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• group by with 3 diffrent

  - by NN

  I have 2 table and I wanna a query with 3 column result in on of them 2 column with view count and title name and in the other 1 column with type_ and i wanna to grouping type_ with max(view count) and show the them title but i didn't have any idea about grouping expression. i think we can solve in by using sub query but i don't know which column use in group by. 2 table join with this expression class pk=resource key i exam this query: SELECT t.title,j.type_ FROM tags asset t,journal article j where type_ in (select type_ from journal article,tags asset where class pk=resource key group by type_) but the answer was wrong

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• How to retrieve Google Appengine Objects by id (Long value) ?

  - by David

  Hi, i have declared an entity the following way: public class MyEntity { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Long id; @Persistent private String text; //getters and setters } Now I want to retrieve the objects using the id. I tried to manage it from the Google Appengine Data Viewer with "SELECT * FROM MyEntity Where id = 382005" or via a query in a servlet. I get no results returned. But i know for sure that the object with the id exists (i made a jsp which queries all objects in the db and displays them in the db). So what is wrong in my query? Am I querying the wrong field? The Google Appengine Data Viewer names the field "ID/name" and it has the value "id=382005". Do I have to query with this names? I've tried but it didn't work out :(

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• Get result from mysql orderd by IN clause

  - by SchlaWiener

  I have the following query SELECT * FROM invoice WHERE invoice_id IN (13, 15, 9, 27) My result is: invoice_id | invoice_number | ... ------------------------------------ 9 | 201006003 | 13 | 201006020 | 15 | 201006022 | 27 | 201006035 | which is the result set I want except that is ordered by the invoice_id (which is an autoincrement value). Now I want the result in the order I specified in my query (13, 15, ...). Is there a way to achive that? The background is that I have a DataTable bound to a DataGridView. The user can filter and sort the result but if he want's to print the result I don't use the DataTable for printing because it only contains the most important columns and instead I pull the whole records from the database and pass it to my printing control. I also tried to extend the existing DataTable with the missing results but that seems to slower than using the IN (...) query.

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• advanced search with mysql

  - by Arsenal

  I'm creating a search function for my website where the user can put in anything he likes in a textfield. It get's matched against anything (name, title, job, car brand, ... you name it) I initially wrote the query with an INNER JOIN on every table that needed to be searched. SELECT column1, column2, ... FROM person INNER JOIN person_car ON ... INNER JOIN car ... This ended up in a query with 6 or 8 INNER JOINs, and a whole lot WHERE ... LIKE '%searchvalue%' Now this query seems to cause a time'out in MySql, and I even got a warning from my hosting provider that the queries just taking up too many resources. Now obviously I'm doing this very wrong, but I was wondering how the correct approach to these kind of search functions is. Thanks!

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• Group by clause return latest row information

  - by I Like PHP

  below is my table structure table_movie_info i_movie_id |movie_actor_id |movie_actress_id |movie_director_id | movie_producer_id 48 | 5 | 9 | 66 | 21 48 | 6 | 15 | 88 | 22 48 | 7 | 12 | 77 | 23 one more table is table_movie movie_id | movie_year | movie_genre_id |movie_rating 1 | 2009 | 6 | 8 2 | 2001 | 5 | 7.5 48 | 2007 | 3 | 6.8 now i need total movie information using both table,i write below query SELECT * FROM table_movie_info LEFT JOIN table_movie ON movie_id = i_movie_id WHERE i_movie_id=48 GROUP BY i_movie_id above query return only one row , but i need such type of information movie_id=48, actors_id list=5,6,7 acttress_id list=9,15,12 etc.. please tell me the optimized query which h return complete information i need. thanks for helping me always.

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• Querying Same Lookup Table With Multiple Columns

  - by dmaruca

  I'm a bit confused on this. I have a data table structured like this: Table: Data DataID Val 1 Value 1 2 Value 2 3 Value 3 4 Value 4 Then I have another table structured like this: Table: Table1 Col1 Col2 1 2 3 4 4 3 2 1 Both columns from Table1 point to the data in the data table. How can I get this data to show in a query? For example, a query to return this: Query: Query1 Column1 Column2 Value 1 Value 2 Value 3 Value 4 Value 4 Value 3 Value 2 Value 1 I'm familiar enough with SQL to do a join with one column, but lost beyond that. Any help is appreciated. Sample sql or a link to something to read. Thanks! PS: This is in sqlite

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• MySQL AND alternative for eatch table in a join

  - by Scott

  I have a simple join in a query however I need to have a condition on both of the tables "confirmed='yes'" but if one of the tables doesn't have any that match the query returns with no rows. Database: .----------parties----------. | id - party_id - confirmed | |---------------------------| | 1 1 yes | | 1 2 no | | 1 3 no | +---------------------------+ .-----------events----------. | id - event_id - confirmed | |---------------------------| | 1 1 no | +---------------------------+ Query: SELECT p.party_id, e.event_id FROM parties p LEFT JOIN events e ON p.id=e.id WHERE p.id = '1' AND p.party_id IN (1,2,3) AND e.event_id IN (1) AND p.confirmed='yes' AND e.confirmed='yes' It returns nothing but I want it to return party_id 1 with a empty event_id. I hope this make sense and I not missing anything, Thanks for your help!

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• MySQL AND alternative for each table in a join

  - by Scott

  I have a simple join in a query however I need to have a condition on both of the tables "confirmed='yes'" but if one of the tables doesn't have any that match the query returns with no rows. Database: .----------parties----------. | id - party_id - confirmed | |---------------------------| | 1 1 yes | | 1 2 no | | 1 3 no | +---------------------------+ .-----------events----------. | id - event_id - confirmed | |---------------------------| | 1 1 no | +---------------------------+ Query: SELECT p.party_id, e.event_id FROM parties p LEFT JOIN events e ON p.id=e.id WHERE p.id = '1' AND p.party_id IN (1,2,3) AND e.event_id IN (1) AND p.confirmed='yes' AND e.confirmed='yes' It returns nothing but I want it to return party_id 1 with a empty event_id. I hope this make sense and I not missing anything, Thanks for your help!

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• Mongo: Finding from multiple queries

  - by waxical

  New to Mongo here. I'm using the PHP lib and trying to work out how I can find in a collection from multiple queries. I could do this by repeating the query with a different query, but I wondered if it can be done in one. I.e. $idsToLookFor = array(2124,4241,5553); $query = $db->thisCollection->find(array('id' => $idsToLookFor)); That's what I'd like to do. However it doesn't work. What I'm trying to do is find a set of results for all the id's at one time. Possible or just do a findOne on each with a foreach/for?

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• SharePoint 2010 search crawl not working

  - by J. Hammond

  I have the following set up: 1 x Windows server 2008 R2 running SQL 1 x Windows server 2008 R2 running SharePoint 2010. I have an issue with the search service application, the crawl appears to run for a never ending amount of time with 0 successes and 0 failures. Checking the Search Application Topology, I find that "Query Component 0" is "Not Responding". I have tried the following: I have ensured that the index directory has the right permissions applied to it and the search service account is in the right groups to consume those permissions. I have re-created the search service application. I have restarted the search service manually. I have trawled the net as much as possible to find a solution but as of yet have not come across something that has resolved this issue. Any input will be very much appreciated

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• Al Zimmermann's Son of Darts

  - by polygenelubricants

  There's about 2 months left in Al Zimmermann's Son of Darts programming contest, and I'd like to improve my standing (currently in the 60s) to something more respectable. I'd like to get some ideas from the great community of stackoverflow on how best to approach this problem. The contest problem is known as the Global Postage Stamp Problem in literatures. I don't have much experience with optimization algorithms (I know of hillclimbing and simulated annealing in concept only from college), and in fact the program that I have right now is basically sheer brute force, which of course isn't feasible for the larger search spaces. Here are some papers on the subject: A Postage Stamp Problem (Alter & Barnett, 1980) Algorithms for Computing the h-Range of the Postage Stamp Problem (Mossige, 1981) A Postage Stamp Problem (Lunnon, 1986) Two New Techniques for Computing Extremal h-bases Ak (Challis, 1992) Any hints and suggestions are welcome. Also, feel free to direct me to the proper site if stackoverflow isn't it.

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• Error: Can't find common super class of ...

  - by PatlaDJ

  I am trying to process with Proguard a MS Windows desktop application (Java 6 SE using the SWT lib provided by Eclipse). And I get the following critical error: Unexpected error while performing partial evaluation: Class = [org/eclipse/swt/widgets/DateTime] Method = [<init>(Lorg/eclipse/swt/widgets/Composite;I)V] Exception = [java.lang.IllegalArgumentException] (Can't find common super class of [java/lang/StringBuffer] and [org/eclipse/swt/internal/win32/TCHAR]) Error: Can't find common super class of [java/lang/StringBuffer] and [org/eclipse/swt/internal/win32/TCHAR] ---------------------------- When I tried to Google the error, it came out only on two spots on the entire web, that astonished me greatly. I am newbie using Proguard and Java code optimization tools at all. Any thoughts and suggestions how to fix this, will be appreciated. Thanks in advance.

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• what is the best way to generate fake data for classification problem ?

  - by Berkay

  i'm working on a project and i have a subset of user's key-stroke time data.This means that the user makes n attempts and i will use these recorded attempt time data in various kinds of classification algorithms for future user attempts to verify that the login process is done by the user or some another person. (Simply i can say that this is biometrics) I have 3 different times of the user login attempt process, ofcourse this is subset of the infinite data. until now it is an easy classification problem, i decided to use WEKA but as far as i understand i have to create some fake data to feed the classification algorithm. can i use some optimization algorithms ? or is there any way to create this fake data to get min false positives ? Thanks

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• Is there any way to get MSVC to pass structs arguments in registers on x64?

  - by Luke

  For a function with signature: struct Pair { void *v1, *v2 }; void f(Pair p); compiled on x64, I would like Pair's fields to be passed via register, as if the function was: void f(void *v1, void *v2); Compiling a test with gcc 4.2.1 for x86_64 on OSX 10.6, I can see this is exactly what happens by examining the disassembly. However, compiling with MSVC 2008 for x64 on Windows, the disassembly shows that Pair is passed on the stack. I understand that platform ABIs can prevent this optimization; does anyone know any MSVC-specific annotations, calling conventions, flags, or other hacks that can get this to work? Thank you!

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• MySQL MyISAM table performance... painfully, painfully slow

  - by Salman A

  I've got a table structure that can be summarized as follows: pagegroup * pagegroupid * name has 3600 rows page * pageid * pagegroupid * data references pagegroup; has 10000 rows; can have anything between 1-700 rows per pagegroup; the data column is of type mediumtext and the column contains 100k - 200kbytes data per row userdata * userdataid * pageid * column1 * column2 * column9 references page; has about 300,000 rows; can have about 1-50 rows per page The above structure is pretty straight forwad, the problem is that that a join from userdata to page group is terribly, terribly slow even though I have indexed all columns that should be indexed. The time needed to run a query for such a join (userdata inner_join page inner_join pagegroup) exceeds 3 minutes. This is terribly slow considering the fact that I am not selecting the data column at all. Example of the query that takes too long: SELECT userdata.column1, pagegroup.name FROM userdata INNER JOIN page USING( pageid ) INNER JOIN pagegroup USING( pagegroupid ) Please help by explaining why does it take so long and what can i do to make it faster. Edit #1 Explain returns following gibberish: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE userdata ALL pageid 372420 1 SIMPLE page eq_ref PRIMARY,pagegroupid PRIMARY 4 topsecret.userdata.pageid 1 1 SIMPLE pagegroup eq_ref PRIMARY PRIMARY 4 topsecret.page.pagegroupid 1 Edit #2 SELECT u.field2, p.pageid FROM userdata u INNER JOIN page p ON u.pageid = p.pageid; /* 0.07 sec execution, 6.05 sec fecth */ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE u ALL pageid 372420 1 SIMPLE p eq_ref PRIMARY PRIMARY 4 topsecret.u.pageid 1 Using index SELECT p.pageid, g.pagegroupid FROM page p INNER JOIN pagegroup g ON p.pagegroupid = g.pagegroupid; /* 9.37 sec execution, 60.0 sec fetch */ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE g index PRIMARY PRIMARY 4 3646 Using index 1 SIMPLE p ref pagegroupid pagegroupid 5 topsecret.g.pagegroupid 3 Using where Moral of the story Keep medium/long text columns in a separate table if you run into performance problems such as this one.

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• Movies recommendation engine conceptual database design

  - by Supyxy

  I am working at an movie recommendations engine and i'm facing a DB design issue. My actual database looks like this: MOVIES [ID,TITLE] KEYWORDS_TABLE [ID,KEY_ID] - where ID is Foreign Key for MOVIES.id and KEY_ID is a key for a text keywords table This is not the entire DB, but i showed here what's important for my problem. I have about 50,000 movies and about 1,3 milion keywords correlations, and basically my algorithm consists in extracting all the who have the same keywords with a given movie, then ordering them by the number of keywords correlations. For example i looked for a movie similar to 'Cast away' and it returned 'Six days and six nights' because it had the most keywords correlations (4 keywords): Island Airplane crash Stranded Pilot The algorithm is based on more factors, but this one is the most important and the most difficult for the approach. Basically what i do now is getting all the movies that have at least one keyword similar to the given movie and then ordering them by other factors which are not important for a moment. There wouldn't be any problem if there weren't so many records, a query lasts in many cases up to 10-20 seconds and some of them return even over 5000 movies. Someone already helped me on here (thanks Mark Byers) with optimizing the query but that's not enough because it takes too longer SELECT DISTINCT M.title FROM keywords_table K1 JOIN keywords_table K2 ON K2.key_id = K1.key_id JOIN movies M ON K2.id = M.id WHERE K1.id = 4 So i thought it would be better if i pre-made those lists with movies recommendations for each movie, but i'm not sure how to design the tables.. whatever is it a good idea or how would you take this approach?

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• How to optimize MATLAB loops?

  - by striglia

  I have been working lately on a number of iterative algorithms in MATLAB, and been getting hit hard by MATLAB's performance (or lack thereof) when it comes to loops. I'm aware of the benefit of vectorizing code when possible, but are there any tools for optimization when you need the loop for your algorithm? I am aware of the MEX-file option to write small subroutines in C/C++, although given my algorithms, this can be a very painful option given the data structures required. I mainly use MATLAB for the simplicity and speed of prototyping, so a syntactically complex, statically typed language is not ideal for my situation. Are there any other suggestions? Even other languages (python?) which have relatively painless matrix tools are an option.

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• Tips for optimizing C#/.NET programs

  - by Bob

  It seems like optimization is a lost art these days. Wasn't there a time when all programmers squeezed every ounce of efficiency from their code? Often doing so while walking 5 miles in the snow? In the spirit of bringing back a lost art, what are some tips that you know of for simple (or perhaps complex) changes to optimize C#/.NET code? Since it's such a broad thing that depends on what one is trying to accomplish it'd help to provide context with your tip. For instance: When concatenating many strings together use StringBuilder instead. If you're only concatenating a handful of strings it's ok to use the + operator. Use string.Compare to compare 2 strings instead of doing something like string1.ToLower() == string2.ToLower()

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• C++ defines for a 'better' Release mode build in VS

  - by darid

  I currently use the following preprocessor defines, and various optimization settings: WIN32_LEAN_AND_MEAN VC_EXTRALEAN NOMINMAX _CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS _SECURE_SCL=0 _HAS_ITERATOR_DEBUGGING=0 My question is what other things do fellow SOers use, add, define, in order to get a Release Mode build from VS C++ (2008,2010) to be as performant as possible? btw, I've tried PGO etc, it does help a bit but nothing that comes to parity, also I'm not using streams, the C++ i'm talking about its more like C but making use of templates and STL algorithms. As it stands now very simple code segments flop when compared to what GCC produces on say an equivalent x86 machine running linux (2.6+ kernel) using 02. Side-Note: I believe a lot of the issues relate directly to the STL version (Dinkum) provided by MS. Could people please elaborate on experiences using STLPort etc with VS C++.

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• jQuery Optimizations

  - by aepheus

  I've just come to the end of a large development project. We were on a tight timeline, so a lot of optimization was "deferred". Now that we met our deadline, we're going back and trying to optimize things. My questions is this: What are some of the most important things you look for when optimizing jQuery web sites. Alternately I'd love to hear of sites/lists that have particularly good advise for optimizing jQuery. I've already read a few articles, http://www.tvidesign.co.uk/blog/improve-your-jquery-25-excellent-tips.aspx was an especially good read.

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• Optimize C# Code Fragment

  - by Eric J.

  I'm profiling some C# code. The method below is one of the most expensive ones. For the purpose of this question, assume that micro-optimization is the right thing to do. Is there an approach to improve performance of this method? Changing the input parameter to p to ulong[] would create a macro inefficiency. static ulong Fetch64(byte[] p, int ofs = 0) { unchecked { ulong result = p[0 + ofs] + ((ulong)p[1 + ofs] << 8) + ((ulong)p[2 + ofs] << 16) + ((ulong)p[3 + ofs] << 24) + ((ulong)p[4 + ofs] << 32) + ((ulong)p[5 + ofs] << 40) + ((ulong)p[6 + ofs] << 48) + ((ulong)p[7 + ofs] << 56); return result; } }

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• Is it possible to shrink rt.jar with ProGuard?

  - by PatlaDJ

  Is there a procedure by which you can optimize/shrink/select/obfuscate only 'used by your app' classes/methods/fields from rt.jar provided by Sun by using some optimization software like ProGuard (or maybe other?). Then you would actually be able to minimize the download size of your application considerably and make it much more secure ? Right? Related questions: Do you know if Sun's "jigsaw project" which is waited to come out, is intended to automatically handle this particular issue? Did somebody manage yet to form an opinion about Avian java alternative? Please share it here. Thank you.

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• In C, would !~b ever be faster than b == 0xff ?

  - by James Morris

  From a long time ago I have a memory which has stuck with me that says comparisons against zero are faster than any other value (ahem Z80). In some C code I'm writing I want to skip values which have all their bits set. Currently the type of these values is char but may change. I have two different alternatives to perform the test: if (!~b) /* skip */ and if (b == 0xff) /* skip */ Apart from the latter making the assumption that b is an 8bit char whereas the former does not, would the former ever be faster due to the old compare to zero optimization trick, or are the CPUs of today way beyond this kind of thing?

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• Compile-time trigonometry in C

  - by lhahne

  I currently have code that looks like while (very_long_loop) { ... y1 = getSomeValue(); ... x1 = y1*cos(PI/2); x2 = y2*cos(SOME_CONSTANT); ... outputValues(x1, x2, ...); } the obvious optimization would be to compute the cosines ahead-of-time. I could do this by filling an array with the values but I was wondering would it be possible to make the compiler compute these at compile-time?

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• How do you design a database to allow fast multicolumn searching?

  - by Fletcher Moore

  I am creating a real estate search from RETS data, but this is a general question. When you have a variety of columns that you would like the user to be able to filter their search result by, how do you optimize this? For example, http://www.charlestonrealestateguide.com/listings.php has 16 or so optional filters. Granted, he only has up to 11,000 entries (I have the same data), but I don't imagine the search is performed with just a giant WHERE AND AND AND ... clause. Or is this typically accomplished with one giant multicolumn index? Newegg, Amazon, and countless others also have cool & fast filtering systems for large amounts of data. How do they do it? And is there a database optimization reason for the tendency to provide ranges instead of empty inputs, or is that merely for user convenience?

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