I have a DataTable which I want to check if values in three of the columns are unique. If not, the last column should be filled with the line number of the first appearance of the value-combination.
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I solved this by iterating the DataTable with two nested for loops and comparing the values. While this works fine for a small amount of data, it gets pretty slow when the DataTable contains a lot of rows.My question is: What is the best/fastest solution for this problem, regarding that the amount of data can vary between let's say 100 and 20000 rows? Is there a way to do this using LINQ? (I'm not too familiar with it, but I want to learn!)
I have a datatable and I want to create a text file using this datatable. I want that each row of the newly created text file is unique. If there is a duplicate row, then it should add * to both rows ( duplicate rows)
I am using following code:
Dim str As String For Each row As DataRow In dataTable.Rows str += row(1) ' This is text data
I have three sub tables that I want to process. For each I want to combine the rows, as they are only different by contents in the second column(I want to do the same to the fourth column, later):
I have a DataTable with multiple columns including AccountNumber, Year, and Month. I am exporting the information in this table to an Excel workbook. Since this table has the potential to be extremely large, I must check the number of records in the table (since Excel can only have 65536 rows or something like that. If the original table is small enough, I need to put all of the records in a single worksheet. If there are too many records for one worksheet, I need to separate the records into multiple worksheets based on AccountNumber. Additionally, if there are too many records for a specific AccountNumber then I need to split that AccountNumber into multiple worksheets based on Year.ng:
Worksheet Name ---- Number of Records 1111 ---- 150,000 2222 ---- 50,000
Dim _tableBackLogs As System.Data.DataTable Do While i - 2 > 0 _tableBackLogs = Global.DataAccess.GetDataTable("SELECT SubjectID,SubjectName,Grade FROM SubjectPI WHERE RegNo='" & CInt(HttpContext.Current.Session("userName")) & "' AND Status='Fail' AND Semester='" & i - 2 & "'") i = i - 2
Doing this replaces the previous data in the DataTable. I want to retain the previous data i.e i want the new rows to be added to the DataTable w/o replacing the previous rows.
Whenever a row is selected in my GridView, I want to take the ID field of my gridview's dataset and form a unique URL with it (use a ?id=1234 parameter). In the Page_Load event I have the following code:
I am working in vb2008.TableAdapterManagers are a new feature in vs 2008 and I would like to understand how to use them properly.I have about 30 tables in my database that are unique to themselves and donot link to other tables.I have created a dataset.xsd in my solution and dragged in my database tables of interest.A unique datatableadapter has been identified in the dataset1.xsd for each datatable.Rather than using the identified datatableadapter for each datatable operation, should I be using the dataadaptermanager for each unique table?
I'm trying to make a method that can get unique values from a specified column of a DataTable. The problem is that the column may be string, integer, etc. I'm not sure what type of variable the (Of T) is.
Private Sub GetColumnUnique(ByVal dbTable As DataTable, ByVal ColumnNumber As Integer, ByVal ColumnType As ???) Dim results As List(ColumnType) = (From item In dbTable.AsEnumerable Select item.Field(ColumnType)(ColumnNumber)).Distinct.ToList End Sub
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.
I have a form with a textbox and a add button. User can write a name down on the textbox and click add button. it will save in a datatable with auto ID. After that, the textbox is cleared and the user can write another name on the text box and click the button. This should add to the existing datatable on memory with existing ID + 1. Show on the gridview. (this is just for display purpose to confirm it works)
I have a datatable like this. Button1.click() event Dim name = txtname.Text Dim dt As New DataTable dt.Columns.Add("ID", GetType(Integer)) [Code] .....
At the moment I have sometime like the code above. in the real program, it is not just name and it is not just one datatable so i just mock up some code. And this code for aspx. <asp:TextBox ID="txtname" runat="server"> </asp:TextBox><asp:Button ID="Button1" runat="server" Text="Button" /> <asp:GridView ID="GridView1" runat="server"> </asp:GridView>
I Have a datatable in .net. I need to flip the location of two of them. For example, a datatable that the select statement had an order by priority clause. The user wants to up the priority of a single row by selecting it and clicking increase priority, how do i move a row up (AKA flip two rows)
Private Sub error_out(ByVal line As Integer, ByVal err_col As Integer, ByVal err_msg As String) Dim ln = t_erori.Rows.Add
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I suspect this is because it's trying to add the same row twice. How can i make this work ? Or what else method could I use to do this ?
I need this datatable because my app is writing some results in there, but any other method to store the results that works with parallel.for would be ok.
The problem is I want merge duplicate serial_no into one row which the value of testong adding to new column. I have tried many ways, but I can't find the solution. Here is my code behind :
I have a datatable object, which is populated from a webservice.Apparently, the web service just throws everything (data) back to me. The data which gets in my datatable looks like this:
I have a Datatable in my code in vb.net. I need to delete rows from the datatable. The name of my Datatable is "temptable".in my row deleting event of a Gridview control. I wrote code as follows:
In the Row_Deleting event of Gridview: temptable.Rows.Remove(Gridview1.Datakeys(e.RowIndex).value)
But,it shows an error as follows: "Cannot cast System.Int32 to System.Data.Datarow".
I have a simple application that uses a database to store usernames and passwords.I have a hidden control that, when activated,should clear all usernames and passwords from the datatable.Then, one admin account is added. I have tried the datatable.clear method BUT while it throws no errors, it doesn't clear the datatable.I have also tried the datatable.reset method, with the same problem. I am now trying this method:
Dim row As DataRow For Each row In Authenticate.Logins row.Delete()[code]....
There were three similar questions in StackOverFlow but none gave an answer.. If have found why this error in occurring but don't know the fix. I am using Strongly Typed Dataset for my project which is created as a dll for DAL. I have added the Sql Server Table into this dataset using the designer and has created a DataAdapter
i want to make a datagrid with 2 columns and many rows
the columns i want to have databinding with a datatable i want the 1 row 1 column of datagrid have data from 1 row of datatable i want the 1 row 2 column of datagrid have data from 2 row of datatable
I am new to vb.net and I am trying to query a database and print out the records in the row to the console window. I got it to work, but I have a feeling that there is a more concise way to do this. One thing that I am sure is wrong is that I had to convert the dataset to a datatable to be able to retrieve the values. Is that correct? Could you take a look at the code below (especially the for loop) and let me know what I can improve upon?
Dim datatable_default_view As DataTable = DataTable.DefaultView.ToTable Dim servicenumber As String = datatable_default_view.Rows.Item(e.RowIndex)("Service Number").ToString If datatable.PrimaryKey.Length = 0 Then Dim keys(0) As DataColumn keys(0) = datatable.Columns("Service Number") datatable.PrimaryKey = keys End If Dim datarow_edited As DataRow = datatable.Rows.Find(servicenumber)
