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• Database contents setting themselves to 0

  - by Luis Armando

  I have a Database that contains 4 tables, however I'm using 1 of them which is separated from the others. In this table I have 4 fields which are varchar and the rest are ints (11 other fields), when the users fill up the DB everything gets saved correctly, however it has happened 3 times so far that the database values for the int's reset to 0 without any apparent reason. At first, I thought, it was because those fields (where the numbers should go) were varchars not ints. However since I changed it, it happened again. I've already double checked my code and I have nothing that even updates or inserts a 0 value. Also I'm using codeigniter and active records which protect against SQL injections AND have XSS filtering enabled, could anyone point out something I might be missing or a reason for this to be happening? Also, I'm pretty sure about the answer of this but, is there ANY way to recover some data?? Other than having to ask everyone to fill in everything again.. =/ ** EDIT ** The Storage Engine is MyISAM and Collation is latin1_swedish_ci, Pack Keys are default, for all intents and purposes it's a normal DB

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• When is Googling it wrong?

  - by Drahcir

  I've been going through Stack Overflow for quite a bit now and noticed certain people (usually experienced programmers) frown upon Googling (researching) certain problems. Since I myself tend to use Google quite a bit to solve certain programming related issues I found certain comments rather demoralising. Now some of you may have come here trigger happy to delete this post but I needed some clarification. I usually Google things that usually syntax related that I would have never figured out on my own. For example I once wondered how to access the properties of a class that I didn't have a direct relationship to. So after a bit of research I discovered reflection and got what I wanted. Now in another scenario is learning a new language, in my case Silverlight were it differs in certain aspects of .NET compared to say ASP.NET. A few weeks ago I had no idea how to load another Silverlight page (usercontrol) and had to Google my way to the solution which I found wasn't as simple as I had imagined. In scenario three is were I myself frown up, that is just stealing a huge chunk of code to avoid doing the work yourself, for example paging a HTML table using JavaScript, where one just copies and pastes the JavasSript code without as much as trying to understand how it works. I do admit I have done this once or twice before for trivial tasks that had very little time limit and weren't all that important but most of the time still have to throw away what I found because it took too much time to adapt it and get what I wanted out of it. In the last scenario, I sometimes have a piece of code that I would be really unhappy about, as in I find it sloppy or too overcomplicated and try to look on the Internet to see other ways to tackle the same problem, let's say filtering through a table. With the knowledge I acquire I learned new coding practices that help me work more efficiently like "Do not repeat yourself" and such. Now in your opinion when do you find it wrong to use Google (or any other researching tool) to find a solution to your problem?

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• T-SQL: Dynamic Query by Selected Column in ASP.NET GridView

  - by jp2code

  I'm trying to modify a stored procedure used in an ASP.NET page. By default, the stored procedure returns all of the data, which can be overwhelming for employees in the plant. I want to add a drop down menu item for the column name and a text box for a value to allow our employees to search the data for their specific items. What I would like to add is the ability to pass in a Column Name and Column Value to search, similar to the following: DECLARE @colName nVarChar(50), @colValue nVarChar(50) SET @colName='EmployeeID' SET @colValue='007135' SELECT Column1, Column2, Column3, Column4, Column5, Column6, Column7 FROM viewNum1 WHERE ((@colName IS NULL) OR (@colValue IS NULL) OR ('['+@colName+']'=@colValue)) If all values passed in (@colValue and @colName), all records return; however, if I try specifying that @colName=EmployeeID and @colValue='007135' (a value that does exist in the database), no records are returned. Next is the problem that I am running an old SQL Server 2000 database that does not allow the stored procedure to access the table column names, and the whole technique looks prone to SQL Injection. Finally, I don't see how to bind my GridView control to this and still have the ability to display all records. How would I write such a filtering stored procedure?

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• Using Linq-To-SQL I'm getting some weird behavior doing text searches with the .Contains method. Loo

  - by Nate Bross

  I have a table, where I need to do a case insensitive search on a text field. If I run this query in LinqPad directly on my database, it works as expected Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase")) // also, adding in the same constraints I'm using in my repository works in LinqPad // Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase") && tbl.IsActive == true) In my application, I've got a repository which exposes IQueryable objects which does some initial filtering and it looks like this var dc = new MyDataContext(); public IQueryable<Table> GetAllTables() { var ret = dc.Tables.Where(t => t.IsActive == true); return ret; } In the controller (its an MVC app) I use code like this in an attempt to mimic the LinqPad query: var rpo = new RepositoryOfTable(); var tables = rpo.GetAllTables(); // for some reason, this does a CASE SENSITIVE search which is NOT what I want. tables = tables.Where(tbl => tbl.Title.Contains("StringWithAnyCase"); return View(tables); The column is defiend as an nvarchar(50) in SQL Server 2008. Any help or guidance is greatly appreciated!

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• JavaScript Keycode 46 is DEL Function key or (.) period sign?

  - by Omar

  Im writing some logic in JavaScript using jquery, where i must check the input content against a REGEX pattern ex: "^[a-zA-Z0-9_]*$" //Alpha-numeric and _ The logic is almost done, i just have a little problem filtering the function key DEL, my logic goes like this: var FunctionsKey = new Array(8, 9, 13, 16, 35, 36, 37, 39, 46); function keypressValidation(key) { if (config.regexExp != null) { if ($.inArray(key, FunctionsKey) != -1) { return true; } else { var keyChar = String.fromCharCode(key); return RegexCheck(keyChar); } } return true; } If the KeyCode is one of those in the array, i let it pass, if not i get the char and compare it against the REGEX. The problem is: in some Browsers the DEL and '.' (period sign) have the same key Code 46. So is there a better logic to filter the function keys or must i write a condition for that case, maybe removing the 46 from the array and try to convert it to char and if is (.) let it go to the Regex function if not let it pass? The other question will be are there more shared Key Codes in some browsers? EDIT: My suggested solution wont work because it doesn't matter which key the user pressed (DEL or period) i always get (.) as CHAR at least on OPERA and FF =(.

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• Handling large (object) datasets with PHP

  - by Aron Rotteveel

  I am currently working on a project that extensively relies on the EAV model. Both entities as their attributes are individually represented by a model, sometimes extending other models (or at least, base models). This has worked quite well so far since most areas of the application only rely on filtered sets of entities, and not the entire dataset. Now, however, I need to parse the entire dataset (IE: all entities and all their attributes) in order to provide a sorting/filtering algorithm based on the attributes. The application currently consists of aproximately 2200 entities, each with aproximately 100 attributes. Every entity is represented by a single model (for example Client_Model_Entity) and has a protected property called $_attributes, which is an array of Attribute objects. Each entity object is about 500KB, which results in an incredible load on the server. With 2000 entities, this means a single task would take 1GB of RAM (and a lot of CPU time) in order to work, which is unacceptable. Are there any patterns or common approaches to iterating over such large datasets? Paging is not really an option, since everything has to be taken into account in order to provide the sorting algorithm.

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• Distinct or group by on some columns but not others

  - by Nazadus

  I have a view that I'm trying to filter with something similar to DISTINCT on some columns but not others. I have a view like this: Name LastName Zip Street1 HouseholdID (may not be unique because it may have multiple addresses -- think of it in the logical sense as grouping persons but not physical locations; If you lookup HouseholdID 4130, you may get two rows.. or more, because the person may have mutiple mailing locations) City State I need to pull all those columns but filter on LastName,Zip, and Street1. Here's the fun part: The filter is arbitrary -- meaning I don't care which one of the duplicates goes away. This is for a mail out type thing and the other information is not used for any other reason than than to look up a specific person if needed (I have no idea why). So.. given one of the records, you can easily figure out the removed ones. As it stands now, my Sql-Fu fails me and I'm filtering in C# which is incredibly slow and is pretty much a foreach that starts with an empty list and adds the row in if the combined last name, zip, and street aren't are not in the list. I feel like I'm missing a simple / basic part of SQL that I should be understanding.

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• jQuery hide all table rows which contain a hidden field matching a value

  - by Famous Nerd

  Though I don't doubt this has been answered I cannot find a great match for my question. I have a table for which I'd like to filter rows based on whether or not they contain a hidden field matching a value. I understand that the technique tends to be "show all rows", "filter the set", "show/hide that filtered set" I have the following jquery but I'm aweful with filter and my filtered set seems to always contain no elements. my table is the usual <table> <tr><td>header></td><td>&nbsp;</tr> <tr> <td>a visible cell</td><td><input type='hidden' id='big-asp.net-id' value='what-im-filtering-on' /> </td> </tr> </table> My goal is to be able to match on tr who's descendent contains a hidden input containing either true or false. this is how I've tried the selector (variations of this) and I'm not even testing for the value yet. function OnFilterChanged(e){ //debugger; var checkedVal = $("#filters input[type='radio']:checked").val(); var allRows = $("#match-grid-container .tabular-data tr"); if(checkedVal=="all"){ allRows.show(); } else if(checkedVal=="matched"){ allRows.show(); allRows.filter(function(){$(this).find("input[type='hidden'][id~='IsAutoMatchHiddenField']")}).hide(); } else if(checkedVal=="unmatched"){ } } Am I way off with the filter? is the $(this) required in the filter so that i can do the descendant searching? Thanks kindly

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• GridView ObjectDataSource LINQ Paging and Sorting using multiple table query.

  - by user367426

  I am trying to create a pageing and sorting object data source that before execution returns all results, then sorts on these results before filtering and then using the take and skip methods with the aim of retrieving just a subset of results from the database (saving on database traffic). this is based on the following article: http://www.singingeels.com/Blogs/Nullable/2008/03/26/Dynamic_LINQ_OrderBy_using_String_Names.aspx Now I have managed to get this working even creating lambda expressions to reflect the sort expression returned from the grid even finding out the data type to sort for DateTime and Decimal. public static string GetReturnType<TInput>(string value) { var param = Expression.Parameter(typeof(TInput), "o"); Expression a = Expression.Property(param, "DisplayPriceType"); Expression b = Expression.Property(a, "Name"); Expression converted = Expression.Convert(Expression.Property(param, value), typeof(object)); Expression<Func<TInput, object>> mySortExpression = Expression.Lambda<Func<TInput, object>>(converted, param); UnaryExpression member = (UnaryExpression)mySortExpression.Body; return member.Operand.Type.FullName; } Now the problem I have is that many of the Queries return joined tables and I would like to sort on fields from the other tables. So when executing a query you can create a function that will assign the properties from other tables to properties created in the partial class. public static Account InitAccount(Account account) { account.CurrencyName = account.Currency.Name; account.PriceTypeName = account.DisplayPriceType.Name; return account; } So my question is, is there a way to assign the value from the joined table to the property of the current table partial class? i have tried using. from a in dc.Accounts where a.CompanyID == companyID && a.Archived == null select new { PriceTypeName = a.DisplayPriceType.Name}) but this seems to mess up my SortExpression. Any help on this would be much appreciated, I do understand that this is complex stuff.

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• How to join multiple tables using LINQ-to-SQL?

  - by user603245

  Hi! I'm quite new to linq, so please bear with me. I'm working on a asp.net webpage and I want to add a "search function" (textbox where user inputs name or surname or both or just parts of it and gets back all related information). I have two tables ("Person" and "Application") and I want to display some columns from Person (name and surname) and some from Application (score, position,...). I know how I could do it using sql, but I want to learn more about linq and thus I want to do it using linq. For now I got two main ideas: 1.) var person = dataContext.GetTable<Person>(); var application = dataContext.GetTable<Application>(); var p1 = from p in Person where(p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1])) select new {Id = p.Id, Name = p.Name, Surname = p.Surname}; //or maybe without this line //I don't know how to do the following properly var result = from a in Application where a.FK_Application.Equals(index) //just to get the "right" type of application //this is not right, but I don't know how to do it better join p1 on p1.Id == a.FK_Person 2.) The other idea is just to go through "Application" and instead of "join p1 ..." to use var result = from a in Application where a.FK_Application.Equals(index) //just to get the "right" type of application join p from Person on p.Id == a.FK_Person where p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1]) I think that first idea is better for queries without the first "where" condition, which I also intended to use. Regardless of what is better (faster), I still don't know how to do it using linq. Also in the end I wanted to display / select just some parts (columns) of the result (joined tables + filtering conditions). I really want to know how to do such things using linq as I'll be dealing also with some similar problems with local data, where I can use only linq. Could somebody please explain me how to do it, I spent days trying to figure it out and searching on the internet for answers. Thank you for your time.

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• AJAX filter MySQL results using checkboxes

  - by keepitnang

  I'm attempting to get to grips with displaying filterable MySQL data within a PHP page based on user checkbox selections. I have a database of domain names and the dates on which these will require renewal as per Nominet DAC information and I can get unfiltered data to display, but filtering results by domain extensions is proving tricky for me to accomplish. I should point out at this stage that I am a serious newcomer to many of the ideas I am trying to learn to work with here, so please be gentle. I have tried following some other articles on here also, but no dice. I have the following so far: HTML <input type="checkbox" class="extensions" name="extensions" value=".co.uk">.co.uk</input> <input type="checkbox" class="extensions" name="extensions" value=".org.uk">.org.uk</input> Script $('.extensions').live('click', function() { var all_boxes = $('.extensions'); var all_boxes_values = []; var i = 0; for (var i; i < all_boxes.length; i++) { if (all_boxes[i].checked) { all_boxes_values.push(all_boxes[i].value) } } var all_boxes_values_clean = all_boxes_values.join(", "); console.log(all_boxes_values_clean); $.get("sql-test.php", {q: all_boxes_values_clean}, function(result) { $("div#output").html(result); } )}); PHP $g = $_GET['q']; $extensionsql=""; $extension=1; if(isset($g)) { $extension=1; $param = "" . str_replace(",", "','", $_GET['q']) . ""; } And that's as far as I have gotten with my limited ability. What I would like to do next is search the column domainName for a string match and return the appropriate results to the user. Something to mimic something like the following but I'm not sure how to achieve it. Any help would be much appreciated: SELECT * FROM `refresh` WHERE `domainName` LIKE '%.co.uk%' AND renewalDate LIKE '%2012-06-30%' ORDER BY `domainName` ASC Thanks

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• Show only div of the product hovering in category grid with jQuery

  - by Dane

  On Magento, I'm trying to get avalable attributes per product in a new div (show/ hide onmouseover) as soon as I hover a product. Unfortunately, my jQuery code opens every div with the same name. I think, I need to do it with jQuery(this) but I tried it in a 1000 different ways, and it won't work. Maybe, somebody here can help me with a better code. jQuery(function() { jQuery('.slideDiv').hide().data('over', false); jQuery('#hover').hover(function() { jQuery('.slideDiv').fadeIn(); }, function() { // Check if mouse did not go over .dialog before hiding it again var timeOut = setTimeout(function() { if (!jQuery('.slideDiv').data('over')) { jQuery('.slideDiv').fadeOut(); clearTimeout(timeOut); } }, 100); }); // Set data for filtering on mouse events for #hover-here jQuery('.slideDiv').hover(function() { jQuery(this).data('over', true); }, function() { jQuery(this).fadeOut().data('over', false); }); }); The PHP just prints the attributes needed. <a href="#" id="hover">Custom Attributes</a> <div class="slideDiv"> <?php $attrs = $_product->getTypeInstance(true)->getConfigurableAttributesAsArray($_product); foreach($attrs as $attr) { if(0 == strcmp("shoe_size", $attr['attribute_code'])) { $options = $attr['values']; print "Größen:<br />"; foreach($options as $option) { print "{$option['store_label']}<br />"; } } } ?> </div> I added the script to [new link] http://jsfiddle.net/xsxfr/47/ so you can see there, that it is not working like this right now :(.

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• Separate "Year" to several worksheets according to one column....

  - by HACHI

  hello! This task is driving me mad... please help! Instead of manually type in the data, i have used VBA to find the year range, put into one column and delete all duplicate ones. But since excel could give more than 20 years, it would be tedious to do all the filtering manually. AND, now i need excel to separate the rows that contain the specific year range in any one the three columns and put them into a new sheet. e.g. The years that excel could find in the three columns(F:H) are ( 2001,2003,2006,2010, 2012,2020.....2033).. and they are pasted in column "S" in sheet 1. How could i tell excel create new sheets for the years ( sheets 2001, sheets 2003, sheet2006....),search through column (F:H) in sheet 1 to see if ANY of those columns contain that year, and paste them into the new sheet. To be more specific, in the newly created "Sheet 2001", the entire row where column(F:H) contains "2001" should be pasted. and in the newly created "Sheet 2033", the entire row where column(F:H) contains "2033" should be pasted.. Enclosed please find the reference. http://www.speedyshare.com/files/23851477/Book32.xls I have got sheet "2002" and "2003" here as results but for the real one i will need more years' sheets (as many as how many excel could extract in the previous stage; as shown in column L ) ...... I think this task should be quite usual (extracting by date), but i couldn't google the result....Pleas help!!I am very clueless about how to do LOOPING.. so please advice and give in more details! Thanks

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• Sort queryset by a generic foreign key (django)?

  - by thornomad

  I am using Django's comment framework which utilizes generic foreign keys. Question: How do I sort a given model's queryset by their comment count using the generic foreign key lookup? Reading the django docs on the subject it says one needs to calculate them not using the aggregation API: Django's database aggregation API doesn't work with a GenericRelation. [...] For now, if you need aggregates on generic relations, you'll need to calculate them without using the aggregation API. The only way I can think of, though, would be to iterate through my queryset, generate a list with content_type and object_id's for each item, then run a second queryset on the Comment model filtering by this list of content_type and object_id ... sort the objects by the count, then re-create a new queryset in this order by pulling the content_object for each comment ... This just seems wrong and I'm not even sure how to pull it off. Ideas? Someone must have done this before. I found this post online but it requires me handwriting SQL -- is that really necessary ?

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• nextgen gallery order issue

  - by mro

  Hi, wonder if anyone can help. I think what I'm after won't be solved by any exsiting code in nextgen plugin (in wordpress) due to the custom way I'm using it hence I come to stackoverflow for some opnions. Bascially - I am only really using the admin of nextgen to work with the gallerys etc. The actual meat of the functionality I'm querying the nextgen DB's direct from my code, I would have loved to use the inbuilt gallerys in nextgen, but my spec specifics were so custom I couldn't. My issue is, I need to pull the images from the DB's in the order it is in the admin (ie if a user pulls the sort order around in the drag and drop area). I have noticed however this doesn't affect the image id order in the DB, and wouldn't expect it to - that would be some complex shifting around just to reorder everytime surely. So obviously when I query the DB the order it's looking at is when it was created, by image id, with my filtering on top. I'm wondering though if there is a way I can query that sort order that's determined in the admin somehow, then at least I could sort the array somehow in the code ? does next gen store it's user custom sort order somewhere ? Hope this makes sense :) any thoughts appreciated. Thanks

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• Performance when querying a View

  - by Nate Bross

  I'm wondering if this is a bad practice or if in general this is the correct approach. Lets say that I've created a view that combines a few attributes from a few tables. My question, what do I need to do so I can query against this view as if it were a table without worrying about performance? All attributes in the original tables are indexed, my concern is that the result view will have hundreds of thousands of records, which I will want to narrow down quite a bit based on user input. What I'd like to avoid, is having multiple versions of the code that generates this view floating around with a few extra "where" conditions to facilitate the user input filtering. For example, assume my view has this header VIEW(Name, Type, DateEntered) this may have 100,000+ rows (possibly millions). I'd like to be able to make this view in SQL Server, and then in my application write querlies like this: SELECT Name, Type, DateEntered FROM MyView WHERE DateEntered BETWEEN @date1 and @date2; Basically, I am denormalizing my data for a series of reports that need to be run, and I'd like to centralize where I pull the data from, maybe I'm not looking at this problem from the right angle though, so I'm open to alternative ways to attack this.

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• How do I add a where filter using the original Linq-to-SQL object in the following scenario

  - by GenericTypeTea

  I am performing a select query using the following Linq expression: Table<Tbl_Movement> movements = context.Tbl_Movement; var query = from m in movements select new MovementSummary { Id = m.DocketId, Created = m.DateTimeStamp, CreatedBy = m.Tbl_User.FullName, DocketNumber = m.DocketNumber, DocketTypeDescription = m.Ref_DocketType.DocketType, DocketTypeId = m.DocketTypeId, Site = new Site() { Id = m.Tbl_Site.SiteId, FirstLine = m.Tbl_Site.FirstLine, Postcode = m.Tbl_Site.Postcode, SiteName = m.Tbl_Site.SiteName, TownCity = m.Tbl_Site.TownCity, Brewery = new Brewery() { Id = m.Tbl_Site.Ref_Brewery.BreweryId, BreweryName = m.Tbl_Site.Ref_Brewery.BreweryName }, Region = new Region() { Description = m.Tbl_Site.Ref_Region.Description, Id = m.Tbl_Site.Ref_Region.RegionId } } }; I am also passing in an IFilter class into the method where this select is performed. public interface IJobFilter { int? PersonId { get; set; } int? RegionId { get; set; } int? SiteId { get; set; } int? AssetId { get; set; } } How do I add these where parameters into my SQL expression? Preferably I'd like this done in another method as the filtering will be re-used across multiple repositories. Unfortunately when I do query.Where it has become an IQueryable<MovementSummary>. I'm assuming it has become this as I'm returning an IEnumerable<MovementSummary>. I've only just started learning LINQ, so be gentle.

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• Why does this SELECT ... JOIN statement return no results?

  - by Stephen

  I have two tables: 1. tableA is a list of records with many columns. There is a timestamp column called "created" 2. tableB is used to track users in my application that have locked a record in tableA for review. It consists of four columns: id, user_id, record_id, and another timestamp collumn. I'm trying to select up to 10 records from tableA that have not been locked by for review by anyone in tableB (I'm also filtering in the WHERE clause by a few other columns from tableA like record status). Here's what I've come up with so far: SELECT tableA.* FROM tableA LEFT OUTER JOIN tableB ON tableA.id = tableB.record_id WHERE tableB.id = NULL AND tableA.status = 'new' AND tableA.project != 'someproject' AND tableA.created BETWEEN '1999-01-01 00:00:00' AND '2010-05-06 23:59:59' ORDER BY tableA.created ASC LIMIT 0, 10; There are currently a few thousand records in tableA and zero records in tableB. There are definitely records that fall between those timestamps, and I've verified this with a simple SELECT * FROM tableA WHERE created BETWEEN '1999-01-01 00:00:00' AND '2010-05-06 23:59:59' The first statement above returns zero rows, and the second one returns over 2,000 rows.

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• Advice on Minimizing Stored Procedure Parameters

  - by RPM1984

  Hi Guys, I have an ASP.NET MVC Web Application that interacts with a SQL Server 2008 database via Entity Framework 4.0. On a particular page, i call a stored procedure in order to pull back some results based on selections on the UI. Now, the UI has around 20 different input selections, ranging from a textbox, dropdown list, checkboxes, etc. Each of those inputs are "grouped" into logical sections. Example: Search box : "Foo" Checkbox A1: ticked, Checkbox A2: unticked Dropdown A: option 3 selected Checkbox B1: ticked, Checkbox B2: ticked, Checkbox B3: unticked So i need to call the SPROC like this: exec SearchPage_FindResults @SearchQuery = 'Foo', @IncludeA1 = 1, @IncludeA2 = 0, @DropDownSelection = 3, @IncludeB1 = 1, @IncludeB2 = 1, @IncludeB3 = 0 The UI is not too important to this question - just wanted to give some perspective. Essentially, i'm pulling back results for a search query, filtering these results based on a bunch of (optional) selections a user can filter on. Now, My questions/queries: What's the best way to pass these parameters to the stored procedure? Are there any tricks/new ways (e.g SQL Server 2008) to do this? Special "table" parameters/arrays - can we pass through User-Defined-Types? Keep in mind im using Entity Framework 4.0 - but could always use classic ADO.NET for this if required. What about XML? What are the serialization/de-serialization costs here? Is it worth it? How about a parameter for each logical section? Comma-seperated perhaps? Just thinking out loud. This page is particulary important from a user point of view, and needs to perform really well. The stored procedure is already heavy in logic, so i want to minimize the performance implications - so keep that in mind. With that said - what is the best approach here?

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• Why use shorter VARCHAR(n) fields?

  - by chryss

  It is frequently advised to choose database field sizes to be as narrow as possible. I am wondering to what degree this applies to SQL Server 2005 VARCHAR columns: Storing 10-letter English words in a VARCHAR(255) field will not take up more storage than in a VARCHAR(10) field. Are there other reasons to restrict the size of VARCHAR fields to stick as closely as possible to the size of the data? I'm thinking of Performance: Is there an advantage to using a smaller n when selecting, filtering and sorting on the data? Memory, including on the application side (C++)? Style/validation: How important do you consider restricting colunm size to force non-sensical data imports to fail (such as 200-character surnames)? Anything else? Background: I help data integrators with the design of data flows into a database-backed system. They have to use an API that restricts their choice of data types. For character data, only VARCHAR(n) with n <= 255 is available; CHAR, NCHAR, NVARCHAR and TEXT are not. We're trying to lay down some "good practices" rules, and the question has come up if there is a real detriment to using VARCHAR(255) even for data where real maximum sizes will never exceed 30 bytes or so. Typical data volumes for one table are 1-10 Mio records with up to 150 attributes. Query performance (SELECT, with frequently extensive WHERE clauses) and application-side retrieval performance are paramount.

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• Getting the type of an array of T, without specifying T - Type.GetType("T[]")

  - by Merlyn Morgan-Graham

  I am trying to create a type that refers to an array of a generic type, without specifying the generic type. That is, I would like to do the equivalent of Type.GetType("T[]"). I already know how to do this with a non-array type. E.g. Type.GetType("System.Collections.Generic.IEnumerable`1") // or typeof(IEnumerable<>) Here's some sample code that reproduces the problem. using System; using System.Collections.Generic; public class Program { public static void SomeFunc<T>(IEnumerable<T> collection) { } public static void SomeArrayFunc<T>(T[] collection) { } static void Main(string[] args) { Action<Type> printType = t => Console.WriteLine(t != null ? t.ToString() : "(null)"); Action<string> printFirstParameterType = methodName => printType( typeof(Program).GetMethod(methodName).GetParameters()[0].ParameterType ); printFirstParameterType("SomeFunc"); printFirstParameterType("SomeArrayFunc"); var iEnumerableT = Type.GetType("System.Collections.Generic.IEnumerable`1"); printType(iEnumerableT); var iEnumerableTFromTypeof = typeof(IEnumerable<>); printType(iEnumerableTFromTypeof); var arrayOfT = Type.GetType("T[]"); printType(arrayOfT); // Prints "(null)" // ... not even sure where to start for typeof(T[]) } } The output is: System.Collections.Generic.IEnumerable`1[T] T[] System.Collections.Generic.IEnumerable`1[T] System.Collections.Generic.IEnumerable`1[T] (null) I'd like to correct that last "(null)". This will be used to get an overload of a function via reflections by specifying the method signature: var someMethod = someType.GetMethod("MethodName", new[] { typeOfArrayOfT }); // ... call someMethod.MakeGenericMethod some time later I've already gotten my code mostly working by filtering the result of GetMethods(), so this is more of an exercise in knowledge and understanding.

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• Using multiple Qt (SQL) Models

  - by radix07

  I have a near real-time application that I am using Qt and an SQLite database to run. I am curious if it is safe to have two separate models access a database at once. I know 2 separate views can access a model just fine, but I can't find any document addressing this. I also realize that SQLite is thread safe for reading, so I don't see a real issue to doing this from the SQLite part of things... Basically I want to use a QSqlTableModel to do the real-time read and write in the background and at the same time use a QSqlQueryModel to give the user desired data. Since I may be doing lots of filtering in the background using the table model I can't use it as the main view as well. I have gotten this to work for the most part, but am not sure if this is the best way to do this. If the models act like multiple SQL queries I don't believe this should be an issue, but I would like to know from someone I bit more knowledgeable about this stuff since this is pretty new to me. Thanks

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• How to remove invalid UTF-8 characters from a JavaScript string?

  - by msielski

  I'd like to remove all invalid UTF-8 characters from a string in JavaScript. I've tried using the approach described here (link removed) and came up with the JavaScript: strTest = strTest.replace(/([\x00-\x7F]|[\xC0-\xDF][\x80-\xBF]|[\xE0-\xEF][\x80-\xBF]{2}|[\xF0-\xF7][\x80-\xBF]{3})|./, "$1"); It seems that the UTF-8 validation regex described here (link removed) is more complete and I adapted it in the same way like: strTest = strTest.replace(/([\x09\x0A\x0D\x20-\x7E]|[\xC2-\xDF][\x80-\xBF]|\xE0[\xA0-\xBF][\x80-\xBF]|[\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}|\xED[\x80-\x9F][\x80-\xBF]|\xF0[\x90-\xBF][\x80-\xBF]{2}|[\xF1-\xF3][\x80-\xBF]{3}|\xF4[\x80-\x8F][\x80-\xBF]{2})|./, "$1"); Both of these pieces of code seem to be allowing valid UTF-8 through, but aren't filtering out hardly any of the bad UTF-8 characters from my test data: UTF-8 decoder capability and stress test. Either the bad characters come through unchanged or seem to have some of their bytes removed creating a new, invalid character. I'm not very familiar with the UTF-8 standard or with multibyte in JavaScript so I'm not sure if I'm failing to represent proper UTF-8 in the regex or if I'm applying that regex improperly in JavaScript. Any help appreciated. Thanks!

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• Sorting a very large text file in Java

  - by Alice

  Hi, I have a large text file I need to sort in Java. The format is: word [tab] frequency [new line] The algorithm for sorting is: Read some of the file, filtering for purlely alphabetic words. Once you have X number of alphabetic words, call Collections.sort and write the result to a file. Repeat until you have finished reading the file. Start reading two sorted files, comparing line by line for the word with higher frequency, and writing at the same time to a new file as to not load much into your memory Repeat until all files are merged into one large file Right now I've divided the large file into smaller ones (sorted by descending frequency) with 10,000 lines each. I know I need to somehow merge these files back together, but I'm not sure how to go about this. I've created a LinkedList to keep track of all the files created. The algorithm says to compare each line in the two files, except I've tried a case where , say file1 = 8,6,5,3,1 and file2 = 9,8,8,8,8. Then if I compare them line by line I would get file3 = 9,8,8,6,8,5,8,3,8,1 which is incorrectly sorted (they should be in decreasing order). I think I'm misunderstanding some part of the algorithm. If someone could point out what I should do instead, I'd greatly appreciate it. Thanks. edit: Yes this is an assignment. We aren't allowed to increase memory unfortunately :(

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• Raspberry Pi broadcast serial port data to local network

  - by D051P0

  I didn't find anything to help me with this problem. What I want is: Serial device sends repeatedly some data to serial port. Raspberry Pi should get this data from RxD and stream it to local network via port 10001 without filtering it. So I can find this device on my pc. This should also work in other direction: Raspberry listen to port 10001 and forward all data from local network to TxD. I'm newbie in Linux World. How can I listen to some port on Raspberry Pi and send broadcast to the same port? I'm using Raspbian Wheezy with soft float. I have found a library Pi4j for Java, that I already use to get and write data from/to serial port. final Serial serial = SerialFactory.createInstance(); serial.addListener(new SerialDataListener() { public void dataReceived(SerialDataEvent event) { forward(event.getData()); } }); event.getData() is a String, which I want to broadcast in my local network. Is it generally a good Idea to use Java for that? I need also a String from port 10001, which I can forward to serial port.

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