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  • Inheritance concept in jpa

    - by megala
    I created one table using Inheritance concept to sore data into google app engine datastore. It contained following coding but it shows error.How to user Inheritance concept.What error in my program Program 1: @Entity @Inheritance(strategy=InheritanceType.JOINED) public class calender { @Id private String EmailId; @Basic private String CalName; @Basic public void setEmailId(String emailId) { EmailId = emailId; } public String getEmailId() { return EmailId; } public void setCalName(String calName) { CalName = calName; } public String getCalName() { return CalName; } public calender(String EmailId,String CalName) { this.EmailId=EmailId; this.CalName=CalName; } } program 2: @Entity public class method { @Id private String method; public void setMethod(String method) { this.method = method; } public String getMethod() { return method; } public method(String method) { this.method=method; } } My constraint is I want ouput like this Calendertable coantain Emailid calenername and method table contain Emailid method How to achive this? thanks inadvance.

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  • How to allow the user to select an input file for my SQL AdventureWorks web application?

    - by salvationishere
    I have a SQL and VS 2008 web application that I need to capture the full file path (directories and file name) from the selected file on the client computer. So user selects a file and then clicks on one of the buttons which transfers control to my code for processing. So how do I get its file path? I can get the file name, but not the path. Maybe problem is that while testing this web app, I am using the server instead of client machine. And I learned that on a server you cannot read the full file path due to security concerns. Is this true? If I just want this to work on client machine, which method/class do you recommend? And then how can I test it? My web app allows the user to select an input file and then map columns from the input .MDF file with columns from the selected Adventureworks table. Finally, after they click on the "Append" button, it adds rows from the input file to that table. So I want to capture the path info after they click this button.

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  • Repeatedly execute a stored procedure

    - by manivineet
    I have a situation where I need to repeatedly execute a stored procedure Now this procedure (spMAIN) has a cursor inside which looks for a value from a table as T1,which has the following structure ID Status ---- -------- 1 New 2 New 3 success 4 Error now the cursor looks for all rows with a status of 'New' Now while processing , if that instance of the cursor encounters an error, another SP say spError needs to be called, the 'Status' column in T1 needs to be updated to 'Error' and spMAIN needs to be called again which again repeats the process, looking for rows with 'new' how do I do it? Also, also, while we are at it, what if an SP has other SPs inside it and if any of those SP raises an error, same thing needs to be done, the T1 table needs to be updated ('Error') and spMAIN needs to be called again. can you also recommend something ? here's some code ALTER PROC zzSpMain AS BEGIN DECLARE @id INT BEGIN TRY IF EXISTS ( SELECT * FROM dbo.zzTest WHERE istatus = 'new' ) BEGIN DECLARE c CURSOR FOR SELECT id FROM zztest WHERE istatus = 'new' OPEN c FETCH NEXT FROM c INTO @id WHILE @@FETCH_STATUS = 0 BEGIN PRINT @id IF @id = 2 BEGIN UPDATE zztest SET istatus = 'error' WHERE id = @id RAISERROR ( 'Error occured', 16, 1 ) END UPDATE zztest SET istatus = 'processed' WHERE id = @id FETCH NEXT FROM c INTO @id END CLOSE c DEALLOCATE c END END TRY begin CATCH EXEC zzSpError END CATCH END

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  • Show bit Column as a checkbox column in unbound Datagridview

    - by Name.IsNullOrEmpty
    Dim Comp = From C In db.Table1 _ Select C.Completed, C.Taken, C.Namne Datagridview1.DataSource = Comp Am using the Entity Framework and Columns Completed and Taken are of bit Datatype. When the query results are displayed in the datagridview, these bit columns are returned as of ColumnType Textbox - so i get a Datagridview textbox column with true or false string values. I want to display Completed and Taken as Checkbox columns (either ticked for True or un-ticked for false) but ofcourse i can't do this in EditColumn dialogue because the Datagridview is unbound. how can i change this in code at runtime

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  • SQL2k8 T-SQL: Output into XML file

    - by Nai
    I have two tables Table Name: Graph UID1 UID2 ----------- 12 23 12 32 41 51 32 41 Table Name: Profiles NodeID UID Name ----------------- 1 12 Robs 2 23 Jones 3 32 Lim 4 41 Teo 5 51 Zacks I want to get an xml file like this: <graph directed="0"> <node id="1"> <att name="UID" value="12"/> <att name="Name" value="Robs"/> </node> <node id="2"> <att name="UID" value="23"/> <att name="Name" value="Jones"/> </node> <node id="3"> <att name="UID" value="32"/> <att name="Name" value="Lim"/> </node> <node id="4"> <att name="UID" value="41"/> <att name="Name" value="Teo"/> </node> <node id="5"> <att name="UID" value="51"/> <att name="Name" value="Zacks"/> </node> <edge source="12" target="23" /> <edge source="12" target="32" /> <edge source="41" target="51" /> <edge source="32" target="41" /> </graph> Thanks very much!

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  • Hide anchors using jQuery

    - by Eric Di Bari
    I've created a dynamic page that, depending on the view type, will sometimes utilize the anchor tags and other times not. Essentially, I want to be able to control if on click the page jumps to the anchor. Is it possible to hide anchor tags using jQUery, so they are essentially removed? I need to be able to re-enable the anchors when necessary, and always show the current anchor in the browser's address bar. It seems to work in FireFox, but not in Internet Explorer. I have three sections: the 'table of contents', the content, and the javascript (jQuery) code Table of Contents <a id="expandLink0" class="expandLinksList" href="#green">What is green purchasing</a><br> <a id="expandLink1" class="expandLinksList" href="#before">Before you buy</a><br> Contents <ul id="makeIntoSlideshowUL">' <li id="slideNumber0" class="slideShowSlide"> <a name="green"></a> <div>Green Purchasing refers to the procurement of products and service...<a href="#topOfPageAnchor" class="topOfPageAnchorClass">Back to Top</a></div> </li> <li id="slideNumber1" class="slideShowSlide"> <a name="before"></a> <div>We easily accomplish the first four bullet points under...<a href="#topOfPageAnchor" class="topOfPageAnchorClass">Back to Top</a></div> </li> </ul> jQuery On Page Load $(".slideShowSlide").each(function() { $(this).children(":first-child").hide(); }); jQuery to re-enable links $(".slideShowSlide").each(function() { $(this).children(":first-child").show(); });

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  • Static variable for communication among like-typed objects

    - by Dan Ray
    I have a method that asynchronously downloads images. If the images are related to an array of objects (a common use-case in the app I'm building), I want to cache them. The idea is, I pass in an index number (based on the indexPath.row of the table I'm making by way through), and I stash the image in a static NSMutableArray, keyed on the row of the table I'm dealing with. Thusly: @implementation ImageDownloader ... @synthesize cacheIndex; static NSMutableArray *imageCache; -(void)startDownloadWithImageView:(UIImageView *)imageView andImageURL:(NSURL *)url withCacheIndex:(NSInteger)index { self.theImageView = imageView; self.cacheIndex = index; NSLog(@"Called to download %@ for imageview %@", url, self.theImageView); if ([imageCache objectAtIndex:index]) { NSLog(@"We have this image cached--using that instead"); self.theImageView.image = [imageCache objectAtIndex:index]; return; } self.activeDownload = [NSMutableData data]; NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:[NSURLRequest requestWithURL:url] delegate:self]; self.imageConnection = conn; [conn release]; } //build up the incoming data in self.activeDownload with calls to didReceiveData... - (void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"Finished downloading."); UIImage *image = [[UIImage alloc] initWithData:self.activeDownload]; self.theImageView.image = image; NSLog(@"Caching %@ for %d", self.theImageView.image, self.cacheIndex); [imageCache insertObject:image atIndex:self.cacheIndex]; NSLog(@"Cache now has %d items", [imageCache count]); [image release]; } My index is getting through okay, I can see that by my NSLog output. But even after my insertObject: atIndex: call, [imageCache count] never leaves zero. This is my first foray into static variables, so I presume I'm doing something wrong. (The above code is heavily pruned to show only the main thing of what's going on, so bear that in mind as you look at it.)

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  • How to combine a Distance and Keyword SQL query?

    - by Jason
    Hi Folks, I have a tables in my database called "points" and "category". A user will input info into both a location input and a keyword input text box. Then I want to find points in my table where the keyword matches either the "title" field in the points table, or the "category" but are within a certain distance from the user's location. I want to order the results by distance. Here are the 2 queries which btoh work independently: $mysql = "SELECT *, ( 3959 * acos( cos( radians('$search_lat') ) * cos( radians( lat ) ) * cos( radians( longi ) - radians('$search_lng') ) + sin( radians('$search_lat') ) * sin( radians( lat ) ) ) ) AS distance FROM points HAVING distance < '$radius'"; $mysql2 = "SELECT * FROM `points` LEFT JOIN category USING ( category_id ) WHERE (point_title LIKE '%$esc_catsearch%' OR category.title LIKE '%$esc_catsearch%')"; Here is what I tried: $sql_search = sprintf("SELECT *,point_id FROM points WHERE point_title LIKE '%%%s%%' UNION SELECT *, ( 3959 * acos( cos( radians('%s') ) * cos( radians( lat ) ) * cos( radians( longi ) - radians('%s') ) + sin( radians('%s') ) * sin( radians( lat ) ) ) ) AS distance FROM points HAVING distance < '%s' ORDER BY distance LIMIT %d , %d", $esc_catsearch, mysql_real_escape_string($search_lat), mysql_real_escape_string($search_lng), mysql_real_escape_string($search_lat), mysql_real_escape_string($radius), $offset, $rowsPerPage); But it tells me there is no know column "distance". If I remove the "Order By" phrase then it works but I'm still not sure this is giving me the results I want. I also tried the query the other way around with the distance search first but that seems to ignore my keyword. Any thoughts would be much appreciated!

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  • MongoDB - proper use of collections?

    - by zmg
    In Mongo my understanding is that you can have databases and collections. I'm working on a social-type app that will have blogs and comments (among other things) and had previously be using MySQL and pretty heavy partitioning in an attempt to limit possible concurrency issues. With MySQL I've stuffed all my user data into a _user database with several tables to further partition the data (blogs, pages, etc). My immediate reaction with Mongo would be to create a 'users' database with one collection per user. In this way user 'zach' blog entries would go into the 'zach' collection with associated comments and such becoming sub-objects in the same collection. Basically like dynamically creating one table per user in MySQL, but apparently without the complexity and limitations that might impose. Of course since I haven't really used Mongo before I'm having trouble gauging the (ahem..) quality of this idea and the potential problems it might cause down the road. I'd like user data to be treated a lot like a users directory in a *nix environment where user created/non-shared (mostly) gets put into one place (currently with MySQL that would be the appname_users as mentioned above). Most of the users data will be specific to the users page(s). Some of the user data which is queried across all site users (searchable user profiles) is currently kept in a separate database/table and I expect things like this could be put into a appname_system database and be broken up into collections and/or application specific databases (appname_profiles). Anyway, since the available documentation on this is currently a little thin and my experience is extremely limited I thought I might find a little guidance from someone with a better working understanding of the system. On the plus side I'd really already been attempting to treat MySQL as a schema-less document-store and doing this with Mongo seems much more intuitive/sane/rational so I'm really looking forward to getting started. Thanks, Zach

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  • Vertical Image Border Changes Alignment when Screen is not maximized

    - by Randy
    I have some pretty straightforward HTML code with a few tables to organize various items of text or images. All works fine except that I need to place a vertical border on both the left and right sides of the screen. I am able to do this with a 2x2 pixel image that I stretch out. When the user has their screen maximized, everything looks great. But when the user hits "Restore Down", then the borders stay in place, but the tables get shoved down so that they start below where the borders end, which is off screen. in other words, the relational alignment between the borders and the tables gets all screwed up. Does anybody know how to make this alignment stay consistent on a restore down? I'm pretty much a newbie with html and asp, so speak slowly. If there is a better method to accomplish this, I'm all ears. Thanks. Here is the relevant section of code: <%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="MasterPage" % <form id="form1" runat="server"> <asp:Image ID="LeftBorder" src="../Images/Border_Blue.jpg" runat="server" WIDTH="15" HEIGHT="1000" BORDER="0" alt="Image Missing" align="left"/> <asp:Image ID="RightBorder" src="../Images/Border_Blue.jpg" runat="server" WIDTH="15" HEIGHT="1000" BORDER="0" alt="Image Missing" align="right" /> <table id="BannerTable" style="height: 100px"> <tr> <td width="934px"> <img src="../Images/Header.jpg" alt="Image Missing" id="ImgBanner" align="left"/></td> </tr> </table>

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  • copy entire row (without knowing field names)

    - by Todd Webb
    Using SQL Server 2008, I would like to duplicate one row of a table, without knowing the field names. My key issue: as the table grows and mutates over time, I would like this copy-script to keep working, without me having to write out 30+ ever-changing fields, ugh. Also at issue, of course, is IDENTITY fields cannot be copied. My code below does work, but I wonder if there's a more appropriate method than my thrown-together text string SQL statement? So thank you in advance. Here's my (yes, working) code - I welcome suggestions on improving it. Todd alter procedure spEventCopy @EventID int as begin -- VARS... declare @SQL varchar(8000) -- LIST ALL FIELDS (*EXCLUDE* IDENTITY FIELDS). -- USE [BRACKETS] FOR ANY SILLY FIELD-NAMES WITH SPACES, OR RESERVED WORDS... select @SQL = coalesce(@SQL + ', ', '') + '[' + column_name + ']' from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 'EventsTable' and COLUMNPROPERTY(OBJECT_ID('EventsTable'), COLUMN_NAME, 'IsIdentity') = 0 -- FINISH SQL COPY STATEMENT... set @SQL = 'insert into EventsTable ' + ' select ' + @SQL + ' from EventsTable ' + ' where EventID = ' + ltrim(str(@EventID)) -- COPY ROW... exec(@SQL) -- REMEMBER NEW ID... set @EventID = @@IDENTITY -- (do other stuff here) -- DONE... -- JUST FOR KICKS, RETURN THE SQL STATEMENT SO I CAN REVIEW IT IF I WISH... select EventID = @EventID, SQL = @SQL end

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  • vertical-align="middle" for td is not working if we use <!doctype ...>

    - by Manohar
    Hi, I am trying to middle align an element, But I have bumped into this problem. I am using this tag: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <body> <table style="width:100%; height: 100%" cellspacing="0" cellpadding="0"> <tr> <td vertical-align="middle"> <div id="progressContainer" style="text-align:center;"> Some string here </div> </td> </tr> </table> </body> </html> If I remove this: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">, its middle aligned properly. Question: Am I doing anything wrong here?

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  • Method Vs Property

    - by obsoleteattribute
    Hi, I'm a newbie to .NET. I have a class called Project, a project can have multiple forecasts.Now If I want to check if the projects has any forecasts or not should I use a readonly boolean property called HasForecast() or should I use a method named HasForecast() which basically returns a boolean value.From framework design guidelines I came to know that methods should be used when the operation is complex,since here I'm retrieving the value of forecasts from DB should I consider method, or since it is a logical data member should I use a property.If I use a property can I call a method in DBLayer from its getter.Please explain Regards, Ravi

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  • t-sql most efficient row to column? for xml path, pivot

    - by ajberry
    create table _orders ( OrderId int identity(1,1) primary key nonclustered ,CustomerId int ) create table _details ( DetailId int identity(1,1) primary key nonclustered ,OrderId int ,ProductId int ) insert into _orders (CustomerId) select 1 union select 2 union select 3 insert into _details (OrderId,ProductId) select 1,100 union select 1,158 union select 1,234 union select 2,125 union select 3,105 union select 3,101 union select 3,212 union select 3,250 -- select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&#x20;','') as Products from _orders o I am looking for the most performant way to turn rows into columns. I have a requirement to output the contents of the db (not actual schema above, but concept is similar) in both fixed width and delimited formats. The above FOR XML PATH query gives me the result I want, but when dealing with anything other than small amounts of data, can take awhile. I've looked at pivot but most of the examples I have found are aggregating information. I just to combine the child rows and tack them onto the parent. For example, for an order it would need to output: OrderId,Product1,Product2,Product3,etc Thoughts or suggestions? I am using SQL Server 2k5.

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  • jdbc nested transactions

    - by Nrj
    What is the behaviour of nested transactions. I am using java + jdbc ? Eg: tx1.begin do stuff1 tx2.begin do stuff2 tx2.commit do stuff1.1 tx1.rollback tx2 is basically inside another function. Will the results from tx2 be persisted ? In case behaviour is db specific, what is it in case of Sql server 2005 ?

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  • XPATH Query: How to get two elements?

    - by Damiano
    Hello My HTML code is: <table> <tr> <td class="data1"><p>1</td></td> <td class="data1"><p>2</td></td> <td class="data1"><p>3</td></td> <td class="data1"><p>4</td></td> </tr> <tr> <td class="data1"><p>5</td></td> <td class="data1"><p>6</td></td> <td class="data1"><p>7</td></td> <td class="data1"><p>8</td></td> </tr> </table> My query is: xpath='//tr//td[@class="data1"][4]/p' The results is: <p>4</p> <p>8</p> The results is correct! but, if I want to get example: <p>3</p> <p>4</p> <p>7</p> <p>8</p> So [3]/p and [4]/p How to get these two elements each <tr> ? Thank you so much!

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  • Full Text Search in SQL Server 2008 shows wrong display_item for Thai language

    - by ensecoz
    I am working with SQL Server 2008. My task is to investigate the issue where FTS cannot find the right result for Thai. First, I have the table which enables the FTS on the column 'ItemName' which is nvarchar. The Catalog is created with the Thai Language. Note that the Thai language is one of the languages that doesn't separate the word by spaces, so '????' '???' '????' are written like this in a sentence: '???????????' In the table, there are many rows that include the word (????); for example row#1 (ItemName: '???????????') On the webpage, I try to search for '????' but SQL Server cannot find it. So I try to investigate it by trying the following query in SQL Server: select * from sys.dm_fts_parser(N'"???????????"', 1054, 0, 0) ...to see how the words are broken. The first one is the text to be broken. The second parameter is to specify that we're using Thai (WorkBreaker, so on). Here is the result: row#1 (display_item: '????', source_item: '???????????') row#2 (display_item: '????', source_item: '???????????') row#3 (display_item: '??', source_item: '???????????') Notice that the first and second row display the wrong display_item '?' in the '????' isn't even Thai characters. '?' in '????' is not a Thai character either. So the question is where did those alien characters come from? I guess this why I cannot search for '????' because the word breaker is broken and keeping the wrong character in the indexes. Please help!

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  • .NET Weird character encoding issue

    - by born to hula
    Our globalization mechanism stores error messages in a SQL 2005 DB. Some of the error messages are used as subjects on email messages sent to the development team. Recently, with no clear reason, we started receiving emails with strangely encoded subjects, such as: =?utf-8?B?Qm1mQm92ZXNwYS5Qb3NUcmFkaW5nRXNwZWNpZmljYWNhbyAtIFN1Y2Vzc28gbm8gcmVwcm 9jZXNzYW1lbnRvLiBEYXRhIFByZWfDo28gPSAzMS8wMy8yMDEwIDAwOjAwOjAwIC0gTsO6bWVyby BkbyBFdmVudG8gZGUgTmVnw7NjaW8gPSAxMDAyIC0gQ8OzZGlnbyBOYXR1cmV6YSBkYSBPcGVyY cOnw6NvID0gQyAtIFNlcn... We don't have any clue on the reason this is happening, nor which encoding pattern is being used here (maybe utf-8?). I'd really appreciate some help.

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  • MySQL where condition but not limited by it

    - by Manny Calavera
    Hello. I would like to run a query on my database like this: SELECT SUM( t1.value ) AS total1, SUM( t2.value ) AS total2, SUM( t3.value ) AS total3, SUM( t4.value ) AS total4 FROM pay1 t1, pay2 t2, pay3 t3, pay4 t4 WHERE t1.date = '2010-04-29' AND t2.date = '2010-04-29' AND t3.date = '2010-04-29' AND t4.date = '2010-04-29' I am generating a report on payments and I would like to see a total of payments from each table based on the matching date. The problem is that some of the tables would not meet the condition of date and I want them to show up with 0 value if not. Currently, if any of the tables does not match the date, I get 0 results. I want to display value of 0 anywhere the date is not met and other fields should appear with the found values. The perfect operand for me would be "ANDOR" so that it won't be limited by any date that doesn't math in any table. Unfortunately, ANDOR does not exist as I am aware of so what should I do ? Can anyone help ? Thanks.

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  • PHP: Aggregate Model Classes or Uber Model Classes?

    - by sunwukung
    In many of the discussions regarding the M in MVC, (sidestepping ORM controversies for a moment), I commonly see Model classes described as object representations of table data (be that an Active Record, Table Gateway, Row Gateway or Domain Model/Mapper). Martin Fowler warns against the development of an anemic domain model, i.e. a class that is nothing more than a wrapper for CRUD functionality. I've been working on an MVC application for a couple of months now. The DBAL in the application I'm working on started out simple (on account of my understanding - oh the benefits of hindsight), and is organised so that Controllers invoke Business Logic classes, that in turn access the database via DAO/Transaction Scripts pertinent to the task at hand. There are a few "Entity" classes that aggregate these DAO objects to provide a convenient CRUD wrapper, but also embody some of the "behaviour" of that Domain concept (for example, a user - since it's easy to isolate). Taking a look at some of the code, and thinking along refactoring some of the code into a Rich Domain Model, it occurred to me that were I to try and wrap the CRUD routines and behaviour of say, a Company into a single "Model" class, that would be a sizeable class. So, my question is this: do Models represent domain objects, business logic, service layers, all of the above combined? How do you go about defining the responsibilities for these components?

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  • NHibernate Child items query using Parent Id

    - by thorkia
    So I have a set up similar to this questions: Parent Child Setup Everything works great when saving the parent and the children. However, I seem to have a problem when selecting the children. I can't seem to get all the children with a specific parent. This fails with: NHibernate.QueryException: could not resolve property: ParentEntity_id of: Test.Data.ChildEntity Here is my code: public IEnumerable<ChildEntity> GetByParent(ParentEntity parent) { using (ISession session = OrmHelper.OpenSession()) { return session.CreateCriteria<ChildEntity>().Add(Restrictions.Eq("ParentEntity_id ", parent.Id)).List<ChildEntity>(); } } Any help in building a proper function to get all the items would be appreciated. Oh, I am using Fluent NHibernate to construct the mappings - version 1 RTM and NHibernate 2.1.2 GA If you need more information, let me know. As per you request, my fluent mappings: public ParentEntityMap() { Id(x => x.Id); Map(x => x.Name); Map(x => x.Code).UniqueKey("ukCode"); HasMany(x => x.ChildEntity).LazyLoad() .Inverse().Cascade.SaveUpdate(); } public ChildEntityMap() { Id(x => x.Id); Map(x => x.Amount); Map(x => x.LogTime); References(x => x.ParentEntity); } That maps to the following 2 tables: CREATE TABLE "ParentEntity" ( Id integer, Name TEXT, Code TEXT, primary key (Id), unique (Code) ) CREATE TABLE "ChildEntity" ( Id integer, Amount NUMERIC, LogTime DATETIME, ParentEntity_id INTEGER, primary key (Id) ) The data store in SQLite.

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  • SQL for Opening Hours

    - by mouthpiec
    Hi, In my shops database I need to have the opening hours. Do you have an idea how i can implement this in my dB? The opening hours are from Monday to Sunday, each day can have 2 opening windows (ex 09:00-12:00, 16:00-19:00)

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  • Hibernate ManyToMany and superclass mapping problem

    - by Jesus Benito
    Hi all, I need to create a relation in Hibernate, linking three tables: Survey, User and Group. The Survey can be visible to a User or to a Group, and a Group is form of several Users. My idea was to create a superclass for User and Group, and create a ManyToMany relationship between that superclass and Survey. My problem is that Group, is not map to a table, but to a view, so I can't split the fields of Group among several tables -which would happen if I created a common superclass-. I thought about creating a common interface, but mapping to them is not allowed. I will probably end up going for a two relations solution (Survey-User and Survey-Group), but I don't like too much that approach. I thought as well about creating a table that would look like: Survey Id | ElementId | Type ElementId would be the Group or UserId, and the type... the type of it. Does anyone know how to achieve it using hibernate annotations? Any other ideas? Thanks a lot

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  • Database Functional Programming in Clojure

    - by Ralph
    "It is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail." - Abraham Maslow I need to write a tool to dump a large hierarchical (SQL) database to XML. The hierarchy consists of a Person table with subsidiary Address, Phone, etc. tables. I have to dump thousands of rows, so I would like to do so incrementally and not keep the whole XML file in memory. I would like to isolate non-pure function code to a small portion of the application. I am thinking that this might be a good opportunity to explore FP and concurrency in Clojure. I can also show the benefits of immutable data and multi-core utilization to my skeptical co-workers. I'm not sure how the overall architecture of the application should be. I am thinking that I can use an impure function to retrieve the database rows and return a lazy sequence that can then be processed by a pure function that returns an XML fragment. For each Person row, I can create a Future and have several processed in parallel (the output order does not matter). As each Person is processed, the task will retrieve the appropriate rows from the Address, Phone, etc. tables and generate the nested XML. I can use a a generic function to process most of the tables, relying on database meta-data to get the column information, with special functions for the few tables that need custom processing. These functions could be listed in a map(table name -> function). Am I going about this in the right way? I can easily fall back to doing it in OO using Java, but that would be no fun. BTW, are there any good books on FP patterns or architecture? I have several good books on Clojure, Scala, and F#, but although each covers the language well, none look at the "big picture" of function programming design.

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