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• PHP code displayed in browser

  - by Drake

  so, I'm working on a databases project, and i'm trying to code incrementally. the problem is, when i go to test the php in browser, it displays the php code after my use of "-". the html printing is displayed properly, which is AFTER the point where the - is. here is the php: <?php function getGraphicNovel(){ include_once("./connect.php"); $db_connection = new mysqli($SERVER, $USERNAME, $PASSWORD, $DATABASE); if (mysqli_connect_errno()) { echo("Can't connect to MySQL Server. Error code: " . mysqli_connect_error()); return null; } $stmt = $db_connection->stmt_init(); $returnValue = "invalid"; if($stmt.prepare("select series from graphic_novel_main natural join graphic_novel_misc")) { $stmt->execute(); $stmt->bind_result($series); while ($stmt->fetch()) { echo "<tr><td>" . $series . "</td></tr>"; } $stmt->close(); } $db_connection->close(); } getGraphicNovel(); ?> here is a link to the page. hopefully it works for people outside the school's network. http://plato.cs.virginia.edu/~paw5k/cainedb/viewall.html if anyone knows why this is happening, your input would be great!

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• Why am I getting "Enter Parameter Value" when running my MS Access query?

  - by DanM

  In my query, I use the IIF function to assign either "Before" or "After" to a field named BeforeOrAfter using AS. When I run this query, however, the "Enter Parameter Value" dialog appears, requesting a value for BeforeOrAfter. If I remove BeforeOrAfter DESC from the ORDER BY clause, I don't get the dialog. Here is the offending query: SELECT d.Scenario, e.Event, IIF(d.LogTime < e.Time, 'Before','After') AS BeforeOrAfter, d.HeartRate FROM Data d INNER JOIN Events e ON d.Scenario = e.Scenario WHERE e.Include = Yes ORDER BY d.Scenario, e.Id, BeforeOrAfter DESC Question: Why is my AS BeforeOrAfter not being recognized by the ORDER BY clause? Why does it ask me to enter a parameter value for "BeforeOrAfter" when I run this query? Note: I tried using brackets, single quotes, double quotes, etc., but none of that made any difference.

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• SharePoint filtered column that only allows item to be used once

  - by Jason

  I have a WSS 3.0 site that I use for change management. There are three primary lists on it -- a bug list, an enhancement list, and a release list. The release list has two lookup columns that provide a list of bugs and enhancements that are included in that particular release. I am trying to figure out how to filter the bug and enhancement list to include only items that have not already been included in another release. All the docs and examples I have seen regarding filtered lookups deal with a query on the list itself. For my situation, and if this was a SQL query, I would need to use a LEFT JOIN to generate the list.

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• Can Ruby Fibers be Concurrent?

  - by Jesse J

  I'm trying to get some speed up in my program and I've been told that Ruby Fibers are faster than threads and can take advantage of multiple cores. I've looked around, but I just can't find how to actually run different fibers concurrently. With threads you can dO this: threads = [] threads << Thread.new {Do something} threads << Thread.new {Do something} threads.each {|thread| thread.join} I can't see how to do something like this with fibers. All I can find is yield and resume which seems like just a bunch of starting and stopping between the fibers. Is there a way to do true concurrency with fibers?

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• A quick over view of facebook's db?

  - by Matt

  Hey guys I find it hard to believe that Facebook uses simple sql, surely it would use some other method but lets assume for now it does use sql how would the code assimilating the 'wall' work? Lets say that there is three tables (just for the example) Friends: id (entry key) - uid(your id) - fid (your mates' id) Wall:id (entry key) - username - comment - time - commentcount comments: id (entry key) - wid (wall id (original comment)) - reply - time Lets forget about the like part and report etc, as well as mod things (ip, ban etc.) How would this work? Select wall.id, wall.username, wall.comment, wall.time, wall.commentcount, comments.wid, comments.reply, comments.time FROM wall inner join comments ON wall.id=comments.wid ORDER BY wall.time; That's your own wall but how do they get friend's? A heap of unions?

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• Is using os.path.abspath to validate an untrusted filename's location secure?

  - by mcmt

  I don't think I'm missing anything. Then again I'm kind of a newbie. def GET(self, filename): name = urllib.unquote(filename) full = path.abspath(path.join(STATIC_PATH, filename)) #Make sure request is not tricksy and tries to get out of #the directory, e.g. filename = "../.ssh/id_rsa". GET OUTTA HERE assert full[:len(STATIC_PATH)] == STATIC_PATH, "bad path" return open(full).read() Edit: I realize this will return the wrong HTTP error code if the file doesn't exist (at least under web.py). I will fix this.

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• Deleting orphans with JPA

  - by homaxto

  I have a one-to-one relation where I use CascadeType.PERSIST. This has over time build up a huge amount of child records that has not been deleted, to such an extend that it is reflected in the performance. Now I wish to add some code that cleans up the database removing all the child records that are not referenced by a parent. At the moment we are talking 400K+ records, at I need to run the code on all customer installations just to be sure they do not run into the same problem. I think the best solution would be to run a named query (because we support two databases) that deletes the necessary records, and this is where I get into problems, because how should I write it in JPQL? The result I want can be defined like the following sql statement, which unfortunaltely does not run on MySQL. DELETE FROM child c1 WHERE c1.pk NOT IN (SELECT DISTINCT p.pk FROM child c2 JOIN parent p ON p.child = c2.pk);

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• MySQL - Return number of rows matching query data?

  - by Keir Simmons

  I have a query as follows: SELECT 1 FROM shop_inventory a JOIN shop_items b ON b.id=a.iid AND b.szbid=3362169 AND b.cid=a.cid WHERE a.cid=1 GROUP BY a.bought The only thing I need to do with this data is work out the number of rows returned (which I could do with mysqli -> num_rows;. However, I would like to know if there is a method to return the number of rows that match the query, without having to run num_rows? For example, the query should return one row, with one result, number_of_rows. I hope this makes sense!

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• MySQL Query - Alternation of WHERE IN

  - by Sadiqur Rahman

  I have a mySQL query which takes 3-4 minutes to be executed. It is a large database. This query uses WHERE IN to find the rows.. So, is there any alternate query/clause/statement for my this query? SELECT r.reg_id, r.first_name, r.last_name, r.email, r.country, e.headline, e.industry, pp.photo FROM basic_registration r LEFT JOIN exp_ind_reg e ON e.reg_id=r.reg_id LEFT JOIN profile_photo pp ON pp.reg_id=r.reg_id WHERE r.reg_id IN (23,228,497,593,761,1204,1491,1894,1895,2128,7,11,20,22,25,26,27,29,31, 32,33,34,37,41,45,47,50,52,53,54,55,62,63,69,75,79,80,82,85,87,88,89,93,96,99, 102,104,106,110,116,117,124,139,143,146,150,157,159,161,162,170,175,176,177, 181,183,197,210,213,215,217,220,226,227,233,240,250,252,255,262,263,268,274,280, 283,285,290,300,312,313,317,324,332,341,347,351,357,368,369,372,373,377, 381,383,398,408,414,416,418,419,422,432,441,446,450,451,453,463,466,469,473,486,511, 522,525,527,529,534,538,541,543,546,564,566,569,577,579,581,585,586,595,598,599,600, 606,611,613,614,621,640,649,654,656,660,667,668,674,682,686,689,693,699,705,720, 734,742,748,753,763,774,775,780,782,784,792,795,804,839,841,862,871,890,929, 930,943,951,965,994,1004,1017,1026,1034,1050,1051,1053,1054,1067,1082,1087,1109, 1119,1121,1124,1136,1147,1187,1197,1214,1224,1226,1230,1241,1255,1318,1323,1358,1361, 1383,1404,1415,1429,1440,1443,1452,1458,1473,1478,1484,1490,1496,1505,1508,1521, 1534,1544,1556,1575,1628,1640,1644,1660,1688,1725,1791,1802,1815,1819,1849,1850,1891, 1896,1897,1911,1917,1923,1924,1926,1927,1930,1956,1959,1961,1967,1983,2006,2016, 2028,2053,2059,2088,2089,2100,2136,2145,2164,2183,2190,2219,2243,2291,2301,2321, 2343,2345,2423,2438,2465,2478,2501,2507,2508,2551,2563,2572,2629,2636,2642,2650, 2670,2693,2695,2724,2732,2801,2803,2839,2847,2867,2899,3024,3061,3068,3071,3093, 3123,3126,3188,3240,3273,3307,3308,3332,3484,3493,3522,3552,3596,3632,3705,3769, 3845,3869,3966,3969,4046,4066,4074,4077,4108,4113,4140,4198,4213,4218,4266,4295, 4312,4345,4365,4369,4380,4425,4453,4485,4486,4488,4493,4494,4495,4500,4513,4515, 4517,4520,4533,4540,4542,4544,4548,4550,4551,4554,4555,4557,4566,4567,4568, 4570,4572,4575,4586,4587,4590,4593,4594,4595,4598,4599,4608,4640,4642,4647,4650, 4661,4664,4679,4681,4685,4686,4698,4707,4708,4709,4711,4712,4714,4715,4717,4719, 4720,4721,4722,4724,4725,4728,4729,4732,4734,4735,4736,4737,4739,4742,4744,4745, 4750,4752,4754,4755,4757,4759,4760,4761,4763,4764,4766,4768,4770,4772,4774,4776, 4777,4789,4790,4791,4793,4795,4796,4797,4799,4803,4804,4805,4806,4808,4809,4811, 4814,4815,4817,4818,4821,4825,4826,4828,4830,4831,4833,4835,4836,4837,4843,4844, 4847,4848,4852,4853,4854,4861,4865,4866,4871,4874,4875,4876,4879,4880,4886,4889, 4890,4891,4892,4893,4894,4896,4899,4900,4904,4908,4914,4915,4916,4917,4918,4922, 4925,4929,4930,4931,4932,4934,4935,4940,4943,4944,4945,4947,4948,4949,4952,4953, 4956,4961,4963,4964,4965,4973,4974,4976,4978,4980,4985,4988,4989,4990,4993,4996, 5001,5009,5014,5016,5017,5018,5019,5021,5023,5024,5025,5028,5032,5033,5041,5042, 5048,5055,5056,5058,5059,5062,5065,5066,5072,5073,5075,5078,5079,5083,5084,5085, 5086,5087,5088,5089,5090,5091,5092,5093,5094,5096,5103,5112,5115,5116,5117,5123, 5125,5126,5127,5128,5130,5131,5132,5133,5134,5137,5138,5139,5140,5141,5146,5148, 5150,5155,5156,5158,5161,5162,5163,5164,5166,5168,5172,5174,5176,5178,5179,5180, 5181,5183,5186,5191,5194,5199,5200,5201,5202,5206,5214,5215,5217,5218,5222,5225, 5226,5227,5235,5236,5237,5243,5245,5246,5248,5251,5252,5254,5255,5256,5257, 5259,5261,5262,5267,5270,5271,5275,5279,5281,5283,5284,5286,5288,5289,5292,5293, 5295,5307,5308,5310,5311,5313,5315,5321,5323,5324,5325,5327,5328,5339,5340,5345, 5351,5353,5355,5356,5357,5358,5359,5363,5364,5365,5366,5369,5370,5371,5372,5373, 5376,5377,5378,5379,5381,5382,5383,5384,5385,5386,5387,5388,5389,5390,5393,5395, 5405,5406,5407,5411,5413,5414,5415,5416,5417,5418,5420,5424,5425,5429,5430,5431, 5432,5433,5434,5435,5437,5441,5451,5460,5467,5473,5476,5506,5524,5528,5530,5534, 5535,5536,5550,5551,5552,5553,5554,5556,5557,5559,5564,5565,5567,5568,5574,5575, 5585,5586,5587,5597,5600,5601,5605,5606,5607,5613,5614,5615,5617,5618,5624,5626, 5627,5628,5640,5643,5644,5645,5647,5648,5649,5650,5660,5661,5670,5671,5673,5674, 5675,5681,5683,5685,5689,5690,5691,5692,5693,5694,5695,5696,5697,5702,5703,5704, 5705,5706,5708,5710,5711,5712,5713,5716,5717,5719,5730,5732,5737,5744,5745,5746, 5748,5749,5750,5752,5753,5754,5756,5757,5758,5759,5761,5762,5763,5764,5765,5767, 5769,5770,5776,5780,5782,5783,5784,5787,5788,5789,5790,5791,5792,5793,5794,5799, 5802,5803,5804,5805,5806,5808,5809,5810,5812,5813,5814,5816,5817,5818,5822,5823,5826, 5827,5829,5830,5831,5848,5849,5850,5851,5852,5854,5856,5858,5859,5863,5864,5865, 5866,5867,5873,5884,5885,5893,5898,5899,5904,5907,5908,5910,5911,5915,5916,5918, 5919,5922,5923,5924,5933,5934,5941,5944,5950,5954,5955,5956,5960,5961,5973,5978,5981, 5982,5983,5984,5985,5986,5987,5988,5989,5990,5998,5999,6000,6002,6003,6004,6006, 6007,6010,6093,6175,6177,6217,6236,6325,6327,6347,6398,6403,6447,6582,6586,6609, 6697,6904,6926,6933,7001,7003,7047,7081,7094,7111,7205,7207,7219,7220,7221,7222, 7224,7227,7228,7229,7230,7232,7237,7238,7241,7268,7274,7275,7276,7281,7300,7307, 7309,7315,7330,7333,7334,7339,7343,7348,7354,7360,7374,7377,7378,7390,7429,7434, 7445,7448,7449,7452,7532,7534,7539,7542,7546,7547,7555,7563,7565,7567,7572,7575, 7576,7577,7578,7579,7585,7611,7907,7926,8100,8134,8205,8324,8337,8339,8350,8351, 8362,8410,8568,8572,8618,8619,8651,8665,8666,8667,8668,9010,9068,9098,9100,9106, 9111,9115,9121,9123,9174,9177,9272,9302,9421,9570,9683,9684,9697,9704,9712,9715,9779, 9790,9792,9793,9795,9798,9814,9818,9856,9866,9876,9886,9891,9908,9912,9928,10508, 10825,11103,11729,12289,12377,12643,12656,12657,12668,12876,12926,12958,13291, 13300,13408,13472,13976,14477,14538,14833,15044,15108,15779,16039,16061,16549, 16556,16562,16564,16565,16571,16573,16574,16576,16577,16584,16589,16590,16591, 16592,16598,16604,16606,16607,16610,16620,16645,16648,16650,16654,16655,16661, 16662,16675,16680,16697,16699,16701,16702,16704,16705,16708,16714,16719,16723, 16724,16727,16729,16731,16732,16743,16750,16752,16755,16758,16772,16774,16782,16787, 16793,16794,16795,16797,16798,16802,16813,16814,16815,16824,16825,16829,16831, 16841,16843,16848,16850,16863,16864,16866,16870,16878,16881,16887,16893,16896,16897, 16900,16902,16909,16912,16936,16944,16948,16958,16960,16963,16974,16978,16993,17012, 17016,17020,17053,17061,17096,17120,17124,17125,17129,17135,17137,17140,17141,17142, 17145,17149,17150,17157,17164,17170,17172,17173,17178,17180,17184,17187,17188, 17192,17196,17197,17200,17201,17206,17207,17221,17223,17227,17236,17244,17246, 17273,17285,17289,17291,17297,17300,17305,17310,17311,17321,17326,17331,17335, 17352,17370,17414,17423,17424,17439,17479,17493,17495,17501,17519,17525,17541, 17571,17590,17614,17755,17838,17846,17848,17852,17853,17855,17858,17861,17871, 17876,17877,17891,17896,17899,17900,17905,17908,17910,17911,17916,17917,17938,17939, 17940,17949,17953,17955,17960,17972,17980,17982,17992,18055,18067,18069,18071,18077, 18108,18127,18134,18136,18140,18142,18143,18158,18162,18178,18192,18196,18206,18217, 18221,18242,18245,18249,18263,18271,18273,18275,18277,18278,18286,18291,18295,18300, 18301,18308,18325,18333,18338,18360,18373,18374,18387,18397,18411,18412,18420,18429, 18434,18455,18478,18484,18534,18779,18790,18804,18821,18851,18964,18965,18977,18990, 18991,19000,19006,19276,19291,19374,19395,19416,19432,19627,19917,19927,19971,19974, 19989,20007,2254,2549,2652,3077,3615,4483,4484,4611,4700,5714,5772,6252,6536,7051, 7102,7107,7591,8167,8286,8935,9937,11089,12344,15830,16343,16644,17359, 17994,18774) AND r.activation=1 ORDER BY r.first_name ASC LIMIT 0, 10;

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• Mysql query different group by

  - by solomongaby

  Hello i have a products table that contains normal products and configurable product It has a basic stucture of: id name price configurable ('yes', 'no') id_configuration Normal products have configurable no and 0 as id configuration, and configurable products have it set to yes and have the same id_configuration value. The current query is: SELECT `products`.* FROM `products`, `categories`, `product_categories` WHERE `categories`.`id` = 23 AND `products`.`id` = `product_categories`.`id_product` AND `categories`.`id` = `product_categories`.`id_category` AND `products`.`active` = 'yes' AND ORDER BY `pos_new` ASC, `created` DESC LIMIT 0,20 I was wondering if there is a way to group by id_configuration, but only for the configurable products. The reason is that i want only one of the configuration products to show in search. I was thinking i could do a join, but was wondering if there is a way to do some kind of special group by. For example for configurable yes the field should be id_configuration otherwise it should be the id field Thanks a lot for any sugestions

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• How to select DISTINCT rows without having the ORDER BY field selected

  - by JannieT

  So I have two tables students (PK sID) and mentors (PK pID). This query SELECT s.pID FROM students s JOIN mentors m ON s.pID = m.pID WHERE m.tags LIKE '%a%' ORDER BY s.sID DESC; delivers this result pID ------------- 9 9 3 9 3 9 9 9 10 9 3 10 etc... I am trying to get a list of distinct mentor ID's with this ordering so I am looking for the SQL to produce pID ------------- 9 3 10 If I simply insert a DISTINCT in the SELECT clause I get an unexpected result of 10, 9, 3 (wrong order). Any help much appreciated.

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• Using a "vo" for joined data?

  - by keithjgrant

  I'm building a small financial system. Because of double-entry accounting, transactions always come in batches of two or more, so I've got a batch table and a transaction table. (The transaction table has batch_id, account_id, and amount fields, and shared data like date and description are relegated to the batch table). I've been using basic vo-type models for each table so far. Because of this table structure structure, though, transactions will almost always be selected with a join on the batch table. So should I take the selected records and splice them into two separate vo objects, or should I create a "shared" vo that contains both batch and transaction data? There are a few cases in which batch records and/or transaction records. Are there possible pitfalls down the road if I have "overlapping" vo classes?

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• Joining different models in Django

  - by Andrew Roberts

  Let's say I have this data model: class Workflow(models.Model): ... class Command(models.Model): workflow = models.ForeignKey(Workflow) ... class Job(models.Model): command = models.ForeignKey(Command) ... Suppose somewhere I want to loop through all the Workflow objects, and for each workflow I want to loop through its Commands, and for each Command I want to loop through each Job. Is there a way to structure this with a single query? That is, I'd like Workflow.objects.all() to join in its dependent models, so I get a collection that has dependent objects already cached, so workflows[0].command_set.get() doesn't produce an additional query. Is this possible?

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• Concurency issues with scheduling app

  - by Sazug

  Our application needs a simple scheduling mechanism - we can schedule only one visit per room for the same time interval (but one visit can be using one or more rooms). Using SQL Server 2005, sample procedure could look like this: CREATE PROCEDURE CreateVisit @start datetime, @end datetime, @roomID int AS BEGIN DECLARE @isFreeRoom INT BEGIN TRANSACTION SELECT @isFreeRoom = COUNT(*) FROM visits V INNER JOIN visits_rooms VR on VR.VisitID = V.ID WHERE @start = start AND @end = [end] AND VR.RoomID = @roomID IF (@isFreeRoom = 0) BEGIN INSERT INTO visits (start, [end]) VALUES (@start, @end) INSERT INTO visits_rooms (visitID, roomID) VALUES (SCOPE_IDENTITY(), @roomID) END COMMIT TRANSACTION END In order to not have the same room scheduled for two visits at the same time, how should we handle this problem in procedure? Should we use SERIALIZABLE transaction isolation level or maybe use table hints (locks)? Which one is better?

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• Safe to KILL a mysql process REPLACEing records in a large myisam table?

  - by threecheeseopera

  I have a REPLACE query running for a few days now on a few MyISAM tables, the largest having 20+million records. I need it to stop. It is, basically: REPLACE INTO really_large_table (a,b,c,d) SELECT e,f,g,h FROM big_table INNER JOIN huge_table ON big_table.x LIKE CONCAT('%', huge_table.y, '%'); I need to KILL it, and I am worried that I may corrupt really_large_table. Because the sub-query itself takes a significant amount of time, the REPLACEing probably occurs (relatively) infrequently; if this is true, does this make it less likely for the data to become corrupted? For the curious, here is the SO question asked about the query I am trying to kill.

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• Rails 4.2: "Assets should not be requested directly without their digests"

  - by Nowaker

  On Rails 4.2.0.beta1 I get an error: Assets should not be requested directly without their digests: Use the helpers in ActionView::Helpers to request fonts/source-sans-pro.woff The stylesheet: @font-face { font-family: 'Source Sans Pro'; font-style: normal; font-weight: 400; src: local('Source Sans Pro'), local('SourceSansPro-Regular'), url(/assets/source-sans-pro.woff) format('woff'); } The configuration is: config.serve_static_assets = true config.assets.js_compressor = :uglifier config.assets.compile = true config.assets.digest = true config.assets.version = '1.0' config.assets.paths << Rails.root.join('app', 'assets', 'fonts') config.assets.precompile += %w(.svg .eot .woff .ttf) Sure I can disable digests and it works again, but I'm interested in using them. Therefore, how do I make use of digests when I need to request source-sans-pro.woff? Please note that I place the fonts in assets/fonts directory, not the public/ directory. I don't see a difference between images and fonts, so I want to keep them under the same directory - app/assets.

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• Which software for intranet CMS - Django or Joomla?

  - by zalun

  In my company we are thinking of moving from wiki style intranet to a more bespoke CMS solution. Natural choice would be Joomla, but we have a specific architecture. There is a few hundred people who will use the system. System should be self explainable (easier than wiki). We use a lot of tools web, applications and integrated within 3rd party software. The superior element which is a glue for all of them is API. In example for the intranet tools we do use Django, but it's used without ORM, kind of limited to templates and url - every application has an adequate methods within our API. We do not use the Django admin interface, because it is hardly dependent on ORM. Because of that Joomla may be hard to integrate. Every employee should be able to edit most of the pages, authentication and privileges have to be managed by our API. How hard is it to plug Joomla to use a different authentication process? (extension only - no hacks) If one knows Django better than Joomla, should Django be used?

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• Problem with update sql with excel

  - by phenevo

  Hi, I have a problem with this query: Update Provinces Set Provinces.DefaultName=T2.Defaultname from Provinces inner join OPENROWSET('Microsoft.Jet.OLEDB.4.0', 'Excel 8.0;Database=C:\provinces.xlsx;HDR=YES', 'SELECT Code, Defaultname FROM [Arkusz1$]') T2 On Provinces.Code = t2.Code where Provinces.Code = T2.Code I get error: Msg 7399, Level 16, State 1, Line 1 The OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)" reported an error. The provider did not give any information about the error. Msg 7303, Level 16, State 1, Line 1 Cannot initialize the data source object of OLE DB provider "Microsoft.Jet.OLEDB.4.0" for linked server "(null)". What is a reason of this unpleasent situation ?

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• Using SalesForce's Web Service to create and set the type of a Task

  - by Alan Williamson

  I am successfully creating a Task using the SalesForce API SOAP API through Java. However, my problem is that I can't seem to set the Type of it. They all default to "Call" but I really want them to be "Email". Can someone point me in the direction of where I can do this? I think it is to do with RecordTypeMapping, but i am somewhat confused as to how to use this in my Java code to look up the particular one for Task type. I feel I have got so close with this. I have the correct WSDL that is giving me the extra method on the Task.java class, but no matter what I pass in, it dies. This doesn't seem to be a huge ask, yet i am perplexed as to which dots to join to get it to work Any help would be appreciated. thanks

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• When to choose which machine learning classifier?

  - by LM

  Suppose I'm working on some classification problem. (Fraud detection and comment spam are two problems I'm working on right now, but I'm curious about any classification task in general.) How do I know which classifier I should use? (Decision tree, SVM, Bayesian, logistic regression, etc.) In which cases is one of them the "natural" first choice, and what are the principles for choosing that one? Examples of the type of answers I'm looking for (from Manning et al.'s "Introduction to Information Retrieval book": http://nlp.stanford.edu/IR-book/html/htmledition/choosing-what-kind-of-classifier-to-use-1.html): a. If your data is labeled, but you only have a limited amount, you should use a classifier with high bias (for example, Naive Bayes). [I'm guessing this is because a higher-bias classifier will have lower variance, which is good because of the small amount of data.] b. If you have a ton of data, then the classifier doesn't really matter so much, so you should probably just choose a classifier with good scalability. What are other guidelines? Even answers like "if you'll have to explain your model to some upper management person, then maybe you should use a decision tree, since the decision rules are fairly transparent" are good. I care less about implementation/library issues, though. Also, for a somewhat separate question, besides standard Bayesian classifiers, are there 'standard state-of-the-art' methods for comment spam detection (as opposed to email spam)? [Not sure if stackoverflow is the best place to ask this question, since it's more machine learning than actual programming -- if not, any suggestions for where else?]

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• counting twice in a query, once using restrictions

  - by Andrew Heath

  Given the following tables: Table1 [class] [child] math boy1 math boy2 math boy3 art boy1 Table2 [child] [glasses] boy1 yes boy2 yes boy3 no If I want to query for number of children per class, I'd do this: SELECT class, COUNT(child) FROM Table1 GROUP BY class and if I wanted to query for number of children per class wearing glasses, I'd do this: SELECT Table1.class, COUNT(table1.child) FROM Table1 LEFT JOIN Table2 ON Table1.child=Table2.child WHERE Table2.glasses='yes' GROUP BY Table1.class but what I really want to do is: SELECT class, COUNT(child), COUNT(child wearing glasses) and frankly I have no idea how to do that in only one query. help?

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• Select all points in a matrix within 30m of another point

  - by pinnacler

  So if you look at my other posts, it's no surprise I'm building a robot that can collect data in a forest, and stick it on a map. We have algorithms that can detect tree centers and trunk diameters and can stick them on a cartesian XY plane. We're planning to use certain 'key' trees as natural landmarks for localizing the robot, using triangulation and trilateration among other methods, but programming this and keeping data straight and efficient is getting difficult using just Matlab. Is there a technique for sub-setting an array or matrix of points? Say I have 1000 trees stored over 1km (1000m), is there a way to say, select only points within 30m radius of my current location and work only with those? I would just use a GIS, but I'm doing this in Matlab and I'm unaware of any GIS plugins for Matlab. I forgot to mention, this code is going online, meaning it's going on a robot for real-time execution. I don't know if, as the map grows to several miles, using a different data structure will help or if calculating every distance to a random point is what a spatial database is going to do anyway. I'm thinking of mirroring two arrays, one sorted by X and the other by Y. Then bubble sorting to determine the 30m range in that. I do the same for both arrays, X and Y, and then have a third cross link table that will select the individual values. But I don't know, what that's called, how to program that and I'm sure someone already has so I don't want to reinvent the wheel. Cartesian Plane GIS

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• So many technologies to choose from. Where does the beginner start?

  - by Sahat

  WPF Silverlight Windows phone 7 w/ Silverlight iPhone OS w/ Objective-C Cocoa w/ Objective-C ASP.NET Android Facebook FBML HTML5 I will be graduating with B.S. in Computer Science soon and have to decide what do I want to learn from this list. I believe it's better to focus on one thing, master it and build up a portfolio to enhance my resume. Bachelor's Degree with no experience, no portfolio won't do me any good. It won't get me a job by itself. I need to have something that will greatly boost my resume. What would it be? iPhone development? ASP.NET web development? Facebook development? Or completely something else that I haven't listed? I understand it's natural for silverlight developers to say "Learn Silverlight", and iPhone developers say "Learn iPhone SDK and Objective-C". So please try to give a constructive, non-biased, non-objective opinion on which technology should I focus on. Please don't close the topic for "subjective/argumentative" reasons. I am just looking for some guidance.

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• subqueries linq

  - by user297378

  Hey all I am trying to do a subquery in linq but the subquery is a value and it seems to not be working, can anyone help out? I am using the entit frame work I keep getting and int to string error not sure why. from lrp in remit.log_record_product join lr in remit.log_record on lrp.log_record_id equals lr.log_record_id where (lrp.que_submit_date >= RadDatePickerStartDate.SelectedDate) && (lrp.que_submit_date <= RadDatePickerEndDate.SelectedDate) select new { lrp.que_submit_date, lr.officer_name, lr.c_fname, lr.c_lname, lrp.price_sold, lrp.product_cost, gap_account_number = (from gap in remit.gap_contracts where gap.log_record_product_id == lrp.log_record_product_id select gap.account_number), iui_account_number = (from iui in remit.iui_contracts where iui.log_record_product_id == lrp.log_record_product_id select iui.account_number), dp_account_number = (from dp in remit.dp_contracts where dp.log_record_product_id == lrp.log_record_product_id select dp.account_number), mpd_account_number = (from mpd in remit.mbp_contracts where mpd.log_record_product_id == lrp.log_record_product_id select mpd.product_account_number) }

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• Creating an interactive website

  - by Aviran

  I want to create an interactive website using aspx and ajax, that there will be an option to create chess game room for example and other players will be able to join. I have 2 Questions: I wonder if you have any idea how can I make that after one player clicks on a button and finish his turn, the other player will be able to do a move. After the first player finish his turn I will change the turn by using the database, but the point is how can I refresh the other player's site so when the other one finish his turn, the turn will come to the second player? When someone creates a room and than close his browser - I need that room to be closed. Shall I use the Session_OnEnd to close the room he opened? Thanks!

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