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• C# : Forcing a clean run in a long running SQL reader loop?

  - by Wardy

  I have a SQL data reader that reads 2 columns from a sql db table. once it has done its bit it then starts again selecting another 2 columns. I would pull the whole lot in one go but that presents a whole other set of challenges. My problem is that the table contains a large amount of data (some 3 million rows or so) which makes working with the entire set a bit of a problem. I'm trying to validate the field values so i'm pulling the ID column then one of the other cols and running each value in the column through a validation pipeline where the results are stored in another database. My problem is that when the reader hits the end of handlin one column I need to force it to immediately clean up every little block of ram used as this process uses about 700MB and it has about 200 columns to go through. Without a full Garbage Collect I will definately run out of ram. Anyone got any ideas how I can do this? I'm using lots of small reusable objects, my thought was that I could just call GC.Collect() on the end of each read cycle and that would flush everything out, unfortunately that isn't happening for some reason.

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• LaTex: how does the include-command work?

  - by HH

  I supposed the include-command copy-pastes code in the compilation, it is wrong because the code stopped working. Please, see the middle part in the code. I only copy-pasted the code to the file and added the include-command. $ cat results/frames.tex 10.31 & 8.50 & 7.40 \\ 10.34 & 8.53 & 7.81 \\ 8.22 & 8.62 & 7.78 \\ 10.16 & 8.53 & 7.44 \\ 10.41 & 8.38 & 7.63 \\ 10.38 & 8.57 & 8.03 \\ 10.13 & 8.66 & 7.41 \\ 8.50 & 8.60 & 7.15 \\ 10.41 & 8.63 & 7.21 \\ 8.53 & 8.53 & 7.12 \\ Latex code \begin{table} \begin{tabular}{ | l | m | r |} \hline $t$ / s & $d_{1}$ / s & $d_{2}$ / s \\ $\Delta h = 0,01 s$ & $\Delta d = 0,01 s$ & $\Delta d = 0,01 s$ \\ \hline % I JUST COPIED THE CODE from here to the file, included. % It stopped working, why? \include{results/frames.tex} \hline $\pi (\frac{d_{1}}{2} - \frac{d_{2}}{2})$ & $2 \pi R h$ & $2 \pi r h$ \\ \hline \end{tabular} \end{table}

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• Colorizing as SAS Map

  - by user601828

  I'm trying to generate a map in SAS where I would like to to make gradual color changes which correspond to my results. So the higher the counts the more intense the color changes. Also I would like to add state labels to the map. Here is my code, so far it produces a white map with varying degress of blue blocks. I'd like the states colored in intense colors, like red, bright pink,brilliant, blues and greens. Can anyone please help me modify the code to add state labels and colorize the map, and below the map add a table summarizing the statistics, like counts and percentages. Thanks in advance. goptions gunit=pct cback=white htitle=4 htext=3 colors=(PAGY LIY STY DEGY dark_yellow very_dark_yellow ) ; title "My Map Results"; proc gmap map=maps.us data=My_data all; id state; block person_per_event/levels=6; choro person_per_event/levels=6; run; quit; I looked at his page before for example if I wanted to make a map like this one http://robslink.com/SAS/democd61/election_2012.htm with my data. I tried modifying the code that he gives on the link, but wasnt very successful. I would like to use that map along with the state labels and keep the colors and represent my data with blocks in the corresponding locations with city and state, and high level counts. The rest of the summary statistics I would like to summarize in a colorful table next to the map, like a dashboard of sorts. Appreciate any help in advance. Thanks, -rachel

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• entity framework vNext wish list

  - by Fred Yang

  I have been intensively studying and use ef4 in my project. I do feel the improvement that it has over version 1. But I found that I have something I cannot get around easily. Here is a list I want it to be better in ef vNext. the model designer should allow multiple view of the same model, so that I don't need cram all my entity into a single view. respect user's manual edit of edmx. Currently, the some database view object simply can not be imported to the model because the designer "smartly" think that the view does not have a primary key, so that I have to manually edit the edmx to correct designer's behavior. But in the next "update from database" task, designer will revert my customization. For now, I simply fallback to manually edit the edmx file at all, or I have to use compare tool to keep the new update, and rollback and put the new update into my old edmx file manually. Designer should be improved to allow default behavior and user's manual control. I want control not to let the designer refresh the change of imported object. support user defined table function. linq is about Composability, stored proc dos not support composability. I wish I could use user defined table function which support this. What are you wishes for EF vNext?

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• Sql server query using function and view is slower

  - by Lieven Cardoen

  I have a table with a xml column named Data: CREATE TABLE [dbo].[Users]( [UserId] [int] IDENTITY(1,1) NOT NULL, [FirstName] [nvarchar](max) NOT NULL, [LastName] [nvarchar](max) NOT NULL, [Email] [nvarchar](250) NOT NULL, [Password] [nvarchar](max) NULL, [UserName] [nvarchar](250) NOT NULL, [LanguageId] [int] NOT NULL, [Data] [xml] NULL, [IsDeleted] [bit] NOT NULL,... In the Data column there's this xml <data> <RRN>...</RRN> <DateOfBirth>...</DateOfBirth> <Gender>...</Gender> </data> Now, executing this query: SELECT UserId FROM Users WHERE data.value('(/data/RRN)[1]', 'nvarchar(max)') = @RRN after clearing the cache takes (if I execute it a couple of times after each other) 910, 739, 630, 635, ... ms. Now, a db specialist told me that adding a function, a view and changing the query would make it much more faster to search a user with a given RRN. But, instead, these are the results when I execute with the changes from the db specialist: 2584, 2342, 2322, 2383, ... This is the added function: CREATE FUNCTION dbo.fn_Users_RRN(@data xml) RETURNS varchar(100) WITH SCHEMABINDING AS BEGIN RETURN @data.value('(/data/RRN)[1]', 'varchar(max)'); END; The added view: CREATE VIEW vwi_Users WITH SCHEMABINDING AS SELECT UserId, dbo.fn_Users_RRN(Data) AS RRN from dbo.Users Indexes: CREATE UNIQUE CLUSTERED INDEX cx_vwi_Users ON vwi_Users(UserId) CREATE NONCLUSTERED INDEX cx_vwi_Users__RRN ON vwi_Users(RRN) And then the changed query: SELECT UserId FROM Users WHERE dbo.fn_Users_RRN(Data) = '59021626919-61861855-S_FA1E11' Why is the solution with a function and a view going slower?

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• How do I query SQLite Database in Android?

  - by kunjaan

  I successfully created the Database and inserted a row however I cannot Query it for some reason. My Droid crashes everytime. String DATABASE_NAME = "myDatabase.db"; String DATABASE_TABLE = "mainTable"; String DATABASE_CREATE = "create table if not exists " + DATABASE_TABLE + " ( value VARCHAR not null);"; SQLiteDatabase myDatabase = null; myDatabase = openOrCreateDatabase(DATABASE_NAME, Context.MODE_PRIVATE, null); myDatabase.execSQL(DATABASE_CREATE); // Create a new row of values to insert. ContentValues newValues = new ContentValues(); // Assign values for each row. newValues.put("value", "kunjan"); // Insert the row into your table myDatabase.insert(DATABASE_TABLE, null, newValues); String[] result_columns = new String[] { "value" }; Cursor allRows = myDatabase.query(true, DATABASE_TABLE, result_columns, null, null, null, null, null, null); if (allRows.moveToFirst()) { String value = allRows.getString(1); TextView foo = (TextView) findViewById(R.id.TextView01); foo.setText(value); } allRows.close(); myDatabase.close();

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• How to query MySQL for exact length and exact UTF-8 characters

  - by oskarae

  I have table with words dictionary in my language (latvian). CREATE TABLE words ( value varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; And let's say it has 3 words inside: INSERT INTO words (value) VALUES ('teja'); INSERT INTO words (value) VALUES ('vejš'); INSERT INTO words (value) VALUES ('feja'); What I want to do is I want to find all words that is exactly 4 characters long and where second character is 'e' and third character is 'j' For me it feels that correct query would be: SELECT * FROM words WHERE value LIKE '_ej_'; But problem with this query is that it returs not 2 entries ('teja','vejš') but all three. As I understand it is because internally MySQL converts strings to some ASCII representation? Then there is BINARY addition possible for LIKE SELECT * FROM words WHERE value LIKE BINARY '_ej_'; But this also does not return 2 entries ('teja','vejš') but only one ('teja'). I believe this has something to do with UTF-8 2 bytes for non ASCII chars? So question: What MySQL query would return my exact two words ('teja','vejš')? Thank you in advance

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• How to (unit-)test data intensive PL/SQL application

  - by doom2.wad

  Our team is willing to unit-test a new code written under a running project extending an existing huge Oracle system. The system is written solely in PL/SQL, consists of thousands of tables, hundreds of stored procedures packages, mostly getting data from tables and/or inserting/updating other data. Our extension is not an exception. Most functions return data from a quite complex SELECT statementa over many mutually bound tables (with a little added logic before returning them) or make transformation from one complicated data structure to another (complicated in another way). What is the best approach to unit-test such code? There are no unit tests for existing code base. To make things worse, only packages, triggers and views are source-controlled, table structures (including "alter table" stuff and necessary data transformations are deployed via channel other than version control). There is no way to change this within our project's scope. Maintaining testing data set seems to be impossible since there is new code deployed to the production environment on weekly basis, usually without prior notice, often changing data structure (add a column here, remove one there). I'd be glad for any suggestion or reference to help us. Some team members tend to be tired by figuring out how to even start for our experience with unit-testing does not cover PL/SQL data intensive legacy systems (only those "from-the-book" greenfield Java projects).

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• how to get Contact database schema.

  - by kamiomar

  Dear, is there any link that provide me the Contact Schema. when i store new phone number in mobile, the informaion store in the database. so i need schema to create my own table for back purpose. i have alreay get People table column by the follwoing code. boolean displayFlag = false; String str = ""; Uri CONTACT_URI = People.CONTENT_URI; Cursor cursor = mContext.getContentResolver().query(CONTACT_URI, null, null, null, null); String columnNames = ""; if (cursor != null) { try { cursor.getCount(); if (cursor.moveToFirst()) { String[] columns = cursor.getColumnNames(); for (int i = 0; i < columns.length; i++) { columnNames += "colName" + cursor.getColumnName(i) + " : " + cursor.getString(i) + "colValue"; } } } finally { cursor.close(); } } createImage(columnNames); if (displayFlag) { Toast.makeText(mContext, str, Toast.LENGTH_SHORT).show(); } } Thanks

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• How do I push another viewController onto the navigationController from within a tabviewController?

  - by user207788

  Hi, I have a project set up using these two tutorials. http://twilloapp.blogspot.com/2009/03/how-to-embed-navigation-controller.html and the link for the second tutorial is at the bottom of the first. The tutorial is slightly outdated but I managed to get it to work as advertised. Now I want to push a new detailedView onto the NavigationController when a user touches a row in the table view. So I added this to my MyTableViewController.m file. - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { // Navigation logic may go here. Create and push another view controller. SecondViewController *detailViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController.xib" bundle:nil]; // ... // Pass the selected object to the new view controller. [self.navigationController pushViewController:detailViewController animated:YES]; [detailViewController release]; } Now when I run this project and touch a row in my table view I am getting an error: asm_Terminating_due_to_uncaught_exception IT seems to be having an issue loading the SecondViewController from nib, however I checked the detailViewController and it is not nil. I know I am missing something and it is more than likely something simple. Please help. Thanks, Bruce

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• how to determine xpaths for ajax element.

  - by Anjali

  I need to detemine xpath for element 'mainForm:queryConfigure:fetchReport'. <span id="mainForm:queryConfigure:j_id18"> <table id="mainForm:queryConfigure:j_id19" class="showReportTable" align="center"> <tbody> <tr> <td> <input id="mainForm:queryConfigure:fetchReport" type="image" src="images/show_report.gif" name="mainForm:queryConfigure:fetchReport"/> </td> </tr> </tbody> </table> </span> i tried selenium.click("//input[@id='mainForm:queryConfigure:fetchReport'][@type='image'][@src='images/show_report.gif']"); AND selenium.click("//input[@id='mainForm:queryConfigure:fetchReport']"); One more case: <div class="tabUnselectedText" align="center"> <a href="javascript:renderPage('mainForm:consoleBeanId.1','Notifications' , 'notifications.faces');">Notifications</a> </div>

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• Problem in filtering records using Dataview (C#3.0)

  - by Newbie

  I have a data table . The data table is basically getting populated from excel sheet. And there are many excel sheets. Henceforth, I have written a utility method for accomplishing the same. Now in some of the excel sheets, there are date columns and in some it is not(only text/string). My function is populating the values properly into the datatable from the excell sheet. But there are many blank rows in the excel sheets some are filled with NULL , some with " ". So I need to filter those records (which are NULL or " " ) first before further processing. What I am after is to use a dataview and apply the filter over there. DataView dv = dataTable.DefaultView; dv.RowFilter = ColumnName + " <> ''"; Well by using metedata (GetOleDbSchemaTable(OleDbSchemaGuid.Columns, restrection)) I was able to get the column names from the excel sheet , so getting the column names is not an issue. But the problem is as I said in some Excel sheet there are date fileds some are not. So the Filter condition of the Dataview needs to be proper. If I apply the above logic, and if it encounters a Datafield, it is throwing error Cannot perform '<' operation on System.DateTime and System.String. Could you people please help me out? I need to filter columns(not known at compile time + their data types) which can have NULL and " " I am using C#3.0 Thanks

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• LinQ XML mapping to a generic type

  - by Manuel Navarro

  I´m trying to use an external XML file to map the output from a stored procedure into an instance of a class. The problem is that my class is of a generic type: public class MyValue<T> { public T Value { get; set; } } Searching through a lot of blogs an articles I've managed to get this: <?xml version="1.0" encoding="utf-8" ?> <Database Name="" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007"> <Table Name="MyValue" Member="MyNamespace.MyValue`1" > <Type Name="MyNamespace.MyValue`1"> <Column Name="Category" Member="Value" DbType="VarChar(100)" /> </Type> </Table> <Function Method="GetResourceCategories" Name="myprefix_GetResourceCategories" > <ElementType Name="MyNamespace.MyValue`1"/> </Function> </Database> The MyNamespace.MyValue`1 trick works fine, and the class is recognized. I expect four rows from the stored procedure, and I'm getting four MyValue<string> instances, but the big problem is that the property Value for the all four instances is null. The property is not getting mapped and I don't really get why. Maybe worth noting that the property Value is generic, and that when the mapping is done using attributes it works perfect. Anyone have a clue? BTW the method GetResourceCategories: public ISingleResult<MyValue<string>> GetResourceCategories() { IExecuteResult result = this.ExecuteMethodCall( this, (MethodInfo)MethodInfo.GetCurrentMethod()); return (ISingleResult<MyValue<string>>)result.ReturnValue; }

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• JQuery UI drag and drop doesn't notice DOM changes happening during the dragging ?

  - by user315677

  Hi everybody, I have a html table in which each line (<tr>) represents a group of client computers. Each line can be expanded to show the clients belonging to the group. The <tr> containing the clients are always generated but hidden and showed when clicking the plus button at the beginning of each line. The clients themselves (they are <div>) can be dragged and dropped in another group as long as this group is already expanded. So far it works fine. What I am trying to achieve now is that the client can be dragged to a collapsed group and after a second or so hovering the group it will be expanded and the client can be dropped amongst the other clients of the group. I programmed the hover using the in and outevents of the droppable and it expands the group all right, but (and now it starts to be hard to explain with words ;) the behavior of the droppable (the client) is still as if the table line that appeared were not there : the in out and drop events of the droppable are fired on the old position of the elements, and the in out and drop events of the newly appeared <tr> are never fired. It looks as if JQuery memorizes the position, size etc. of the elements when the drag starts, and these values are not updated if there is a change in the DOM before the drop happens... Can someone confirm this behavior is normal, or can it be caused by another problem in my own code ? Any workaround ? (the question is quite bloated already so I don't include any code but I'll gladly upload it if required)

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• How can I get the rank of rows relative to total number of rows based on a field?

  - by Arms

  I have a scores table that has two fields: user_id score I'm fetching specific rows that match a list of user_id's. How can I determine a rank for each row relative to the total number of rows, based on score? The rows in the result set are not necessarily sequential (the scores will vary widely from one row to the next). I'm not sure if this matters, but user_id is a unique field. Edit @Greelmo I'm already ordering the rows. If I fetch 15 rows, I don't want the rank to be 1-15. I need it to be the position of that row compared against the entire table by the score property. So if I have 200 rows, one row's rank may be 3 and another may be 179 (these are arbitrary #'s for example only). Edit 2 I'm having some luck with this query, but I actually want to avoid ties SELECT s.score , s.created_at , u.name , u.location , u.icon_id , u.photo , (SELECT COUNT(*) + 1 FROM scores WHERE score > s.score) AS rank FROM scores s LEFT JOIN users u ON u.uID = s.user_id ORDER BY s.score DESC , s.created_at DESC LIMIT 15 If two or more rows have the same score, I want the latest one (or earliest - I don't care) to be ranked higher. I tried modifying the subquery with AND id > s.id but that ended up giving me an unexpected result set and different ties.

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• Return unordered list from hierarchical sql data

  - by Milan

  I have table with pageId, parentPageId, title columns. Is there a way to return unordered nested list using asp.net, cte, stored procedure, UDF... anything? Table looks like this: PageID ParentId Title 1 null Home 2 null Products 3 null Services 4 2 Category 1 5 2 Category 2 6 5 Subcategory 1 7 5 SubCategory 2 8 6 Third Level Category 1 ... Result should look like this: Home Products Category 1 SubCategory 1 Third Level Category 1 SubCategory 2 Category 2 Services Ideally, list should contain <a> tags as well, but I hope I can add it myself if I find a way to create <ul> list. EDIT 1: I thought that already there is a solution for this, but it seems that there isn't. I wanted to keep it simple as possible and to escape using ASP.NET menu at any cost, because it uses tables by default. Then I have to use CSS Adapters etc. Even if I decide to go down the "ASP.NET menu" route I was able to find only this approach: http://aspalliance.com/822 which uses DataAdapter and DataSet :( Any more modern or efficient way?

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• What is an elegant way to solve this max and min problem in Ruby or Python?

  - by ????

  The following can be done by step by step, somewhat clumsy way, but I wonder if there are elegant method to do it. There is a page: http://www.mariowiki.com/Mario_Kart_Wii, where there are 2 tables... there is Mario - 6 2 2 3 - - Luigi 2 6 - - - - - Diddy Kong - - 3 - 3 - 5 [...] The name "Mario", etc are the Mario Kart Wii character names. The numbers are for bonus points for: Speed Weight Acceleration Handling Drift Off-Road Mini-Turbo and then there is table 2 Standard Bike S 39 21 51 51 54 43 48 Out Bullet Bike 53 24 32 35 67 29 67 In Bubble Bike / Jet Bubble 48 27 40 40 45 35 37 In [...] These are also the characteristics for the Bike or Kart. I wonder what's the most elegant solution for finding all the maximum combinations of Speed, Weight, Acceleration, etc, and also for the minimum, either by directly using the HTML on that page or copy and pasting the numbers into a text file. Actually, in that character table, Mario to Bower Jr are all medium characters, Baby Mario to Dry Bones are small characters, and the rest are all big characters, except the small, medium, or large Mii are just as what the name says. Small characters can only ride small bike or small kart, and so forth for medium and large.

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• SQL UNION ALL with a INNER JOIN

  - by kOhm

  I'm looking for the best way to display all rows from two tables while joining first by one field (dwg) then where applicable a 2nd join on part. Table1 data consists of schematics(dwg) along with a list of parts required to build the item depicted in the drawing. Table2 consists of data about the actual parts ordered to build the schematic. Some parts in table2 are a combination of parts in table1 (ex: foo and bar in table1 were ordered as foobar in table2). I can display all rows in both tables with UNION ALL, but this doesn't join on both the dwg and part fields. I looked at FULL OUTER JOIN also, but I haven't figured out how to join first by dwg, then by part. Here is an example of the data. table1 table2 dwg part qty order dwg part qty ----- ----- ----- ----- ----- ----- ----- 123 foo 1 ord1 123 foobar 1 123 bar 1 ord1 123 bracket 2 123 widget 2 ord2 123 screw 4 123 bracket 4 ord2 123 nut 4 456 foo 1 ord2 123 widget 2 ord2 123 bracket 2 ord3 456 foo 1 Desired output: The goal is to create a view that provides visibility to all parts in table1 and the associated orders in table2 (including those parts that appear in one but not the other table) so that I can see all the drawing parts in table1 and the associated records in table2 along with records in table2 where the part wasn't in table1. part_request_order_report dwg part qty order part qty ----- ----- ----- ------ ----- ----- 123 foo 1 123 bar 1 123 widget 2 ord2 widget 2 123 bracket 4 ord1 bracket 2 123 bracket 4 ord2 bracket 2 123 ord1 foobar 1 123 ord1 screw 4 123 ord1 nut 4 456 foo 1 ord3 foo 1 Is this possible? Or am I better off iterating through the data to build the report table? Thanks in advance.

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• Have trouble when using heredoc syntax in PHP

  - by wamp

  <?php $output = <<< END <table style="display: table;" class="listview rowstyle-rowhighlight" id="resourcegrid"> <thead> <tr> <th width="70"></th> <th style="-moz-user-select: none;" class="sortable fd-column-0"><a class="fdTableSortTrigger" href="#">Name</a></th> <th style="-moz-user-select: none;" class="sortable fd-column-1"><a class="fdTableSortTrigger" href="#">Contributor</a></th> <th style="-moz-user-select: none;" class="sortable fd-column-3"><a class="fdTableSortTrigger" href="#">Modified</a></th> </tr> </thead><tbody> END; echo $output; When I run it reports : Parse error: parse error on line 2 But I don't see anything abnormal.

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• Why can't I save CSS changes in FireBug?

  - by Dean

  FireBug is the most convenient tool I've found for editing CSS - so why isn't there a simple "Save" option? I am always finding myself making tweaks in FireBug, then going back to my original .css file and replicating the tweaks. Has anyone come up with a better solution? EDIT: I'm aware the code is stored on a server (in most cases not my own), but I use it when building my own websites. Firebug's just using the .css file FireFox downloaded from the server, it knows precisely what lines in which files its editing, I can't see why there's not an "Export" or "Save" option which allows you to store the new .css file. (Which I could then replace the remote one with). I have tried looking in temporary locations, and choosing file-save and experimenting with the output options on FireFox, but I still haven't found a way. Here's hoping someone has a nice solution... EDIT 2: The Official Group has a lot of questions, but no answers.

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• SQL Queries SELECT IN and SELECT NOT IN

  - by Sequenzia

  Does anyone know why the results of the following 2 queries do not add up to the results of the 3rd one? SELECT COUNT(leadID) FROM leads WHERE makeID NOT IN (SELECT uploadDataMapID FROM DG_App.dbo.uploadData WHERE uploadID = 3 AND uploadRowID = 1) AND modelID NOT IN (SELECT uploadDataMapID FROM DG_App.dbo.uploadData WHERE uploadID = 3 AND uploadRowID = 2) SELECT COUNT(leadID) FROM Leads WHERE makeID IN (SELECT uploadDataMapID FROM DG_App.dbo.uploadData WHERE uploadID = 3 AND uploadRowID = 1) OR modelID IN (SELECT uploadDataMapID FROM DG_App.dbo.uploadData WHERE uploadID = 3 AND uploadRowID = 2) SELECT COUNT(leadID) FROM Leads The first query is the count I need. The second one is to tell the user how many records were suppressed based on the contents of the DG_App.dbo.uploadData table. The third query is just a straight count of all the records. When I run these the results of query 1 + the results of query 2 comes up about 46K records less than the count of the entire table. I have played with grouping the WHERE statements with () but that did not change the counts at all. This is MSSQL Server 2012. Any input on this would be great. Thanks

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• C++0x rvalue references - lvalues-rvalue binding

  - by Doug

  This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

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• Using hashing to group similar records

  - by Neil Dobson

  I work for a fulfillment company and we have to pack and ship many orders from our warehouse to customers. To improve efficiency we would like to group identical orders and pack these in the most optimum way. By identical I mean having the same number of order lines containing the same SKUs and same order quantities. To achieve this I was thinking about hashing each order. We can then group by hash to quickly see which orders are the same. We are moving from an Access database to a PostgreSQL database and we have .NET based systems for data loading and general order processing systems, so we can either do the hashing during the data loading or hand this task over to the DB. My question firstly is should the hashing be managed by DB, possibly using triggers, or should the hash be created on-the-fly using a view or something? And secondly would it be best to calculate a hash for each order line and then to combine these to find an order-level hash for grouping, or should I just use a trigger for all CRUD operations on the order lines table which re-calculates a single hash for the entire order and store the value in the orders table? TIA

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• Create PDF from HTML page with formatting retained in PDF in ASP.Net

  - by Vishal Avhad

  I am trying to convert an HTML page to a PDF using iTextSharp.dll in ASP.Net. I am able to convert the contents to my PDF , but the problem is that the Formatting of HTML page (which is inline) get removed from my PDF created. For instance I have the following code block to be formatted from my HTML page to PDF. <table style="width:90%; float:left; background:#dddddd; padding:15px; border:1px solid #000; color:#000;"><tr><td style="text-transform:uppercase; font-size:14px;font-weight:bold;">SPECIAL DELIVERY FOR:</td></tr><tr><td style="padding-left:40px; font-size:12px; color:#4e4e4e;">Name: #CustomerName# <br /><br /><label> <b>Date: #CreatedOn# </b></label><br /> </td></tr> </table> I have to format my PDF with much more HTML codes like this. I have used the Stylesheet class also, but that was not much of help.

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• Rails: creating a custom data type, to use with generator classes and a bunch of questions related t

  - by Shyam

  Hi, After being productive with Rails for some weeks, I learned some tricks and got some experience with the framework. About 10 days ago, I figured out it is possible to build a custom data type for migrations by adding some code in the Table definition. Also, after learning a bit about floating points (and how evil they are) vs integers, the money gem and other possible solutions, I decided I didn't WANT to use the money gem, but instead try to learn more about programming and finding a solution myself. Some suggestions said that I should be using integers, one for the whole numbers and one for the cents. When playing in script/console, I discovered how easy it is to work with calculations and arrays. But, I am talking to much (and the reason I am, is to give some sufficient background). Right now, while playing with the scaffold generator (yes, I use it, because I like they way I can quickly set up a prototype while I am still researching my objectives), I like to use a DRY method. In my opinion, I should build a custom "object", that can hold two variables (Fixnum), one for the whole, one for the cents. In my big dream, I would be able to do the following: script/generate scaffold Cake name:string description:text cost:mycustom Where mycustom should create two integer columns (one for wholes, one for cents). Right now I could do this by doing: script/generate scaffold Cake name:string description:text cost_w:integer cost_c:integer I had also had an idea that would be creating a "cost model", which would hold two columns of integers and create a cost_id column to my scaffold. But wouldn't that be an extra table that would cause some kind of performance penalty? And wouldn't that be defy the purpose of the Cake model in the first place, because the costs are an attribute of individual Cake entries? The reason why I would want to have such a functionality because I am thinking of having multiple "costs" inside my rails application. Thank you for your feedback, comments and answers! I hope my message got through as understandable, my apologies for incorrect grammar or weird sentences as English is not my native language.

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