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  • CONVERT(int, (datepart(month, @search)), (datepart(day, @search)), DateAdd(year, Years.Year - (datepart(year, @search)))

    - by MyHeadHurts
    In the query the top part is getting all the years that will run in the stored procedure. Works fine But at first i just wanted to run the queries for yesterdays date for all the years, but now i realized i want the user to select a date that will be in a parameter @search Booked <= CONVERT(int,DateAdd(year, Years.Year - Year(getdate()), DateAdd(day, DateDiff(day, 2, getdate()), 1))) this should be easy because normally it would just be Booked <= CONVERT(int,@search) but the problem is i want to do something like a Booked <= CONVERT(int, (datepart(month, @search)), (datepart(day, @search)), DateAdd(year, Years.Year - (datepart(year, @search))) would something like that work i dont need to worry about subtracting days but i still need to worry about the years WITH Years AS ( SELECT DATEPART(year, GETDATE()) [Year] UNION ALL SELECT [Year]-1 FROM Years WHERE [Year]>@YearToGet ), q_00 as ( select DIVISION , DYYYY , sum(PARTY) as asofPAX , sum(APRICE) as asofSales from dbo.B101BookingsDetails INNER JOIN Years ON B101BookingsDetails.DYYYY = Years.Year where Booked <= CONVERT(int,DateAdd(year, Years.Year - Year(getdate()), DateAdd(day, DateDiff(day, 2, getdate()), 1))) and DYYYY = Years.Year group by DIVISION, DYYYY, years.year having DYYYY = years.year ),

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  • Repository pattern - Switch out the database and switch in XML files

    - by glasto red
    Repository pattern - Switch out the database and switch in XML files. Hello I have an asp.net MVC 2.0 project and I have followed the Repository pattern. Periodically, I am losing access to the database server so I want to have another mechanism in place (XML files) to continue developing. It is not possible to have a local version of the db unfortunately! I thought this would be relatively easy using the Repository pattern, to switch out the db repositories and switch in XML versions. However, I am having real trouble coming up with a solution. I have tried LinqToXML but then ran into problems trying to return a List of News items as the LinqToXML ToList returns Generic.List Should I be mapping the XElement list over to the News list by hand? It just seems a bit clunky compared to LinqToSQL attributes on the News class and then simply doing a Table.....ToList(); Any direction would be appreciated. Thanks

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  • ASP MVC C#: LINQ Foreign Key Constraint conflicts

    - by wh0emPah
    I'm having a problem with LINQ. I have 2 tables (Parent-child relation) Table1: Events (EventID, Description) Table2: Groups (GroupID, EventID(FK), Description) Now i want to create an Event an and a child. Event e = new Event(); e.Description = "test"; Datacontext.Events.InsertOnSubmit(event) Group g = new Group(); g.Description = "test2"; g.EventID = e.EventID; Datacontext.Groups.InsertOnSubmit(g); Datacontext.SubmitChanges(); When i debug, i can see that after inserting the event. the EventID has gotten a new value (auto increment). But when Datacontext.SubmitChanges(); gets called. I get the following exception "The INSERT statement conflicted with the FOREIGN KEY constraint ... I know this can be solved by creating a relation in the LINQ diagram between Events and groups. And then setting the entity itself. But i don't want to load the events everytime i ask a list of groups. All i need is some way that when inserting the group fails, the event insert won't be comitted in the database. Sorry if this is a bit unclear, My english isn't really good. Thanks in advance!

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  • c#/.NET SQLite -- REINDEX not working?

    - by borg17of20
    Hello all, I'm trying to reindex a table in a simple database that I created using SQLite.NET and VS2008. I need to reindex tables after every DELETE command and here is the code snippet I have written (it does not work): SQLiteCommand currentCommand; String tempString = "REINDEX tf_questions"; //String tempString = "REINDEX [main].tf_questions"; //String tempString = "REINDEX main.tf_questions"; currentCommand = new SQLiteCommand(myConnection); currentCommand.CommandText = tempString; currentCommand.ExecuteNonQuery() When run within my program, the code produces no errors, but it also doesn't reindex the "tf_questions" table. In the above example, you will also see the other query strings I've tried that also don't work. Please help, Thanks

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  • Start position for a reused t- sql cursor?

    - by Span
    I'm working on a stored procedure that uses a cursor on a temporary table (I have read a bit about why cursors are undesirable, but in this situation I believe I still need to use one). In my procedure I need to step through the rows of the table twice. Having declared the cursor, already stepped through the temporary table once and closed the cursor, would the position of the cursor remain at the end of the table when re-opened or does it reposition itself to the initial starting position (ie: before the first row)? Alternatively, to reposition the cursor must I do a 'FETCH FIRST' before stepping through again? Am I right to assume the 'cost' of doing this repositioning and reusing the cursor would be less than deallocating and reallocating the cursor?

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  • convert clob to varchar2

    - by Shamik
    I have a Oracle table whose column is a CLOB datatype. I want to read the content of this table as a text. I tried select dbms_lob.substr( sqltext, 4000, 1 ) from test but this one selects only the first 4000 bytes. How to read the entire content ? there are more than 4000 characters in the sqltext column. Please advise.

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  • Are soft deletes a good idea?

    - by Khou
    Are soft deletes a good idea or a bad idea? Instead of actually deleting a record in your database, you would just flag it as "IsDeleted" = true, and upon recovery of the record you could just flag it as "False". Is this a good idea?

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  • Tapestry / JDBC - Storing Date

    - by Ben
    So Im using Tapestry and trying to store a date from a beaneditform into a simple Access database. It wont work, Im getting Null pointer exceptions and I cannot understand why. String onSuccess() { System.out.println("in on success!"); String nextPage = null; try { Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); connection = DriverManager.getConnection("jdbc:odbc:FYP_Users"); DateFormat df = new SimpleDateFormat("dd/MM/yyyy"); Date ed = occasion.getEventDate(); String reportDate = df.format(ed); statement.executeUpdate("INSERT INTO Events (UserName, EventName, EventDate, EventTime, EventDetails, People, Rating) " + "VALUES ('" + login.getUserName() + "', '" + occasion.getEventName()+ "', '" + reportDate + "', '" + occasion.getEventTime() + "', '" + occasion.getEventDetails() + "', '" + occasion.getPeople() + "', '"+ "1" +"')"); connection.close(); occasion = new Occasion(); //occasion.setUserName(occasion.getUserName()); occasion.setEventName(occasion.getEventName()); occasion.setEventDate(occasion.getEventDate()); occasion.setEventTime(occasion.getEventTime()); occasion.setEventDetails(occasion.getEventDetails()); occasion.setPeople(occasion.getPeople()); //occasion.setRating(occasion.getRating()); nextPage = "UserIndex"; } catch (SQLException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();} return nextPage; } Stack trace java.util.Calendar.setTime(Unknown Source) java.text.SimpleDateFormat.format(Unknown Source) java.text.SimpleDateFormat.format(Unknown Source) java.text.DateFormat.format(Unknown Source) myappj.pages.CreateOccasion.onSuccess(CreateOccasion.java:61) myappj.pages.CreateOccasion.dispatchComponentEvent(CreateOccasion.java) org.apache.tapestry5.internal.structure.ComponentPageElementImpl.dispatchEvent(ComponentPageElementImpl.java:902) org.apache.tapestry5.internal.structure.ComponentPageElementImpl.triggerContextEvent(ComponentPageElementImpl.java:1081) org.apache.tapestry5.internal.structure.InternalComponentResourcesImpl.triggerContextEvent(InternalComponentResourcesImpl.java:263) org.apache.tapestry5.corelib.components.Form._$advised$onAction(Form.java:398) org.apache.tapestry5.corelib.components.Form$onAction$invocation_128ef468876.invokeAdvisedMethod(Form$onAction$invocation_128ef468876.java) org.apache.tapestry5.internal.services.AbstractComponentMethodInvocation.proceed(AbstractComponentMethodInvocation.java:71) org.apache.tapestry5.ioc.internal.services.LoggingAdvice.advise(LoggingAdvice.java:37) org.apache.tapestry5.internal.transform.LogWorker$1.advise(LogWorker.java:54) org.apache.tapestry5.internal.services.AbstractComponentMethodInvocation.proceed(AbstractComponentMethodInvocation.java:80) org.apache.tapestry5.corelib.components.Form.onAction(Form.java) org.apache.tapestry5.corelib.components.Form.dispatchComponentEvent(Form.java) org.apache.tapestry5.internal.structure.ComponentPageElementImpl.dispatchEvent(ComponentPageElementImpl.java:910) org.apache.tapestry5.internal.structure.ComponentPageElementImpl.triggerContextEvent(ComponentPageElementImpl.java:1081) org.apache.tapestry5.internal.services.ComponentEventRequestHandlerImpl.handle(ComponentEventRequestHandlerImpl.java:75) org.apache.tapestry5.internal.services.ImmediateActionRenderResponseFilter.handle(ImmediateActionRenderResponseFilter.java:42) $ComponentEventRequestHandler_128ef45bf4a.handle($ComponentEventRequestHandler_128ef45bf4a.java) org.apache.tapestry5.internal.services.AjaxFilter.handle(AjaxFilter.java:42) $ComponentEventRequestHandler_128ef45bf4a.handle($ComponentEventRequestHandler_128ef45bf4a.java) org.apache.tapestry5.services.TapestryModule$36.handle(TapestryModule.java:2164) $ComponentEventRequestHandler_128ef45bf4a.handle($ComponentEventRequestHandler_128ef45bf4a.java) $ComponentEventRequestHandler_128ef45bea5.handle($ComponentEventRequestHandler_128ef45bea5.java) org.apache.tapestry5.internal.services.ComponentRequestHandlerTerminator.handleComponentEvent(ComponentRequestHandlerTerminator.java:43) $ComponentRequestHandler_128ef45be99.handleComponentEvent($ComponentRequestHandler_128ef45be99.java) org.apache.tapestry5.internal.services.ComponentEventDispatcher.dispatch(ComponentEventDispatcher.java:46) $Dispatcher_128ef45be9b.dispatch($Dispatcher_128ef45be9b.java) $Dispatcher_128ef45be92.dispatch($Dispatcher_128ef45be92.java) org.apache.tapestry5.services.TapestryModule$RequestHandlerTerminator.service(TapestryModule.java:245) org.apache.tapestry5.internal.services.RequestErrorFilter.service(RequestErrorFilter.java:26) $RequestHandler_128ef45be93.service($RequestHandler_128ef45be93.java) org.apache.tapestry5.services.TapestryModule$4.service(TapestryModule.java:778) $RequestHandler_128ef45be93.service($RequestHandler_128ef45be93.java) org.apache.tapestry5.services.TapestryModule$3.service(TapestryModule.java:767) $RequestHandler_128ef45be93.service($RequestHandler_128ef45be93.java) org.apache.tapestry5.internal.services.StaticFilesFilter.service(StaticFilesFilter.java:85) $RequestHandler_128ef45be93.service($RequestHandler_128ef45be93.java) myappj.services.AppModule$1.service(AppModule.java:90) $RequestFilter_128ef45be8e.service($RequestFilter_128ef45be8e.java) $RequestHandler_128ef45be93.service($RequestHandler_128ef45be93.java) org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:90) org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:81) org.apache.tapestry5.ioc.internal.util.ConcurrentBarrier.withRead(ConcurrentBarrier.java:85) org.apache.tapestry5.internal.services.CheckForUpdatesFilter.service(CheckForUpdatesFilter.java:103) $RequestHandler_128ef45be93.service($RequestHandler_128ef45be93.java) $RequestHandler_128ef45be88.service($RequestHandler_128ef45be88.java) org.apache.tapestry5.services.TapestryModule$HttpServletRequestHandlerTerminator.service(TapestryModule.java:197) org.apache.tapestry5.internal.gzip.GZipFilter.service(GZipFilter.java:53) $HttpServletRequestHandler_128ef45be8a.service($HttpServletRequestHandler_128ef45be8a.java) org.apache.tapestry5.internal.services.IgnoredPathsFilter.service(IgnoredPathsFilter.java:62) $HttpServletRequestFilter_128ef45be87.service($HttpServletRequestFilter_128ef45be87.java) $HttpServletRequestHandler_128ef45be8a.service($HttpServletRequestHandler_128ef45be8a.java) org.apache.tapestry5.services.TapestryModule$2.service(TapestryModule.java:726) $HttpServletRequestHandler_128ef45be8a.service($HttpServletRequestHandler_128ef45be8a.java) $HttpServletRequestHandler_128ef45be85.service($HttpServletRequestHandler_128ef45be85.java) org.apache.tapestry5.TapestryFilter.doFilter(TapestryFilter.java:127) org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084) org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360) org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:722) org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:404) org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139) org.mortbay.jetty.Server.handle(Server.java:324) org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:842) org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:648) org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211) org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395) org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:450)

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  • mysql query is producing more results than it should

    - by user253530
    SELECT S.CLIENT,S.IP_DOMAIN as IP, IFNULL(K.DATE, DATE '0000-00-00') AS RecentDate FROM PLD_SERVERS AS S JOIN PLD_SEARCHES AS K ON S.ID = K.SERVER_ID This query will produce as many results as entries in the PLD_SEARCHES. For example: I have 3 entries in PLD_SERVERS and 18 entries in PLD_SEARCHES. The output of this query will be 18 but i need it to be 3 (as the number of PLD_SERVERS entries) with the recent date as a join field from PLD_SEARCHES.

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  • Entity Attribute Value Database vs. strict Relational Model Ecommerce question

    - by Dr. Zim
    It is safe to say that the EAV/CR database model is bad. That said, Question: What database model, technique, or pattern should be used to deal with "classes" of attributes describing e-commerce products which can be changed at run time? In a good E-commerce database, you will store classes of options (like TV resolution then have a resolution for each TV, but the next product may not be a TV and not have "TV resolution"). How do you store them, search efficiently, and allow your users to setup product types with variable fields describing their products? If the search engine finds that customers typically search for TVs based on console depth, you could add console depth to your fields, then add a single depth for each tv product type at run time. There is a nice common feature among good e-commerce apps where they show a set of products, then have "drill down" side menus where you can see "TV Resolution" as a header, and the top five most common TV Resolutions for the found set. You click one and it only shows TVs of that resolution, allowing you to further drill down by selecting other categories on the side menu. These options would be the dynamic product attributes added at run time. Further discussion: So long story short, are there any links out on the Internet or model descriptions that could "academically" fix the following setup? I thank Noel Kennedy for suggesting a category table, but the need may be greater than that. I describe it a different way below, trying to highlight the significance. I may need a viewpoint correction to solve the problem, or I may need to go deeper in to the EAV/CR. Love the positive response to the EAV/CR model. My fellow developers all say what Jeffrey Kemp touched on below: "new entities must be modeled and designed by a professional" (taken out of context, read his response below). The problem is: entities add and remove attributes weekly (search keywords dictate future attributes) new entities arrive weekly (products are assembled from parts) old entities go away weekly (archived, less popular, seasonal) The customer wants to add attributes to the products for two reasons: department / keyword search / comparison chart between like products consumer product configuration before checkout The attributes must have significance, not just a keyword search. If they want to compare all cakes that have a "whipped cream frosting", they can click cakes, click birthday theme, click whipped cream frosting, then check all cakes that are interesting knowing they all have whipped cream frosting. This is not specific to cakes, just an example.

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  • Database design - alternatives for Entity Attribute Value (EAV)

    - by Bob
    Hi, see http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters for similar topic. My question: i want to design a database, that will be used for a production facility of different types of products where each product has its own (number of) parameters. because i want the serial numbers to be in one tabel for overview purposes i have a problem with these different paraeters . One solution could be EAV, but it has its downsides, certainly because we have +- 5 products with every product +- 20.000 serial numbers (records). it looks a bit overkill to me... I just don't know how one could design a database so that you have an attribute in a mastertable that says: 'hey, you could find details of this record in THAT detail-table". 'in a way that you qould easely query the results) currenty i am using Visual Basic & Acces 2007. but i'm going to Visual Basic & MySQL. thanks for your help. Bob

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  • Cannot attach an entity that already exists.

    - by coure06
    i am trying to update code via Linq, but getting this error Cannot attach an entity that already exists. C# code is here var con = (from c in cmsContentTable where c.ContentName == contentId select c).FirstOrDefault(); cmsContentTable.Attach(con); con.ContentData = "New Value"; cmsContentTable.Context.SubmitChanges();

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  • LoginView inside FormView control is not databinding on PostBack

    - by subkamran
    I have a fairly simple form: <asp:FormView> <EditItemTemplate> <asp:LoginView> <RoleGroups> <asp:RoleGroup roles="Blah"> <ContentTemplate> <!-- Databound Controls using Bind/Eval --> </ContentTemplate> </asp:RoleGroup> </RoleGroups> </asp:LoginView> <!-- Databound Controls --> </EditItemTemplate> </asp:FormView> <asp:LinqDataSource OnUpdating="MyDataSource_Updating" /> I handle my LinqDataSource OnUpdating event and do some work handling some M:N fields. That all works. However, once the update is finished (and I call e.Cancel = true), the LoginView control does not databind its children... so they are all blank. The FormView's viewstate is still fine, as all the rest of the controls outside of the LoginView appear fine. I even handle the FormView_DataBound event and a Trace shows that the FormView is being databound on postback. Why then is the LoginView not keeping its ViewState/being databound? Here's a sample code snippet showing the flow: protected void MyDataSource_Updating(object s, LinqDataSourceUpdateEventArgs e) { try { Controller.DoSomething(newData); // attempts to databind again here fail // frmView.DataBind(); // MyDataSource.DataBind(); // LoginView.DataBind(); } catch { // blah } finally { e.Cancel = true; } }

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  • One to many too much data returned - MySQL

    - by Evan McPeters
    I have 2 related MySQL tables in a one to many relationship. Customers: cust_id, cust_name, cust_notes Orders: order_id, cust_id, order_comments So, if I do a standard join to get all customers and their orders via PHP, I return something like: Jack Black, jack's notes, comments about jack's 1st order Jack Black, jack's notes, comments about jack's 2nd order Simon Smith, simon's notes, comments about simon's 1st order Simon Smith, simon's notes, comments about simon's 2nd order The problem is that *cust_notes* is a text field and can be quite large (a couple of thousand words). So, it seems like returning that field for every order is inneficient. I could use *GROUP_CONCAT* and JOINS to return all *order_comments* on a single row BUT order_comments is a large text field too, so it seems like that could create a problem. Should I just use two separate queries, one for the customers table and one for the orders table? Is there a better way?

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  • TSQL - TOP X in FROM Subquery?

    - by EWizard
    Can someone please enlighten me to a way to filter a subquery that is located in a FROM clause? I would like it to look something like this: SELECT * FROM TABLE_A LEFT JOIN (TOP 8 TABLE_B ) ON TABLE_B.id = TABLE_A.id

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  • Can't enter to webadmin in godaddy mssql

    - by gon009
    I just pay for the deluxe plan in godaddy for my website but I have a problem, I created the database in mssql and when I click to webadmin ,it redirects me to: http://mssql.myname.com/silentlogon.aspx with the message: This webpage is not available. But if I create a mysql database everything is ok, idk what I am doing wrong , I know I cant contact GoDaddy but the line is busy or when I talk to them they don't understand. Thanks four your time and help :)

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  • Sharepoint OLE DB - field not updateable

    - by Pandincus
    I need to write a simple C# .NET application to retrieve, update, and insert some data in a Sharepoint list. I am NOT a Sharepoint developer, and I don't have control over our Sharepoint server. I would prefer not to have to develop this in a proper sharepoint development environment simply because I don't want to have to deploy my application on the Sharepoint server -- I'd rather just access data externally. Anyway, I found out that you can access Sharepoint data using OLE DB, and I tried it successfully using some ADO.NET: var db = DatabaseFactory.CreateDatabase(); DataSet ds = new DataSet(); using (var command = db.GetSqlStringCommand("SELECT * FROM List")) { db.LoadDataSet(command, ds, "List"); } The above works. However, when I try to insert: using (var command = db.GetSqlStringCommand("INSERT INTO List ([HeaderName], [Description], [Number]) VALUES ('Blah', 'Blah', 100)")) { db.ExecuteNonQuery(command); } I get this error: Cannot update 'HeaderName'; field not updateable. I did some Googling and apparently you cannot insert data through OLE DB! Does anyone know if there are some possible workarounds? I could try using Sharepoint Web Services, but I tried that initially and was having a heck of a time authenticating. Is that my only option?

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  • Can a DevExpress XtraGrid be filled using a a Dynamic SELECT statement string

    - by Gerhard Weiss
    Can a DevExpress XtraGrid be filled using a a Dynamic SELECT statement string? i.e. SELECT * FROM Employee or SELECT * FROM Dependents To fill our XtraGrids currently, we use a ORM that creates entities. To do this it takes a lot of steps and time. What is driving me to ask this question is we do a lot of client aquistions where we get hundreds of files. I do not want to create entities for all of these then have to create an XtraGrid for each entity. Ideally if I can just feed it a SELECT statement and the XtraGrid could render it then I could use the XtraGrid very nice data minipulation features (Filter, Group By, etc). If you have any other ideas or suggestions please to not hesitate to post them.

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  • Use a stored procedure parameter for unit parameter of DATE_SUB

    - by Mike
    I would like to know if it's possible to pass a parameter to a mysql stored procedure and use this parameter as the unit parameter of the DATE_SUB function. It seems that the unit parameter is a reserved word so I don't know if there's a type for unit. Exemple of what I'm trying to do : DELIMITER $$ DROP PROCEDURE IF EXISTS `test` $$ CREATE DEFINER=`root`@`%` PROCEDURE `test`(param1 unit) BEGIN select DATE_SUB(now(), INTERVAL 1 param1); END $$ DELIMITER ;

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  • Build and render infinite hierarchical category tree from self-referential category table

    - by FreshCode
    I have a Categories table in which each category has a ParentId that can refer to any other category's CategoryId that I want to display as multi-level HTML list, like so: <ul class="tree"> <li>Parent Category <ul> <li>1st Child Category <!-- more sub-categories --> </li> <li>2nd Child Category <!-- more sub-categories --> </li> </ul> </li> </ul> Presently I am recursively rendering a partial view and passing down the next category. It works great, but it's wrong because I'm executing queries in a view. How can I render the list into a tree object and cache it for quick display every time I need a list of all hierarchical categories?

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  • Linq - how does it work??

    - by clarkeyboy
    Hey, I have just been looking into Linq with ASP.Net. It is very neat indeed. I was just wondering - how do all the classes get populated? I mean in ASP.Net, suppose you have a Linq file called Catalogue, and you then use a For loop to loop through Catalogue.Products and print each Product name. How do the details get stored? Does it just go through the Products table on page load and create another instance of class Product for each row, effectively copying an entire table into an array of class Product? If so, I think I have created a system very much like this, in the sense that there is a SiteContent module with an instance of each Manager class - for example there is UserManager, ProductManager, SettingManager and alike. UserManager contains an instance of the User class for each row in the Users table. They also contain methods such as Create, Update and Remove. These Managers and their "Items" are created on every page load. This just makes it nice and easy to access users, products, settings etc in every page as far as I, the developer, am concerned. Any any subsequent pages I need to create, I just need to reference SiteContent.UserManager to access a list of users, rather than executing a query from within that page (ie this method separates out data access from the workings of the page, in the same way as using code behind separates out the workings of the page from how the page is layed out). However the problem is that this technique seems rather slow. I mean it is effectively creating a database on every page load, taking data from another database. I have taken measures such as preventing, for example, the ProductManager from being created if it is not referenced on page load. Therefore it does not load data into storage when it is not needed. My question is basically whether my technique does the exact same thing as Linq, in the sense of duplicating data from tables into properties of classes.. Thanks in advance for any advice or answers about this. Regards, Richard Clarke

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  • How can I write a clean Repository without exposing IQueryable to the rest of my application?

    - by Simucal
    So, I've read all the Q&A's here on SO regarding the subject of whether or not to expose IQueryable to the rest of your project or not (see here, and here), and I've ultimately decided that I don't want to expose IQueryable to anything but my Model. Because IQueryable is tied to certain persistence implementations I don't like the idea of locking myself into this. Similarly, I'm not sure how good I feel about classes further down the call chain modifying the actual query that aren't in the repository. So, does anyone have any suggestions for how to write a clean and concise Repository without doing this? One problem I see, is my Repository will blow up from a ton of methods for various things I need to filter my query off of. Having a bunch of: IEnumerable GetProductsSinceDate(DateTime date); IEnumberable GetProductsByName(string name); IEnumberable GetProductsByID(int ID); If I was allowing IQueryable to be passed around I could easily have a generic repository that looked like: public interface IRepository<T> where T : class { T GetById(int id); IQueryable<T> GetAll(); void InsertOnSubmit(T entity); void DeleteOnSubmit(T entity); void SubmitChanges(); } However, if you aren't using IQueryable then methods like GetAll() aren't really practical since lazy evaluation won't be taking place down the line. I don't want to return 10,000 records only to use 10 of them later. What is the answer here? In Conery's MVC Storefront he created another layer called the "Service" layer which received IQueryable results from the respository and was responsible for applying various filters. Is this what I should do, or something similar? Have my repository return IQueryable but restrict access to it by hiding it behind a bunch of filter classes like GetProductByName, which will return a concrete type like IList or IEnumerable?

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  • Opinions on sensor / reading / alert database design

    - by Mark
    I've asked a few questions lately regarding database design, probably too many ;-) However I beleive I'm slowly getting to the heart of the matter with my design and am slowly boiling it down. I'm still wrestling with a couple of decisions regarding how "alerts" are stored in the database. In this system, an alert is an entity that must be acknowledged, acted upon, etc. Initially I related readings to alerts like this (very cut down) : - [Location] LocationId [Sensor] SensorId LocationId UpperLimitValue LowerLimitValue [SensorReading] SensorReadingId Value Status Timestamp [SensorAlert] SensorAlertId [SensorAlertReading] SensorAlertId SensorReadingId The last table is associating readings with the alert, because it is the reading that dictate that the sensor is in alert or not. The problem with this design is that it allows readings from many sensors to be associated with a single alert - whereas each alert is for a single sensor only and should only have readings for that sensor associated with it (should I be bothered that the DB allows this though?). I thought to simplify things, why even bother with the SensorAlertReading table? Instead I could do this: [Location] LocationId [Sensor] SensorId LocationId [SensorReading] SensorReadingId SensorId Value Status Timestamp [SensorAlert] SensorAlertId SensorId Timestamp [SensorAlertEnd] SensorAlertId Timestamp Basically I'm not associating readings with the alert now - instead I just know that an alert was active between a start and end time for a particular sensor, and if I want to look up the readings for that alert I can do. Obviously the downside is I no longer have any constraint stopping me deleting readings that occurred during the alert, but I'm not sure that the constraint is neccessary. Now looking in from the outside as a developer / DBA, would that make you want to be sick or does it seem reasonable? Is there perhaps another way of doing this that I may be missing? Thanks. EDIT: Here's another idea - it works in a different way. It stores each sensor state change, going from normal to alert in a table, and then readings are simply associated with a particular state. This seems to solve all the problems - what d'ya think? (the only thing I'm not sure about is calling the table "SensorState", I can't help think there's a better name (maybe SensorReadingGroup?) : - [Location] LocationId [Sensor] SensorId LocationId [SensorState] SensorStateId SensorId Timestamp Status IsInAlert [SensorReading] SensorReadingId SensorStateId Value Timestamp There must be an elegant solution to this!

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  • Sorting Anonymous Types

    - by strobaek
    I have a question of how to sort an anonymous type. Using Linq2SQL I have the following query, which returns a list of submissions: var submissions = EventSubmissions .Where(s => s.EventId.Equals(eventId)); Consider the following interface (somewhat simplyfied): public interface IQuerySorter { IOrderedQueryable Sort(IQueryable query); IOrderedQueryable<T> Sort<T, U>(IQueryable<T> query, Expression<Func<T,U>> selector); ... } Using this interface allows me to implement a number of 'sorters', e.g. on Date, Rating or whether or not a submission has been nominated (for voting). sortedQuery = sorter.Sort(submissions) So far so good. A submission can be made "votable". I get the number of votes a nominated submission may have using the following query: var withVoteCount = submissions .Select(s => new {NumberOfVotes = s.Votes.Count(), Submission = s}); I would like to sort this new query by NumberOfVotes using my "general" sorter class, but run into the problem that the anonymous type/member does not seem to live outside the repository-method, hence I am unable to sort on it. Any input would be greatly appreciated.

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