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  • [MYSQL] Select users who own both a dog and a cat

    - by matte
    Hi, I have this sample table: CREATE TABLE `dummy` ( `id` int(11) NOT NULL AUTO_INCREMENT, `userId` int(11) NOT NULL, `pet` varchar(50) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ; INSERT INTO `dummy` (`id`, `userId`, `pet`) VALUES(1, 1, 'dog'); INSERT INTO `dummy` (`id`, `userId`, `pet`) VALUES(2, 1, 'cat'); INSERT INTO `dummy` (`id`, `userId`, `pet`) VALUES(3, 2, 'dog'); INSERT INTO `dummy` (`id`, `userId`, `pet`) VALUES(4, 2, 'cat'); INSERT INTO `dummy` (`id`, `userId`, `pet`) VALUES(5, 3, 'cat'); INSERT INTO `dummy` (`id`, `userId`, `pet`) VALUES(6, 4, 'dog'); How can I write the statements below in mysql: Retrieve all users who own both a dog and a cat Retrieve all users who own a dog or a cat Retrieve all users who own only a cat Retrieve all users who doesn't own a cat Thanks!

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  • HTML Chrome Audit Specify Image Dimensions

    - by AKRamkumar
    I just started using the chrome developer tools for some basic html websites and I used the audit tool. I had two identical images, one with the height and width attribute, and one without. On the Resources section, both the latency and the download time were identical. However, the Audit showed Specify image dimensions (1) A width and height should be specified for all images in order to speed up page display. Does this actually help? And are there any other ways to speed up page time? This is only a splash page for the website I am building and as such it is only html, no css or javascript or anything. I have already compressed the images but I want to speed up load time even more. Is there a way?

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  • free sql script to get a list of countries, provinces/states and their cities.

    - by reggie
    I am working on a registration page for a php website as mysql as the backend database. I need a sql script to insert the list of countries with their associated provinces and the provinces with their associated cities. I need all the countries, provinces and cities all over the world which are related to each other. I can get the individual list of countries, provinces and cities but there is no list that relates them together.. any help appreciated.. thanks in advance.

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  • What kind of data processing problems would CUDA help with?

    - by Chris McCauley
    Hi, I've worked on many data matching problems and very often they boil down to quickly and in parallel running many implementations of CPU intensive algorithms such as Hamming / Edit distance. Is this the kind of thing that CUDA would be useful for? What kinds of data processing problems have you solved with it? Is there really an uplift over the standard quad-core intel desktop? Chris

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  • The fastest way to do a collection subtraction

    - by Tony
    I have two Sets. Set<B> b is the subset of Set<A> a. they're both very huge Sets. I want to subtract b from a , what's the best practice to do this common operation ? I've written to many codes like this , and I don't think it's efficient. what's your idea ? for(int i = 0 ; i < a.size(); i++) { for (int j=0 ; j < b.size() ;j++) { // do comparison , if found equals ,remove from a break; } } And I want to find an algorithm , not only applies to Sets, also works for Array.

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  • C++: how to truncate the double in efficient way?

    - by Arman
    Hello, I would like to truncate the float to 4 digits. Are there some efficient way to do that? My current solution is: double roundDBL(double d,unsigned int p=4) { unsigned int fac=pow(10,p); double facinv=1.0/static_cast<double>(fac); double x=static_cast<unsigned int>(x*fac)/facinv; return x; } but using pow and delete seems to me not so efficient. kind regards Arman.

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  • ActionScript - clicking and determining the sprite's class

    - by TheDarkIn1978
    i'd like to add all or most of my mouse events to stage, but in order to do that i need to be able to tell what is the type of the sprite being clicked. i've added two sprites to the display list, one of which is from a class called Square, the other from a class called Circle. var mySquare:Sprite = new Square(); var myCircle:Sprite = new Circle(); addChild(mySquare); addChild(myCircle); now when i click on these sprites, i'd like to know from which class they are from, or which type of sprite it is. //mousePoint returns mouse coordinates of the stage var myArray:Array = stage.getObjectsUnderPoint(mousePoint()); if (myArray[myArray.length - 1] is Sprite) ... so far i know how to do is determine if it IS a sprite display object, but since i'll only be working with sprites i need something more specific. rather than checking "is Sprite", is there a way i can check "is Square" or "is Circle"? if (myArray[myArray.length - 1] is Square)

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  • Simple Python Challenge: Fastest Bitwise XOR on Data Buffers

    - by user213060
    Challenge: Perform a bitwise XOR on two equal sized buffers. The buffers will be required to be the python str type since this is traditionally the type for data buffers in python. Return the resultant value as a str. Do this as fast as possible. The inputs are two 1 megabyte (2**20 byte) strings. The challenge is to substantially beat my inefficient algorithm using python or existing third party python modules (relaxed rules: or create your own module.) Marginal increases are useless. from os import urandom from numpy import frombuffer,bitwise_xor,byte def slow_xor(aa,bb): a=frombuffer(aa,dtype=byte) b=frombuffer(bb,dtype=byte) c=bitwise_xor(a,b) r=c.tostring() return r aa=urandom(2**20) bb=urandom(2**20) def test_it(): for x in xrange(1000): slow_xor(aa,bb)

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  • UPDATE query that fixes orphaned records

    - by Jed
    I have an Access database that has two tables that are related by PK/FK. Unfortunately, the database tables have allowed for duplicate/redundant records and has made the database a bit screwy. I am trying to figure out a SQL statement that will fix the problem. To better explain the problem and goal, I have created example tables to use as reference: You'll notice there are two tables, a Student table and a TestScore table where StudentID is the PK/FK. The Student table contains duplicate records for students John, Sally, Tommy, and Suzy. In other words the John's with StudentID's 1 and 5 are the same person, Sally 2 and 6 are the same person, and so on. The TestScore table relates test scores with a student. Ignoring how/why the Student table allowed duplicates, etc - The goal I'm trying to accomplish is to update the TestScore table so that it replaces the StudentID's that have been disabled with the corresponding enabled StudentID. So, all StudentID's = 1 (John) will be updated to 5; all StudentID's = 2 (Sally) will be updated to 6, and so on. Here's the resultant TestScore table that I'm shooting for (Notice there is no longer any reference to the disabled StudentID's 1-4): Can you think of a query (compatible with MS Access's JET Engine) that can accomplish this goal? Or, maybe, you can offer some tips/perspectives that will point me in the right direction. Thanks.

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  • atomic operation cost

    - by osgx
    Hello What is the cost of the atomic operation? How much cycles does it consume? Will it pause other processors on SMP or NUMA, or will it block memory accesses? Will it flush reorder buffer in out-of-order CPU? What effects will be on the cache? Thanks.

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  • Optimizing Haskell code

    - by Masse
    I'm trying to learn Haskell and after an article in reddit about Markov text chains, I decided to implement Markov text generation first in Python and now in Haskell. However I noticed that my python implementation is way faster than the Haskell version, even Haskell is compiled to native code. I am wondering what I should do to make the Haskell code run faster and for now I believe it's so much slower because of using Data.Map instead of hashmaps, but I'm not sure I'll post the Python code and Haskell as well. With the same data, Python takes around 3 seconds and Haskell is closer to 16 seconds. It comes without saying that I'll take any constructive criticism :). import random import re import cPickle class Markov: def __init__(self, filenames): self.filenames = filenames self.cache = self.train(self.readfiles()) picklefd = open("dump", "w") cPickle.dump(self.cache, picklefd) picklefd.close() def train(self, text): splitted = re.findall(r"(\w+|[.!?',])", text) print "Total of %d splitted words" % (len(splitted)) cache = {} for i in xrange(len(splitted)-2): pair = (splitted[i], splitted[i+1]) followup = splitted[i+2] if pair in cache: if followup not in cache[pair]: cache[pair][followup] = 1 else: cache[pair][followup] += 1 else: cache[pair] = {followup: 1} return cache def readfiles(self): data = "" for filename in self.filenames: fd = open(filename) data += fd.read() fd.close() return data def concat(self, words): sentence = "" for word in words: if word in "'\",?!:;.": sentence = sentence[0:-1] + word + " " else: sentence += word + " " return sentence def pickword(self, words): temp = [(k, words[k]) for k in words] results = [] for (word, n) in temp: results.append(word) if n > 1: for i in xrange(n-1): results.append(word) return random.choice(results) def gentext(self, words): allwords = [k for k in self.cache] (first, second) = random.choice(filter(lambda (a,b): a.istitle(), [k for k in self.cache])) sentence = [first, second] while len(sentence) < words or sentence[-1] is not ".": current = (sentence[-2], sentence[-1]) if current in self.cache: followup = self.pickword(self.cache[current]) sentence.append(followup) else: print "Wasn't able to. Breaking" break print self.concat(sentence) Markov(["76.txt"]) -- module Markov ( train , fox ) where import Debug.Trace import qualified Data.Map as M import qualified System.Random as R import qualified Data.ByteString.Char8 as B type Database = M.Map (B.ByteString, B.ByteString) (M.Map B.ByteString Int) train :: [B.ByteString] -> Database train (x:y:[]) = M.empty train (x:y:z:xs) = let l = train (y:z:xs) in M.insertWith' (\new old -> M.insertWith' (+) z 1 old) (x, y) (M.singleton z 1) `seq` l main = do contents <- B.readFile "76.txt" print $ train $ B.words contents fox="The quick brown fox jumps over the brown fox who is slow jumps over the brown fox who is dead."

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  • A question about complex SQL statement

    - by william
    Table A has columns ID and AName, Table B has columns BName and ID. B.ID is foreign key of A.ID. Write a SQL statement to show data like: print column AName and C which describe whether Table B has ID in Table A, if exists 1 or else 0. So if A is: 1 aaa 2 bbb B is: something,2 output is: aaa,0 bbb,1

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  • LINQ query code for complex merging of data.

    - by Stacey
    I've posted this before, but I worded it poorly. I'm trying again with a more well thought out structure. Re-writing this a bit to make it more clear. I have the following code and I am trying to figure out the shorter linq expression to do it 'inline'. Please examine the "Run()" method near the bottom. I am attempting to understand how to join two dictionaries together based on a matching identifier in one of the objects - so that I can use the query in this sort of syntax. var selected = from a in items.List() // etc. etc. select a; This is my class structure. The Run() method is what I am trying to simplify. I basically need to do this conversion inline in a couple of places, and I wanted to simplify it a great deal so that I can define it more 'cleanly'. class TModel { public Guid Id { get; set; } } class TModels : List<TModel> { } class TValue { } class TStorage { public Dictionary<Guid, TValue> Items { get; set; } } class TArranged { public Dictionary<TModel, TValue> Items { get; set; } } static class Repository { static public TItem Single<TItem, TCollection>(Predicate<TItem> expression) { return default(TItem); // access logic. } } class Sample { public void Run() { TStorage tStorage = new TStorage(); // access tStorage logic here. Dictionary<TModel, TValue> d = new Dictionary<TModel, TValue>(); foreach (KeyValuePair<Guid, TValue> kv in tStorage.Items) { d.Add(Repository.Single<TModel, TModels>(m => m.Id == kv.Key),kv.Value); } } }

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  • Javascript Running slow in IE

    - by SharePoint Newbie
    Hi, Javascript is running extremely slow on IE on some pages in our site. Profiling seems to show that the following methods are taking the most time: (Method, count, inclusive time, exclusive time) JScript - window script block 2,332 237.98 184.98 getDimensions 4 33 33 eh 213 32 32 extend 446 30 30 tt_HideSrcTagsRecurs 1,362 26 26 String.split 794 18 18 $ 717 49 17 findElements 104 184.98 14 What does "JScript - window script block" do? We are using jquery and prototype. Thanks,

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  • Parameterized SQL statements vs. very simple method

    - by Philipp G
    When I started to write the first SQL-Statements in my programs I felt quite comfortable with protecting myself against SQL-Injection with a very simple method that a colleague showed me. It replaced all single quotes with two single quotes. So for example there is a searchfield in which you can enter a customername to search in the customertable. If you would enter Peter's Barbershop The SELECT Statement would look like SELECT * FROM Customers WHERE Customername = 'Peter''s Barbershop' If now an attacker would insert this: ';DROP TABLE FOO; -- The statement would look like: SELECT * FROM Customers WHERE Customername = ''';DROP TABLE FOO;--' It would not drop any table, but search the customertable for the customername ';DROP TABLE FOO;-- which, I suppose, won't be found ;-) Now after a while of writing statements and protecting myself against SQL-Injection with this method, I read that many developers use parameterized statements, but I never read an article where "our" method was used. So definitely there is a good reason for it. What scenarios would parameterized statements cover but our method doesn't? What are the advantages of parameterized statements compared to our method? Thanks Philipp

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  • Slow retrieval of data in SQLITE takes a long using ContentProvider

    - by Arlyn
    I have an application in Android (running 4.0.3) that stores a lot of data in Table A. Table A resides in SQLite Database. I am using a ContentProvider as an abstraction layer above the database. Lots of data here means almost 80,000 records per month. Table A is structured like this: String SQL_CREATE_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_A + " ( " + COLUMN_ID + " INTEGER PRIMARY KEY NOT NULL" + "," + COLUMN_GROUPNO + " INTEGER NOT NULL DEFAULT(0)" + "," + COLUMN_TIMESTAMP + " DATETIME UNIQUE NOT NULL" + "," + COLUMN_TAG + " TEXT" + "," + COLUMN_VALUE + " REAL NOT NULL" + "," + COLUMN_DEVICEID + " TEXT NOT NULL" + "," + COLUMN_NEW + " NUMERIC NOT NULL DEFAULT(1)" + " )"; Here is the index statement: String SQL_CREATE_INDEX_TIMESTAMP = "CREATE INDEX IF NOT EXISTS " + TABLE_A + "_" + COLUMN_TIMESTAMP + " ON " + TABLE_A + " (" + COLUMN_TIMESTAMP + ") "; I have defined the columns as well as the table name as String Constants. I am already experiencing significant slow down when retrieving this data from Table A. The problem is that when I retrieve data from this table, I first put it in an ArrayList and then I display it. Obviously, this is possibly the wrong way of doing things. I am trying to find a better way to approach this problem using a ContentProvider. But this is not the problem that bothers me. The problem is for some reason, it takes a lot longer to retrieve data from other tables which have only upto 12 records maximum. I see this delay increase as the number of records in Table A increase. This does not make any sense. I can understand the delay if I retrieve data from Table A, but why the delay in retrieving data from other tables. To clarify, I do not experience this delay if Table A is empty or has less than 3000 records. What could be the problem?

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  • MySQL to fill in missing dates when using GROUP BY DATE(table.timestamp) without joining on temporar

    - by twmulloy
    Hello, after reading through a couple similar Qs/As I haven't quite found the solution I'm looking for. The table data I have is GROUP BY DATE(timestamp) and returning a count, example result: [timestamp] = 2010-05-12 20:18:36 [count] = 10 [timestamp] = 2010-05-14 10:10:10 [count] = 8 Without using a temporary table, or calendar table is there a way to fill in those missing dates? so that with the same table data would return (adding the bold row): [timestamp] = 2010-05-12 20:18:36 [count] = 10 [timestamp] = 2010-05-13 00:00:00 [count] = 0 [timestamp] = 2010-05-14 10:10:10 [count] = 8 Thanks!

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  • SQL Server lock/hang issue

    - by mattwoberts
    Hi, I'm using SQL Server 2008 on Windows Server 2008 R2, all sp'd up. I'm getting occasional issues with SQL Server hanging with the CPU usage on 100% on our live server. It seems all the wait time on SQL Sever when this happens is given to SOS_SCHEDULER_YIELD. Here is the Stored Proc that causes the hang. I've added the "WITH (NOLOCK)" in an attempt to fix what seems to be a locking issue. ALTER PROCEDURE [dbo].[MostPopularRead] AS BEGIN SET NOCOUNT ON; SELECT c.ForeignId , ct.ContentSource as ContentSource , sum(ch.HitCount * hw.Weight) as Popularity , (sum(ch.HitCount * hw.Weight) * 100) / @Total as Percent , @Total as TotalHits from ContentHit ch WITH (NOLOCK) join [Content] c WITH (NOLOCK) on ch.ContentId = c.ContentId join HitWeight hw WITH (NOLOCK) on ch.HitWeightId = hw.HitWeightId join ContentType ct WITH (NOLOCK) on c.ContentTypeId = ct.ContentTypeId where ch.CreatedDate between @Then and @Now group by c.ForeignId , ct.ContentSource order by sum(ch.HitCount * hw.HitWeightMultiplier) desc END The stored proc reads from the table "ContentHit", which is a table that tracks when content on the site is clicked (it gets hit quite frequently - anything from 4 to 20 hits a minute). So its pretty clear that this table is the source of the problem. There is a stored proc that is called to add hit tracks to the ContentHit table, its pretty trivial, it just builds up a string from the params passed in, which involves a few selects from some lookup tables, followed by the main insert: BEGIN TRAN insert into [ContentHit] (ContentId, HitCount, HitWeightId, ContentHitComment) values (@ContentId, isnull(@HitCount,1), isnull(@HitWeightId,1), @ContentHitComment) COMMIT TRAN The ContentHit table has a clustered index on its ID column, and I've added another index on CreatedDate since that is used in the select. When I profile the issue, I see the Stored proc executes for exactly 30 seconds, then the SQL timeout exception occurs. If it makes a difference the web application using it is ASP.NET, and I'm using Subsonic (3) to execute these stored procs. Can someone please advise how best I can solve this problem? I don't care about reading dirty data... Thanks

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  • Multiple WCF calls for a single ASP.NET page load

    - by Rodney Burton
    I have an existing asp.net web application I am redesigning to use a service architecture. I have the beginnings of an WCF service which I am able to call and perform functions with no problems. As far as updating data, it all makes sense. For example, I have a button that says Submit Order, it sends the data to the service, which does the processing. Here's my concern: If I have an ASP.NET page that shows me a list of orders (View Orders page), and at the top I have a bunch of drop down lists for order types, and other search criteria which is populated by querying different tables from the database (lookup tables, etc). I am hoping to eventually completely decouple the web application from the DB, and use data contracts to pass information between the BLL, the SOA, and the web app. With that said, how can I reduce the # of WCF calls needed to load my "View Orders" page? I would need to make 1 call get the list of orders, and 1 call for each drop down list, etc because those are populated by individual functions in my BLL. Is it good architecture to create a web service method that returns back a specialized data contract that consists of everything you would need to display a View Orders page, in 1 shot? Something like this pseudocode: public class ViewOrderPageDTO { public OrderDTO[] Orders { get; set; } public OrderTypesDTO[] OrderTypes { get; set; } public OrderStatusesDTO[] OrderStatuses { get; set; } public CustomerListDTO[] CustomerList { get; set; } } Or is it better practice in the page_load event to make 5 or 6 or even 15 individual calls to the SOA to get the data needed to load the page? Therefore, bypassing the need for specialized wcf methods or DTO's that conglomerate other DTO? Thanks for your input and suggestions.

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  • Faster integer division when denominator is known?

    - by aaa
    hi I am working on GPU device which has very high division integer latency, several hundred cycles. I am looking to optimize divisions. All divisions by denominator which is in a set { 1,3,6,10 }, however numerator is a runtime positive value, roughly 32000 or less. due to memory constraints, lookup table is not option. Can you think of alternatives? I have thought of computing float point inverses, and using those to multiply numerator. Thanks

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  • What are logical and path queries

    - by NomeN
    I'm reading a paper which mentions that a language for refactoring has three specific requirements. functional features (like ML) logical queries (like Datalog) path queries (like Datalog) I know what they mean by functional features, but I'm not totally clear on the latter two and can't find a clear explanation either. Although I have a good idea after what I could find on the subjects, I need to be sure so here goes: Could the SO-community please clearly explain to me what logical queries and path queries are? Or at the very least what the people from the paper meant?

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  • Lucene search taking TOOO long.

    - by Josh Handel
    I;m using Lucene.net (2.9.2.2) on a (currently) 70Gig index.. I can do a fairly complicated search and get all the document IDs back in 1 ~ 2 seconds.. But to actually load up all the hits (about 700 thousand in my test queries) takes 5+ minutes. We aren't using lucene for UI, this is a datastore between processes where we have hundreds of millions of pre-cached data elements, and the part I am working on exports a few specific fields from each found document. (ergo, pagination doesn't make since as this is an export between processes). My question is what is the best way to get all of the documents in a search result? currently I am using a custom collector that does a get on the document (with a MapFieldSelector) as its collecting.. I've also tried iterating through the list after the collector has finished.. but that was even worse. I'm open to ideas :-). Thanks in advance.

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  • Using TCP Acks to measure latency to a server?

    - by Ted Graham
    I am trying to measure latency to a server that I don't control. This is in a colocated environment, so the latency is on the order of 500 us (.5 ms). I understand that Cisco gear frequently deprioritizes ICMP traffic, making ping times unreliable. Is there a way for me to tell if this is the case on the gear I am traversing? Can I use TCP acknowledgements to determine the minimum latency to the remote server? To do this, I would somehow need to force the remote server to send a TCP ack immediately on receiving my data.

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