I have several installations of my Linq-to-Sql app running in the field. Now I've created a new version, which adds a new column to a certain table. I've added this column in the dbml file. But when updating the installation, I want to preserve the existing database. How to handle this? Linq-to-SQL doesn't seem to like this inconsistency.Is there an easy way to update the existing database using my new dbml file?
View 1 RepliesI'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.
what's the best way to handle the updates to the database.For example i have one datagridview that's binded to a datatable (with two fields, id auto incremented and a varchar). The user can do all the operations Insert, Update, Delete.If i insert one row (only the text) and call the update method to save the changes to the database, and after that remove the same row and call the update method the adapter will throw a exception because it didn't update the datatable with the value of the id. So the best way to do this is always calling the fill method after every update?
View 22 RepliesI am planning to write an application which will be available in 2 versions. one free and the other one paid. The only difference is that in free versions only a maximum of 2 DB entries are allowed. but its unlimited in paid version
View 3 RepliesHow to handle the return value of the sql query and store in the database?
View 1 RepliesI am planning to write an application which will be available in 2 versions. one free and the other one paid.The only difference is that in free versions only a maximum of 2 DB entries are allowed. but its unlimited in paid version.DB does not have more than 1 table with 5/6 fields.I am planning to use xml for free version and SQLite for paid version. Is this ok? are there any other options?
View 1 Repliesusing the sql server management studio we can create users to access the database. so we can grant several privileges as well as revoke some. so i want to create a login form with those user's. how to do it. is there any other way [code] in the connection i have to mention the user also.. is it possible. if its possible.
View 1 RepliesWhats the best way to handle the connection to a db when it's accessed often? I have an app where the user selects an item from a drop down list(call to the db) and then a picture of the item is returned along with it's relevant information(another call to the db). Small application but basically every action results in a call to the database. Should i just be filling like a global dataset and then accessing the information from there(if thats possible)? The database is stored locally(currently an Access Db but will be SQL in the future)
View 3 RepliesI have run into this problem a few times and have never come up with a good answer. I figure others must have dealt with this already.I have a datareader returned from the database and I want to use the values therein however values may or may not contain NULL. I would like to have a unction that takes in the value from the datareader and returns the value if it is not NULL and blank space if it is NULL.The problem I have is that the data-type of the variable I am testing is variable. It can be a String, and Integer or a DateTime. Can anyone suggest a simple way to test the value and then return the original value (as same data-type if possible) or something else if it is NULL
View 5 RepliesI am reading dates from a table in a database to display in a DataGridView column that is formatted as a date. The problem is that when the value is null in the database my program errors out because it cant convert the value to a date. How do you guys handle this? *Edit: If I set the value of my date variable to "Nothing" it displays as "1/1/0001" in my DataGridView, and I would like the cell to be empty for the null dates.
View 24 RepliesI'm trying to handle DBNull exception while reading data from database. It's my code:
...
Dim SQLRDAs SqlDataReader
...
val1= GetStringFromDB(Trim(SQLRD("Name")))
val2= GetStringFromDB(Trim(SQLRD("Level")))
[Code]...
But still I get Conversion from type 'DBNull' to type 'String' is not valid. error.
I wrote an application to handle a joystick with directinput. It works fine if it uses the handle of the main window but it doesnt happen the same if the handle is the one of the component that contains the joystick's operation.
I mean:
main form handle: 15
component handle (which is inside the window and the joystick needs the focus of this component to work): 25
It always work if the handle i initilizate the device is the main form (15).How can i use only the handle of the component?
In CRUD application development we have to face the issues with concurencies in Ids such as Generate and display UNique EmployeeIDs on forms. Currently i'm writting .DLL file that has a class that will handle concurrencies.
But i'm puzziled with the Question, is this concurrency handle is part of the software developer or Database developer?
Possible Duplicate: Can .NET intercept and change css files?
I have configured IIS6 to get .NET to handle css files.I did the following steps
Launch IIS Manager Right-click on Default Web Site Click on the Home Directory tab Under Application Settings click on Configuration.Add a new association for .css and map it to .NET executable:
C:WINDOWSMicrosoft.NETFrameworkv2.0.50727aspnet_isapi.dll
How can I check if this is working, i.e. I want to change the default style of a page depending on the url, i.e. if the referer url is http://intranet, it should continue to use the old existing style style1.css, if the referer url is http://intranetv2, it should use the new style style2.css.
I can't get a handle on the syntax. Can anyone give me a simple demo?
View 3 RepliesI am trying to get a handle on the correct way and easiest way to do things. By easiest I am not talking about being lazy just accessing and modifying later on. I have started using my own classes and such but I have a few questions. Sometimes I want to create a control on the fly through code instead of using the designer. Should I create this control in the main form file or in a separate class? If I make it in another class it seems harder to access later on. Then again if I dont know that the control is going to be created(user clicks a button to add a control) how can I access it? Also it seems alot harder to access certain things when it is in another class. For example if I create a new window in a class and then want to check if it is there or not it is alot harder to do.
View 5 RepliesAre there anyone know how to get the handle of a standard Combobox using API?
View 3 RepliesHow do i get the handle of a NotifyIcon?
View 4 RepliesI need the intPtr for a form. Control.FromHandle(control) gives me the control from a handle, but I need the opposite--get the handle from a control. How do I do this?
View 2 RepliesI need to get the handle of a control as an IntPtr to pass to a screen capture class in vb.Net 3.0. Tried this but get an invalid handle exception.
Dim hwnd As IntPtr = Runtime.InteropServices.GCHandle.Alloc(CanvasMap)
I am trying to create a small utility that tracks desktop usage in detail, to the level of individual text boxes etc.... in other applications. However, it is proving quite tricky. I thought I had it nailed using the Windows api. The below code is just a snipet of the code but essentially it provides me the handle of the control that the mouse is over. I thought from here, it would be easy to to the same thing but to provide the handle of the control that the cursor was actually clicked on, for example, if someone is filling in a text box in an application, they would not necessarily move the mouse to get to the text box, they may tab to it. Does anyone know if there is a way to get the handle of the control that is in use?
Private Sub Timer1_Tick(sender As Object, e As System.EventArgs) Handles Timer1.Tick
Dim ptx As Integer = Cursor.Position.X
Dim pty As Integer = Cursor.Position.Y
[code]....
I need to get the handle of a window with a specific name from my vb.net application. The form isn't actually from my application.
View 1 RepliesI am going mad about getting the process id for one existing handle on VB2008.I tried both GetWindowThreadProcessId(hwnd, pid) and GetProcessId(hwnd), while PID always returns 0, I tried the same things in VBA of Excel, it works perfect, so this is somewhat weird,
View 8 RepliesI have referred DLL in my project. I have to handle the event from DLL in VB.net code. I guess we can do using WithEvents. Can you give me complete picture?
View 2 RepliesI am having a SP run in my VB application every 10 seconds to check for any new rows that have been inserted to the database since the last check. What is the best way to do this? Most likely it will be 0 or 1 rows, but I am afraid at random times it maybe more than 1 and so I thought I would fill it in a DataSet, but I came in here to see if there are any other better ways. If dataset is the best way, how do I do a For Each Row in the dataset to process some VB code for each row?
View 20 RepliesI read stuff from a SQL DB (database) using a data set. Some of the columns in the DB may contain NULL. I want to go through the table in the dataset and print, or use in some other way, the data. But when I try to use a certain data that corresponds to a NULL in the DB my program crashes.How can I detect - in the dataset - that it has no value and that I shouldn't try to use it?
Private Sub Get�rendenLista(ByVal e As System.EventArgs)
'----------------------------------------------------------------------
' This function fetches a list of �rende from the table �rende
'----------------------------------------------------------------------
Dim cno As New SqlConnection
[code]....
The short program below runs just fine when it is the only item on a form. However, when I put it into the ItemInsertTemplate of a ListView control, I get the following message:
Handles clause requires a WithEvents variable defined in the containing type or one of its base types
Line 30: Protected Sub btnDate_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnDate.Click
The error message identifies Line 30 as the problem.I get the same message for Sub clnEvent_SelectionChanged How do I correct this?
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="clnControl.aspx.vb" Inherits="clnControl" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
[code].....
Does anybody know if there is an API function that would let me cancel a print job.I already know how to get a handle to a printer and how to enumerate the print jobs using the printer handle.
View 1 Replieshow to make VB handle my associated files.I made a program that opens fine when from the EXE file. But however, when I try to open it from the associated file, it behaves the same way as if opened from the EXE.So, where (in what method?) do I tell VB how to handle those files?
View 8 RepliesI am retrieving a database object and trying to set the values of the object's fields to various textboxes in my vb.net page
View 3 Replies