Fastest Alternative To Datatable.Select To Narrow Cached Data?
Sep 28, 2009
I have a search function on my company's website (based on .NET 2.0) that allows you to narrow the product catalog using up to 9 different fields. Right now, after you make your selections on the frontend I am building a dynamic query and hitting the database (SQL Server) to get the resulting list of items numbers. I would like to move away from hitting the database everytime and do all of this in memory for faster results. Basically a 3500 - 4500 row "table" with 10 columns: the item number (which could be a primary key) and the 9 attribute fields (which have repeating values for many many rows).
There can be any number of different searches between the 9 columns to get the items you want:
Column A = 'foo' AND Column D = 'bar'
Column B = 'foo' AND Column C = 'bar' AND Column I = 'me'
Column H = 'foo'
etc...
Based on my research, the .Select() function seems like the slowest way to perform the search, but it stands out to me as being the quickest and easiest way to perform the narrowing searches to get the list of item numbers:
MyDataSet.Select("Column B = 'foo' AND Column E = 'bar' AND Column I = 'me'")
In my specific case, what method I use as an alternative that has the same narrowing functionality and better performance instead of settling for the datatable.select() method?
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Feb 23, 2012
I am little bit stuck here .. I have a datatable as _
Dim dtPupil As New DataTable
dtPupil.Columns.Add("PupilId", GetType(Integer))
dtPupil.Columns.Add("Forename", GetType(String))
dtPupil.Columns.Add("Surname", GetType(String))
I made a select (assuming names combination will be unique)
Dim strQuery As String = "Forename ='" & forename & "' and Surname = '" & surname & "'"
Dim dr As DataRow()
dr = dTablePupil.Select(strQuery)
I wanna have PupilId as an Integer of the row that match, so
Dim PupilID As Integer = ??????????
What do I need to write here ? There will only be 1 row returned.
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Dec 19, 2009
The next step is I need to build a randomizer to randomly select a row and read the columns of that row into varibles.I have a working randomizer that can randomly pick a number between min and max values but what I don't know if how to select a row / How to find out how many rows are available and how to read the values into varibles.Am I right in declaring an Integer Varible then using:
AvailableRows = DDT.Rows.Count
Then use my Random Function to pick a number between 0 and AvailableRows
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May 26, 2011
I was able to do this via a SELECT CASE statement, however I'm always trying to improve my code writing and was wondering if there was a better approach. Here's the scenario:Each document has x custom fields on it.There's y number of documentsHowever there's only 21 distinct custom fields, but they can obviously have n different combinations of them depending on the form.So here's what I did, I created an object called CustomFields like so:
Private Class CustomFields
Public agentaddress As String
Public agentattorney As String
[code].....
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Apr 28, 2011
This has been driving me insane all day and I think I have the problem narrowed down, but it just doesn't make sense how it could be happening. I have 2 public shared functions and 2 private shared functions. One provides a list of custom objects and one filters the objects based on some parameters in the function call. Both return List(of custom object). The 2 private shared functions are the predicate functions used in the List(of t).RemoveAll function.
[Code]...
Now, the next time I call the GetItemList function it only returns 50 item objects, not the 100 item objects that it should be returning due to the cache being set! I have verified this in the debugger and by running many, many different tests to see what combinations of parameters may be causing the problem. In my testing, as soon as one of the .RemoveAll functions is used the GetItemList item list will get set to whatever the NarrowItemList function returned.
Even if the cache wasn't being set correctly, shouldn't it just get the data again from the database and return 100 items again? What could I be missing???
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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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Apr 8, 2009
I am getting array of selected datarows from a datatable.select.I use the commands below to get that array or datarows
Dim foundRows() As DataRow
strExpression =
Here is what I tried.I have looked at examples by MS but they all just write to the screen and I have no interest in that.
For Each rowWork In foundRows
dtWork.Rows.Add(rowWork)
Next[code]....
"LineOfBusiness = 'CPP'"
foundRows = modXchange.pdtWork.Select(strExpression)
Now, I want to place the rows from foundrows into an empty data table.I did what I thought was the obvious but that only returns a bunch of rows with no data
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Aug 2, 2011
Unable to select multiple column in datatable
Code:
Dim Activitydtb As DataTable = DirectCast(ViewState("TalentcharacterActivty"), DataTable)
grdviewactivity.DataSource = Activitydtb.Select("SELECT
[Code].....
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Apr 4, 2011
I have a select statement and it will go to a datatable object, I would like to do the following
textbox1.text=datatable(first field value)
textbox2.text=datatable(second field value)
textbox3.text=datatable(third field value)
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Oct 7, 2011
I am trying to make a very narrow form. It doesn't seem to allow me to resize to less than 132 in design mode. I've played with the Min and Max and had no luck. Is there another property I need to change, or is there a minimum width?I've removed the control box and the text, and played with the border type as well.
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Sep 3, 2011
I'm working with ReportViewer in asp.net, VS 2008.All of my reports are rendering on the screen in a very narrow format. As in only 16 characters across. I've tried adjusting the rdlc layout as well as the reportviewer c
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Dec 13, 2011
What is an alternative way of presenting tabular data aside from DGV? I tried DGV but i cant seem to populate the DGV automatically using datasets. Is there a way to manually place my data on the DGV using the read.Item("column1")?
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Oct 22, 2010
Well this listbox contains sensitive data not very important but i dont want the end user to be able to see what the listbox contains, therefore i have hidden the listbox But my question is how do i store this information i could easily write it to a text file i know but the user could locate the text file. So i attempted to create my text file as a resource and that failed as i can read from it i cant write to it. More simplistic question. I have data i need to save from a listbox but if i save it as a text file the user could still access it and i dont want the user to be able to acesss the file i would like it to be internal because i also dont want the user to be able to delete the file?
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Dec 15, 2009
I thought this would be simple but obviously not!
Basically, I have a date and want to do a 'between' on two date columns like this:
myDataTable.Select(myDate & " between (StartDate and EndDate)")
Where StartDate and EndDate are date columns that do exist in the DataTable.
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Apr 9, 2012
I have a datatable and I would like to get the MAX number from this table where Term Number (first Column) is a certain value. If my datatable is declared as dtMyTable, I'm assuming I need to use dtMyTable.Select(), but I'm not sure if this is the best way.
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Feb 24, 2012
I'm trying to get value from Datatable after Select Method.Select Method should return only one record.
Dim y As DataTable = CType(HttpContext.Current.Session("tb"), DataTable)
Dim products = y.[Select]("StnID" = "'" + stnID + "'")
Dim size = DirectCast(Products(0)("Shape"), String)
if I replace products with y--(DirectCast(y.Rows(0)("Shape"), String), it works.(which is before Select method, so it's useless) products is datarow object and I can't seem to get the value same way as datatable.How do I get value from datarows?
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Nov 20, 2011
I have pulled information from a database into a datatable (dtCustomerInfo) then I expanded on the columns by processing the data and I can display this in a datagridview without any problem. However, the data is in detail and I want to ultimately summarize by customer name.The code below has a commented sql statement that is the statement I ultimately want but it is not working. However, the idea is that I want to Select from one datatable into another but run aggregate sum on several columns so that I will get one record per customer showing totals for each column.So I broke it down to just pull all data possible into the second table.[code]I do know the grouping in the current select * statement does nothing but my issue is more that the columns do not show up.
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Jun 6, 2010
I need to Quarry from Data Table Like
select Name, Address from myDataTable where name = 'x'
and
select distinct(name) from myDataTable
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Dec 28, 2010
I need filter for multiple values on one column using the DataTable.Select method.
Dim totalFatal As Integer =
m_DataSet.Tables("tblAccidentNonMotorist").Select(String.Format("[AccidentNumber] = '{0}' AND CONTAINS([InjuryClass], '"01" OR "02" OR "03"'", accidentNumber)).Length
[code].....
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Apr 8, 2009
I was trying to write the following select stmt but i am getting an error that the parsename is not identified.
[Code]...
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Oct 31, 2010
how to copy data from datatable to table in dataset i ry this but its readonly property
ds.datatable1=newdt.copy
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Aug 10, 2011
I am updating a data table (dt_report_crypt) from an encrypted csv file in the code below:I decrypt the colums and update the same dreport_crypt, such that it will contain de-crypted data.This part is working wellI however need to use this de-crypted datatable as a data source to update a second table(dt_report), using the sql SELECT command to filter relevant data,
Dim dt_report As DataTable
Dim dt_report_crypt As DataTable
Using cn As
[code].....
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May 15, 2012
I m' trying to select a row and then edit, and no error on debuggiing but the changes are not saved on the database
[Code]....
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Mar 20, 2009
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.
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Aug 12, 2009
I've defined a function:
Public Class GeneralFunctions
Function StartsWith(ByVal sStart As String, ByVal sWord As String) As Boolean
Return Strings.Left(sWord, Len(sStart)).Equals(sStart)
[code].....
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Jun 11, 2010
I am working on a vb.net app for a handheld using Windows CE and I have a few columns of data loaded in a datatable from a text data file. Some of the records can have duplicate Account IDs so I cannot use a primary key. What I want to do is take an Account ID entered and filter on just those records. I need to loop through all records with this Account ID, make updates to any of them and then clear the filter.
how to set a filter on a column based on a given string such as an account number? And loop through these records? Can I modify the records at that time?
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Feb 19, 2012
Is there a function to write this in DataTable Select method in VB.net?SQL Query that I would like useSELECT id from mytable where id in ('a','b','c')
I have this code to create query but it would be nice if I can use IN clause
For Each typeitem In shapecb.Items
If Stntypeitem.Selected = True Then
[code].....
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Mar 28, 2010
I want to filter a virtual table (DataTable) and return only matching items into another datatable which eventualy is the datasource of a datagrid. The datagrid displays the result. The purpose is to reduce the network traffic while still providing the function. So as type on the textbox provided, the virtual table which was earlier populated by a disconnected Ado ADO connection, is re-queried and filtered into the new datatable.
how to go about this. It is a windows application and i am using dot net 3.5, VB 2008.
Here is my code:
Dim filtDT
If MYQDT.Rows.Count <= 0 Then
MsgBox("The data is been cleared")
[Code]....
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Jun 15, 2010
I am trying to use the Select on a datatable and am having some trouble. I got it to find a match on rows in a datatable I fill with data in multiple columns. But I cannot seem to loop through the results to do something with it. Here is my code below. The table is already filled with data.
[Code]...
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May 14, 2011
I have a dataset, which have a column create_date which have value(5/12/2011 12.54.00) , but i want to select the value from dataset with date only not by time (i.e. 5/12/2011),[code]
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