Find A DataTable Row By Column Value Using LINQ?
Jan 7, 2012
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.
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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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Mar 27, 2012
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?
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May 7, 2010
How can I query a DataTable to find all of the unique values in a column? SQL has the 'unique' or 'distinct' keywords, but I dont know how to do this against a DataTable.
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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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Mar 15, 2009
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
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Dec 28, 2011
I've got two data tables with store numbers. I need to find out what store numbers are in one data table that arent in another.say one table A might look like:
34, 35, 39
the other table B may be
34, 35, 39, 45
I need to find the 45 If I use nested For Next I can get matches but anything not a match would show up not just the 45 value as the next progresses.
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Nov 16, 2010
I have been trying to find the last filled column row in a sheet using this.
clast = xlapp.ActiveSheet.Cells.Find("*", SearchOrder:=XlSearchOrder.xlByColumns, SearchDirection:=XlSearchDirection.xlPrevious).Column
rlast = xlapp.ActiveSheet.Cells.Find("*", SearchOrder:=XlSearchOrder.xlByColumns, SearchDirection:=XlSearchDirection.xlPrevious).Row
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Sep 25, 2009
i'm trying to get my program to look up a string and find a match in an access database in column "PhoneNumber" and return the value from column "FullName" on the same row to a different string
so it would go like this: (i really don't know much about accessing databases)
Dim PhoneNumber As String
Dim FullName As String
PhoneNumber = TextBox1.Text
FullName =
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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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Apr 17, 2011
Is it possible to do the following rounding scheme?
36 = 40
37 = 40
38 = 40
[Code]...
I guess what I'm asking is if there's a way to find the value of the number in the ones column and tens column.
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Oct 27, 2011
After Filling a DataTable in GridView's DataSource . A column with check box Type appears but it created as read only column and I can't enable it or make it editable... even i tried .readonly = false and still can't be edited
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Feb 10, 2010
I'm trying to convert DataTable to Linq using
DIm result = From r in dt.AsEnumerable()
Select new ( col1 = r.Field<integer>("id"), col2 = r.Field<string>("desc"))
But i get error near 'new (' saying type expected.
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Apr 16, 2009
I found the following example on [URL] Unfortunately, I need it in VB and it's using some constructs that neither I nor the automated code converters reciognize. Anyone out there know how this should be written in VB.Net? (the problem spot is the "select new {...")
PeopleDataSet ds = new PeopleDataSet();
using (PeopleDataContext context = new PeopleDataContext())
{
[Code].....
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Apr 24, 2012
I need help converting datatable to xml using Linq. I could do it with hardcoded column names as you can see in my code .. but i need it without hardcoding it ..Example datatable ..My linq query ..
Dim xmlDoc As New XDocument(
From row In dt.AsEnumerable()
From row In dt.AsEnumerable()[code]......
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May 25, 2011
I'm completely dense here, but I'm trying to get some stats from a DataTable. One of the columns in the datatable is called "colour".I need to find out how many of each instance of "colour" are in the datatable.
I'm trying:
Dim q = From p In PGWorkingDataTable _
Group p By p("colour") Into Group _
[code].....
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Jan 23, 2009
Why does the following code give an error?
[Code]...
If I change the code to remove the second field, as below, then the code does not give an error.
[Code]...
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Sep 21, 2010
discovered the compact mode of this instructions vs usual code. I found sample code for selecting, etc. from a datatable, transforming a column in a list or array - all operations are "Select"s - readonly.I need to make an simple update on a certain rows (using LINQ) from a DISCONNECTED datatable for which now I'm using this
for each dr as datarow in dtable.Rows
dr("MyField") = 77
next
[code].....
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Jan 13, 2011
I have two DataTables:
dt1 - personid, name
dt2 - personid
I want to create a third datatable to include records from dt1 when they are NOT in dt2 using LINQ. In this case, I can bind the third datatable to a dropdownlist.
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Jan 21, 2011
Am new to the concept Linq.I created a var where i joined 3 tables to get the data and then bind it in a datatable and create a csv file. Now i want to use an additioanl table in the same variable to be bind with the datatable but my problem is i cant use join here since i dnt have any common col or primary col in this additional table.How do i add this extra table?
[Code]...
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Apr 20, 2009
I'm writing a small web app in VB.NET and I would like to do paging for my DataTable in the following function :
Public Shared Function Testing(ByVal KeyWord As String, ByVal CurrentPage As Integer, ByVal PageSize As Integer) As DataTable
Dim db As New BibleDataClassesDataContext
[code].....
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Jan 24, 2012
Currently, I am using a loop to find the row I want to update.
Public Sub pubsub_SetUserDGVColumnWidth(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewColumnEventArgs)
' update all user settings for the given column
[Code]....
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Dec 22, 2009
I wish to output an IEnumerable type (dictionary(of T) would be perfect, otherwise a datatable would be acceptable) that provides an aggregation of the data within the datatable.In SQL I would write the query as such: select groupByColumn, sum(someNumber) from myTable group by groupByColumn
In VB.NET the closest I have got to this (achieved using information here) is: dt is a datatable containing two columns, referred to by index in p below Dim q = From p In dt Group p By p(0) Into Sum(p(1)) Select p(0), SumOfNumber = Sum
However I receive error: "Range variable name can be inferred only from a simple or qualified name with no arguments." on the p(0) element. Therefore my question is as follows:How can I resolve this error? How do I process the result (q) as an IEnumerable type? Life isn't made any easier because I'm using Linq in unfamiliar vb.net. Many examples are in C#, but I haven't really come across anything suitable even in C#.
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Jul 8, 2010
i want to use linq to fetch data from datatable.I have 2 tables in Cache and i want to join these tables then get value from resultset.I pasted Original Sql query and my linq query here.My linq query returns nothing.Where do i miss?My original sql query returns 1 row,but q1 is nothing
[Code].....
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Aug 2, 2011
I write the code below. I want to make short using linq count.
Dim query0 = From obj In dtAginglist _
Where (obj.Field(Of String)("CurrentStatus") = "Open" Or obj.Field(Of String)("CurrentStatus") = "Acknowledge") _
[Code]....
I try to use code below but it dosen't work with if source is datatable.
Dim orderCounts = From c In customers New With { _
c.CustomerID, Key .OrderCount = c.Orders.Count() }
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Feb 21, 2012
syntax of the LINQ query to use GROUP something BY something and select some fields of the datatable. i am having a datatable filled with some rows, i am trying to fill the datagridview with the GROUP BY query output of some fields.
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Dec 30, 2010
I have a string say, str = "system.Int16" I want to add a column in DataTable say, dt = new DataTable()I want DataType for that column as per 'str', i.e. System.Int16 Then How to? dt.Columns.Add("MyColumn", ...)
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Nov 18, 2010
there is two datatable at some datasetsone of them is tbl1 and fileds is (pcode,points) other table is tbl2 and fields is (pcode,stoped)"pcode" is equal at two tables
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Jul 20, 2010
How can i write this query with LINQ to a FoxPro database?SELECT count(*) FROM Table group by item1I wrote it as below, but it doesn't work
Dim Query
Dim dt As New DataTable
Dim da = New Odbc.OdbcDataAdapter("SELECT * FROM table1",connection)
[code].....
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Nov 3, 2009
I am looking for sample linq code snippet which uses System.Linq.Dynamic against a datatable.
Dim entities = (From ent In dt.AsEnumerable().Where(String.Format("IsUSFederal == {0}", "true")) _
Select Description = ent("Description"), Acronym = ent("Acronym")).ToList
I am getting an error "there is no accessible Where can be called with these arguments". I have included the DynamicLinq.vb file and the application compiles fine (aside from this error). I have included Imports System.Linq.Dynamic but it doesn't appear to be working.
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