DataTable.Compute Function - Grabbing The String Value
Feb 24, 2012
I have an app that contains a DataTable that I must summarize. In that table is a Status column (also the index order) and I want to write a loop in which I compute the count for each status. So I wrote my loop and tried to use the compute function of the Datatable class, but I cannot get it working due to some constraints - specifically this...
[Code]....
You can see what I am doing here is grabbing the string value of the Status column, and then trying to get a count of how many records have that Status. My ultimate goal was to cycle the Table and count each time the status changes. But the error I get has to do with where I store the Status in a String, and then issue the second parameter on the Compute function which contains a variable (sumString) and this is where Compute is crashing - and of course, I can see why - my Status is not literal and thus not in quotes.
Generally speaking, is there any way to manage this kind of thing? In my (very) old FoxPro days one would use a macro such as "Status = &sumString" and VFP would translate sumString to its literal. I have never discovered a way to do that in .NET.
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Feb 24, 2011
this function enables you to calculate a full arithmetic calculation , as 5*(3+2)+6 , but : it's limited with (+,-,*,/) signs . is there any way to add a support for the another signs (like : !,sin,cos,tan,root,^,log and another signs) to give the user the ability to calculate a full calculation including the other signs which cannot be calculated within the compute.datatable function ?
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Jul 20, 2011
I need to round the result from compute.8/19, how can i round this result to two decimal.Is there any symbol i can use for compute function to recognize the rounding format, because not must be two decimal,sometime may one or in integer?
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Mar 21, 2012
I do have the following problem extracting records from a datatable, based on date.
I am using Datatable.compute to sum the relevant rows, at least I'm trying to!
CrTot is a variable of type double
BankTrans is a datatable
dteRecDte is a datetimepicker component
CrTot = BankTrans.Compute("sum(bank_amount)",
"bank_amount > 0 And date_bank_reconciled <="
& dteRecDte.Value.Date)
doing the sum calculation on it's own works properly. I now need to check that the date of the "date_bank_reconciled" field is less than or equal to the value of the date entered in the datetimepicker "dteRecDte.Value.Date", so that only rows with a date either less than or the same as that in the datetimepciker are returned.
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Oct 25, 2009
I need help with this line of code: Me.avgsalespricetxt.Text = Me.dtsold.Compute("AVG(Convert([Selling Price]),'System.Int32'))")
Here is all the code i have so far, I need to Average a column in my datatable from what i have read "Compute method supports expressions and they support CONVERT function that you could use inside of the expression."
[Code]...
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Mar 16, 2009
I am using datatable.comput to calculate the avg of a data column. The data column's datatype = integer, so it returns a integer avg value as well. Can i make it to return double value?
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Aug 22, 2010
I have forums and it has a name on it in the smae place evry time no matter which userpage im on.
HTML
<dl class="stats">
<dt>Gamertag</dt>
<dd>Yoshi910</dd>
</dl>
the Name is always under Gamertag. Is there a way for me to Grab that name in .net
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May 14, 2009
I want to calculate variance of a col in my datatable object. If i apply datatable.compute(Var(...)), i gives a negative result. Variance can't be negative. And it I just apply it to half of the data, it works fine. Does datatable.compute has a limited capacity?
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Feb 28, 2010
I have a datatable with 2 columns named TimeStamp and value. After I populate the table with rows, I am using the table's compute method to get the max value like this....
MyTable.Compute("MAX(value)", Nothing)
Is there is a way to get the row (or more specifically the TimeStamp value) where the max was found?
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Nov 25, 2009
I'm currently grabbing HTML from my site using webrequest and storing it in a string. I'm looking to take this string, and scrape all of the prices in order to calculate this against my cost price (for a consistent profit spreadsheet). What is the most feasible way to do this? Would using a webbrowser control be a better idea?
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Mar 17, 2009
I have a column: {2,2,null}. If i use datatable.compute to compute the avg of this column, will it return 2 or 1.66? In another word, will this function ignore the null value?
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Jun 24, 2011
I have a string that contains multiple instances of a dollar sign followed by a positive number. I need to grab each instance out using regex. Here's an example of a string:
"This that $1 who $2" Here's what I have so far using vb.net: Dim wordSplitMatches As Match = Regex.Match("This that $1 who $2", "($d+)+")This works great for grabbing the $1 but how do I set it up so that I get multiple groups with all the matches in?
[Code]...
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Apr 11, 2011
I have the following function so far and I dont know how to continue
Public Function getdetails(ByVal id as Integer) as Data.DataTable
Dim query as string
Dim mydatatable as Data.DataTable = new Data.DataTable()
[code]....
basically I am using to C# and just learning vn.net..What I want to do is save the information t,id and t.color in a datatable in vb.net..How do i do that.
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Jul 24, 2009
I import my records into dataset1.table(0) I have invoice line items in dataset1 I want the total of all line items for a specific invoice# So I get SUM(col1 * col2) **WHERE invoice# = StrVarInvoice#?
For Each dataRow As DataRow In DataSet1.Tables(1).Rows
netamt = DataSet1.Tables(0).Compute("SUM(unitprce * quantity)", String.Empty)
Next
'My Try but is there a better way?? ? Do I have to loop through all records?
For Each dataRow1 As DataRow In DataSet1.Tables(1).Rows
If dataRow("invoice#") = StrVarInoivce# Then
netamt = DataSet1.Tables(0).Compute("SUM(unitprce * quantity)", String.Empty)
totamt = totamt + netamt
Next
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May 13, 2012
i create a Class to update data from remote sql server to local compact sql server data. I write two method one method check if any update date in remote server method like..[code]Last i Call SaveLocalDatabase method. But When i check table in my local compact sql server database there has no data update.is any think missing to write. i Think i found a problem. i use LocalTable.Merge(dTable, True). When Merge Call then rowstate remain unchange.
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Nov 8, 2011
I have a custom DropDownField for a GridView. I have to specify the DataSourceMethod property to the name of a function. I can not use a SqlDataConnector object. I want to take the name of the function (e.g.MyNamespace.MyClass.GetYears) and get the resulting object and assign it to a DropDownList data source.I know I will need to use the CallByName function
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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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Jun 13, 2011
I have 1 string : abc @#ABC.xyz123ZYX
Now I need to encode the string:
The encoding alphabetic characters,
CODE:
With this string, after encoding, the result is: zyx @#ZYX.cba123ABC
About Function Encrypt and Function Decrypt?
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Aug 21, 2009
Some programs implement command parameters, Like my favourite computer game - Crysis - has them and windows media player has them.But how could i implement them in VB.NET..I want to have a component of my program built as a seperate exe - so it can be an Optional component.But of course the seperate exe, on load, needs data passing to it.So i need something like Process.start("Componentname.exe", "/StartDL <Suchandsuchastring>)/StartDL will need to call a function, and the string that it uses will be given to the function to initiate a download?
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May 17, 2010
I have a function that converts a .csv file to a datatable. One of the columns I am converting is is a field of names that have a comma in them i.e. "Doe, John" when converting the function treats this as 2 seperate fields because of the comma. I need the datatable to hold this as one field Doe, John in the datatable.
Function CSV2DataTable(ByVal filename As String, ByVal sepChar As String) As DataTable
Dim reader As System.IO.StreamReader
Dim table As New DataTable
Dim colAdded As Boolean = False
[Code]...
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Jul 29, 2010
I have two functions in a class. One function returns a datatable, the other one returns a dataset. Both functions are identical except of the return type (Datatable or dataset). I would like to have only one function which returns either dataset or datatable depending on what the user of the class wants. How can I do this.
Following code shows my function returning a datatable:
Public Shared Function ExecuteSPDatatable(ByVal storedProcedure As String, ByVal ParamArray parameters() As SqlParameter) As DataTable
Dim tbl As DataTable
[Code].....
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Jun 15, 2010
This is bug in VB 2008
Dim dsExpre as New DataTable
Table has Two Fields (ExprID, Expression)
112,xyz
113,abc
Private Sub..........
Dim rsExpr as DataRow=Nothing
Dim i as Integer
[Code] .....
The Problem is, When i becomes 2, Table Data also becomes "q", Why....?
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Oct 6, 2009
Datatable object within class function + garbage collection?
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Feb 4, 2010
The following output produces a string with no closing xml tag. m_rFlight.Layout = m_rFlight.Layout + "<G3Grid:Spots>" + Me.gvwSpots.LayoutToString() + "</G3Grid:Spots>"
This following code works correctly
m_rFlight.Layout = m_rFlight.Layout + "<G3Grid:Spots>" + Me.gvwSpots.LayoutToString()
m_rFlight.Layout = m_rFlight.Layout + "</G3Grid:Spots>" 'add closing tag
What's going on here, what's the reason the first example isnt working and the second is?
The gvwSpots.LayoutToString() function returns a string.
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Mar 7, 2012
I've been looking at threading to make my webapplications more responsive. I've found out how to thread a sub that takes no variables and doesn't return anything, but I can't find out how to achieve this for a function that takes variables and returns something. here is an example
[Code]...
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Sep 27, 2010
When I declare two datatables and fill them both from a datatable returned by a function in class, that when i filter the one it seems to filter the other aswell?
For example:
I declare the datatable and initiate my class:
Dim DatatableOne As New Datatable
Dim DatatableTwo As New Datatable
Dim MyClass As New MyClass
I then call the function that returns a datatable and apply it to datatable1 and 2 Then fill two DataGrids with the table:
DatatableOne = MyClass.GetTable()
DatatableTwo = MyClass.GetTable()
DatatableOne.DefaultView.RowFilter = "Name = 'Tom'"
[CODE]...
For some reason i don't understand but both grids end up with the filtered data?
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Dec 20, 2010
string function(s) to change only first letter of string to Upper Case?
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Jul 29, 2011
I want the Function to accept List(Of String), Array & String and similarly return List(Of String), Array & String respectively. The Function simply adds a string (month) to the input collection. I just want to use it for string, array and list with needing to think of conversions.
[Code]...
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May 14, 2009
I'm following this tutorial: [URL]..except I'm connecting to my own data source - a MS Access database.This is the query I have setup with the dataset:
SELECT Terminal_ID, SUM(Transaction_Quantity) AS Total
FROM tblTransaction
WHERE TransactionType_ID=3 and Transaction_DateTime>[@fromdate]
GROUP BY Terminal_ID
The debug fails immediately because it needs the extra parameter so I change the code from:
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'tetrisDataSet.tblTransaction' table. You can move, or remove it, as needed.
Me.tblTransactionTableAdapter.Fill(Me.tetrisDataSet.tblTransaction)
[code].....
The error I get on build is:Too many arguments to 'Public Overridable Overloads Function Fill(dataTable As tetrisDataSet.tblTransactionDataTable) As Integer
...I gave it the extra parameter, so what gives? Something special I need to do as it's a datetime field?
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Nov 4, 2010
If I have a string Metal is hot : Metal length is 5 cm ; Metal is red. I want to get the sub string that is talking about length: hence I want to extract "Metal length is 5 cm".
[Code]...
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