Use The DataTable.WriteXml Method To Create An XML File Without Erasing Previous Content In That File?
Feb 18, 2011
I have to generate an XML file from several database tables. I could use the WriteXml method of the DataSet to do it, but the database tables are really huge and I can't add all those tables in the DataSet at the same time or it may cause a problem because of the big amount of memory used. Then I decided to use the DataTable's WriteXml method and save table after table, but the the generated file only stores the information of the last DataTable.WriteXml's call. How can I preserve the previous XML data when adding all that information?
My current project is to process several files. The files come from a Unix server and have been SFTP'd to the Windows XP machine. (That's fixed protocol, I don't have control over it.) My problem now is that the Unix new line characters and Windows characters don't match. The solution is to read the file line by line and replace 0x0A with 0x0D + 0x0A, or Asc 10 with Asc 13 + Asc 10, or vbLf with vbCrLf, however you like to say it.Well I have a working function to do this, but any extra speed I could squeeze out of it would be fantastic. The text files I'm working with can reach sizes of about 100MB. So to the question:
Q: What is the fastest way to read a file in, change characters as necessary and then write the file out?Here is my current working code.
Private Sub FormatCharacters(ByVal files As String()) Try For Each fileName As String In files FileSystem.Rename(fileName, fileName & ".old")
Friends I want to try my hands on encryption/decryption. What I want is to export the dataTable content in encrypted format to a file. And when needed import back.
I am able to do the export import as XML file, but how to encrypt the data? Regards Pranabjyoti (If a post answers your query mark the post as answer)
When i output my dataset to an xml file, 87 nested tables with 218 class object (system.type.object) columms i get 247,691 instances of output like this."msdata:InstanceType="LotNet.LForm+Pointer, Learing Programs, Version=1.3.0.9, Culture=neutral, PublicKeyToken=null" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">" In this case the decluration is more then twice the size of the Pointer. Is there any way to supress this kind of output the data is only used for internal consumption by other moduals.
I am stack at work finishing my program.I have a piece of code to write an xml file.
Dim ds As New DataSet Dim dt As DataTable = GetDtable() ds.Tables.Add(dt)
[code]....
That work will write an XML file whatever I put in the datatable (or dataset). It is just a simple code and it works fine. The problem is it will replace the old file everytime the new file is created. I really don't want that to happen. I also want to include 2 variables (username, sessionID) also time of the file created in the file name. So file name will be Username_sessionID_time.xml rathen than a fixed name.
Im learning Visual Basic 2010 on my programming class and we reached the part of file handling. Here i tried to make a simple program that can create a text file with the content of what i type on the textbox, basically i create the file if it doesn't exist, and if it already exists i append the content to it. Once the file is saved i can read it using the "Open" button. Unfortunataly, whenever i try to create the file, the compiler gives me an error saying that it cannot modify a closed file, although i've followed up the execution instruction by instruction and i can't find the error.
Imports System.IO Public Class Form1 Dim body As String
How to correctly insert image data from XML file to database table using sql server CE and openxml,XML file is written by vb.net DataSet.WriteXml method?image data is stored in database table is :
0x89504E47.my XML file Content after written by WriteXml method is : <?xml version="1.0" standalone="yes"?> <Data> <Table> <image>iVBORw0KGgoAAAANSUhEUgAAAcIAAAGuCAYAAAADLg..</image> </Table> </Data>
but after inserting with openrowset and openxml using stored procedure to another database table its value changes to this :0x2F0039006A002F00340041004100510.and is not the first value and raises an error in vb.net for opening image from database.
how to create a save to text file method with a try catch in the method in a class and then call this save method from a button on a window form. I am currently doing the save method under the button directly but to tell you the truth i would prefer to just do it one time and call it from different locations in the various forms i have, then copying it all the time.
I want to know how to create our own file, such as: (.Docx). If we opened the file in notepad the characters contained in the that's file could not understand, so i would like to know by what method of making the it's file? Is the file created and use encryption method or what?
My code is crap, so I don't really think it will be useful because I've been going about it differently than I really want to:[code]..... I really don't wanna be loading a file in, I just wanna use XMLDocument() to create a file from my DataTable.But, my file ain't coming out right and I'm sorta just lost as to how this is all supposed to fit together.
I wrote an application which parses a website and downloads an mp4 file from website. User can select the path where he wants to download the video. When I try to download I get an exception for the file, Access Denied to Path. When I gave the permissions to folder that I chose, then works fine. How can I resolve that problem? End-User will select the folder. How do I change the permissions?
I need a bit of advice. I am working on my project with the listbox. I know how to create a source to get the strings from the text file using ReadLine method, but I have no idea how to split the strings in the text file by on the third commas and ignore the other strings while select with the matched strings on the listbox for each row.Here it is an example listbox Here it is an example items on the listbox
random item 1 random item 2 random item 3 random item 4 random item 5
And here it is an example text file.
example strings one, any strings 1, any random strings 1, other strings 1, final end of strings 1 example strings two, any strings 2, any random strings 2, other strings 2, final end of strings 2 example strings three, any strings 3, any random strings 3, other strings 3, final end of strings 3 example strings four, any strings 4, any random strings 4, other strings 4, final end of strings 4 example strings five, any strings 5, any random strings 5, other strings 5, final end of strings 5
The listbox is display the list of an example items, so if I select the "random item 1" item on the listbox, it read the strings through in the text file on the first line to get the strings on the third commas in the same line which it is (any random strings 1) to split it while ignore the other strings (other strings 1, final end of strings 1) that come fourth and fifth commas. So, if I select the "random item 2" item on the listbox, it read the the strings through in the text file on the second line to get the strings on the third commas in the same line which it is (any random strings 2) to split it while ignore the other strings (other strings 2, final end of strings 2) that come fourth and fifth commas and so on...That is what I am trying to achieve by select the each listbox item to get the correct strings for each line in the text file that come on the third commas while to ignore the other strings.
I don't know whether it is simple or not because i am new to programming. my requirement is : In my vb.net winform application, the filenames of the files present in "D:Project" willbe displayed in DataGridView1 control. Now I want to load these files one after another into memory stream buffer and add the headers("ID","Name","Class") to the content in the file. Then I want to save these files in "C:" with "_de" as suufix to the filename i.e.,sample_de.csv.
I have a textbox on a form that is set to allow dragdrop operations from txt files.Basically you drag a .txt file onto the txtbox, the content of the text file is displayed in the textbox.All is working fine, however after the textfile is displayed in the textbox, the text box text is for some reason is highlighted.I don't want the text to be highlighted (or selected) after it's being displayed on the textbox.Second issue, after I close the file that I dragged, for some reason even if I didn't make any changes to the file, it is acting as if the file has changed.In another words, if I open a text file using my MenuItem Open item, and if I do not change the file, If I close the file it's fine it closes.However, if I close a file that I draged into the text box and then close the file without changing anything in it, the stringcompare function is telling me that the file has changed... I can't understand why.
I do one project in visual basic 2010.In visual basic 6 project can be make Package and deployment (setup file or install file) file using Package and deployment wizard.But in visual basic 2010 express edition does not have Package and deployment wizard.how to make Package and deployment (setup file or install file) file in visual basic 2010 project?
I want to load a csv file (A comma delimited text file) into a datatable. I found the OdbcDataAdapter Class which looks perfect, but it says it is supported only in version 1.1 of the .NET Framework.
Is there a better way to import a csv file into a datatable? the first line has the column headers.
I am using Visual Studio 2008, using version 3.5 of the .NET framework
I am trying to create a log file which I am going to use to populate some controls (DataGridView or Treeview). I am trying to figure out if should use text files or XML files to do so. Effectively the log will highlight multiple phases in a client-side app. The log will be written to at various phases when the project is running. The user will always have the options move on to the next phase or save progress and exit the project. As such, I want the log file to highlight how far the user has progressed throught the various phases AND I want the log to highlight varous information from each phase. Whenever the user starts the project, they will be given the option to load existing log files. So the project will have to read these log files and append them where necessary as the user progresses.
I am not sure what the best way to do this is and below is a rudimentary approach using text files. As you can see, the top of the file would have a summary of all the phases and whether or not the user completed each phase. Next each phase would have a data section highlighting what data was stored along the way. I have used a ":" to denote each section. Then within each section I would obviously need to use a delimeter for all my data. So if Phase1 = True, then I would load all the pertinent data from "Phase1:" into the desired control. Can anyone provide an efficient way of doing this and provide some insight as to whether I should use XML instead. The phases my change during development and I am not sure yet which controls I will be using. Does XML provide more flexibility.
In summary I am looking to create, read/write and append log files and populate controls with the data in varous sections of the log file. Example:
I've got an app which uses a background worker to copy files. It works fine but some files are quite large and it "appears" as though the app isn't doing anything. Is there an alternative to the File.Copy method of copying files so I can report on the progress of individual file copies, like the percentage complete?
i am very new to VB. I am working on file operation such as show files, copy file, delete file, show current directory, rename folder, make folder. My problem right now is with delete and copy file. I have a method of delete and copy but i dont know how to pass this method on a button.
I need to save a datatable to a binary file , in binary format , in order to make the process fast because the datatable may contain up ten millions rows. So , XML is not favorable because it makes the file large sized , and the process will be slow.
I managed to save the datatable to a binary file , and it works fine , but the problem when I try to add new rows to the existing binary file (using a datatable with the same schema , but different rows data) , it copies the schema of the datatable to the binary file, making it very large.
I am Reading a Text File using Stream Reader. I am Reading line by line . At one point of time , If I want to go back and Read the Previous line,, Is there any method to implement that.. I have tried calling to function ( whose argument is Line number) which opens the same text File , and read upto theline number , but it does n't work as expected ,
I have nine pictures that I need to animate -I need to use the ToString method and a counter to concatenate a file name into a string variable from the Image.FromFile method. Once the counter reaches its maximum value, and the last picture is displayed, the counter should be reset to zero or one depending on how the first image file has been name. Also a static counter variable should be incremented in the time routine. what I have so far -- I know what I have to do; however, I just do not know how to code this properly.. Right now I have this going thru a button procedure but it needs to go through a timer.
i'm creating some PDF reports for my application, i wish to open them directly without saving them, so to allow the user to decide what to do with them.
I've build my procedure, i thinks it works fine (the same procedure with filestream instead of memorystram show me what i want).
But i don't know how to open the document written using memorystream...
Private Sub PatientFields() txtFirstName.Text = pa.Tables(0).Rows(intcurrentindex).Item("Forename").ToString() txtLastName.Text = pa.Tables(0).Rows(intcurrentindex).Item("Surname").ToString()
[Code]....
Once the search is executed I want to be able to click "refresh" and the original table is then shown in the datagridview. If I try adding after the search sub is completed:
Hi, I'm using the Drawline method by capturing coordinates entered into 4 textboxes and then printing the image onto a picturebox. However, I can't get the previous line to be redrawn along with the new line that needs to be drawn. I understand that it refreshes when using the picturebox.refresh() function.
The code is:Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
