.net - 'cross-referencing' DataTable's?
Jun 15, 2010
I have a DataGridView that is being filled with data from a table. Inside this table is a column called 'group' that has the ID of an individual group in another table.
What I would like to do, is when the DataGridView is filled, instead of showing the ID contained in 'group', I'd like it to display the name of the group. Is there some type of VB.net 'magic' that can do this, or do I need to cross-reference the data myself?
Here is a breakdown of what the 2 tables look like:
table1
id
group (this holds the value of column id in table 2)
weight
[code]....
BTW - I am using Visual Studio Express.
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Feb 5, 2012
I have a data table, i want to add a new column on that table, the data in that new column will depend in the data from another column. Now i can think of two ways to accomplish this, first is loop through the whole table and do the statements to get my new columns appropriate data. the second approach would be to give the new column an expression, then convert the table to xml (to remove the expression) then convert the xml string back to datatable.
Now, is there any other way around this? what could be the most optimized way in solving this task?
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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 24, 2012
I am a self-taught noob and have been given the task of developing someone elses code. I have rebuilt someone elses solution into my dev machine and able to run with some minimal bugs. I don't know where to add an .xls file into my solution
System.IO.FileNotFoundException was unhandled
FileName=TestRec.xls
Message=Could not find file 'TestRec.xls'.
[code].....
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Apr 25, 2010
I have a line of VB code which looks like this : If GroupTagDropDownList.SelectedValue Is "1" Then The system doesn't throw up any errors for it but the statement doesn't appear to work.
I think that the problem must lie in how I've referenced the '1' value - I've tried putting single quotation marks around it but it appears to make no difference at all.
There is definitely a value in the drop down list of value '1' but it doesn't appear to be read at all.
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Sep 9, 2010
I have been given a .dll file (implemented in C++) that I want to use in my VB.NET application.When I try to add a reference to this dll using Visual Studio I get the following error:A reference to 'path-to-dll' could not be added. Please make sure that the file is accessible, and that it is a valid assembly or COM component.
Based on this error I concluded that I need to register the dll. Since it has been implemented with unmanaged code I tried to use the regsvr32 tool to register it. But when I try to register the dll using this tool I get the following error:Name-Of-DLL was loaded, but the DllRegisterServer entry point was not found. This file cannot be registered. how do I add a reference to this dll in my VB.NET application?If I have to register it, how?
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Aug 10, 2011
Imports System.Runtime.CompilerServices
Module StringExtensions
<Extension()>
Public Sub Print(ByVal aString As String)
[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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Sep 28, 2010
I need to reference a C++ dll from my Java project. The method that I need to expose is actually written in Visual Basic. Is there any way to access the Visual Basic code in C++, so that it can eventually be accessed in the Java project?
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Dec 7, 2010
I have a java class that is used to for ssl connections to a web server. I have got some of it converted however there are serveral java libraries that i have been unable to figure out how to call or reference in vb.net. First off i'm not even sure if it's possible to reference them. In Java code they look like this:
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
[code].....
I'll use the last one for example: I get a "Namespace or type specified in the Imports 'org.xml.sax.SAXExeption' doesn't contain any public member or cannot be found. make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use aliases.
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Apr 19, 2011
I've been poking around in some projects written by one of our contractors, and he seems to be storing a lot of settings in the main "app.config" file for the application, using, for example:
<add key="SomeClass/SomeValue" value="False"/>
And then referencing the key value in the "SomeClass" class in "SomeProjectLibrary" using
ConfigurationManager.AppSettings.Get("SomeClass/SomeValue")
While this works, I guess, it also pretty much sucks. I was wondering if anyone knew of some more elegant way of creating variables in the "app.config" file, which could then be used across various applications within a Solution?
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Jun 11, 2012
I'm developing an app in which there's hundreds of different calculations involved and would like for my app's admins to be able to tweak these calculations by specifying the formulas.For example, my database table contains price and quantity. One of the columns 'X' might contain "(price * quantity) over the past 7 days". How can I allow my app's admins to change the calculation from "7 days" to "14 days"?
Is there some way to make calculations dynamic within VB.NET or do I have to rely on stored procedures and write some code to alter those procedure if a change is needed? What are the best practices in this type of a scenario?Ideally, I would like to use something similar to the "Tags" box used when posting questions on here to bring up the available fields and add mathematical operators in between them to perform calculations. It might be adding more complexity, but would be great if an existing calculation isn't overwritten so that it could be used in building a new formula.
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Jun 30, 2011
I was directed to update an old VB6 dll to VB .net as we are moving away from COM objects. The dll contains one function that does a bunch of high math calculations. I opened up a new class project in VS 2005, Imported System.Math, and then basically copied the function code from the VB6 project into the new class. When compiling, I made the assemble COM-Visible and also checked the Register for COM Interop in the project properties. I then copied the dll and tlb files to Windows/system32 and tried to register using Regasm.exe.
Even though I'm using the correct version for .Net 2, I still get error RegAsm : error RA0000 : Failed to load 'C:WINDOWSsystem32eagetairmiles.dll' because it is not a valid .NET assembly. When attempting to add a reference to it in my new .Net project, I see it in the COM tab - but in the location it was developed in, and I receive the following error: Converting the type library to a .Net assembly failed. Type library mydllname was exported from a CLR assembly and cannot be re-imported as a CLR assembly.
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Feb 20, 2009
how to create a class yet, and I think I need to learn how.I am wanting to shorten my code in a form, thinking of creating several classes to do so.Lets use a Listview as a reference if you dont mind.Say there is a listview, you have a numeral amount of if statments to fill by. Is there a way to create a class(is this the way to go) so that you can open the class to modify that specific block of code? Example of questionYou have multiple items you need to add for each if statement. Animal as a group Dog as an item 14 years as a sub item Cat as an item 11 years as a sub itemIs this the way to go, if so how do you create a class and call it from a form?Davids Learning
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Mar 15, 2010
Ive have a listview on my form and need to populate it with data from my Table called "tblCustomers". However I need to only retrieve records based on field that is populated with data called "Joe". In order for the SQL syntax to retrieve the name "Joe" then the SQL syntax needs to reference the Label on the form called "lblName" which will have the name "Joe" as the caption.
How can my dataset have SQL data that references my label object on my form?
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