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• Changing the indexing on existing table in SQL Server 2000

  - by Raj

  Guys, Here is the scenario: SQL Server 2000 (8.0.2055) Table currently has 478 million rows of data. The Primary Key column is an INT with IDENTITY. There is an Unique Constraint imposed on two other columns with a Non-Clustered Index. This is a vendor application and we are only responsible for maintaining the DB. Now the vendor has recommended doing the following "to improve performance" Drop the PK and Clustered Index Drop the non-clustered index on the two columns with the UNIQUE CONSTRAINT Recreate the PK, with a NON-CLUSTERED index Create a CLUSTERED index on the two columns with the UNIQUE CONSTRAINT I am not convinced that this is the right thing to do. I have a number of concerns. By dropping the PK and indexes, you will be creating a heap with 478 million rows of data. Then creating a CLUSTERED INDEX on two columns would be a really mammoth task. Would creating another table with the same structure and new indexing scheme and then copying the data over, dropping the old table and renaming the new one be a better approach? I am also not sure how the stored procs will react. Will they continue using the cached execution plan, considering that they are not being explicitly recompiled. I am simply not able to understand what kind of "performance improvement" this change will provide. I think that this will actually have the reverse effect. All thoughts welcome. Thanks in advance, Raj

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• Call method immediately after object construction in LINQ query

  - by Steffen

  I've got some objects which implement this interface: public interface IRow { void Fill(DataRow dr); } Usually when I select something out of db, I go: public IEnumerable<IRow> SelectSomeRows { DataTable table = GetTableFromDatabase(); foreach (DataRow dr in table.Rows) { IRow row = new MySQLRow(); // Disregard the MySQLRow type, it's not important row.Fill(dr); yield return row; } } Now with .Net 4, I'd like to use AsParallel, and thus LINQ. I've done some testing on it, and it speeds up things alot (IRow.Fill uses Reflection, so it's hard on the CPU) Anyway my problem is, how do I go about creating a LINQ query, which calls Fills as part of the query, so it's properly parallelized? For testing performance I created a constructor which took the DataRow as argument, however I'd really love to avoid this if somehow possible. With the constructor in place, it's obviously simple enough: public IEnumerable<IRow> SelectSomeRowsParallel { DataTable table = GetTableFromDatabase(); return from DataRow dr in table.Rows.AsParallel() select new MySQLRow(dr); } However like I said, I'd really love to be able to just stuff my Fill method into the LINQ query, and thus not need the constructor overload.

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• ambient values in mvc2.net routing

  - by Muhammad Adeel Zahid

  Hello Everyone, i have following two routes registered in my global.asax file routes.MapRoute( "strict", "{controller}.mvc/{docid}/{action}/{id}", new { action = "Index", id = "", docid = "" }, new { docid = @"\d+"} ); routes.MapRoute( "default", "{controller}.mvc/{action}/{id}", new { action = "Index", id = "" }, new { docConstraint = new DocumentConstraint() } ); and i have a static "dashboard" link in my tabstrip and some other links that are constructed from values in db here is the code <ul id="globalnav" class = "t-reset t-tabstrip-items"> <li class="bar" id = "dashboard"> <%=Html.ActionLink("dash.board", "Index", pck.Controller, new{docid =string.Empty,id = pck.PkgID }, new { @class = "here" })%> </li> <% foreach (var md in pck.sysModules) { %> <li class="<%=liClass%>"> <%=Html.ActionLink(md.ModuleName, md.ActionName, pck.Controller, new { docid = md.DocumentID}, new { @class = cls })%> </li> <% } %> </ul> Now my launching address is localhost/oa.mvc/index/11 clearly matching the 2nd route. but when i visit any page that has mapped to first route and then come back to dash.board link it shows me localhost/oa.mvc/7/index/11 where 7 is docid and picked from previous Url. now i understand that my action method is after docid and changing it would not clear the docid. my question here is that can i remove docid in this scenario without changing the route. regards adeel

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• Update parameter not working on bound DropDownList

  - by ProfK

  I have a DropDownList declared like this: <asp:DropDownList ID="campaignTypeList" runat="server" Width="150px" DataTextField="Name" DataValueField="CampaignTypeId" DataSourceID="campaignTypesDataSource" SelectedValue='<%# Bind("CampaignTypeID") %>'> </asp:DropDownList> Using the designer, my SqlDataSource is configured as follows1: <asp:SqlDataSource ID="campaignDataSource" runat="server" ConflictDetection="CompareAllValues" ConnectionString="<%$ ConnectionStrings:ProVantageMediaManagement %>" SelectCommand="ActivationCampaignGetById" SelectCommandType="StoredProcedure" UpdateCommand="ActivationCampaignUpdate" UpdateCommandType="StoredProcedure"> <SelectParameters> <asp:QueryStringParameter DefaultValue="98" Name="campaignId" Direction="Input" QueryStringField="id" Type="Int32" /> </SelectParameters> <UpdateParameters> <asp:QueryStringParameter DefaultValue="98" Name="campaignId" Direction="Input" QueryStringField="id" Type="Int32" /> <asp:Parameter Name="campaignName" Type="String" /> <asp:Parameter Name="campaignTypeId" Type="Int32" /> </UpdateParameters> </asp:SqlDataSource> Yet when the update command is sent to the DB, the campaignTypeId value is always 1, no matter which item is selected in the DropDownList. What am I doing wrong? 1 Bonus points for telling us what a ControlParameter is meant for, if not for handling values of controls in a scenario like this.

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• Left/Right/Inner joins using C# and LINQ

  - by Keith Barrows

  I am trying to figure out how to do a series of queries to get the updates, deletes and inserts segregated into their own calls. I have 2 tables, one in each of 2 databases. One is a Read Only feeds database and the other is the T-SQL R/W Production source. There are a few key columns in common between the two. What I am doing to setup is this: List<model.AutoWithImage> feedProductList = _dbFeed.AutoWithImage.Where(a => a.ClientID == ClientID).ToList(); List<model.vwCompanyDetails> companyDetailList = _dbRiv.vwCompanyDetails.Where(a => a.ClientID == ClientID).ToList(); foreach (model.vwCompanyDetails companyDetail in companyDetailList) { List<model.Product> productList = _dbRiv.Product.Include("Company").Where(a => a.Company.CompanyId == companyDetail.CompanyId).ToList(); } Now that I have a (source) list of products from the feed, and an existing (target) list of products from my prod DB I'd like to do 3 things: Find all SKUs in the feed that are not in the target Find all SKUs that are in both, that are active feed products and update the target Find all SKUs that are in both, that are inactive and soft delete from the target What are the best practices for doing this without running a double loop? Would prefer a LINQ 4 Objects solution as I already have my objects. EDIT: BTW, I will need to transfer info from feed rows to target rows in the first 2 instances, just set a flag in the last instance. TIA

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• Lost with hibernate - OneToMany resulting in the one being pulled back many times..

  - by Andy

  I have this DB design: CREATE TABLE report ( ID MEDIUMINT PRIMARY KEY NOT NULL AUTO_INCREMENT, user MEDIUMINT NOT NULL, created TIMESTAMP NOT NULL, state INT NOT NULL, FOREIGN KEY (user) REFERENCES user(ID) ON UPDATE CASCADE ON DELETE CASCADE ); CREATE TABLE reportProperties ( ID MEDIUMINT NOT NULL, k VARCHAR(128) NOT NULL, v TEXT NOT NULL, PRIMARY KEY( ID, k ), FOREIGN KEY (ID) REFERENCES report(ID) ON UPDATE CASCADE ON DELETE CASCADE ); and this Hibernate Markup: @Table(name="report") @Entity(name="ReportEntity") public class ReportEntity extends Report{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name="ID") private Integer ID; @Column(name="user") private Integer user; @Column(name="created") private Timestamp created; @Column(name="state") private Integer state = ReportState.RUNNING.getLevel(); @OneToMany(mappedBy="pk.ID", fetch=FetchType.EAGER) @JoinColumns( @JoinColumn(name="ID", referencedColumnName="ID") ) @MapKey(name="pk.key") private Map<String, ReportPropertyEntity> reportProperties = new HashMap<String, ReportPropertyEntity>(); } and @Table(name="reportProperties") @Entity(name="ReportPropertyEntity") public class ReportPropertyEntity extends ReportProperty{ @Embeddable public static class ReportPropertyEntityPk implements Serializable{ /** * long#serialVersionUID */ private static final long serialVersionUID = 2545373078182672152L; @Column(name="ID") protected int ID; @Column(name="k") protected String key; } @EmbeddedId protected ReportPropertyEntityPk pk = new ReportPropertyEntityPk(); @Column(name="v") protected String value; } And i have inserted on Report and 4 Properties for that report. Now when i execute this: this.findByCriteria( Order.asc("created"), Restrictions.eq("user", user.getObject(UserField.ID)) ) ); I get back the report 4 times, instead of just the once with a Map with the 4 properties in. I'm not great at Hibernate to be honest, prefer straight SQL but I must learn, but i can't see what it is that is wrong.....? Any suggestions?

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• Populating dropdownlist in asp.net mvc doesn't seem to work for me...

  - by Pandiya Chendur

  I use a dropdownlist in one of my create.aspx but it some how doesnt seem to work... public IEnumerable<Materials> FindAllMeasurements() { var mesurements = from mt in db.MeasurementTypes select new Materials() { Id= Convert.ToInt64(mt.Id), Mes_Name= mt.Name }; return mesurements; } and my controller, public ActionResult Create() { var mesurementTypes = consRepository.FindAllMeasurements().AsEnumerable(); ViewData["MeasurementType"] = new SelectList(mesurementTypes, "Id", "Mes_Name"); return View(); } and my create.aspx has this, <p> <label for="MeasurementTypeId">MeasurementType:</label> <%= Html.DropDownList("MeasurementType", ViewData["MeasurementType"])%> <%= Html.ValidationMessage("MeasurementTypeId", "*") %> </p> When i execute this i got these errors, System.Web.Mvc.HtmlHelper<CrMVC.Models.Material>' does not contain a definition for 'DropDownList' and the best extension method overload 'System.Web.Mvc.Html.SelectExtensions.DropDownList(System.Web.Mvc.HtmlHelper, string, System.Collections.Generic.IEnumerable<System.Web.Mvc.SelectListItem>)' has some invalid arguments 2.cannot convert from 'object' to 'System.Collections.Generic.IEnumerable<System.Web.Mvc.SelectListItem>

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• How do I write this MySQL query?

  - by CT

  I am working on an Asset DB using a lamp stack. In this example consider the following 5 tables: asset, server, laptop, desktop, software All tables have a primary key of id, which is a unique asset id. Every object has all asset attributes and then depending on type of asset has additional attributes in the corresponding table. If the type is a server, desktop or laptop it also has items in the software table. Here are the table create statements: // connect to mysql server and database "asset_db" mysql_connect("localhost", "asset_db", "asset_db") or die(mysql_error()); mysql_select_db("asset_db") or die(mysql_error()); // create asset table mysql_query("CREATE TABLE asset( id VARCHAR(50) PRIMARY KEY, company VARCHAR(50), location VARCHAR(50), purchase_date VARCHAR(50), purchase_order VARCHAR(50), value VARCHAR(50), type VARCHAR(50), notes VARCHAR(200))") or die(mysql_error()); echo "Asset Table Created.</br />"; // create software table mysql_query("CREATE TABLE software( id VARCHAR(50) PRIMARY KEY, software VARCHAR(50), license VARCHAR(50))") or die(mysql_error()); echo "Software Table Created.</br />"; // create laptop table mysql_query("CREATE TABLE laptop( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), serial_number VARCHAR(50), esc VARCHAR(50), user VARCHAR(50), prev_user VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Laptop Table Created.</br />"; // create desktop table mysql_query("CREATE TABLE desktop( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), serial_number VARCHAR(50), esc VARCHAR(50), user VARCHAR(50), prev_user VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Desktop Table Created.</br />"; // create server table mysql_query("CREATE TABLE server( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Server Table Created.</br />"; ?> How do I query the database so that if I search by id, I receive all related fields to that asset id? Thank you.

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• php sessions in database only writing part of information to the table...

  - by Ronedog

  I'm having difficulty figuring out what's going on here, hoping some one can help me out. I have been using php, mysql storing my session information in the database. The app is only running on localhost, vista. In the php.ini file I commented out the "session.save_handler = files" line and am using a php class to handle the session writes/reads, etc. My login process is this: Submit login credentials via login.php. login.php calls loginprocess.php. loginprocess.php verifies user, and if valid starts a new session and adds data to the session vars, then it redirects to index.php. Here's the problem. the loginprocess.php page has a bunch of session vars that get set like $_SESSION['account_id'] = $account_id; etc. but when I go to index.php and do a var_dump($_SESSION) it just says "array() empty". However, if I do a var_dump($_SESSION) in loginprocess.php, just before the redirection line header("Location: ../index.php"); then it shows all the data in the session variable. If I look in the database where the session information is stored, there is data in the session_id field, created_ts field, and expires field, but the session_data field has nothing inside of it and in the past this is the field where all my session data was stored. How could I be able to var_dump the session in loginprocess.php, but the data not exist in the db table, is it using some kind of caching? I cleared my cookies, etc...but no change. Why is the session_id, being written to the table, but the actual session data is not? Any ideas are appreciated. Thanks.

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• How do I join three tables with SQLalchemy and keeping all of the columns in one of the tables?

  - by jimka

  So, I have three tables: The class defenitions: engine = create_engine('sqlite://test.db', echo=False) SQLSession = sessionmaker(bind=engine) Base = declarative_base() class Channel(Base): __tablename__ = 'channel' id = Column(Integer, primary_key = True) title = Column(String) description = Column(String) link = Column(String) pubDate = Column(DateTime) class User(Base): __tablename__ = 'user' id = Column(Integer, primary_key = True) username = Column(String) password = Column(String) sessionId = Column(String) class Subscription(Base): __tablename__ = 'subscription' userId = Column(Integer, ForeignKey('user.id'), primary_key=True) channelId = Column(Integer, ForeignKey('channel.id'), primary_key=True) And the SQL commands that are executed to create them: CREATE TABLE subscription ( "userId" INTEGER NOT NULL, "channelId" INTEGER NOT NULL, PRIMARY KEY ("userId", "channelId"), FOREIGN KEY("userId") REFERENCES user (id), FOREIGN KEY("channelId") REFERENCES channel (id) ); CREATE TABLE user ( id INTEGER NOT NULL, username VARCHAR, password VARCHAR, "sessionId" VARCHAR, PRIMARY KEY (id) ); CREATE TABLE channel ( id INTEGER NOT NULL, title VARCHAR, description VARCHAR, link VARCHAR, "pubDate" TIMESTAMP, PRIMARY KEY (id) ); NOTE: I know user.username should be unique, need to fix that, and I'm not sure why SQLalchemy creates some row names with the double-quotes. And I'm trying to come up with a way to retrieve all of the channels, as well as an indication on what channels one particular user (identified by user.sessionId together with user.id) has a subscription on. For example, say we have four channels: channel1, channel2, channel3, channel4; a user: user1; who has a subscription on channel1 and channel4. The query for user1 would return something like: channel.id | channel.title | subscribed --------------------------------------- 1 channel1 True 2 channel2 False 3 channel3 False 4 channel4 True This is a best-case result, but since I have absolutely no clue as how to accomplish the subscribed column, I've been instead trying to get the particular users id in the rows where the user has a subscription and where a subscription is missing, just leave it blank. The database engine that I'm using together with SQLalchemy atm. is sqlite3 I've been scratching my head over this for two days now, I've no problem joining together all three by way of the subscription table but then all of the channels where the user does not have a subscription gets omitted. I hope I've managed to describe my problem sufficiently, thanks in advance.

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• How can you connect to a password protected MS Access Database from a Spring JdbcTemplate?

  - by Tim Visher

  I need to connect to a password protected MS Access 2003 DB using the JDBC-ODBC bridge. I can't find out how to specify the password in the connect string, or even if that is the correct method of connecting. It would probably be relevant to mention that this is a Spring App which is accessing the database through a JdbcTemplate configured as a datasource bean in our application context file. Some relevant snippets: from application-context.xml <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate"> <property name="dataSource" ref="legacyDataSource" /> </bean> <bean id="jobsheetLocation" class="java.lang.String"> <constructor-arg value="${jobsheet.location}"/> </bean> <bean id="legacyDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${jdbc.legacy.driverClassName}" /> <property name="url" value="${jdbc.legacy.url}"/> <property name="password" value="-------------" /> </bean> from our build properties jdbc.legacy.driverClassName=sun.jdbc.odbc.JdbcOdbcDriver jdbc.legacy.url=jdbc:odbc:Driver\={Microsoft Access Driver (*.mdb)};Dbq\=@LegacyDbPath@;DriverID\=22;READONLY\=true Any thoughts?

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• UIScrollView loading an image

  - by treasure

  i must say i m not very good at this. and you probably know that (cause noone bothers to answer my questions) but i will keep on trying!!! lol here it goes! i wanted to find an "easy" way to use the pinch/zoom function on my app! so i decided to use a UIScrollView. so far so good. i load my image from an sqlite db like so: - (void)loadView { self.title = @"ScrollView"; imageView = [[UIImageView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame]; imageView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; imageView.contentMode = UIViewContentModeScaleAspectFit; imageView.backgroundColor = [UIColor blackColor]; self.view = imageView;} and - (void)viewWillAppear:(BOOL)animated {imageView.image = entity.imageA} I followed a tutorial but i cnnot seem to be able to load my image at all: - (void)vieDidLoad { imageView = [[UIImageView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame]; imageView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; imageView.contentMode = UIViewContentModeScaleAspectFit; imageView.backgroundColor = [UIColor blackColor]; //when i have this it does load the image but when i cant load my own data!! /*UIImageView *tempImageView = [[UIImageView alloc] initWithImage:[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://www.austinbull.com/clonemines.png"]]]]; [self setMyImage:tempImageView]; [tempImageView release];*/ myScrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height); myScrollView.maximumZoomScale = 4.0; myScrollView.minimumZoomScale = 0.75; myScrollView.clipsToBounds = YES; myScrollView.delegate = self; [myScrollView addSubview:imageView]; self.view = scrollView; [window makeKeyAndVisible]; } (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return myImage; } any help would be appreciated! thank you for your time!

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• ibatis throwing NullPointerException

  - by Prashant P

  i am trying to test ibatis with DB. I get NullPointerException. Below are the class and ibatis bean config, <select id="getByWorkplaceId" parameterClass="java.lang.Integer" resultMap="result"> select * from WorkDetails where workplaceCode=#workplaceCode# </select> <select id="getWorkplace" resultClass="com.ibatis.text.WorkDetails"> select * from WorkDetails </select> POJO public class WorkplaceDetail implements Serializable { private static final long serialVersionUID = -6760386803958725272L; private int code; private String plant; private String compRegNum; private String numOfEmps; private String typeIndst; private String typeProd; private String note1; private String note2; private String note3; private String note4; private String note5; } DAOimplementation public class WorkplaceDetailImpl implements WorkplaceDetailsDAO { private SqlMapClient sqlMapClient; public void setSqlMapClient(SqlMapClient sqlMapClient) { this.sqlMapClient = sqlMapClient; } @Override public WorkplaceDetail getWorkplaceDetail(int code) { WorkplaceDetail workplaceDetail=new WorkplaceDetail(); try{ **workplaceDetail= (WorkplaceDetail) this.sqlMapClient.queryForObject("workplaceDetail.getByWorkplaceId", code);** }catch (SQLException sqlex){ sqlex.printStackTrace(); } return workplaceDetail; } TestCode public class TestDAO { public static void main(String args[]) throws Exception{ WorkplaceDetail wd = new WorkplaceDetail(126, "Hoonkee", "1234", "22", "Service", "Tele", "hsgd","hsgd","hsgd","hsgd","hsgd"); WorkplaceDetailImpl impl= new WorkplaceDetailImpl(); **impl.getWorkplaceDetail(wd.getCode());** impl.saveOrUpdateWorkplaceDetails(wd); System.out.println("dhsd"+impl); } } I want to select and insert. I have marked as ** ** as a point of exception in above code Exception in thread "main" java.lang.NullPointerException at com.ibatis.text.WorkplaceDetailImpl.getWorkplaceDetail(WorkplaceDetailImpl.java:19) at com.ibatis.text.TestDAO.main(TestDAO.java:11)

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• OOP - Handling Automated Instances of a Class - PHP

  - by dscher

  This is a topic that, as a beginner to PHP and programming, sort of perplexes me. I'm building a stockmarket website and want users to add their own stocks. I can clearly see the benefit of having each stock be a class instance with all the methods of a class. What I am stumped on is the best way to give that instance a name when I instantiate it. If I have: class Stock() { ....doing stuff..... } what is the best way to give my instances of it a name. Obviously I can write: $newStock = new Stock(); $newStock.getPrice(); or whatever, but if a user adds a stock via the app, where can the name of that instance come from? I guess that there is little harm in always creating a new child with $newStock = new Stock() and then storing that to the DB which leads me to my next question! What would be the best way to retrieve 20 user stocks(for example) into instances of class Stock()? Do I need to instantiate 20 new instances of class Stock() every time the user logs in or is there something I'm missing? I hope someone answers this and more important hope a bunch of people answer this and it somehow helps someone else who is having a hard time wrapping their head around what probably leads to a really elegant solution. Thanks guys!

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• nullable bool is being passed to the controller null all the time regardless of the value

  - by user1807954

  I'm trying to pass a nullable bool to my controller. But when I pass the bool value from my view to the controller, it's being passed null all the time regardless of the value it has in my view. Here is my view: @model Cars.Models.Car @using (Html.BeginForm("Index", "Home", FormMethod.Post, new { id = "CategoryFormID"})) { <label>Convertible:</label> <input type="checkbox" id="ConvertibleID" name="convertible"/> <button type="submit" name="submit" value="search" id="SubmitID">Search</button> } And my controller: [HttpPost] public ActionResult Index(bool? convertible){ var cars = from d in db.Car select d; if (convertible.HasValue) { cars = cars.Where(x => x.Convertible == convertible); } return View("SearchResult", cars); } I also have other fields such as drop down lists and text fields, but they're being passed flawless. Any help would be really appreciated. Update: Thank you for your fast responds. However, I did try giving it a value="True" as you guys suggested. There is only 2 options now: null and true. But my intention is to use nullable bool to have three options: null (when user doesn't touch the checkbox), true(checked) and false(unchecked). I know it sounds not smart and silly, but I'm just trying to figure out how nullable bool is working, and what is the intention of having such a thing in C# (I'm new with C#). I was wondering if it is possible to do so with just checkbox and without the use of dropdownlist or radio buttons.

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• Understanding MongoDB (and NoSQL in general) and how to make the best use of it

  - by Earlz

  Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have three collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is, what if the author's name changed? You'd have to go through updating a ton of posts and comments. But is this an okay thing to do with NoSQL?

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• linq: SQL performance on high loaded web applications

  - by Alex

  I started working with linq to SQL several weeks ago. I got really tired of working with SQL server directly through the SQL queries (sqldatareader, sqlcommand and all this good stuff).  After hearing about linq to SQL and mvc I quickly moved all my projects to these technologies. I expected linq to SQL work slower but it suprisongly turned out to be pretty fast, primarily because I always forgot to close my connections when using datareaders. Now I don't have to worry about it. But there's one problem that really bothers me. There's one page that's requested thousands of times a day. The system gets data in the beginning, works with it and updates it. Primarily the updates are ++ @ -- (increase and decrease values). I used to do it like this UPDATE table SET value=value+1 WHERE ID=@I'd It worked with no problems obviously. But with linq to SQL the data is taken in the beginning, moved to the class, changed and then saved. Stats.registeredusers++; Db.submitchanges(); Let's say there were 100 000 users. Linq will say "let it be 100 001" instead of "let it be increased by 1". But if there value of users has already been increased (that happens in my site all the time) then linq will be like oops, this value is already 100 001. Whatever I'll throw an exception" You can change this behavior so that it won't throw an exception but it still will not set the value to 100 002. Like I said, it happened with me all the time. The stas value was increased twice a second on average. I simply had to rewrite this chunk of code with classic ado net. So my question is how can you solve the problem with linq

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• How do you filter a view of a DataTable in .Net 3.5 sp1 using WPF c# and xaml?

  - by Tony

  I found the MSDN example code for getting the default view of a collection and adding a filter to the view, but most of it is for .Net 4.0. I'm on a team that is not currently switching to 4.0, so I don't have that option. None of the examples I found used a DataTable as the source, so I had to adapt it a little. I'm using a DataTable because the data is comming from a DB ans it's easy to populate. After trying to implement the MSDN examples, I get a "NotSupportedException" when I try to set the Filter. This is the c# code I have: protected DataTable _data = new DataTable(); protected BindingListCollectionView _filteredDataView; ... private void On_Loaded(Object sender, RoutedEventArgs e) { _filteredDataView = (BindingListCollectionView)CollectionViewSource.GetDefaultView(_data); _filteredDataView.Filter = new Predicate(MatchesCurrentSelections); // throws NotSupportedException } ... public bool MatchesCurrentSelections(object o){...} It seems that either BindingListCollectionView does not support filtering in .Net 3.5, or it just doesn't work for a DataTable. I looked at setting it up in XAML instead of the C# code, but the XAML examples use collections in resources instead of a collection that is a memberof the class, so I have no idea how to set that up. Does any one know how to filter a view to a DataTable?

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• NHibernate collections: many-to-many relationships

  - by Brad Heller

  I've got two models, a Product model and a ShoppingCart model. The ShoppingCart model has a collection of products as a property called Products (List). Here is the mapping for my ShoppingCart model. <class name="MyProject.ShoppingCart, MyProject" table="ShoppingCarts"> <id name="Id" column="Id"> <generator class="native" /> </id> <many-to-one name="Company" class="MyProject.Company, MyProject" column="CompanyId" /> <property name="ExternalId" column="GUID" generated="insert" /> <property name="Name" column="Name" /> <property name="Total" column="Total" /> <property name="CreationDate" column="CreationDate" generated="insert" /> <property name="UpdatedDate" column="UpdatedDate" generated="always" /> <bag name="Products" table="ShoppingCartContents" lazy="false"> <key column="ShoppingCartId" /> <many-to-many column="ProductId" class="MyProjectMyProject.Product, MyProject" fetch="join" /> </bag> </class> When I try to save to the DB, the ShoppingCart is saved, but the mapping rows in ShoppingCartContents aren't save, making me thing that there's an issue with the mapping. Where am I going wrong here?

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• Hibernate noob fetch join problem

  - by Bruce

  Hi all I have two classes, Test2 and Test3. Test2 has an attribute test3 that is an instance of Test3. In other words, I have a unidirectional OneToOne association, with test2 having a reference to test3. When I select Test2 from the db, I can see that a separate select is being made to get the details of the associated test3 class. This is the famous 1+N selects problem. To fix this to use a single select, I am trying to use the fetch=join annotation, which I understand to be @Fetch(FetchMode.JOIN) However, with fetch set to join, I still see separate selects. Here are the relevant portions of my setup.. hibernate.cfg.xml: <property name="max_fetch_depth">2</property> Test2: public class Test2 { @OneToOne (cascade=CascadeType.ALL , fetch=FetchType.EAGER) @JoinColumn (name="test3_id") @Fetch(FetchMode.JOIN) public Test3 getTest3() { return test3; } NB I set the FetchType to EAGER out of desperation, even though it defaults to EAGER anyway for OneToOne mappings, but it made no difference. Thanks for any help! Edit: I've pretty much given up on trying to use FetchMode.JOIN - can anyone confirm that they have got it to work ie produce a left outer join? In the docs I see that "Usually, the mapping document is not used to customize fetching. Instead, we keep the default behavior, and override it for a particular transaction, using left join fetch in HQL" If I do a left join fetch instead: query = session.createQuery("from Test2 t2 left join fetch t2.test3"); then I do indeed get the results I want - ie a left outer join in the query.

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• DataReader already open when using LINQ

  - by Jamie Dixon

  I've got a static class containing a static field which makes reference to a wrapper object of a DataContext. The DataContext is basically generated by Visual Studio when we created a dbml file & contains methods for each of the stored procedures we have in the DB. Our class basically has a bunch of static methods that fire off each of these stored proc methods & then returns an array based on a LINQ query. Example: public static TwoFieldBarData[] GetAgesReportData(string pct) { return DataContext .BreakdownOfUsersByAge(Constants.USER_MEDICAL_PROFILE_KEY, pct) .Select(x => new TwoFieldBarData(x.DisplayName, x.LeftValue, x.RightValue, x.TotalCount)) .ToArray(); } Every now and then, we get the following error: There is already an open DataReader associated with this Command which must be closed firs This is happening intermittently and I'm curious as to what is going on. My guess is that when there's some lag between one method executing and the next one firing, it's locking up the DataContext and throwing the error. Could this be a case for wrapping each of the DataContext LINQ calls in a lock(){} to obtain exclusivity to that type and ensure other requests are queued?

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• Passing arguments and values from HTML to jQuery (events)

  - by Jaroslav Moravec

  What is the practice to pass arguments from HTML to jQuery events function. For example getting id of row from db: <tr class="jq_killMe" id="thisItemId-id"> ... </tr> and jQuery: $(".jq_killMe").click(function () { var tmp = $(this).attr('id).split("-"); var id = tmp[0] // ... } What's the best practise, if I want to pass more than one argument? Is it better not to use jQuery? For example: <tr onclick="killMe('id')"> ... </tr> I didn't find the answer on my question, I will be glad even for links. Thanks. Edit (pre solution) So you suggested two methods to do that: Add custom attributes to element (XHTML) Use attribute ID and parse it by regex Attribute data-* attributes in HTML5 Use hidden children elements I like first solution, but... I would like to (I have to (employer)) produce valid code. Here is a nice question and answers: http://stackoverflow.com/questions/994856/so-what-if-custom-html-attributes-arent-valid-xhtml And the second is not so pretty as the first, but valid. So the compromise is... The third is the solution for future, but here is a lot of CMS where we have to use XHTML or HTML4. (And HTML5 is the long process)

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• Structuring input of data for localStorage

  - by WmasterJ

  It is nice when there isn't a DB to maintain and users to authenticate. My professor has asked me to convert a recent research project of his that uses Bespin and calculates errors made by users in a code editor as part of his research. The goal is to convert from MySQL to using HTML5 localStorage completely. Doesn't seem so hard to do, even though digging in his code might take some time. Question: I need to store files and state (last placement of cursor and active file). I have already done so by implementing the recommendations in another stackoverflow thread. But would like your input considering how to structure the content to use. My current solution Hashmap like solution with javascript objects: files = {}; // later, saving files[fileName] = data; And then storing in localStorage using some recommendations localStorage.setObject(files): Currently I'm also considering using some type of numeric id. So that names can be changed without any hassle renaming the key in the hashmap. What is your opinion on the way it is solved and would you do it any differently?

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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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• How to submit Nothing as a route value to ASP MVC

  - by Adam

  I have a route with several optional parameters. These are possible search terms in different fields. So, for example, if I have fields key, itemtype and text then I have in global.asax: routes.MapRoute( _ "Search", _ "Admin.aspx/Search/{Key}/{ItemType}/{Text}", _ New With {.controller = "Admin", .action = "Search" .Key = Nothing, .ItemType = Nothing, .Text = Nothing} _ ) My action takes optional parameters: Function Search(Optional ByVal Key As String = Nothing, _ Optional ByVal ItemType As Integer = 0, _ Optional ByVal Text As String = Nothing, _ Optional ByVal OtherText As String = Nothing) It then checks if the Key and Text strings have a non-null (and non-empty) value and adds search terms to the db request as needed. However, is it possible to send in a null value for, for example, Key but still send in a value for Text? If so, what does the URL look like? (Admin.aspx/Search//0/Foo doesn't work :) ) I know I can handle this using a parameter array instead, but wondered if this was possible using the sort of route described? I could of course define some other value as equivalent to null (for example, a space/%20) but is there any way to send a null value in the URL? I'm suspecting not, but thought I'd see if anyone knew of one. I'm using ASP MVC 2 for this project.

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