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.
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
[Code]....
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:
[Code]...
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
In a DataTable object, is there added overhead to looking up a column value by name thisRow("ColumnA") rather than by the column index thisRow(0)? In which scenarios might this be an issue. I work on a team that has lots of experience writing VB6 code and I noticed that didn't do column lookups by name for DataTable objects or data grids. Even in .NET code, we use a set of integer constants to reference column names in these types of objects. I asked our team lead why this was so, and he mentioned that in VB6, there was a lot of overhead in looking up data by column name rather than by index. Is this still true for .NET?
[Code]...
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.
View 8 Repliesi have two datragridviewcomboboxcolumn,and two textbox column in a datagridview.each combobox column is binded to separate binding source.
column names are sl_no,col_empname,col_empworktype,Col_Hours etc.and
displaymember,datapropertyname,valuemember and for comboxcolumn are
col_empname:-emp_name,emp_id,emp_id
col_empworktype:-worktypename,worktypeid,worktypeid
[Code]...
I have a Dynamic DataTable Created at runtime. The Setup is like so
Id | Name | Age
-----------------
3 | Mike | 21
6 | John | 43
8 | Sara | 34
What I am trying to do is come up with a linq statement I could use to find and update specific rows.
Such as a statement to change AGE to '33' WHERE ID = '3'
My code So far is:
-[VB.NET]-
Dim MyRow As DataRow = From column In MyTable.Rows Where column("Id") = 3
MyRow(0)("Age") = 33
But this is not updating my DataTable entry.
I have this code that use to sort a datatable.
Dim sortingIndex As Integer = orderby
Dim DataTableNew As DataTable = New DataTable
DataTableNew = dt.Clone
Dim query = (From c In dt.AsEnumerable Order By c.Field(Of String)(sortingIndex) Ascending)
query.CopyToDataTable(DataTableNew, LoadOption.OverwriteChanges)
My problem is that with this method I always need (Of String) for it to work, so the date columns are also managed as Strings witch is the problem. Is there a way to use the correct type so the sorting is based on the type of the column?
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
View 6 Repliesi am having trouble putting a value in a textbox. Each time a ticket is sold i put the total price in a textbox, each time a ticket is sold for the same concert it increases by adding its self to the total price. It works at the first sale, but after that it breaks down. here is the code
Private Function DisplayMoneyTaken() As Integer
Dim totalMoney As Integer
'open the database connection
[Code].....
I have a datatable which has 5 column. It is possible to copy only its 2 column in and save it into new datatable.I used this code but it copies all the 5 column
Code:
Dim qry As DataTable = (From obj In temptable Where obj.Item("Column1") = 0 _
Select obj).CopyToDataTable
i used this one but it is not supported
Code:
Dim qry As DataTable = (From obj In temptable Where obj.Item("Column1") = 0 _
Select obj.item("Column1"), obj.item("Column2")).CopyToDataTable
It seems that on clicking datagridview column header, the column will be automatically sorted based on the column type. I have a column showing some numbers. If column type is string, it sorts "1","20","3" into "1","20","3". If column type is double, it sorts into "1","3","20" which is the result that I want. However, there might be some erros in the numbers and error messages(text) will show in the cell instead of numbers. So I cannot set the column type as double. I want to ignore these error messages and sort all the numbers. How can I do this?
Also, I need to add some background colors to different rows in datagridview. So in the column header click event, I call the bkgColor Sub to achieve this. My question is that how can I override the sorting method in this event?
Private Sub DataGridView1_ColumnHeaderMouseClick(sender As Object, e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles DataGridView1.ColumnHeaderMouseClick
Try
[code]....
How can i get the Column Index and the Row Index when I click on the ListView?The ListView1.FocusedItem.GetSubItemAt(e.X, e.Y).Text function only gets the text of the first column, I can't find the option of getting the Index of the Column and Row upon clicking.
View 9 RepliesIs there a way to find the column index of a datagridview column using the columns DataPropertyName?I currently use a loop (shown below in the class) which is kind of ugly, but it works. I'd like to do something like this, which seems more elegant.My goal is this, I store the users DataGridView column settings (i.e. DisplayIndex, Visible, & Width).When the user opens the form that contains the datagridview I want to get those settings from the database and apply the settings to the datagridview.[code]
View 5 RepliesI'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?
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
[Code]...
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.
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...
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]...
View 1 RepliesI 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.
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?
how to create ascending order datatable in asp.net without sorting method
View 3 RepliesI have a LINQ Query:
[Code]...
This works great and sorts on L_Name. But I am trying to allow the user to sort the gridview themselves so I am passing in the SortExpression as a string. But I don't know how to incorperate the SortExpression into the LINQ Query. I tried Order By c. & SortExpression but that did not work.
Is it possible to get the row index of a DataTable so that you can access the previous and next row? For example I have a DataTable that contains two columns ChapterTitle and PageURL. This is for a table of contents of a book. ChapterTitle is the chapter name and PageURL is an HTML page that contains the chapter (chaptername.html). When going into one chapter of the book I want to be able to tell which is the next and previous chapter.
After finding the chapter that I'm currently in how can get the next and previous rows?
ChapterTable.Select("PageURL = '" & PageURL& "'")
How can i get the index of an element in datatable which i got using the select method of datatable as
dim d as new datatable= 'some data source'
dim dr() as datarow
dr=dt.select("some condition")
now i want to find the index of first or second item which i have retrieved in data row. i mean there index in data table with out use of loops as loops take a lot of time when there is huge data in data table.
I am wanting to update a datatable which is been created dynamically. Each row has a unique Id column. How can I retreive the row and update a column in it using the Id column
[Code]....
How should I use linq to sort my data when my data contain both numbers and letters? For example my current linq
Dim MyQuery = From c In XDoc.Descendants() _
Where c.Attribute(Y) IsNot Nothing And c.Attribute(Str) IsNot Nothing _
Order By Val(c.Attribute(Y).Value), Val(c.Attribute(X).Value) _
Select Str = c.Attribute(Str)
Returns something like the following
13
167
172
231
44
49
Which is not what I would like it to be...
The output should be like the one below:
13
44
49
167
172
231
I know this is old hat, but when you're faced with a problem you cannot solve yourself, you need to find someone with the correct answer.In short, go to the wise.
I am working on an application that has a lot of records, and it uses a listbox control bound to a binding source attached to a table in a data source.A new record with data is added to the binding source's attached table, and, of course, to the underlying sqlServer database table:
[Code]...
I have a data set in the User control . It was working fine but now when I started using another copy of the user control it started showing error DataTable internal index is corrupted: '5'.
dim dv as dataview
dv = new dataview(ds.tables("Names")
dv.rowFilter ="CatNum ='"& val&"'" 'This will always give one row only
dv.item(0)("Names") = myvalue ' here the exception is occurring
I understand that DataTable.Select() returns an array of rows. I just want to know whether these is a way to get the row indexes as well.
View 4 Replies