Read A Very Large Database Table In Program?
Apr 22, 2011
I'm developing a VB.NET application to obtain data from any data source (using an odbc connection string), and because this i can't use specific .net connectors like MySql.Net connector and i can't previously know if the file/DMBS supports LIMIT parameter. This app will read data from a table in the data source and use the information to make some files. At this point there was no problem with some tables because they are less than 3,000,000 records length, but there is a table that has 5,000,000+ rows length, and when i send the query the connection is lost. I'm working with OdbcDataReader, because i read on MSDN site that this is the best way to read a table one row at time and i just use each record once.[code]...
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Jun 9, 2011
I want to write a program to do Markov chain, but my states are quite large. First of all I calculate all the transition probabilities and revenues for all states(1381860 total states), and store in a multidimensional array. Public RevArr(0 To 9, 0 To 750, 0 To 282) As Long
After that the iteration of markov chain should use these as inputs to calculate the steady-state probabilities. But when I try to run the main code I got this error.Exception of type 'System.OutOfMemoryException' was thrown.
The following is the declaration of second array I add just another dimension for storing all the iterations, but I get this error. Dim stateprob(IT + 1, 0 To 9, 0 To 750, 0 To 282) As single
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Jul 27, 2010
I hate to ask this question on this forum, but I'm having a lot of trouble finding it on these online tutorials. Basically, I'm learning about SQL, VB.NET, and how to glue the two together, and I've learned about using SqlCommand.executeScalar() to get the first entry in a table. But that's all it's really good for, right? Or is there something more to the story here?
Basically, I'm wanting to ask about how to pull in a FULL table from a SQL database while using VB.NET, as well as how to pry substrings and stuff from it. Again I'm having to ask this on this forum because all these online tutorials seem to ignore the subject completely.
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Mar 31, 2009
what I am trying to do is i have a table with four records and I want to write it to a txt file. I am running sql server 2000.I am able to connect to my database and I am able to right data to a txt file my only problem is it always returns the 1st row of data.
Dim FILE_NAME As String = "C: emp est2.txt"
Dim conn As New SqlClient.SqlConnection
Dim da As New SqlClient.SqlDataAdapter
[code]....
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Apr 29, 2009
If I have this to read from an access database, how could I translate it to read from an oracle database with the same table/field information? I know nothing about oracle but I assume I cannot use the oledbdataadapter that I am used to when connecting with an oracle DB.
[Code]...
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Mar 6, 2009
I have following XML structure, how can i use XML reader to read it as its quite large.[code]...
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Mar 16, 2010
I am trying to read this XML document.
An excerpt:
<datafile xmlns:xs="[URL]" xmlns:xsi="[URL]" xsi:noNamespaceSchemaLocation="wiitdb.xsd">
<WiiTDB version="20100217113738" games="2368"/>
<game name=" Wanted: 50 Wacky Jobs (DEMO) (USA) (EN)">
<id>DHKE18</id><type/>
<region>NTSC-U</region>
[Code] .....
It just skips the "While iter.MoveNext" part of the code. I tries it with a simple XML file, and it works fine.
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Oct 7, 2011
I need to read the second-to-last line of a very large log file.
I can't read the entire thing into memory, count lines, etc etc. I can't use Filestream.Setlength because that needs readwrite access and the log will be opened by another application. And it has to be fast. However, the line ends in a cr/lf meaning the last line is actually empty. Been struggling with this all day, and its hurting my head! Not good on a Friday!
I have a function that can read the last line but can't get it to go one line up. I can get it to read characters from the end of the line, but that's not much of a help with a variable length line!
Maybe fs SeekOrigin would work as it could run backwards looking at an example from MSDN - need to get the data before the last cr/lf and end at the next one... hmmm... problem is that that example also writes the text backwards as well.
I'm monitoring the log for particular entries for issues that are causing us grief at the moment.
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Jun 18, 2011
How to update a record database table from unbound datagridview using vb.net
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Sep 1, 2011
ive a dictionary database with table having 32000 entries... ive bound it to the listbox(using binding source and dataset)... but when the program starts it hangs for 1-2 minutes in the beginning..
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Feb 7, 2011
This is a problem with MS Access, but I can't seem to find an MS Access Forum, so I'm asking it here.I have a large table of just one field. The field type is Byte. I use CTRL C and CTRL V to make a copy of the table.I then compare the Source and Destination tables and lo and behold they are different at about record number 8 million.I also tried an Append Query to append to an empty table (I haven't tried a Make Table query).But, similar corruption.The source and destination tables do not end up the same. The Record where the failure occurs varies, but it is always greater than 8 million.I tried this on MS Access 2002 and 2010 (both with an Access 2002 database).
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Jan 22, 2011
[Code] my issue is that now i need two cases, first i need a query that will return the date created and modified of the table and i also need to know if its possible to query a list of table names in the database ordered by date created but that have a certain thing in their names. for example the database contains the following tables: [Code] and what i need the query to return is the tables that contain "Data", settings and employees are for the other functions of the program. so the query should return the 4 data tables in order of date created. but i have no idea how to go about doing that in the query, does anyone know how this is done?
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Jan 9, 2010
I am developing a vb.net application in SQL server 2005 ,now i would like to import MS access database tables from a network into sql server 2005 database, using stored procedure or vb.net code without using SQL server 2005 Wizard .
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Mar 31, 2010
I need to display 3 columns and a varying amount of rows (typically around 50) in a windows form, kinda like excel. The data will likely be longer than the window, so a scroll bar will have to come into play somewhere.
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Jan 8, 2011
I am having a problem with my program that is desinged to read a 3rd party text file database. I posted previosuly about a problem inserting an item in a new row and the column was expectig a different data type. It appears that sometimes the column is being determined to be of decimal value, I dont understand why. the fields contain information such as
Col1
F123456
CLW-12321 etc....
So my column fills with
123456
12321 the letters just get chopped off
So I added MaxScanRows = 0 to my schema file and that took care of the problem
Except now several of my columns that contain Date Values are coming back
9/24/2010 00:00:00
without the setting MaxScanRows = 0
The date returned 9/24/2010
Here is the code for my schema ini file I am creating:
HTML
Dim fs As New FileStream("Schema.ini", FileMode.Create, FileAccess.Write)
Dim writer As New StreamWriter(fs)
[CODE]............
I have been trying different settings hence the dimmed out lines
Here is the code to fill the datatable:
HTML
[CODE].............
I am thinking that without the MaxScanRows = 0 setting the datatype for Col1 is being incorrectly determined
I am not sure what is happening with other columns that contain date values. Apparently If i use MaxScan Rows=0 all columns are being pulled over as string value which creates numerous problems. If I dont use maxscanrows then all columns appear to be correct except Col21 MLSNUM which is being pulled in as a decimal. Can I change that in the schema file?
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Mar 12, 2010
i am trying to create a program that connects to a database and shows table fields in listview in windows form i manage to do that but i want now to have a button to take the total of a column in a list box ,lets say from the column "money"?
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Jan 5, 2012
I am using vb.net with phpMyAdmin MySql database. While running the piece of code below, the program hangs in the for loop before the variables are assigned values from the data table(dt)...
'Check for appraisal period-----------------------------------------------------------------------
Dim sqlCheckDate As String = "SELECT * FROM tblappraisalsetting where appSetID=(select max(appSetID) from tblappraisalsetting);"
[CODE]................
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Aug 11, 2012
I am having a remote server it has INVENTORY DATABSE , and also iam having same databse in my local system. I want to populate by local database table with my Remote database table through Vb.net code by click a button. How to do this .
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Aug 30, 2009
I want to add a new table in my accdb and copy the content tfrom an existing table into the new one.
Is there an easy way to do this?
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Dec 17, 2008
I have problem, how I can import HEX file to my program in VB .NET? And I have question if I can import, What size of file I can import? I have 200MB - 400MB HEX files?? Can I import so huge files?
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Mar 13, 2012
I'm faced with a (fun, actually) data mining problem; I have raw ASCII files from instruments, and I want to move that data (~100 GB) into a database, then be able to run various algorithms determining correlations of time series, etc. I would like to write the mining algorithms in Visual Basic (.net, VS 2010 right now), and be able to do visualizations with VB code I have in hand.On the nature of the data: think of a set of several thousand devices, each recording a measurement at a given interval - so I'm talking time-series vectors.
I spent today re-acquainting myself with VB.NET's interface to (in one case) a Microsoft Access database. What used to be fairly simple - DAO I think it was - involved tables, recordsets, etc (and that would likely be fine). Now I seem to be required to have a weird variety of generally useless objects, e.g. 'adapters', 'datasets', etc. The problem is that I know exactly what I need, and all this extraneous stuff just gets in the way (certainly in coding complexity and opaqueness, and likely in efficiency as well).If any of these mechanisms gave me a kind of virtual access to the entire dataset, and let me control caching parameters, etc.it might be great, but I found nothing along those lines.
Anyway, I tried a number of different approaches, and none seemed at all aimed at what I need to do: efficiently do math on a large dataset. I can't believe I'm the first to have this problem, but I can find no useful wisdom out there. I'd be comfortable with pretty much any underlying database mechanism: MySQL, SQL Server, MS Access, but ideally something generally SQL based (I may eventually have to transition this entire system to draw from a client's SQL database, though that's not an overriding concern now). Other than that I want simplicity and efficiency. I thought my old ODBC techniques would work, and to some extent they do, though modifying tables seemed to have bizarre problems (no errors, but not modifications either).
I do have a fairly aggressive deadline to show some algorithm results, so my focus in the short term is to get something reasonable working *in* the short term - in other words, it's less important to me to pick the 'fastest' relational database than it is to pick a database that lets me focus on coding the algorithms, not working through tedious data access coding. If this db could be any smaller, I'd have tried to do it all 'in memory' at least for proving concepts; I don't want to have to learn an entire jargon and approach just to be able to retrieve data points, and write out new info (e.g., first derivatives of time series).
Perhaps I'll need to bite the bullet and just write something myself, a .dll perhaps just to save and restore large time series vectors. It seems a bit frightening to me that one would have to do this in this age, what with all the database systems out there, but I don't have much time to work through arcane interface logic.
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Dec 27, 2009
I am currently helping to write a Visual Basics program that was originally writing with access.The Original Access program has been used and modified over the past 5 years, During that time the database has gotten pretty big.The problem I am having is If I add the entire database to my data sources it creates data tables for every Table and Stored procedure even when they are not currently used in the program resulting in a 20+ minute build time just to debug.I am currently only adding Tables and Stored Procedures as i need them, so its not that much of a problem now, but as I continue to work and add tables the build time is going to go back up, and Id hate to have to wait 20+ minutes to test a small tweak I made.
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Oct 14, 2009
I'm trying to load a large CSV file into a Microsoft SQL Server Compact 3.5 database. I've tried using the following: Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser("filename.txt") MyReader.TextFieldType = FileIO.FieldType.Delimited MyReader.SetDelimiters(",")Then splitting the data with MyReader.ReadFields() etc, before using this data to add rows to a dataset in a database table in my project. However, my CSV files are very large, at above 9.5 million rows, and this takes forever, if the computer doesn't crash also. Does anyone have a better idea for what to do? I would like the CSV file to be loaded into the database table, to enable me to sort it, and undertake some querys and maths. The CSV data structure is:2,193,761.40000000000012,43,1510.22,8,1929.60000000000012,22,2564.52,22,2791.70000000000032,19,2971.6000000000004
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Apr 9, 2010
Details: I want to compare these above two table1 and 2 . The unmatched records should be save in a new table .
objectives
1 Should take input the table and fields we want to match each other.
2 Then after searching or reading the record from table and selected fields save the unmatch records in a new table
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Feb 7, 2011
I am currently trying to create a program to list a large group of numbers for me. My final goal is to have every 2, 3, 4, ..., and 9 digit number containing only "1" "2" and "3". I thought I would go about this by using the following VB.NET program and then copying it into a text editor, and using find & replace to eliminate all other numbers.
Public Class Form1
Dim Start As Integer = 333333333
Dim Counter As Integer = 333333333
[Code].....
it fails due to the massive amount of processing that needs to take place. However, adding the intervals requires a great deal of time for each number to be displayed without any crashes.
Is there some way (in VB.NEt or another language) to get the number list I want in a short (an hour or less) amount of time?
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Feb 8, 2010
[code].....
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Feb 21, 2012
The Adventureworks database is used extensively for tutorials in Visual Basic applications. This has many tables that can be bound to a solution. What I would like to know is, when using such a large database with many tables and using lots of them, is it better to construct your program with a number of projects all under one solution or to put everything into a single project. If you use a number of projects, what is the syntax for accessing each module from a menu strip in your main form? I know how to do this in a single project - all you do is Form(x).show. In Adventureworks, you have a table for Employees that could be put into a single project with a number of forms - one for data entry, one for displaying all of the employees, a filter to a single employee, etc., etc.
If two small projects rely on each other for some reason, again the syntax for linking them could be an issue. Would it be better to combine them into a single project? My reason for asking is that I would feel safer if I created an application on a project by project basis and then brought them all together in one solution. This way they can be tested individually and then linked together where necessary. Making a disastrous mistake in one then only requires a small re-write rather than the headache caused by a total crash of the whole solution. I would like to know which option professional developers take. I am using Visual Studio 2008 Professional and SQL 2005 Express
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Oct 14, 2011
I've build a large program with many references. F.e.:
System.Data.DataSetExtensions
System.Linq.Dynamic
I've to write a Dynamic Linq Expression: [URL]
In my case: Dim query As IEnumerable = ds.Sales.Where(strWhere)
But with System.Data.DataSetExtensions Where is misinterpreted. The compiler expects (Datarow, Integer, Boolean). If I delete System.Data.DataSetExtensions everything is ok with this expression, but I get many other errors, so I need this reference. What can I do that the Where is interpreted correctly?
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Sep 22, 2011
I have to export the data from the database to .txt file, I have the code below that does export it to .txt file but I'm having problems with this code because the data that I'm exporting is about 5 000000 records, it is quite slow and sometimes the pc can't handle it and stops the exporting.
Dim saveFile As New SaveFileDialog
If saveFile.ShowDialog = Windows.Forms.DialogResult.OK Then
command = New SqlCommand
[Code]....
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Mar 15, 2008
i am using visual studio 2005 and database sql server 2000. i want to read table of database and readed data insert in temporary table again update that inserted record.
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