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  • SQL SERVER – Puzzle Involving NULL – Resolve – Error – Operand data type void type is invalid for sum operator

    - by pinaldave
    Today is Monday let us start this week with interesting puzzle. Yesterday I had also posted quick question here: SQL SERVER – T-SQL Scripts to Find Maximum between Two Numbers Run following code: SELECT SUM(data) FROM (SELECT NULL AS DATA) t It will throw following error. Msg 8117, Level 16, State 1, Line 1 Operand data type void type is invalid for sum operator. I can easily fix if I use ISNULL Function as displayed following. SELECT SUM(data) FROM (SELECT ISNULL(NULL,0) AS DATA) t Above script will not throw an error. However, there is one more method how this can be fixed. Can you come up with another method which will not generate error? Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • Why does Linq to Entity Sum return null when the list is empty?

    - by Hannele
    There are quite a few questions on Stack Overflow about the Linq to Entity / Linq to SQL Sum extension method, about how it returns null when the result set is empty: 1, 2, 3, 4, 5, 6, 7, and many more, as well as a blog post discussing the issue here. Now, I could go a flag these as duplicates, but I feel it is still an inconsistency in the Linq implementation. I am assuming at this point that it is not a bug, but is more or less working as designed. I understand that there are workarounds (for example, casting the field to a nullable type, so you can coalesce with ??), and I also understand that for the underlying SQL, a NULL result is expected for an empty list. But because the result of the Sum extension for nullable types is also not nullable, why would the Linq to SQL / Linq to Entity Sum have been designed to behave this way?

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  • Why does Linq to Entity Sum return null when the result set is empty?

    - by Hannele
    There are quite a few questions on Stack Overflow about the Linq to Entity / Linq to SQL Sum extension method, about how it returns null when the result set is empty: 1, 2, 3, 4, 5, 6, 7, and many more, as well as a blog post discussing the issue here. I feel it is an inconsistency in the Linq implementation. I am assuming at this point that it is not a bug, but is more or less working as designed. I understand that there are workarounds (for example, casting the field to a nullable type, so you can coalesce with ??), and I also understand that for the underlying SQL, a NULL result is expected for an empty result set. But because the result of the Sum extension for non-nullable types is also non-nullable, why does the Linq to SQL / Linq to Entity Sum behave this way?

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  • SQL Selects on subsets

    - by Adam
    I need to check if a row exists in a database; however, I am trying to find the way to do this that offers the best performance. This is best summarised with an example. Let's assume I have the following table: dbo.Person( FirstName varchar(50), LastName varchar(50), Company varchar(50) ) Assume this table has millions of rows, however ONLY the column Company has an index. I want to find out if a particular combination of FirstName, LastName and Company exists. I know I can do this: IF EXISTS(select 1 from dbo.Person where FirstName = @FirstName and LastName = @LastName and Company = @Company) Begin .... End However, unless I'm mistaken, that will do a full table scan. What I'd really like it to do is a query where it utilises the index. With the table above, I know that the following query will have great performance, since it uses the index: Select * from dbo.Person where Company = @Company Is there anyway to make the search only on that subset of data? e.g. something like this: select * from ( Select * from dbo.Person where Company = @Company ) where FirstName = @FirstName and LastName = @LastName That way, it would only be doing a table scan on a much narrower collection of data. I know the query above won't work, but is there a query that would? Oh, and I am unable to create temporary tables, as the user will only have read access.

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  • How to iteratively generate k elements subsets from a set of size n in java?

    - by Bea Metitiri
    Hi, I'm working on a puzzle that involves analyzing all size k subsets and figuring out which one is optimal. I wrote a solution that works when the number of subsets is small, but it runs out of memory for larger problems. Now I'm trying to translate an iterative function written in python to java so that I can analyze each subset as it's created and get only the value that represents how optimized it is and not the entire set so that I won't run out of memory. Here is what I have so far and it doesn't seem to finish even for very small problems: public static LinkedList<LinkedList<Integer>> getSets(int k, LinkedList<Integer> set) { int N = set.size(); int maxsets = nCr(N, k); LinkedList<LinkedList<Integer>> toRet = new LinkedList<LinkedList<Integer>>(); int remains, thresh; LinkedList<Integer> newset; for (int i=0; i<maxsets; i++) { remains = k; newset = new LinkedList<Integer>(); for (int val=1; val<=N; val++) { if (remains==0) break; thresh = nCr(N-val, remains-1); if (i < thresh) { newset.add(set.get(val-1)); remains --; } else { i -= thresh; } } toRet.add(newset); } return toRet; } Can anybody help me debug this function or suggest another algorithm for iteratively generating size k subsets? EDIT: I finally got this function working, I had to create a new variable that was the same as i to do the i and thresh comparison because python handles for loop indexes differently.

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  • Use Linq to SQL to generate sales report

    - by Richard Reddy
    I currently have the following code to generate a sales report over the last 30 days. I'd like to know if it would be possible to use linq to generate this report in one step instead of the rather basic loop I have here. For my requirement, every day needs to return a value to me so if there are no sales for any day then a 0 is returned. Any of the Sum linq examples out there don't explain how it would be possible to include a where filter so I am confused on how to get the total amount per day, or a 0 if no sales, for the last days I pass through. Thanks for your help, Rich //setup date ranges to use DateTime startDate = DateTime.Now.AddDays(-29); DateTime endDate = DateTime.Now.AddDays(1); TimeSpan startTS = new TimeSpan(0, 0, 0); TimeSpan endTS = new TimeSpan(23, 59, 59); using (var dc = new DataContext()) { //get database sales from 29 days ago at midnight to the end of today var salesForDay = dc.Orders.Where(b => b.OrderDateTime > Convert.ToDateTime(startDate.Date + startTS) && b.OrderDateTime <= Convert.ToDateTime(endDate.Date + endTS)); //loop through each day and sum up the total orders, if none then set to 0 while (startDate != endDate) { decimal totalSales = 0m; DateTime startDay = startDate.Date + startTS; DateTime endDay = startDate.Date + endTS; foreach (var sale in salesForDay.Where(b => b.OrderDateTime > startDay && b.OrderDateTime <= endDay)) { totalSales += (decimal)sale.OrderPrice; } Response.Write("From Date: " + startDay + " - To Date: " + endDay + ". Sales: " + String.Format("{0:0.00}", totalSales) + "<br>"); //move to next day startDate = startDate.AddDays(1); } }

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  • Same Data Appear only once.

    - by friendishan
    I have the following code which produces following output:- <? $tablaes = mysql_query("SELECT * FROM members where id='$order[user_id]'"); $user = mysql_fetch_array($tablaes); $idsd=$user['id']; $rPaid=mysql_query("SELECT SUM(`price`) AS total FROM order_history WHERE type!='rent_referral' AND date>'" . strtotime($time1) . "' AND date<'" . strtotime($time2) . "'"); $hdPaid = mysql_fetch_array($rPaid); $sPaid=mysql_query("SELECT SUM(`price`) AS total FROM order_history WHERE user_id='$idsd' AND type!='rent_referral' AND date>'" . strtotime($time1) . "' AND date<'" . strtotime($time2) . "'"); while ($hPaid = mysql_fetch_array($sPaid)) { ?> <td><?=$user['username']?></td> <td><?=$hPaid['total']?></td> <? } ?> </tr> It appears like this http://dl.dropbox.com/u/14384295/darrenan.jpg I want same data to appear only once.. Like Username: Vegas and price with him only once.

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  • Numerology with Python And Django

    - by Asinox
    Hi guys, i have a function that give me the result that im expecting in console mode, but if i try to use the function with Django, the page never load and just have a loop calculating and never end. Any idea ? *sorry with my english Console function (WORK GREAT): def sum_digitos(n): sum = 0; while n != 0: sum += n % 10 n /= 10 if sum > 9: x = str(sum) y =list(x) sum = int(y[0]) + int(y[1]) return sum print sum_digitos(2461978) Django views: def Calcular(request): if request.method == 'POST': form = NumerologiaForm(request.POST) if form.is_valid(): sum = 0; ano = str(request.POST['fecha_year']) mes = str(request.POST['fecha_month']) dia = str(request.POST['fecha_day']) data = dia + mes + ano fecha = int(data) while fecha != 0: f = fecha sum += f % 10 f /= 10 if sum > 9: x = str(sum) y =list(x) sum = int(y[0]) + int(y[1]) resultado = get_object_or_404(Numero,numero = sum) return HttpResponseRedirect(resultado.get_absolute_url()) else: form = NumerologiaForm() return render_to_response('numerologiaForm.html',{'form':form})

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  • Extract a subset of XML file using XSL

    - by Lucas -luky- Noleto
    I have this XML file: <Response> <errorCode>error Code</errorCode> <errorMessage>msg</errorMessage> <ResponseParameters> <className> <attribute1>a</attribute1> <attribute2>b</attribute2> </className> </ResponseParameters> </Response> And I want the output to be: <className> <attribute1>a</attribute1> <attribute2>b</attribute2> </className> My current XSL file is including also "ResponseParameters" tag, which I do not want. EDIT: note that the node className is dynamic. I do not know what will be this name at runtime. <?xml version="1.0"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:output indent="yes" /> <xsl:template match="/"> <xsl:copy-of select="//ResponseParameters"> </xsl:copy-of> </xsl:template> </xsl:stylesheet>

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  • Validate subset of a form using jQuery Validate plugin

    - by Andrew Davey
    My HTML form has a number of divs that are the steps of a wizard. Upon clicking a "next" button I want to validate just the active div. I'm using the jQuery.Validate.js plugin. Each div has an ID, so I want a way to say something like: wizardForm.validate().element('#first-step :input') but this only validates the first input, not all of them. How can I validate all inputs within a div?

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  • Hibernate JPA 2.0 CriteriaQuery, subset listing and counting at once

    - by Jeroen
    Hello, I recently started using the new Hibernate (EntityManager) 3.5.1 with JPA 2.0, and I was wondering if it was possible to both retrieve a (sub-set) of entities and their count from a single CriteriaQuery instance. My current implementation looks as follows: class HibernateResult<T> extends AbstractResult<T> { /** * Construct a new {@link HibernateResult}. * @param criteriaQuery the criteria query * @param selector the selector that determines the entities to return */ HibernateResult(CriteriaQuery<T> criteriaQuery, Selector selector, EntityManager entityManager) { CriteriaBuilder builder = entityManager.getCriteriaBuilder(); // Count the entities CriteriaQuery<Long> countQuery = builder.createQuery(Long.class); Root<T> path = criteriaQuery.from(criteriaQuery.getResultType()); countQuery.select(builder.count(path)); final int count = entityManager.createQuery(countQuery).getSingleResult().intValue(); this.setCount(count); // List the entities according to selector TypedQuery<T> entityQuery = entityManager.createQuery(criteriaQuery); entityQuery.setFirstResult(selector.getFirstResult()); entityQuery.setMaxResults(selector.getMaxRecords()); List<T> entities = entityQuery.getResultList(); this.setEntities(entities); } } The thing is that I want to count all entities that match my criteria query, but the count method from CriteriaBuilder only seems to take Expression as argument. Is there any quick way of converting my criteria query to an expression?

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  • Summing / Running totals

    - by John
    I have 4 columns: Name, Week, Batch and Units Produced (Cols, A,b,c,d). In column e, I need to keep running totals based on name and week. When the week changes for the same person, restart the total. Fred, 12, 4001, 129.0 Answer in e: 129.0 Fred, 12, 4012, 234.0 Answer in e: 363.0 Fred, 13, 4023, 12.0 Answer in e: 12.0 John, 12, 4003, 420.0 Answer in e: 420.0 John, 13, 4021, 1200.0 Answer in e: 1200.0 John, 13, 4029, 120.0 Answer in e: 1320.0 I need to be able to copy the formula to over 1000 rows.

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  • LEFT OUTER JOIN SUM doubles problem

    - by Michael
    Hi I've got two tables: Table: Shopping shop_id shop_name shop_time 1 Brian 40 2 Brian 31 3 Tom 20 4 Brian 30 Table:bananas banana_id banana_amount banana_person 1 1 Brian 2 1 Brian I now want it to print: Name: Tom | Time: 20 | Bananas: 0 Name: Brian | Time: 101 | Bananas: 2 I used this code: $result = dbquery("SELECT tz.*, tt.*, SUM(shop_time) as shoptime, count(banana_amount) as bananas FROM shopping tt LEFT OUTER JOIN bananas tz ON tt.shop_name=tz.banana_person GROUP by banana_person LIMIT 40 "); while ($data5 = dbarray($result)) { echo 'Name: '.$data5["shop_name"].' | Time: '.$data5["shoptime"].' | Bananas: '.$data5["bananas"].'<br>'; } The problem is that I get this instead: Name: Tom | Time: 20 | Bananas: 0 Name: Brian | Time: 202 | Bananas: 6 I just don't know how to get around this.

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  • Flex - Drag and drop - Drop a subset of multiple items

    - by flanagann
    I'm developing two DataGrid with drag and drop support. Multiple items can be selected from the source data grid, and dropped into the target data grid. I'm using an drag and drop event listener which completes the operation only in certain cases. I'm using event.preventDefault() but it doesn't work, since it stops the drag and drop from all the items. My aim is, for example, finally dropping 2 elements from the total 4 elements that I previously selected. public function onDropPermission(event:DragEvent):void { var sourceGrid:mx.controls.DataGrid = new mx.controls.DataGrid(); sourceGrid = event.dragInitiator as mx.controls.DataGrid; var targetGrid:mx.controls.DataGrid = new mx.controls.DataGrid(); targetGrid = event.target as mx.controls.DataGrid; var i:int; for (i = 0; i < sourceGrid.selectedIndices.length; i++) { var j:int; for (j = 0; j < dataGroupPermissions.length; j++) { var permission:Permission = new Permission; permission = dataGroupPermissions[j] as Permission; if (permission.id == sourceGrid.selectedItems[i].id) { event.preventDefault(); } } } }

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  • git-svn on subset of large svn repo

    - by an146
    repo layout: a/1 a/2 a/3 ... b/1 b/2 ... c/1 c/2 ... git-svn works perfect for me if I work on 1 svn repo subdir. But right now I'm facing the need to work on several subdirs (like, a/1, a/2, and b/1), and there's much shit in repo besides them. I've managed to write a regexp for this, but git-svn with --ignore-paths seems to check each file's name against this regexp, instead of skipping entire folders, so it's too slow. /* Probably I should file a bug report about this */ So -- any ideas of handling this? If some Mercurial svn agent can do selective clones, it's OK too, but I'd better stick with git. My another idea was some selective svn proxy, but I haven't succeeded in googling anything like that. Thanks!

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  • Is information a subset of data?

    - by Jason Baker
    I apologize as I don't know whether this is more of a math question that belongs on mathoverflow or if it's a computer science question that belongs here. That said, I believe I understand the fundamental difference between data, information, and knowledge. My understanding is that information carries both data and meaning. One thing that I'm not clear on is whether information is data. Is information considered a special kind of data, or is it something completely different?

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  • shell script passing subset of arguments

    - by arav
    From the wrapper shell scripts i am calling the Java program. I want the Unix shell script to pass all the arguments to java program except the EMAIL argument. HOW Can i remove the EMAIL argument and pass the rest of the arguments to the java program. EMAIL argument can come at any position. valArgs() { until [ $# -eq 0 ]; do case $1 in -EMAIL) MAILFLAG=Y shift break ;; esac done } main() { valArgs "$@" $JAVA_HOME/bin/java -d64 -jar WEB-INF/lib/test.jar "$@"

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  • Speedup writing C programs using a subset of the Python syntax

    - by psihodelia
    I am constantly trying to optimize my time. Writing a C code takes a lot of time and requires much more keyboard touches than say writing a Python program. However, in order to speed up the time required to create a C program, one can automatize many things. I'd like to write my programs using smth. like Python but with C semantics. It means, all keywords are C keywords, but syntax is optimized. For example, this C code: #include "dsplib.h" #include "coeffs.h" #define MODULENAME "dsplib" #define NUM_SAMPLES 320 typedef float t_Vec; typedef struct s_Inter { char *pc_Name; struct s_Inter *px_Next; }t_Inter; typedef struct s_DspLibControl { t_Vec f_Y; }t_DspLibControl; void v_DspLibName(void) { printf("Module: %s", MODULENAME); printf("\n"); } int v_DspLibInitInterControl(t_DspLibControl *px_Con) { int y; px_Con->f_Y = 0.0; for(int i=0;i<10;i++) { y += i * i; } return y; } in optimized pythonized version can look like: include dsplib, coeffs define MODULENAME="dsplib", NUM_SAMPLES=320 typedef float t_Vec typedef struct s_Inter: char *pc_Name struct s_Inter *px_Next t_Inter typedef struct s_DspLibControl: t_Vec f_Y t_DspLibControl v_DspLibName(): printf("Module: %s", MODULENAME); printf("\n") int v_DspLibInitInterControl(t_DspLibControl *px_Con): int y px_Con->f_Y = 0.0 for int i=0;i<10;i++: y += i * i return y My question is: Do you know any VIM script, which allows to translate an original pythonized C code into a standard C code? For example, one is writing a C code but uses pythonized syntax, once she decides to translate pythonized blocks into standard C, she selects such blocks and press some key. And she doesn't save such pythonized code of course, VIM translates it into standard C.

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  • MySQL - getting SUM of MAX results from 2 tables

    - by SODA
    Hi, Here's my problem: I have 2 identical tables (past month data, current month data) - data_2010_03, data_2010_04: Content_type (VARCHAR), content_id (INT), month_count (INT), pubDate (DATETIME) Data in month_count is updated hourly, so for each combination of content_type and content_id we insert new row, where value of month_count is incrementally updated. Now I try something like this: SELECT MAX(t1.month_count) AS max_1, MAX(t2.month_count) AS max_2, SUM(max_1 + max_2) AS result, t1.content_type, t1.content_id FROM data_2010_03 AS t1 JOIN data_2010_04 AS t2 ON t1.content_type = t2.content_type AND t1.content_id = t2.content_id WHERE t2.pubDate < '2010-04-08' AND t1.content_type = 'video' GROUP BY t1.content_id ORDER BY result desc, max_1 desc, max_2 desc LIMIT 0,10 I get an error "Unknown column 'max_1' in 'field list'. Please help.

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  • How to calculate running totals of subsets of data in a table

    - by John
    I have 4 columns: Name, Week, Batch and Units Produced (Cols, A,B,C,D). In column E, I need to keep running totals based on name and week. When the week changes for the same person, restart the total. Fred, 12, 4001, 129.0 Answer in e: 129.0 Fred, 12, 4012, 234.0 Answer in e: 363.0 Fred, 13, 4023, 12.0 Answer in e: 12.0 John, 12, 4003, 420.0 Answer in e: 420.0 John, 13, 4021, 1200.0 Answer in e: 1200.0 John, 13, 4029, 120.0 Answer in e: 1320.0 I need to be able to copy the formula to over 1000 rows.

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  • Copying a subset of data to an empty database with the same schema

    - by user193655
    I would like to export part of a database full of data to an empty database. Both databases has the same schema. I want to maintain referential integrity. To simplify my cases it is like this: MainTable has the following fields: 1) MainID integer PK 2) Description varchar(50) 3) ForeignKey integer FK to MainID of SecondaryTable SecondaryTable has the following fields: 4) MainID integer PK (referenced by (3)) 5) AnotherDescription varchar(50) The goal I'm trying to accomplish is "export all records from MainTable using a WHERE condition", for example all records where MainID < 100. To do it manually I shuold first export all data from SecondaryTable contained in this select: select * from SecondaryTable ST outer join PrimaryTable PT on ST.MainID=PT.MainID then export the needed records from MainTable: select * from MainTable where MainID < 100. This is manual, ok. Of course my case is much much much omre complex, I have 200+ tables, so donig it manually is painful/impossible, I have many cascading FKs. Is there a way to force the copy of main table only "enforcing referntial integrity". so that my query is something like: select * from MainTable where MainID < 100 WITH "COPYING ALL FK sources" In this cases also the field (5) will be copied. ====================================================== Is there a syntax or a tool to do this? Table per table I'd like to insert conditions (like MainID <100 is only for MainTable, but I have also other tables).

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  • Express any number as the sum of 4 prime numbers [Doubts]

    - by WarDoGG
    I was give a problem to express any number as sum of 4 prime numbers. Conditions: Not allowed to use any kind of database. Maximum execution time : 3 seconds Numbers only till 100,000 If the splitting is NOT possible, then return -1 What i did : using the sieve of eratosthenes, i calculated all prime numbers till the specified number. looked up a concept called goldbach conjecture which expresses an even number as the summation of 2 primes. However, i am stuck beyond that. Can anyone help me on this one as to what approach u might take ? The sieve of eratosthenes is taking 2 seconds to count primes till 100,000 :(((

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  • Positive result, negative result and current balance. How do you make starting balance show current result?

    - by Tine
    I have 3 columns. Column A shows positive result and if the result is negative then it is in a column B. Column B shows negative result and if the result is positive then it is in a column A. (meaning that either columns can have 0.00 in the cell (empty zero cells)). Column C has starting assets and it also shows the current balance that while result A or B are adding up and current balance is showing the current result. What is the proper formula for this I hope I was clear with my problem. Please help. Thanks in advance!

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  • R: Select subset of dataframe by non-unique ids

    - by amarillion
    Suppose I have a dataframe like this one: df <- data.frame (id = c("a", "b", "a", "c", "e", "d", "e"), n=1:7) and a vector with ids like this one: v <- c("a", "b") How can I select the rows of the dataframe that match the ids in v? I can't use the id column for rownames because they are not unique.

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