VS 2010 Most Efficent Way Of Adding Rows To A Datatable?
Feb 28, 2012
I'm populating a datatable with this
Using con As New MySqlConnection(strCon)
'get users direct friends
Dim cmd As MySqlCommand = New MySqlCommand("SELECT distinct f.* FROM friends f WHERE (f.UserID = ?UserID) AND (f.FriendUserID <> ?FriendUserID)", con)
cmd.Parameters.AddWithValue("?UserID", UserID)
[Code]...
now I need to create another command, datatable and datareader in this same function and add the rows of that datatable to the one above. What is the most efficient way of doing this?
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May 8, 2012
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):
'Sub table 1
xx|C201 |02300877 |Samsung |....
xx|C201 |02300877 |Toshiba |....
xx|C213 |02300877 |Samsung
[code]....
p.s. For the fourth column, Manufacturer information , I want to do the same and I'd probably get something like this for the final table:
xx| C201,C213,C606,C619 |02300877 | Samsung
xx| C201,C213,C606,C619 |02300877 | Toshiba
xx| C303, C305,C712 |02301163
xx| C207, C209, C708 |02301165
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Aug 20, 2010
listA is list of integerdtListB is DataTableI'm checking that if StudentId of ListA doesn't exist in dtListB, then add it to the dtListB.
Dim stidListA, stIdListB As Integer
For Each la In listA
stidListA = la.StudentId
[code].....
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Feb 4, 2010
I have a data table in a loop that adds rows on each loop. During the loop i collect an array of unknown size. At the end of the loop i want to add a new row to the datatable with eachelement of the array as a field.[code]I could hard code this if i knew how many item would be in the array but i dont.Is there any way i can loop through the array and append the value to a row?
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May 21, 2011
I am trying to add the returned values from an array to the rows in a data table: Here is my current code the values load properly into the list box but not the table, each row ends up with the same value.
current code not working correctly
Dim dtrow As DataRow
Dim lat As Double = CDbl(34.213209)
[Code]....
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Jul 12, 2011
I'm trying to query a DataTable to get a collection of rows but I'm finding that my search string has to be the exact length of the columns width. So, for example this won't work:
Dim rows As DataRow() = (From r In myTable.AsEnumerable() Where r.Field(Of String)("fname") = "Bob").ToArray()
...but this will:
Dim rows As DataRow() = (From r In myTable.AsEnumerable() Where r.Field(Of String)("fname") = "Bob ").ToArray()
The search term ("Bob") has to be padded with spaces to make it equal in length to the column width (10 characters). Is this how it's supposed to work or am I doing something wrong?Also, how can I do a LIKE search? So for example, I want to search for all names that start with "Bo" or whatever. ie. "Bo*".
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Feb 15, 2010
I want to delete the rows of a DATABLE that verify a criterion. Someone would be so kind to show me how do this.For example, I have a DataTable with "customers" and I want to delete customers who live in "Madrid"... criterion: CityCustomer='Madri
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Feb 6, 2011
When I query a DataTable using LINQ, are the rows returned as references? Either way, is it possible to control this behaviour, so that rows are either returned as references or as new rows?My guess is that all objects are returned as references by default, since that seems to be the normal behaviour in most programming languages.
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May 3, 2012
I have a Datatable with one column of the table being 'PartNum(product part number)'. I used EntriesTable.DefaultView.Sort = "PartNum ASC" to sort the whole Table, with respect to the information in this column. Now I'm just trying to further sort the table by grouping rows that have same info under that column together and do something to each of such groups. but I'm kinda stuck here.
I'm thinking of creating some sub-DataTables out of the original one and have these sub-tables to hold those rows with same info under "PartNum". Does anyone have ideas how to do that? maybe with DataReader or DataView ,
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Feb 1, 2012
I am trying to insert an initial line (0) into a datagridview (named params). The program will then read each cell in that row, pass them through a function and return values be placed into the next line (1). This will continue until one of the parameters reaches some set point. The problem that I am having is that when I try to insert a new line, it appears above the initial one and not below it like I would like it to.
Here's my code so far:
Private Sub HurricaneWinds_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim init_xrange() As Double = New Double() {0.0, 0.0, 0.0, 40.0, 0.0}
For i As Integer = 0 To 4
params(i, 0).Value = init_xrange(i)
[Code] .....
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Jul 20, 2010
I have an array which holds the following items
for example
Quote:
myArray(0) = (1)
myArray(1) = (4,2)
myArray(2) = (10,15,20)
[Code]....
and then am trying to add other column based on items available in myArray().
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Apr 14, 2012
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.
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Feb 3, 2010
I have a session which contains a datatable and also have a function which returns a datatable. I need to add these two. How can I do this? The below code is to be replaced with correct code.
Session("Table")=Session("Table")+obj.GetCustomer() where obj is an object of the business layer.
The '+' sign cannot be used to add these two, so how can I do this?
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May 29, 2009
I have a DGV that has a datasource to load the rows I need for display.
Now, I need to save the selected rows to a DataTable.
binding the DGV. I created the DataTable in my DataSet dsProfiles1 and created a BindingSource - bsDataTableDGV
DataTable:
ClientID Int32 not null PK
ClientName String not null
ProgramNo Int32 Not Null
[Code].....
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Feb 15, 2012
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>
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Aug 16, 2010
I have a form that i want to be saved to my database. The form is adding a new record to my sql server 2005 database but it is not bringing the text over with it. The new record in my db is just an empty row. Here is my code.Add to database section ( i have removed the connectionstring for privacy reasons)
<%@ Page aspcompat="true" Debug="true" %>
<html>
<head>
<title>Form to database</title>
[code]....
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Jan 14, 2011
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)
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Jul 13, 2010
I have this sub :
Private Sub error_out(ByVal line As Integer, ByVal err_col As Integer, ByVal err_msg As String)
Dim ln = t_erori.Rows.Add
[Code]....
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.
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May 13, 2012
I have one datatable tempDT with value :
[Code]...
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 :
[Code]...
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Apr 17, 2009
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:
Dept Code Value
Science ABC 5
Science ABC 6
[code].....
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Apr 8, 2010
At the moment I use this code but I have 591 rows to delete and it takes forever to loop and delete each row on an individual basis
[Code]...
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Feb 10, 2012
i need to delete some rows from datatable
i don't know the indexes i have 2 columns to idendify the rows to delete
how to achive this in easy way
i don't want to delete inside loop wat will happen if i have 2 million rows? tats why i don't want to delete indendify the rows and delete in loop
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Mar 20, 2009
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".
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Jan 9, 2009
IDE : VS 2008,Platform : .NET 3.5,Here is my DataTable columns :ID Note DetailI want to write sth like this :
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Jul 29, 2010
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]....
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Feb 21, 2011
I'm trying to set the same value for all rows for a single column in a datatable without using for loop. Any faster methods to achieve the same.
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Feb 22, 2010
am just curious to know...which is the better or more efficient way of these two?
Note: tblOD is a DataTable
For dtrows As Long = 0 To tblOD.Rows.Count - 1
dgv1.Rows.Add(tblOD(dtrows)(0), tblOD(dtrows)(1), _
[code].....
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Jun 13, 2011
Way to access datatable rows
[code]...
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May 2, 2012
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
[Code]...
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Dec 6, 2010
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.
[Code]...
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!)
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