LINQ Statement Where Result Count Is Used In Expression's Condition?
Mar 23, 2009
I have a requirement where I have to add items into a List(Of T) (let's call it Target) from an IEnumerable(Of T) (let's call it Source) using Target.AddRange() in VB.NET.
Target.AddRange(Source.TakeWhie(Function(X, Index) ?))
The ? part is a tricky condition that is something like: As long as the as yet unenumerated count is not equal to what is needed to fill the list to the minimum required then randomly decide if the current item should be taken, otherwise take the item.Somethig like...
Source.Count() - Index = _minimum_required - _curr_count_of_items_taken _
OrElse GetRandomNumberBetween1And100() <= _probability_this_item_is_taken
' _minimum_required and _probability_this_item_is_taken are constants
The confounding part is that _curr_count_of_items_taken needs to be incremented each time the TakeWhile statement is satisfied. How would I go about doing that? I'm also open to a solution that uses any other LINQ methods (Aggregate, Where, etc.) instead of TakeWhile.If all else fails then I will go back to using a good old for-loop =)
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Nov 2, 2010
I have added a column to a Datatable called CallsPerDay which is there to tell me how many telephone calls have been made on a particular day or days.Is there a datacolumn.expression which will allow me to Filter on the day, count the rows and then populate this added column with the result.
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Jan 25, 2012
What I have right now is this:
Dim users = From users In tempTable _
Distinct Select users.Item("s_userid")
Dim usersCount As Integer = users.Count
But I pretty sure I shouldn't have to do that. I should be able to get the count in/from that first linq query.
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Jun 16, 2011
I have something that I want to do and what looks very simple, but I cannot get it to work. I want to build a function that gets as input a xdocument and some other strings. It should have a return that contains a filtered part of the xdocument in a way that I can use it as input for a new Linq function. This is what I mean:
Private Function fncGetFilteredDecendantsOfNode(ByVal xdocDoc As XDocument, _
[Code]...
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Sep 15, 2010
Can a LINQ or a LAMBDA expression be used to count the 1's in a binary string ?For example, if I convert a number to its BINARY using.>>
Dim binaryString As String = Convert.ToString( numberVariable, 2 )
1) Without using a loop such as a FOR NEXT loop, can I count the number of 1's in the STRING using LINQ or a LAMBDA expression?
2) Can I get the indexes of where the 1's are at in a collection such as a LIST using LINQ or a LAMBDA expression?I know the syntax of some LINQ expressions, however, I don't know which method may be suitable.
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Dec 17, 2010
I have a stored procedure that repeats a block of T-SQL statements using WHILE logic until it finds a matching record in a table. When I execute the procedure directly from the SQL Management Studio, it works and returns a record, even when the statements within the WHILE logic have to be repeated over and over again before a matching record is found.
However, when I use the same stored procedure as the commandtext property of an sqlcommand object in Visual Studion 2008 (VB) and call the executereader method of the sqlcommand, the resulting SqlDataReader will only return a row if the T-SQL statements within the WHILE logic find a matching record after a single pass. If it takes more than one pass to find a matching record the SqlDataReader does not return a row. It's like it abandons the execution of the stored procedure after the first pass of the statements within the While logic, disregarding the repetition.
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Jan 1, 2010
I was convinced that If <expression> Then <statement [:statement]> Else [statements] in concrete form of If a = b Then SayHello() Else SayBye() End has sense. I read article on msdn on If-then-else, but I forgot why I was reading, so I concluded, that snippet above means this
If a = b Then HelloIsSaid : IsNotEnded Else ByeIsSaid : IsEnded But I have tested it now, and I see, that Else without statement is nothing more than decoration. It would be pretty good if it had function I described. Do you think its good request? Or do you know any circumstance where this Else has some function?
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Jan 7, 2010
I have a dataset that I search using the
dataset.tables("table").Select("WHERE clause")
method to query. I then use a datarepeater to display the results. Is there a way to programatically tell if no results are returned? I'm aware of the Dataset.tables.Rows.count, but can this be done after the select method?
[Code]...
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Jun 24, 2011
I am developing a VB.NET ASPX file and am trying to run a string query in VB.NET, but now I get the above error message. How can I determine the cause? Some of the code in this
[Code]...
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Jun 16, 2010
I think im going mad but can some show me what im missing, it must be some stupidly simple i just cant see the wood for the trees.BOTH side of this if then else statement are being executed?
Ive tried commenting out the true side and moving the condition to a seperate variable with the same result. However if i explicitly set the condition to 1=0 or 1=1 then the if then statement is operating as i would expect. i.e. only executing one side of the equation...
The only time ive seen this sort of thing is when the compiler has crashed and is no longer compiling (without visible indication that its not) but ive restarted studio with the same results, ive cleaned the solution, built and rebuilt with no change?
Dim dset As DataSet = New DataSet
If (CboCustomers.SelectedValue IsNot Nothing) AndAlso (CboCustomers.SelectedValue <> "") Then
Dim Sql As String = "Select sal.SalesOrderNo As SalesOrder,cus.CustomerName,has.SerialNo,
[code]....
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Feb 25, 2010
I need to write an sql statement that has an IF condition in it
This is my current statment:
"SELECT * From History Where DelNoteNum = " & delNote & " ORDER BY StockLoc"
What I need to do though is if the StockLoc > 4000 then group by ProductCode. I definatly only need to do this if the stock location is greater than 4000 though.
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Jun 16, 2010
i want to make condition statement in my function. i use this method : [code]if i try to insert a data already in the database, the function will directly go to the updateDatabase()the problem is, if i try to insert the data that currently not in the database, the function will directly go to update database as well.
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Mar 23, 2009
My code is:
CODE:
Now i want to know can i use select case instead of if (condition)statement in this code?
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Mar 26, 2009
I'm not reciving any errors at all this is Still my homework on the Compound Intrest and it's due tommarow and well an if statement isn't working
Private Sub btnCalc_Click(ByVal sender As Object, _
ByVal e As EventArgs) Handles btnCalc.Click
Dim decAmount As Decimal = 0D
[Code].....
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Aug 25, 2011
Whats wrong with the below query, I am getting this error: Nullable object must have a value.
[Code]...
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Sep 3, 2010
I want to filter records dynamically on user choice. The user may choose to show the debit amount greater than credit or credit amount greater than debit. Accordingly I want to put a condition similar to either totDebit>totCredit orTotCredit>totDebit`
Dim query = _
From product In Bills.AsEnumerable() _
Group product By accode = product.Field(Of String)("ACCODE"), _
[Code]....
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May 4, 2011
I have a IF statement which is checking each row in the data table (for a match) and ELSE statement with commands which are executed if the If statement is not satisfied. Now I would like to write like so that it goes to the Else part BUT ONLY for values which are not satisfied in the IF statement. If I am more specific; I would like to calculate values if a match is found and just print them if it is not fond (usually there are both cases). Now the problem is the bold text; if there is a match found I don't want it processed BUT if the match is found I do. How can I write that?
currencyPosition = 0
Dim d As Integer = w + 100
For Each currency In Ary
[CODE]..........................
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Jun 24, 2011
I have the following SQL:
[Code]...
I want to put it (the select count statement) in this LINQ statement so I can get the sales count in my linq statement: Dim TheLeads = (From L In DB.Leads Where L.IsDeleted = False Select L).ToList() Is this possible to do in LINQ?
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Aug 19, 2010
I'm basically trying to emulate a query like the below in LINQ:
DECLARE @id INT
SET @id = 1
SELECT
q.txtLQRdisplayName AS DisplayName,
[code]....
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Jun 22, 2011
How to update columns in datatable using linq without conditions. I have an idea that I'm just gonna loop all the data in the datatable but don't know what comes in LINQ.
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Mar 22, 2011
I have a form that contains multiple conditional or if statements on several defferent for controls.
Example: Radio Buttons, TextBoxes and CheckBoxes.
I am intending to create an order form(demo) where the user can select multiple products.
I have a default order number that changes by one everytime an order is successful.
An order is only successful if all the information on the form is entered correctly.
My question is where do I insert the code for the order number?
Basically for the order number I have a counter that count by increment of one if an order is successful.
Meaning when the user hit place order, and all the infromation is right, then the order numer goes to 1 from zero.
Where do I add the condition for the order number since all the fields must first be completed.
Do I have to create a whole line of if else statements?
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Oct 11, 2011
Im trying to get the result of an SQL statement and store it in an integer variable "count" in vb so it can then be displayed on my website showing the user the total Open records:SELECT COUNT (recordID) FROM [tbl_Records] WHERE [Status] = 'Open'
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Dec 24, 2011
I've been working with my project. I make a quiz and I put check value for every label. If the user is correct the label with shows or else the label is in a hide status. My problem now is how do I count those labels to display his/her result. If there are 3 labels shown in the form in automatically the user got 3 points and that "3" with be put into a textbox...
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Nov 30, 2011
I am doing a sql statement to get all the data that starts with "A" in the database.
[Code]...
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Dec 1, 2011
I need to count the number of:
[Code]...
Can Regular Expression be used of this purpose? It's okay if they're in separate function, but I need to somehow get the counts of each of the above.
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Aug 16, 2010
I want to execute an SQL statement and put the result in to a data table.
Sub getvehicletypes()
Dim dt As New DataTable
Dim intLine As Integer = 0
[Code].....
Once Ive got it in a dataset I need to work out how to search the dataset for a code and return the corresponding description and vice versa
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Jul 31, 2010
I'm relatively new to VB. I want to perform a SELECT statement that uses a variable to return a value, example;
mysql> SELECT room_description FROM room_descriptions WHERE current_room = 'someVariable';
And display the result in a TextBox i.e. TextBox.text = someVariable.
So how do I perform a query from VB that passes a variable? How do I assign the result to a variable?
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Apr 11, 2012
I'm having trouble with a null result, when I compare the query it said I cant it give the following error "sequence contains no elements"
Dim existe = (
p In abc.Ventadetalles
Where p.idarticulo = txtArticulo.Text
[code].....
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May 8, 2011
i have a table with data title and date of the data inserted.and right now i want to do count to make the statistic out of it.can i do multiple count in one sql statement?like from, the column date, i want to count how many on this month, and how many in this year, until month selected. this is what i have come up, for now.
SELECT a.trigger_type_code
, c.trigger_name
, COUNT(*) AS number
FROM issue_trigger a
[code]....
by this is only for one count.
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Dec 1, 2010
I want to display an image if 2 conditions are met. The data item is not null. The value of the data item is greater than 0 Markup
<img id="Img1" runat="server" visible='<%#IIF( DataBinder.Eval(Container.DataItem, "amount") is DBNull.Value Or DataBinder.Eval(Container.DataItem, "amount") = 0, False, True)%>' src="/Images/check.png" />
Error message: Operator '=' is not defined for type 'DBNull' and type 'Integer'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.InvalidCastException: Operator '=' is not defined for type 'DBNull' and type 'Integer'.
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