VS 2008 Select From Excel Returning Null Data Instead Of Real Data?
Dec 22, 2010
I typed this question once already, hit preview, and somehow never got the preview and lost what I typed. It has been that kind of a day.So here is my quick overview then I am going shopping. I am using OLE DB to select from an excel spreadsheet. It has over 15000 rows and 33 columns. Sometimes even when a cell is not null, it is returning a null value. If I just do a "select * where [termination date] is not null", for example, it will return no rows even though I can see with my own eyes that sometimes termination date is not null.
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Mar 10, 2010
I have a problem with importing an excel into a data grid.
Here is my code:
Try
Dim _Obj As New ExcelConnection.ExcelConnection
_Obj.ImportAttendence("c:Info_pc.xls", DataGrid1)
Catch ex As Exception
End Try
In the excel i have numers and text and "Service Pack", "Processor Speed" and "Numar procesoare(Number of processors)" and the values for these are numers. in the data grid when i import the excel those values doesn't appear, i receive the value "null".
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Jun 5, 2012
i have a program that function as a DAQ System.i have input channel to gather information from sensors. The reading of each sensor such as voltage, current and temperature are displayed in the textbook. As we all know, DAQ system is involve taking data real-time measurement.My problem is:
1. how to update each row automatically as time goes on. the value in the textbook is updated by each second.Below figure shows how the excel can be written automatically row by row, as time ticking for a sec. this update will stop as the timer stop.
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Nov 24, 2009
I am working on a project that is able to display real time data from sensors from micro-controller. I am able to do so by sending the data through the serial port and then use vb 2005 to show the data. However, I want to save those data from vb 2005 to excel. How am I able to do it ? I am able to use vb to insert data to excel step by step, cell by cell using the following codes.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim oExcel As Object
Dim oBook As Object
Dim oSheet As Object
[code]....
Lets say TextBox1.Text and TextBox2.Text is my real time data. How do I save it to the excel sheet displaying the data in cell A2, A3, A4 when the time goes by. Eg. If I want to save TextBox1.Text to excel it would be, the data in the 1st seconds in cell A2, data in the 2nd seconds in A3, 3rd seconds A4, 4th seconds in A5, A6 and so on...
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Feb 16, 2011
Having trouble importing a value from a .csv file to a .csv file. This this done because data needs to be massaged and the data file renamed. This is a user interface. Do not want to have the user touch the .csv in any way except upload to the application so the applicaiton can do manipulation. Either way here is the issue.
There is a column in the original .csv file that contains a zip code. The first row of the .csv has a value of 17003 in the zip code column. In the second row of the .csv the zip code column has a value of 11746-9984. The value in the zip code column from the second row always comes back as a Null value. My guess is that the OleDbDataAdapter is defining some kind of Schema. Again, the first row containing the zip code column probably insists the value must be numeric. When the data table field is established it probably gets defined as numeric. If that is true and the second row of the .csv zip code column is not numeric that must cause the zip code value to be Null.[code]...
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Jan 5, 2012
I m into automation development of FMCG products using Micro-controllers. I get real time data Barcode 2D from TCP/IP connection. My task is to compare the result do some Computation with them and Store the incoming Barcode and results into a Excel sheet in a folder. I m successful with the basic working. Am currently working at slow speed of 1 barcode(22 char info) per second from the TCP/IP data (barcode scanner). Now, comes the real issue. I need to process atleast 5 barcodes per sec ( <200ms per process). I m partially successful with 3 Barcode per second(300 ms per process). so, thats like 300ms per processing. I need to achieve less than 200ms for entire processing. I have used threads and timers. but I m unable to achieve. Seems like storing in Excel takes more than 250ms. Since i come from micro controllers background 1msec is a lotta time to process for me. I m not sure how much time does it take and trust me i find it difficult to guage the time here.
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Apr 3, 2012
My code seems to behave a way I don't understand. Sometimes it returns null as expected and sometimes it returns a value when its supposed to be null. How can someone explain this? Here is the code that selects from access and displays the result in a messagebox:
cmd5.Connection = cnn
cmd5.CommandText = "SELECT receipt_num " & _
"FROM brought_coffee, farmer where crop_year= " & yr & " and " & _
"brought_date=#" & dtt & "# and farmer_centre='" & ctr & _
[code]....
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Jun 22, 2010
I have an Excel based algo-trading app that needs to take in lots of real-time data, and make trading decisions based on the calculations driven by the data. It is not one of those "read-only" stock ticker kinda spreadsheets.I created a COM object with VB.NET that runs in its own thread space which collects data from a socket, and when the data is read it raises an Event with data attached. In Excel VBA, the event handler parses the data, puts them to the right places on the spreadsheet to feed calculations (so far it sounds like a stock ticker app), and then, based on the results of the various calculations it does something.The problem is that when the user starts to click around the spreadsheet while there is large amount of data coming, the event handler's cell updating breaks apart. If the app is left alone without user action, it stands well. My frustration comes from not understanding what happens to the main thread when a user clicks around. Either the event handler blocks the user action, or the user action blocks the event handler (under which case I will put in some queuing facility). But I just don't see how user action can break the code (like causing VBA to stop executing)
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Mar 29, 2012
Using VB.Net, I am reading an Excel spreadsheet does anyone know what might cause a cell to be read as VBNull when it contains data?the cell clearly contains data. and what is extra weird is all the same cells in the rows before and after the bad one have the little green triangle in the upper left corner, indicating an error - but they all read fine the cell that reads as NULL is the cell in row 4 above
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Mar 12, 2012
Somebody know how I can read data from a device connected rs232?Im write it in a text box?
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May 25, 2012
I have been trying to find and/or think up a way for data to automatically update a data table.I have a log that shows all the customers that came in today with various information. There could be twenty or thirty employees adding to this log or updating or doing things with that customer. This information is in a Data Table on a ASPX page in Visual Studio 2010 that the code is binded in the aspx.vb page that is calling a page in my APP_CODE database file that calls a query in my Database to get the information.My question is could someones actions on a different computer make my computer refresh or to re-bind that data.I have thought of some kind of timer/counter maybe that looks to see if the count of the log is different.
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May 2, 2009
I am busy with a VB2008 EXPRESS program that reads is data via a network cable. Saving the data on the same computer as my program is not a problem, but I must also make this data available to other users in the network and update their screens in real time. In other words I need a COPY of my running program on each networked computer when requested by the user in the network. I have looked at SQL, XML pages and inheritance. But I am confused, what is the best way???
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Sep 29, 2011
I have a Business Logic Layer that contains function that return datatables. I'm writing a function that will return just the records that begin with the string passed in. this is what I've come up with so far:
Public Function FetchBusinessAreas(ByVal area As String) As List(Of BusinessArea)
Dim AreasList As New List(Of BusinessArea)
Dim dt As DataTable
[code].....
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Feb 4, 2011
I am still a newbie with VB. If I return a number the if statement works fine, with opening the new form and updating it as needed. Id the if statement returns a Null from the database it crashes.
[code]...
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May 4, 2012
I am trying to read data from an excel sheet but there is an exception saying that no value given for one or more required parameters which I don't understand. Here is my code upto where the error is pointing to:
Dim MyConnection As System.Data.OleDb.OleDbConnection
Dim DtSet As System.Data.DataSet
Dim MyCommand As System.Data.OleDb.OleDbDataAdapter
[code]....
The exception points to that last line MyCommand.Fill(DtSet) which shows me that there is a problem with my select statement. Previously my code reads the data and displays it without the where clause in the select but when I added the where statement so that it can only read data from rows where the column I has a value equal to 176, it instead gives an exception that shows that some required parameter is missing a value?
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Jun 22, 2010
I can't get past this error in my loop through the data reader specifically dr(12). I tried adding .To String but that doesn't seem to work either. Can someone help me with what need to do so it can read even if there is a Null value. My code is below:
While objDataReader.Read()
'Set up DataRow object
Dim dr As DataRow = DataReaderTable.NewRow
[code].....
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Jan 14, 2009
my table is:
CREATE TABLE [dbo].[VarianceReport](
[ID] [int] IDENTITY(1,1) NOT NULL,
[FN] [nvarchar](50) NOT NULL,
[Fdate] [nvarchar](50) NOT NULL,
[code]....
But inserted null value when all textbox is temp!?!How to resolve this problem and best way for this action?
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Jan 22, 2011
I am trying to retrieve the data from EXCEL 2003 spreadsheet from row 8 onwards because from Row 1 to Row 7 the row is merged columns from A1 to K1, A2 to K2, A3 to K3, A4 to K4, A5 to K5, A6 to K6, A7 to K7.
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Oct 7, 2009
I am trying to read excel data (Excel 2007 SP1, on Windows XP SP3) with visual basic .net 2008 (VB 9.0 SP1). I have tried several attempts and whatever I do I am getting the following error message: System.Runtime.InteropServices.COMException was unhandled ErrorCode=-2147319784 Message="Altes Format oder ungültige Typbibliothek. (Exception from HRESULT: 0x80028018 (TYPE_E_INVDATAREAD))" Source="Microsoft.Office.Interop.Excel" Message="Altes Format oder ungültige Typbibliothek." Translated: Old format or unknown type libraryI have added the reference "Microsoft Excel 12.0 Object Library" to my project. I am assuming that I might have to add a different or an additional reference, but I do not have any clue which one to use. List of things I have already done:- Searched other forums- Altered the language settings- Tried it on an other Computer (Win XP SP3, Excel 2007, Visual Basic 2008 Express)- Ran the diagnostics tool in Excel - Updated all updates etc...- Reinstalled Visual BasicI really do not have any clue why it should not work?
Imports excel = Microsoft.Office.Interop.Excel
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim xlsApp As excel.Application
[code]....
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Nov 2, 2009
I am having a problem trying to get a real time back from this code.
Code:
Public Sub Time()
Dim StartTime As TimeSpan = TimeSpan.Parse(txtStart.Text)
Dim EndTime As TimeSpan = TimeSpan.Parse(txtEnd.Text)
[Code]....
I am using a start time of 09:25 and an end time of 10:15 to test this with. I would like it to return 50, as 50 real world minutes went by. I am getting -1331385.
This is mostly someone else's code from a different forum. I have never used a TimeSpan method before and they keep telling me it works "like what I asked for".
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Jan 14, 2009
I'm working on a windows forms application (.NET 4.0).My form contains a 'Fast Line' chart using the Microsoft chart control included in VS2010.The chart gets filled with about 20,000 datapoints.My application then starts receiving market data from a server via DDE (Dynamic Data Exchange) in real-time and adds it the chart.
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Sep 19, 2010
I have to send a sequence of video frames over UDP as fast and real-time as possible and while I got the basics working, I am running into all sorts of difficulties. Some of my goals:Data will normally be sent over dial-up (hence UDP instead of TCP), but also needs to support fast Ethernet.It's OK to occasionally drop frames (hence UDP instead of TCP).Need low latency. The frame the remote receives should be one that was recently sent (no more than a few frames waiting in buffers).I need to be able to detect the effective bandwidth so that I can compress the frames more or less to keep frame rate up.I break up frame data into one or more datagrams of about 500 bytes and each has a sequence number and other info. The receiver reassembles the entire frame and detects if any datagrams are missing.If the receiver detects more than a certain percentage of dropped frames (e.g. 50% over the last 10 frames), I send a TCP message to the sender to slow down by 50%. Sender than slowly increases speed by 5% each subsequent frame.Using System.Net.Sockets.UdpClient to send and receive the data.I have a separate TCP channel used for control messages back to sender.My main difficulty right now is detecting the effective bandwidth and dealing with latency, especially over dial-up (max ~4,000 bytes/sec). For example, if I try to send 100,000 bytes/second using TcpClient.Send() they ALL seem to arrive (no dropped datagrams) but with large latency by the time last datagram arrives. I think the TcpClient.Send() function is blocking until the buffer is able to send which messes up my current algorithm.
Can anybody point me to any sources of information for how to:Detect actual bandwidth over UDP.A better algorithm for dynamically adjusting bandwidth to suit the available pipe.Send data smoothly at the desired bandwidth.A way to detect and keep latency down to a minimum.I have been spinning my wheels over the last week and every time I solve one problem it seems another rears up is head.
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Jan 11, 2012
are there any ways that i can extract my data from database and display it into my listbox in real-time? which means that whatever is updated in my database must immediately be inserted into the listbox without the need of refreshing or pressing any buttons. Immediate display.
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Jun 24, 2012
methods/procedures for sending real time data from a VB.net app to a web server (asp.net) for real time display. My question relates to the best method to send the data from the desktop app and the best way to receive and handle the data on the server. I'm not asking for sample code, just some idea of what methods to research. I am currently using a text file upload method but I'm sure there is a more efficient way of achieving this.
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Jun 30, 2011
I got the System.Data.DataRowView when I tried to select the data from sql database. These are my code:
......
myCommand = New SqlCommand("SELECT FirstName +' '+ LastName FROM tblVisitor", myConnection)
myAdapter = New SqlDataAdapter(myCommand)
[Code].....
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Jun 3, 2011
i hve create combobox & text box and add database source to my project...i know how to binding data or load data to combobox using SELECT query..but can i change SELECT to INSERT query cz i wont when i type data into textbox,data will be in database...second..can i binding without add database to project..i mean mydatabase in debug folder..i hve problem binding data if database is not in myproject..
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Mar 9, 2012
I'm using EF version 4.1, and would like to have the data from the database in realtime, i.e. if you open the application it detects if there is new data in the database, and update the above it! is It possible to do this? I am using EF 4.1 code first time
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Sep 29, 2011
I have a driver for the device and I already have it integrated into an application.
It is a Human Input Device with buttons.
Controlling the device is not the issue nor is receiving button presses.
I want to retrieve the actual data that is being sent from the device to the computer and from the computer to the device.
I have seen a lot of hardware approaches but not any software approaches(that work right).
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May 25, 2010
Basically I have a program that receives real time data from microcontroller and displays it in a text box. What I would now like to do is to store the values received into a table that can be viewed when the receive program finishes. However I still want the values displayed as they are received in addition to being stored in a table of some sort.
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Apr 11, 2011
i want 2 select data from data gridview and want retrive that data into another form in to the textbox ...is it possible ? i 'm doing like this for that
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.[code...]
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