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  • MySQL Sub-query.. Doesn't provide proper information after 3 entries into table.

    - by Chris Keefer
    After I get 3 rows in my forum_threads table this no longer does it's job; to organize a list of active forum threads and put the most recently responded-to thread at the top of the list, followed by second most recent posted-to thread, followed by third, fourth, etc. Like I said, the query works wonders up until there is a fourth row added to forum_threads. SELECT forum_threads.*, forum_posts.thread_id FROM forum_threads INNER JOIN (SELECT MAX(id) AS id, thread_id as thread_id FROM forum_posts group by thread_id order by id DESC) forum_posts ON forum_threads.id = forum_posts.thread_id

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  • How can i resolve the N+1 Selects problem ?

    - by Maxime ARNSTAMM
    Hello everyone, I have trouble understanding how to avoid the n+1 select in jpa or hibernate. From what i read, there's the 'left join fetch', but i'm not sure if it still works with more than one list (oneToMany).. Could someone explain it to me, or give me a link with a clear complete explanation please ? I'm sorry if this is a noob question, but i can't find a real clear article or doc on this issue. Thanks

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  • Optimize slow ranking query

    - by Juan Pablo Califano
    I need to optimize a query for a ranking that is taking forever (the query itself works, but I know it's awful and I've just tried it with a good number of records and it gives a timeout). I'll briefly explain the model. I have 3 tables: player, team and player_team. I have players, that can belong to a team. Obvious as it sounds, players are stored in the player table and teams in team. In my app, each player can switch teams at any time, and a log has to be mantained. However, a player is considered to belong to only one team at a given time. The current team of a player is the last one he's joined. The structure of player and team is not relevant, I think. I have an id column PK in each. In player_team I have: id (PK) player_id (FK -> player.id) team_id (FK -> team.id) Now, each team is assigned a point for each player that has joined. So, now, I want to get a ranking of the first N teams with the biggest number of players. My first idea was to get first the current players from player_team (that is one record top for each player; this record must be the player's current team). I failed to find a simple way to do it (tried GROUP BY player_team.player_id HAVING player_team.id = MAX(player_team.id), but that didn't cut it. I tried a number of querys that didn't work, but managed to get this working. SELECT COUNT(*) AS total, pt.team_id, p.facebook_uid AS owner_uid, t.color FROM player_team pt JOIN player p ON (p.id = pt.player_id) JOIN team t ON (t.id = pt.team_id) WHERE pt.id IN ( SELECT max(J.id) FROM player_team J GROUP BY J.player_id ) GROUP BY pt.team_id ORDER BY total DESC LIMIT 50 As I said, it works but looks very bad and performs worse, so I'm sure there must be a better way to go. Anyone has any ideas for optimizing this? I'm using mysql, by the way. Thanks in advance Adding the explain. (Sorry, not sure how to format it properly) id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t ALL PRIMARY NULL NULL NULL 5000 Using temporary; Using filesort 1 PRIMARY pt ref FKplayer_pt77082,FKplayer_pt265938,new_index FKplayer_pt77082 4 t.id 30 Using where 1 PRIMARY p eq_ref PRIMARY PRIMARY 4 pt.player_id 1 2 DEPENDENT SUBQUERY J index NULL new_index 8 NULL 150000 Using index

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  • How to terminate a thread which has spawned another thread which is sleeping?

    - by Bobb
    I have a long running thread made from Thread.Start(). It spawns a background thread using QueueUserWorkItem which sleeps most of the time. Then the class-owner get disposed I call thread1.Join() but naturally it doesnt return because its child background thread is sleeping. What would be the right solution to gracefully terminate a thread which has other threads with little hassle?

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  • What do you call this functional language feature?

    - by Jimmy
    ok, embarrassing enough, I posted code that I need explained. Specifically, it first chains absolute value and subtraction together, then tacks on a sort, all the while not having to mention parameters and arguments at all, because of the presense of "adverbs" that can join these functions "verbs" What (non-APL-type) languages support this kind of no-arguments function composition (I have the vague idea it ties in strongly to the concepts of monad/dyad and rank, but its hard to get a particularly easy-to-understand picture just from reading Wikipedia) and what do I call this concept?

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  • quick java question

    - by j-unit-122
    private static char[] quicksort (char[] array , int left , int right) { if (left < right) { int p = partition(array , left, right); quicksort(array, left, p - 1 ); quicksort(array, p + 1 , right); } for (char i : array) System.out.print(i + ” ”); System.out.println(); return array; } private static int partition(char[] a, int left, int right) { char p = a[left]; int l = left + 1, r = right; while (l < r) { while (l < right && a[l] < p) l++; while (r > left && a[r] >= p) r--; if (l < r) { char temp = a[l]; a[l] = a[r]; a[r] = temp; } } a[left] = a[r]; a[r] = p; return r; } } hi guys just a quick question regarding the above coding, i know that the above coding returns the following B I G C O M P U T E R B C E G I M P U T O R B C E G I M P U T O R B C E G I M P U T O R B C E G I M P U T O R B C E G I M O P T U R B C E G I M O P R T U B C E G I M O P R T U B C E G I M O P R T U B C E G I M O P R T U B C E G I M O P R T U B C E G I M O P R T U B C E G I M O P R T U when the sequence BIGCOMPUTER is used but my question is can someone explain to me what is happening in the code and how? i know abit about the quick-sort algorithm but it doesnt seem to be the same in the above example.

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  • Order by is not working

    - by coure06
    With Results as ( SELECT Top(100) percent ROW_NUMBER() over (Order by (select 1)) as RowNumber, Ad.Date, Title FROM Ad inner join Job on Ad.Id = Job.AdId Order by case When @sortCol='Date' and @sortDir='ASC' Then Date End ASC, case When @sortCol='Date' and @sortDir='DESC' Then Date End DESC ) Select * from Results Where RowNumber BETWEEN @FirstRow AND @LastRow END Whatever is passed in @sortDir and @sortCol it does not work.What am I doing wrong?

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  • How to get N random string from a {a1|a2|a3} format string?

    - by Pentium10
    Take this string as input: string s="planets {Sun|Mercury|Venus|Earth|Mars|Jupiter|Saturn|Uranus|Neptune}" How would I choose randomly N from the set, then join them with comma. The set is defined between {} and options are separated with | pipe. The order is maintained. Some output could be: string output1="planets Sun, Venus"; string output2="planets Neptune"; string output3="planets Earth, Saturn, Uranus, Neptune"; string output4="planets Uranus, Saturn";// bad example, order is not correct Java 1.5

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  • How to find the worst performing queries in MS SQL Server 2008?

    - by Thomas Bratt
    How to find the worst performing queries in MS SQL Server 2008? I found the following example but it does not seem to work: SELECT TOP 5 obj.name, max_logical_reads, max_elapsed_time FROM sys.dm_exec_query_stats a CROSS APPLY sys.dm_exec_sql_text(sql_handle) hnd INNER JOIN sys.sysobjects obj on hnd.objectid = obj.id ORDER BY max_logical_reads DESC Taken from: http://www.sqlservercurry.com/2010/03/top-5-costly-stored-procedures-in-sql.html

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  • python multiprocessing member variable not set

    - by Jake
    In the following script, I get the "stop message received" output but the process never ends. Why is that? Is there another way to end a process besides terminate or os.kill that is along these lines? from multiprocessing import Process from time import sleep class Test(Process): def __init__(self): Process.__init__(self) self.stop = False def run(self): while self.stop == False: print "running" sleep(1.0) def end(self): print "stop message received" self.stop = True if __name__ == "__main__": test = Test() test.start() sleep(1.0) test.end() test.join()

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  • Parameter has no walue

    - by Simon
    string queryString = "SELECT SUM(skupaj_kalorij)as Skupaj_Kalorij " + "FROM (obroki_save LEFT JOIN users ON obroki_save.ID_uporabnika=users.ID)" + "WHERE users.ID= " + a.ToString() + " AND obroki_save.datum =?"; using (OleDbCommand cmd = new OleDbCommand(queryString,database)) { cmd.Parameters.Add("@datum", OleDbType.Char).Value = DateTime.Now.ToShortDateString(); } Why doesn't the parametr datum get the date value? (the value of at least one complex parameter has not been determined )

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  • CASE statement within WHERE statement

    - by niao
    Greetings, I would like to include CASE Statement inside my where statement as follows: SELECT a1.ROWGUID FROM Table1 a1 INNER JOIN Table2 a2 on a1.ROWGUID=a2.Table1ROWGUID WHERE a1.Title='title' AND (CASE WHEN @variable is not null THEN a1.ROWGUID in (SELECT * FROM #TempTable)) However, this 'CASE' statement does not work inside 'WHERE' statement. How can I do it correct?

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  • What is your favorite NumPy feature?

    - by Gökhan Sever
    Share your favourite NumPy features / tips & tricks. Please try to limit one feature per line. The question is posted in parallel at ask.scipy.org We welcome you to join the conversation there -with the main idea of collecting the Scientific Python related questions under one roof. Feel free to dual-post or post at your favourite site...

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  • Add string to another string

    - by daemonfire300
    Hi there, I currently encountered a problem: I want to handle adding strings to other strings very efficiently, so I looked up many methods and techniques, and I figured the "fastest" method. But I quite can not understand how it actually works: def method6(): return ''.join([`num` for num in xrange(loop_count)]) From source (Method 6) Especially the ([numfor num in xrange(loop_count)]) confused me totally.

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  • Mysql question: is there something like IN ALL query?

    - by jaycode
    For example this query: SELECT `variants`.* FROM `variants` INNER JOIN `variant_attributes` ON variant_attributes.variant_id = variants.id WHERE (variant_attributes.id IN ('2','5')) And variant has_many variant_attributes What I actually want to do is to find which variant has BOTH variant attributes with ID = 2 and 5. Is this possible with MySQL? Bonus Question, is there a quick way to do this with Ruby on Rails, perhaps with SearchLogic?

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  • What is the best XNA book, which can teach you the 2d & 3d game programming from basic to advance?

    - by Setve
    1- What is the best XNA book, which can teach the 2d & 3d game programming from basic to advance? Is it possible after reading that book create professional looking 3d games??? 2- Any suggestion how can become professional game developer with XNA, and create cool 3d games? 3- Is it XNA industry standard for creating games? 4- Is it any work place can join as XNA game developer?

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  • SQL ORDER BY thing1 ASC, thing2 DESC not working

    - by William
    it puts item1 down as DESC for some reason. edit: $sql_result = mysql_query("SELECT post, name, trip, Thread, sticky FROM (SELECT MIN(ID) AS min_id, MAX(ID) AS max_id, MAX(Date) AS max_date FROM test_posts GROUP BY Thread ) t_min_max INNER JOIN test_posts ON test_posts.ID = t_min_max.min_id WHERE Board=".$board." ORDER BY sticky ASC, max_date DESC", $db); http://prime.programming-designs.com/test_forum/viewboard.php?board=0&page=3

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  • Biggest performance improvement you've had with the smallest change?

    - by JoelFan
    What's the biggest performance improvement you've had with the smallest change? For example, I once improved the performance of a certain page on a high-profile web app by a factor of 10, just by moving "where customerID = ?" to a different place inside a complicated SQL statement (before my change it had been selecting all customers in a join, then later selecting out the desired customer).

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  • Why am I unable to create a trigger using my SqlCommand?

    - by acidzombie24
    The line cmd.ExecuteNonQuery(); cmd.CommandText CREATE TRIGGER subscription_trig_0 ON subscription AFTER INSERT AS UPDATE user_data SET msg_count=msg_count+1 FROM user_data JOIN INSERTED ON user_data.id = INSERTED.recipient; The exception: Incorrect syntax near the keyword 'TRIGGER'. Then using VS 2010, connected to the very same file (a mdf file) I run the query above and I get a success message. WTF!

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  • Is there a way to opt-out from WP8 when submiting an Windows Phone app?

    - by Igor Kulman
    I have a Windows Phone app build using the 7.1 SDK that works great on WP7 but does not work at all on WP8 (I am using multicast using UDP and WP8 can join the group but send/receives no message for some reason, other people having the same problem: UDP multicast group on Windows Phone 8). Is there a way to opt-out from WP8 when I submit my app? I just want the app to be available t WP7 users. I am looking for something like the 256MB opt-out option.

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  • How can I do the multiple replace in python?

    - by prosseek
    As asked and answered in HERE, I need to replace '[' with '[[]', and ']' with '[]]'. I tried to use s.replace(), but as it's not in place change, I ran as follows to get a wrong anwser. path1 = "/Users/smcho/Desktop/bracket/[10,20]" path2 = path1.replace('[','[[]') path3 = path2.replace(']','[]]') pathName = os.path.join(path3, "*.txt") print pathName -- /Users/smcho/Desktop/bracket/[[[]]10,20[]]/*.txt How can I do the multiple replace in python? Or how can I replace '[' and ']' at the same time?

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  • Having a Link Only Appear If a Logged-In User Appears on a Dynamic List

    - by John
    Hello, For the function below, I would like the link <div class="footervote"><a href="http://www...com/.../footervote.php">Vote</a></div> to only appear if the logged in user currently appears on editorlist.php. (I. e. if the loginid in the function corresponds to any of the usernames that currently appear in editorlist.php.) Appearing on editorlist.php is something that is dynamic. How can I do this? Thanks in advance, John function show_userbox() { // retrieve the session information $u = $_SESSION['username']; $uid = $_SESSION['loginid']; // display the user box echo '<div id="userbox"> <div class="username">'.$u.'</div> <div class="submit"><a href="http://www...com/.../submit.php">Submit an item.</a></div> <div class="changepassword"><a href="http://www...com/.../changepassword.php">Change Password</a></div> <div class="logout"><a href="http://www...com/.../logout.php">Logout</a></div> <div class="footervote"><a href="http://www...com/.../footervote.php">Vote</a></div> </div>'; } On editorlist.php: $sqlStr = "SELECT l.loginid, l.username, l.created, DATEDIFF(NOW(), l.created) AS days, COALESCE(s.total, 0) AS countSubmissions, COALESCE(c.total, 0) AS countComments, COALESCE(s.total, 0) * 10 + COALESCE(c.total, 0) AS totalScore, DATEDIFF(NOW(), l.created) + COALESCE(s.total, 0) * 10 + COALESCE(c.total, 0) AS totalScore2 FROM login l LEFT JOIN ( SELECT loginid, COUNT(1) AS total FROM submission GROUP BY loginid ) s ON l.loginid = s.loginid LEFT JOIN ( SELECT loginid, COUNT(1) AS total FROM comment GROUP BY loginid ) c ON l.loginid = c.loginid GROUP BY l.loginid ORDER BY totalScore2 DESC LIMIT 10"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"samplesrec1edit\">"; while ($row = mysql_fetch_array($result)) { echo '<tr>'; echo '<td class="sitename1edit1"><a href="http://www...com/.../members/index.php?profile='.$row["username"].'">'.stripslashes($row["username"]).'</a></td>'; echo '<td class="sitename1edit2">'.($row["countSubmissions"]).'</td>'; echo '<td class="sitename1edit2">'.($row["countComments"]).'</td>'; echo '<td class="sitename1edit2">'.($row["days"]).'</td>'; echo '<td class="sitename1edit2">'.($row["totalScore2"]).'</td>'; echo '</tr>'; } echo "</table>";

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  • Community "Groups" feature (Ruby on Rails)

    - by timstepp
    Are there any good examples/plugins that enable users to create groups within a community application. For example, I would like to create a Group class and add it to something like Community Engine (http://communityengine.org/). Essentially, users need to be able to create and manage groups that other users can join (much like Facebook Pages). Thanks!

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  • mysql query and index

    - by parm.95
    Does this query will be faster with a index on "t.type1" and "x.type1" or only index on "x.type1" is enought? SELECT t.id, x.id FROM t INNER JOIN x ON x.type1=t.type1 WHERE t.id=1

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  • I want to display the missing (non-matching) records

    - by Eric
    Is there a way to program the following SQL query SELECT dbo.Assets_Master.Serial_Number, dbo.Assets_Master.Account_Ident, dbo.Assets_Master.Disposition_Ident FROM dbo.Assets_Master LEFT OUTER JOIN dbo.Assets ON dbo.Assets_Master.Serial_Number = dbo.Assets.Serial_Number WHERE (dbo.Assets.Serial_Number IS NULL) in c# .net code using dataviews or data relation or something else? I have a spreadsheet of about 4k rows and a data table that should have the same records but if not I want to display the missing (non-matching) records from the table. Thanks, Eric

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