Error : The Data Reader Has Been Used Before It Is Assigned A Value
Oct 18, 2010
I'm having a bit of trouble developing my login page! Currently i have 2 text boxes which a user can input a username and password. My form should then check whether this data relates to the data in the database and either grant or deny access.The error i'm receiving occurs at the line "If theDataReader.HasRows Then"It says 'The data reader has been used before it is assigned a value"
Here is my code:
Imports
System.Data.SqlClient
Partial
[code]....
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Sep 14, 2009
When I use this code it gives a syntax error near sqlStatement.ExecuteReader()[code]...
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Aug 18, 2009
I have a show button.The user will select a data from the dropdown list of the combo and on clicking the show button the corresponding data will be fetched from the database and will be shown in the corresponding fields.So I did this
Private Sub Show_Btn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Show_Btn.Click
Using connection As New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0;Data Source=BankAccount.mdb")
connection.Open()
Dim command As New OleDbCommand("Select * from BankAccount", connection)
Dim reader As OleDbDataReader = command.ExecuteReader()
[Code]...
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Jan 28, 2011
I am new to VB. I was trying to insert a record into access database with data reader. I was getting OVERFLOW error at runtime. My understanding is that overflow error occurs when we assign values that to variables that exceeds the maximum size of the data type.
Following is my code
Private Sub InsertRecord(ByVal CustomerID As Integer)
Dim RowArray() As String = Split(Me.lblRow.Text)
Dim intPrice As Integer
Dim decTotalPrice As Decimal
Dim mySQL As String
[Code] .....
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Mar 30, 2008
My program does not build because of the following error. I understand the part about a null value, to a degree, but the assigned value I'm not sure about. by clarifying it's meaning. To me, there's nothing obvious about why it's not working.
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Jul 20, 2011
I have made a application that detects already saved hotkeys and data assigned to them, so now whenever I press the hotkey to send the assigned data to active window it does sends the data to active but it won't stop sending data...I am calling my function that reads data from the database in timer device and the function that detects the hotkey...
Here is my code
Private Sub Hot_Checker_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Hot_Checker.Tick
gKey.CheckBox()
'is the object that calls the function to check the pressed hotkey
keyTemp = gKey.getHkey()
[Code] .....
trying to find the main error that is causing this to happen, after pressing the hotkey my app won't stop sending the data to the active window. My app should wait for the next hotkey press rather than sending data.
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Jan 23, 2012
I'm working on a small project, and ran into an issue. I'm creating new picture boxes on a form to represent a control. My question is how would I code a click event for an object that isn't on the forum initially? Also, how can I keep track of which object is assigned to which data in an array? (IE picturebox 0 is array(0) of data)
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Sep 9, 2009
how to pull/fetch data from SQL DB using Data Reader and loding to XML file.
After that I will have write code to read XML file and download to CSV file and Test files.
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Mar 21, 2010
can data reader be used as a data source for a grid control?
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Jun 15, 2009
I have a data reader "dr " that returns a row fo data, Assume dr returns values of 6 columns I need to create an instance of DatarRow using "dr", so that later I can create a collection of datarow objects that I will be adding to a table. However, how do I create a DataRow using dr object?
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Feb 4, 2011
I'm having some issues with my MSR after it reads that data. I can find the device and read the data without any issues. When I try to do anything except message box the data, the code hangs without erroring out. What I'm trying to accomplish is that on each swipe of the MSR, a MDI child form is created. I get nothing when I try to create a new child or a new form from the DataEvent of the MSR.[code]
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Oct 7, 2011
Currently i am using this code
[Code]...
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Jul 24, 2010
How do I really use data reader in vb.net. I'm using odbc to connect mysql and vb.net. Function I declared on a module:
Public Function form2search(ByVal drugname As String) As OdbcDataReader
cmd.CommandText = "SELECT * FROM drug WHERE Drug_name LIKE'%" & drugname & "' "
Return cmd.ExecuteReader
End Function
[Code] .....
I see a result, but it only loads the first item on the database. I've put this code in the text_changed event. What's the proper way of doing this? And what's wrong with the 2nd code, why is it only loading the first data. As you can see the con is the module where I declared the function. Then I created an object of it in the form.
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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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May 18, 2011
I want to launch a application called Foxit Reader pdf Reader .I know System.Diagnostics.Process.Start(path) can do it but . Requirements are Foxit Reader should be installed on machine.Now if it is installed how to serarch for the path of its Executable to provide the parameter as I can not hardcode the path for different machines.
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Aug 10, 2009
I am using SQl data reader to get value from SQL database.Language VB.NET.After getting data into reader, i run a while loop
While reader.Read
If reader.HasRows() Then
/* Proessing of data *[code]....
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Jul 1, 2009
Are there any examples on how to implement a datareader? I have try copying the code from MSDN but;--"Dim reader as SQLDataReader = command. ExecuteReader()"Where it is placed? As a declariton at the beggining of a form? or as as VB resource?and then how those it bind a to a dataGridView? How can I loop through each rows once is bind to use the contents of the column/row?I can perform the above function easly inside of MS Access using VBA. I have gone through various books from WROX but none of them show a clear example or the code is obsolete.
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Oct 15, 2010
I'm switching over from PHP to vb.net. And some of the concepts are a bit different. Mainly I struggle with concepts and keywords, so it hard to look stuff up. Currently I'm creating a dashboard and needs to run a lot of different sql queries. But I see where I should be able to minimize my code. But things that I have tired don't work. Example below of two chunks of code that I should be able to put in some type of loop and increment a value for my sqlstring and textbox output.
[Code]...
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May 27, 2010
i have create a procedure to return data reader value, but it not return and returning null reference?
'Public Shared Sub GetData(ByVal Tablename As String, ByVal queryfield As String, ByVal Id As String, ByVal lblmsg As Label)
' Try
' Dim Cons As OleDb.OleDbConnection = DBHelper.GetConnection
' Dim Com As OleDb.OleDbCommand = New OleDb.OleDbCommand("Select * FROM [" & Tablename & "] WHERE [" & queryfield & "]=" & Val(Id), Cons)
[code]....
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Aug 1, 2009
i wanted to ask how to make picturebox1 ,to which functions are already assigned, perform the same function as picturebox2 ,to which no functions are assigned.For example:I have already made picturebox1 and have assigned it alot of function like when play button is pressed then picturebox1.visible = true and when we press pause button picturebox1.visible = false. So now i decided to make a theme and have to remove the picturebox1 and want to allow the picturebox2 to havefunction of picturebox1.But when i disable the theme the function of picturebox1 should go back to picturebox1.
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Feb 18, 2011
I'm reading a xml document via a text reader, this is my code
[Code]...
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Feb 13, 2010
I'm using VB 2008 to received data from serial port (RFID Reader). below is the coding that i used. the problem's, the RFID Tag number does not display on the textboxt. [code]....
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Jun 21, 2010
How can i check if some value exists in the data reader
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Aug 16, 2010
I have the first form and create 5 checkboxes which are connected to my db. Whichever checkbox is checked and the value will be inserted into the db (value: 1; data type: tinyint).And now, the second form will pull out the data base on the which checkbox is checked when the button is clicked. But for somehow i got stucked at the following code.
The first form:
Dim nValue As Boolean
If chkbox5.Checked = True Then
nValue = 1
[code].....
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Oct 15, 2010
I have a column ("Notes") in a sqlexpress database as nvarchar(1000). It will basically hold notes. It is pulled froma richtextbox control.[code]...
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Jun 17, 2010
How to populate a combo box using SQL Data Reader in DAL, BAL and UI atmosphere. Please find below my code snippets and correct me if I'm wrong anywhere in this code.
'DAL Code
Public Function PopulateComboBox() As SqlDataReader
_cnCon = New SqlConnection(_conString)
_cnCon.Open()
[Code]....
What should be the UI code? Is the code specified in DAL and BAL is correct? I knoiw how to fill the combo box with values from SQL Data Reader. But I dont know how this can be done in 3 Tier application.
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Oct 18, 2009
I have a table in my database and I want to return the rows in a data reader and retrieve them in variables. I can do that well but I can only return the last record. The reader doesn't process all the rows.
Try
Dim myconecction As String
myconecction = My.Settings.DataSource
[Code]......
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Jun 15, 2010
I'm using the following function to generate a list of users connected to a selected database. How would I change this to a single line for multiple identical results?For example: "sa (3) - MYCOMPUTER" rather than listing "sa - MYCOMPUTER" three times?
Function ConnectedUsers(ByVal SelectedDatabase As String, ByVal SelectedInstance As String)
Dim myCommand As SqlCommand
Dim dr As SqlDataReader
[code]....
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Dec 30, 2008
I've set up a stream reader to get data from a serial file, functionality for that is already set up.
My problem is that the program seems to be missing out every other line of code in the file, which kinda defeats the point of a serial file. [code]...
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Feb 28, 2012
I am having an issue with both Adobe Reader and FoxIt Reader when trying to print a PDF document. Both issues are different but a solution to either one will allow me to fix my issue.The issue I am having with Adobe Reader when trying to print using the following code is that it will not print it to the network printer I specify but just the default printer.
Dim AdobeReader As New Process
AdobeReader.StartInfo.CreateNoWindow = False
AdobeReader.StartInfo.Verb = "print"
[code].....
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