.net - DataTable Sort Test?
Jul 22, 2010
I was asked this question recently in a test, which I didn't pass. For the life of me, I couldn't spot what the problem was. It's probably something really obvious as well, but even a colleague of mine couldn't spot it either. The best I could come up with was issues with bottlenecks and naming inconsistencies of parameters! I blame it on the fact I've not done any vb.net for years, I've been doing C# mostly these days
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The question: This function, although it will successfully sort a datatable, has a major problem with it.What is the problem? Re-write the function in either C# or VB.Net using LINQ.
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Sep 15, 2011
I have two tables, dt & dtResults.dt contains 3 columns named: vchInstrumentAnalyteID, bintAnalyteCodeID, & vchAnalyteCode dtResults contains several columns including the columns in dt
I want to get vchInstrumentAnalyteID from the first row in dt and test if it exists in the vchInstrumentAnalyteID column in dtResults. If it exists, I want to use that value from dt to filter rows in dtResults and fill all the filtered rows with data from that row in dt. Then loop to the next row in dt.
I have this code, which is close to what I need, but I can't get it working.
' put analyte data in results table
For Each drA As DataRow In dt.Rows
If
[Code]....
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Jun 22, 2010
I'm trying to sort a DataTable using the following code:
Private Function sortDataTable(ByVal dTable As DataTable) As DataTable
Dim dView As New DataView(dTable)
dView.Sort = "Field ASC"
Return dTable
End Function
But it doesn't work. What is wrong? How can I sort the DataTable?
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Sep 1, 2011
I currently have a datagridview that is built from a datatable So lets say we have 6 columns
A B C D E G
So the users will select there data from another program and paste into the the table. So lets assume that the data that is pasted is; (the column names are automatically put in)
A B C D E G
123 456 789 101 112 134
So the table will now look like following (I remove the first row because its the same as the column name)
A B C D E G
A B C D E G
123 456 789 101 112 134
My problem is that the users can rearrange thier tables(column index) so lets say user A has the table in this format
A B D E C G
123 456 101 112 789 134
So when they paste into the program, it will look like
A B C D E G
A B D E C G
123 456 101 112 789 134
So now "C" "D" "E" are incorrect and i need to swap those columns to be the same as the column name. I'm not sure how to attack this problem.My thoughts were to paste the data as is, than see what the first row in each column equals.so if it equals "A" assign it an index 0
B 1
C 2
This seems theres too many steps and will slow down the app...
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May 7, 2010
I have a piece of code that filters a datatable based upon the cumilative value of records in a particular field. In short i specify a number and the filter counts through the records (rows) in the datatable and select the records that together are either exactly equal to or do not exceed a specified value (defined in a combo box on a form).[code]...
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Feb 2, 2010
I have got a datatable which contains many columns in which three are main:
hotelid
dshotelid
hotelname
Some hotels contain only dshotelid, some contains only hotelid and some contain both dshotelid and hotelid.
I need sort in such way so that those hotels who got both dshotelid and hotelid should be on top and then those hotels who have got only dshotelid and at last those hotels who have got only hotelid...
create such a sort expression.
I created this :
dtmaintable.DefaultView.Sort = "dshotelid, hotelid"
but it Is not giving me desired output.
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Apr 3, 2009
I have some comboboxes that are binded to some fields in a datatable
is it possible to sort each single combobox without soting the datatable?
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Jun 5, 2011
how to create ascending order datatable in asp.net without sorting method
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Mar 23, 2012
I need to sort a datatable. I do it with linq this an example
Dim query = From c In dt.AsEnumerable _
Order By c.Field(Of DateTime?)("LastPurchaseDate"), _
c.Field(Of String)("LastName") Descending
Dim dv As DataView = query.AsDataView
But my problem is that i need to sort the fields not by passing the name of the column but the index of that.
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Dec 10, 2010
I want to sort my datatable column(0) alphabetically, but cant seem to find a way to do it. Just to give you an idea:
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Feb 21, 2011
I am creating a datatable and then adding a column to it which is filled with data from existing column and parsed into correct format DateSold is my existing column from my datafile and I create NewDateSold by adding the column to the existing table and then parsing the information in date format.
This is added to a binding source which then is used to populate a combobox I want to be able to sort the combo box by NewDateSold Desc I was able to this on the original column by simply using the "order By" in my query, it seems now that I added new column it is no longer sorted? I am finding different solution such as using dataview and wish to know the best way to do this
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Dec 1, 2011
First off a great piece of code [URL] you saved me soooo much time. I am a somewhat newbee to VB2010 and was wondering how would i go about setting lets say setting column(4) to a date format so that i can get it to sort in the correct order.
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May 21, 2011
I am trying to go through a datatable and sort records that fall within a certain criteria, one being distance.I have a function that will get the distance between two points based on Lon/Lat and my records in table have Lon/Lat Values
exisitng code
Dim dtrow As DataRow
Dim lat As Double = CDbl(34.213209)
Dim lon As Double = CDbl(-118.629276)
[code]....
I can I now use the function to filter records in table that are with a certain distance?
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Aug 2, 2010
I have a page which lists all the files in a particular folder (all PDFs), using a data-table and gridview. I'm currently sorting this table by the filename (by using a dataview), which isn't that helpful, and I want the gridview of files sorted by the file created or file modified date (as recorded in Windows). If that's not possible, a second option would be to extract the date from the file name string (no problem doing that), and sort the dataview/datatable or gridview based on that.
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Nov 20, 2010
If want to do a DataView.Find on a DataTable that is already 'ORDERED' by the Column I am seaching, so a DataView.SORT should not be necessary, but it throws an Exception if I don't give a .sort command before the .find command. Is there any way to avoid this apparant duplication ? and speed up the search time. Its a very large table - 1 million rows. I am using VB 2010
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Sep 25, 2010
I don't understand the error, Argument not specified for parameter 'test' of 'Public Shared Function TestThis(test As String)'.
Partial Public Class Form1
Shared Sub ReceiveCallback(ByVal ar As IAsyncResult)
Form1.Invoke(TestThis, New Object(){"test"}) 'error
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Dec 15, 2010
How can I improve this bit below to make the items in the TreeView to sort faster or something totally different to sort them easier?
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Jul 5, 2011
I have a MyObject; myObjects as List(Of MyObject) and a delegate Comparison(Of MyObject) that uses a lot of comparison functions (ByA, ByB, ByC etc) Ã la:
Shared Function CompareMyObjectsByName(x As MyObject, y As MyObject) As Integer
Return x.Name.CompareTo(y.Name)
End Function
[Code].....
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May 25, 2009
[code]...
and from VB6 project I reference to Test.dll but an error messege was appear A reference to Test.dll file could not be added (If I create VB NET project and reference to file Test.dll it OK )
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Sep 20, 2011
Probably a dumb question, but can you write a unit test project in one language to test against another project in a different language?I'd like to translate one of our VB assemblies into C#, but want to build unit tests to verify the results. I've tried to set a unit test project up to do this, but I can't seem to access the VB code within a unit test... I can't figure out if I'm just missing/doing something stupid, or it really isn't allowed.
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Jan 29, 2009
Sub Sort()
ReDim RollsCC(NumOfPlayers - 1)
For N As Integer = 0 To (NumOfPlayers - 1)[code]....
Here I am creating a temp single dimensional array, merging my 2d array into it, and then attempting to sort it by Rolls(N,1), which is a integer 1-6, Everything seems to be working right with the exception of this.
RollsCC.Sort(RollsCC, 0, 1)
How would one specify a numeral sort based on the first character in the string? im aware that I am switching Rolls(n,1) and Rolls(n,0) information during the sort.
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Apr 12, 2012
Currently my ListView sorts items by image.index. So 0 is at the top, then 1, 2 and so on. Think of it as an IRC chat room nick list. Ops at top then the rest are sorted alphabetically
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Jun 8, 2009
I am trying to sort an arraylist using .Sort() but am not sure what to put in the () for the field/column I want to sort on. Here is the portion of my code that creates the array from a SQL Query
[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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