader()
DataGrid1.DataSource = (reader.GetSchemaTable())
reader.Close()
But this just displays the details of the table columns. For example row 1 has details about usrID, row 2 usrTel ect rather than the actual data of the table.
I Have a c++ program that is already completed but has no ineterface. So What I am trying to do is translate the c++ code over to Visual Basic, which is trickier than I thought. I need to browse for a text file, cross reference that with a csv file which will match IDs and replace in the text file, outputting to a textbox to save
View 18 Repliesi having a syntax error when im inserting data to two table.i check all the spelling and also i put [] in my reserved word.. by the way here's the code..[code]
View 6 Replieshow to find the row position/index in a data table, using a value from another table. For example, I use the row position from Linkingtable1 to get my value for CustomerID, but i want to use the CustomerID to search the CustomerTable for its row position, in order to show the Customers Name in a text box, As currently when loading the textbox shows the customerID. I understand the code to get the names from the rows in the datatable, its just finding the row position of the customerID.
View 9 Replieshow to get 1 Thing from a internal DB but. i use a external DB to show the online games. But now the other players must see a list of online games.
vb.net
Dim conn As MySqlConnection
'connect to DB
[Code].....
Im trying to fumble my way through selecting data from a mysql table and populating it to a combo box. I feel Im almost there, could someone look over my code and see whats going wrong?
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim con As New MySqlConnection
[Code].....
I was a VB6 programmer. And back in the day global variables, functions and subroutines were put in a module. The program started in the module using a sub named Main(). Now in vb2010 it looks like using sub Main() is possible only for console apps, which is not what I want, I'm still trying to write a windows app but it looks like everything has to go at the top of the starting form?? How is this good coding practice? Shouldn't public vars and functions be in their own module?What is considered best practice?Are there any links that would walk me through the differences between vb6 and vb2010?
View 2 RepliesI've worked out how to display charts in VB 2010 Express, but now I'm needing the user to input data into a spreadsheet/table that will be used within the program. I know that table is no longer available and neither is the OWC11 set. Is my remaining option then to use DataGridView? I know it is SQL based and I don't have much experience there yet, but I didn't want to commit to it if there is another method that would work just as well. The values that are put in by the user does not need to be preserved.
View 3 RepliesI am using Datagridview to show some table data from database. It is working but its appearance is not what i am looking for.Is there a way to edit columns and rows manually ?This is a list of what i want to do :
1. First of all i want to change column captions. because they are like "Fld_name" etc.
2. There is a column that shows date. I want to write a code for it ( convert date type )
3. I want to add a button at the end of each row and write a code for it ( show detail about that record )
I have a situation with an application of mine where I noticed I get a different result when the application is installed in comparison to it running in Visual Studio. If the application is installed a certain aberration pops up in this computer graphics application at a certain point in one of the screens but if I run the same group of settings or you could say the same "screen" running the application from Visual Studio I don't see the aberration ever happen. I tried deleting the bin and obj folders and then rebuilding before creating an installation and it doesn't change anything and whether I use InstallShield or create an installation using ClickOnce I still see the same issue. I have Enable application framework unchecked but found it makes no difference checked or unchecked
View 9 RepliesWill setting the DLL to release hide descriptive names & class info?
View 4 RepliesI have a user interface app that allows you to drag/drop in files - and it turns them into HttpListener request POST's to another EXECUTABLE that I have running - let's call it BACKEND1.BACKEND1 will be running on a SERVER when this gets ready for production use.Lots and lots of users running the UI - all dragging in files - all getting POST'ed to BACKEND1 - with the file included as a memory stream in the POST. BACKEND1 responds to the UI with a "sequential" file number assigned to the file centrally on the server.
On the SERVER is also running another EXECUTABLE - let's call it BACKEND2. It's job is to work with the DRAG'd in files.Both BACKEND1 and BACKEND2 sit on the same SERVER. At the moment I am writing the memory stream to DISK in BACKEND1 - and POSTing the FILENAME to BACKEND2 for it to work on.Would it be better to not write the file in BACKEND1 but instead include it in the POST to BACKEND2 - where it can be written to DISK?
Is having LARGE HTTP REQUEST's a burden when sent between two EXECUTABLES on the same machine?My primary goal is to have a really available BACKEND1 talking the the UI instances running out in the world. I'm concerned that doing the file i/o in BACKEND1 is "expensive" - and I don't care about the performance of BACKEND2 as much.
