Way To Clear A Datatable
Feb 12, 2009
I am filling a datatable and after storing the values I want in two variables I want to clear my datatable or erase it.[code]...
As the above code is in a function (and I am calling this function many times) it causes me problems. The variables id and entitycode store the first values (the first time I run the function) and then it always use them. That's why I want after storing the values in variables to also clear the datatable or even erase it (and rebuild it when I rerun the function).
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Feb 28, 2009
I have a form with a tabcontrol. The tabcontrol has two pages. The first has a form that the user fills and clicks on a button to store the values on a SQL database. The second has a combobox that is filled on the click event of the button with the values of a field of a database table. I put the filling of the combobox on the button's click event in order to display the new (stored) value. The problem is that if the user repeats the above procedure then the displayed values (in the combobox) are doubled, tripled etc. I tried to clear the datatable that I am creating and filling after assigning its values in the combobox but it doesn't work. [Code]
This code is on the button's click event. But it returns an empty combobox. I can't understand why is doing this as first I am filling the combobox with the values from the datatable and then I clear it. Any suggestions for solving the above problem?
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Jun 11, 2010
I am working on a vb.net app for a handheld using Windows CE and I have a few columns of data loaded in a datatable from a text data file. Some of the records can have duplicate Account IDs so I cannot use a primary key. What I want to do is take an Account ID entered and filter on just those records. I need to loop through all records with this Account ID, make updates to any of them and then clear the filter.
how to set a filter on a column based on a given string such as an account number? And loop through these records? Can I modify the records at that time?
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Feb 18, 2010
I want to understand a situation; it's related to datatable clear().I have a code that populate a typed datatable from Excel in a separate thread using a backgroundworker. This works well, the table is filled and I can see the data. Now, I want to clear the data from table and restart the import. The operation is ten times slower than the first time. My datatable variable is declared like this:Private dt as new DataTable - not a local variableI want that all subs from class to be able to use the table, that's the reason I declared the table as private. What I want is to be able to create a new instance of dt (or clear allocated memory) - maybe this is the reason for slowdown.
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Nov 28, 2009
I'm trying to clear a DataTable and repopulate it, and the DataTable is bound to a DataGridView. Here's the code I'm executing:
vb.net
Using reader As MySqlDataReader = myCommand.ExecuteReader
SyncLock tableLock
running.Clear()
[Code]...
If you want to replace this standard messagebox, handle the DataError-expection
When debugging, there is no break in the code. The messagebox just pops up without showing me exaclty where the error is located.
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Dec 13, 2011
this is currently my code to clear my 5 textboxes
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
TextBox1.Clear()
TextBox2.Clear()
TextBox3.Clear()
TextBox4.Clear()
TextBox5.Clear()
End Sub
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May 17, 2009
I have a timer that runs every time by itself, and for the code the runs in it I would like to have it clear the dataset before it does anything, the timer runs every 10 seconds, so I tried to do dataset.clear but it would crash if the dataset had no values
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Jun 23, 2011
in hyper teriminal when i press "ctrl+L" is to clear terminal screen how to write the code in vb.net? Hyperterminal is connecting to serial comport.when i try this it work and return line on debug
serialport.writeline ("at+cmgl=1")
i try this but not work and it still show some lines on debug
serialport.writeline (vbcrtl +"L")
serialport.WriteLine("vbCrLf + l")
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Sep 20, 2010
way to clear textboxes in VB.Net and what is the difference between the two methods? I have also seen people be critical of folk using clear objects on their forms and i can see why but in this case, i am only learning.
txtbox1.Clear()
or
txtbox1.Text = ""
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Jul 15, 2009
wan to ask about anyone know the code about how to clear all the data inside the data grid view without clear the binding source...
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Feb 28, 2011
In my winform program (in vb.net) I wrote:
Dim dt As New DataTable
'Get data from DB into dt
'...
[Code].....
But when I run the program, Clear() cleared both dt and dttemp! Why? Aren't dt and dttemp supposed to be two distinct instances of DataTable?
(I finally found a solution - dttemp = dt.Copy() instead of dttemp = dt. But I still can't see why Copy() was necessary in this case.
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Mar 26, 2010
I am using the StreamWriter to create a log file for my application. However I do not see a method on how to clear the file (make the file blank again). Also before I clear the file I want to rename it so that I can have multiple log files, a new one produced everytime the application runs.
[Code]...
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Aug 18, 2011
I am trying to display value of the field ("UserID") for every row exists in datatable to checkboxlist(make the checkboxlist item selected).
I used for loop, but only the field value from last row of RoleUsers table is selected in the checkboxlist.
Here is my code
Private Sub DisplayRoleUser()
Dim conn As SqlConnection
Dim cmd As SqlCommand
[Code].....
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Mar 15, 2010
I have a datatable and I apply a filter to the defaultview.rowfilter property of that datatable. If I then loop through the rows collection of the datatable, will I only be able to see those rows that the filter applies to, or will it loop through all the rows?
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Apr 21, 2010
I am working on a project that takes an xml schema and xml data files and places them into a DataTable, the 2 files are generated from a working table that i have written to disk. I wish to load these 2 files into a DataTable. Here is What i have
vb.net
Friend Function CreateTable(ByVal tableName As String) As Boolean
Dim table As New DataTable(tableName)
table.ReadXmlSchema(tableName & ".xsd")
[code]....
this however produces the following error on line 3
Quote:
System.ArgumentException was unhandled Message=DataTable 'get_item_list' does not match to any DataTable in source.
get_item_list is the parameter passed into this function (tableName)
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May 20, 2011
I have a datagridview bound to a datatable setting its datasource property to the datatable. I would like to have a child form that contains a list of columns associated with the datatable that contains a checkbox that will allow the user to hide and show the columns ( I do not know the best control to use here) (I assume this is the easy part as All i need to do is loop through each of the datatable's columns to get the column name)
now I would like save these visible columns on some event like form_closing so that the next time the user opens the form up it will remember the settings
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Apr 16, 2012
I came across a problem with using a BindingSource as my DataGridViews.DataSource. Whenever I applied a filter to a column in the BindingSource and the user makes changes that don't match the column filter the DataGridViewRows would automatically disappear. A similar thing would happen when applying a Sort to a column. If the user made any changes the DridGirdViewRows would automatically sort causing rows to be moved around. This was not ideal for my application and there isn't anyway to stop this from happening with the BindingSource.
To correct this issue I have to use subsets of data. I use a DataView to apply the filter and sort to the main DataTable, which creates the subset DataTable.The problem is when I use the DataView.ToTable method I loose the Primary Key and RowError information. So I have to reapply this information everytime the user filters or sorts the DataGridView.Is there a better way to get a subset DataTable?[code]...
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Jun 5, 2012
I have a datatable that has a resource in one field and hours used in another, it looks like this -
Resource Hours Used
Manager 1
Accountant 1
Field Staff 2
Accountant 3
Manager 4
Manager 1
Administrator 6
Field Staff 4
Manager 0.5
Administrator 1
What I want to do is be able to create a summary of the data table above that groups multiple occurrences of a resource and adds up the hours used for that resource, creating a summary that looks like this -
Resource Hours Used
Manager 6.5
Accountant 4
Field Staff 6
Administrator 7
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May 28, 2007
Is there a simple way to assign a populated datatable's columns to another empty datatable? That is, I want to copy a datatable's structure only but not its data.
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Feb 17, 2011
I'm using vb.net 2010.I have a DataSet with a Table and data. MyDataSet1 which contains Table1 I want to create another table that is the same as the Table1 but without data, but it should have the columns, etc.
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Apr 8, 2009
I am getting array of selected datarows from a datatable.select.I use the commands below to get that array or datarows
Dim foundRows() As DataRow
strExpression =
Here is what I tried.I have looked at examples by MS but they all just write to the screen and I have no interest in that.
For Each rowWork In foundRows
dtWork.Rows.Add(rowWork)
Next[code]....
"LineOfBusiness = 'CPP'"
foundRows = modXchange.pdtWork.Select(strExpression)
Now, I want to place the rows from foundrows into an empty data table.I did what I thought was the obvious but that only returns a bunch of rows with no data
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Nov 18, 2009
load the contents of a query from a dataTable Adapter into a datatable?
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Aug 6, 2010
I am trying to add NewRow to the database by using datatable in dataset, but before I do that I want to make sure that row is not already there. I create new row for the datatable I am working with, fill it with information. I fill datatable with the row from database that has the same primary key as my NewRow by using tableadapter.fill method, but when I do that my NewRow that was never added to the datatable is filled with information from database(and not information that I assigned to it). I count rows in my datatable before I fill it and it's 0, so why is my NewRow affected by Fill command? (I am using VB.NET 2005 Framework 2.0)
[Code]....
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Apr 7, 2012
I'm trying to copy one row from DataTable to another, I looked almost everywhere and I can't find a reason why this is happening, I'm using ImportRow and still the New DataTable is empty. Here's one of the answers similar I found and It's still not working!:
Dim newTable As New DataTable
Dim dsFrom As New DataTable
For Each DBShoes In list
Dim iShoeID As Integer
[code]....
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Oct 31, 2010
how to copy data from datatable to table in dataset i ry this but its readonly property
ds.datatable1=newdt.copy
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Aug 10, 2011
I have an asp.net application where I have a datatable ("DataTableA") that returns just one column ("ProductID").
I want to read each row of "ProductID", process some business logic, then copy both those columns (ProductID & ProductIDBusinessLogicValue) to DataTableB. This DataTableB is then displayed on the asp.net page.
What would bhe the best way to read each row of DataTableA ?
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Aug 10, 2011
I am updating a data table (dt_report_crypt) from an encrypted csv file in the code below:I decrypt the colums and update the same dreport_crypt, such that it will contain de-crypted data.This part is working wellI however need to use this de-crypted datatable as a data source to update a second table(dt_report), using the sql SELECT command to filter relevant data,
Dim dt_report As DataTable
Dim dt_report_crypt As DataTable
Using cn As
[code].....
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Apr 4, 2011
I have a select statement and it will go to a datatable object, I would like to do the following
textbox1.text=datatable(first field value)
textbox2.text=datatable(second field value)
textbox3.text=datatable(third field value)
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Mar 16, 2011
Is there a way to nest a datatable into another datatable? I know you can do this with gridviews but thats not what I'm looking for.
Also, I don't want to merge the datatables. What I'm trying to do is have a datatable with 2 columns and each column containing different datatables.
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Feb 3, 2010
I have a session which contains a datatable and also have a function which returns a datatable. I need to add these two. How can I do this? The below code is to be replaced with correct code.
Session("Table")=Session("Table")+obj.GetCustomer() where obj is an object of the business layer.
The '+' sign cannot be used to add these two, so how can I do this?
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