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  • Use Django ORM as standalone [closed]

    - by KeyboardInterrupt
    Possible Duplicates: Use only some parts of Django? Using only the DB part of Django I want to use the Django ORM as standalone. Despite an hour of searching Google, I'm still left with several questions: Does it require me to set up my Python project with a setting.py, /myApp/ directory, and modules.py file? Can I create a new models.py and run syncdb to have it automatically setup the tables and relationships or can I only use models from existing Django projects? There seems to be a lot of questions regarding PYTHONPATH. If you're not calling existing models is this needed? I guess the easiest thing would be for someone to just post a basic template or walkthrough of the process, clarifying the organization of the files e.g.: db/ __init__.py settings.py myScript.py orm/ __init__.py models.py And the basic essentials: # settings.py from django.conf import settings settings.configure( DATABASE_ENGINE = "postgresql_psycopg2", DATABASE_HOST = "localhost", DATABASE_NAME = "dbName", DATABASE_USER = "user", DATABASE_PASSWORD = "pass", DATABASE_PORT = "5432" ) # orm/models.py # ... # myScript.py # import models.. And whether you need to run something like: django-admin.py inspectdb ... (Oh, I'm running Windows if that changes anything regarding command-line arguments.).

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  • Web Shop Schema - Document Db

    - by Maxem
    I'd like to evaluate a document db, probably mongo db in an ASP.Net MVC web shop. A little reasoning at the beginning: There are about 2 million products. The product model would be pretty bad for rdbms as there'd be many different kinds of products with unique attributes. For example, there'd be books which have isbn, authors, title, pages etc as well as dvds with play time, directors, artists etc and quite a few more types. In the end, I'd have about 9 different products with a combined column count (counting common columns like title only once) of about 70 to 100 whereas each individual product has 15 columns at most. The three commonly used ways in RDBMS would be: EAV model which would have pretty bad performance characteristics and would make it either impractical or perform even worse if I'd like to display the author of a book in a list of different products (think start page, recommended products etc.). Ignore the column count and put it all in the product table: Although I deal with somewhat bigger databases (row wise), I don't have any experience with tables with more than 20 columns as far as performance is concered but I guess 100 columns would have some implications. Create a table for each product type: I personally don't like this approach as it complicates everything else. C# Driver / Classes: I'd like to use the NoRM driver and so far I think i'll try to create a product dto that contains all properties (grouped within detail classes like book details, except for those properties that should be displayed on list views etc.). In the app I'll use BookBehavior / DvdBehaviour which are wrappers around a product dto but only expose the revelent Properties. My questions now: Are my performance concerns with the many columns approach valid? Did I overlook something and there is a much better way to do it in an RDBMS? Is MongoDb on Windows stable enough? Does my approach with different behaviour wrappers make sense?

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  • How can I map stored procedure result into a custom class with linq-to-sql?

    - by Remnant
    I have a stored procedure that returns a result set (4 columns x n Rows). The data is based on multiple tables within my database and provides a summary for each department within a corporate. Here is sample: usp_GetDepartmentSummary DeptName EmployeeCount Male Female HR 12 5 7 etc... I am using linq-to-sql to retrieve data from my database (nb - have to use sproc as it is something I have inherited). I would like to call the above sproc and map into a department class: public class Department { public string DeptName {get; set;} public int EmployeeCount {get; set;} public int MaleCount {get; set;} public int FemaleCount {get; set;} } In VS2008, I can drag and drop my sproc onto the methods pane of the linq-to-sql designer. When I examine the designer.cs the return type for this sproc is defined as: ISingleResult<usp_GetDepartmentSummaryResult> What I would like to do is amend this somehow so that it returns a Department type so that I can pass the results of the sproc as a strongly typed view: <% foreach (var dept in Model) { %> <ul> <li class="deptname"><%= dept.DeptName %></li> <li class="deptname"><%= dept.EmployeeCount %></li> etc... Any ideas how to achieve this? NB - I have tried amending the designer.cs and dbml xml file directly but with limited success. I admit to being a little out of my depth when it comes to updating those files directly and I am not sure it is best practice? Would be good to get some diretion. Thanks much

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  • Using JSF, PrimeFaces and JPA: Create Basic WebApp without using Generated CRUD Classes, Forms, etc

    - by user2774489
    I am trying to build a basic CRUD application with NetBeans 7.4, JSF, PrimeFaces and JPA using MySQL. I have successfully done this by using the NetBeans wizards. I want to do this from scratch, no wizards. There seems to be a lack of support for the combo of JSF, PrimeFaces and JPA. When I say "lack", I mean a full example (I might be asking too much), without using the CRUD auto-gen templates/classes AND shows actual queries coded and passed to the datatables(primefaces). YouTube is full of non-English speaking examples using Hibernate (not JPA) and other examples that show flashy GUI's with no code. So far I understand you need an @Entity class (provides the physical build of the tables), a Controller (serializable) and the .xhtml web page to show the datatable.. what else? Also, I'm not seeing any posts or examples where queries are using with JPA/JSF and how they are tied together (in one place). I need to connect the dots here so that I can leverage JSF/JPA to create simple queries to populate my PF DataTables. I've read the blogs and I've googled the intranets until I'm blue in the face. Sending me a list of URL's to read to learn about each product is something I've already done. I get what they do independently, but am looking for the "How do they all connect" answer with maybe some basic code examples!! :)

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  • Which Table Should be Master and Child in Database Design

    - by Jason
    I am quickly learning the ins and outs of database design (something that, as of a week ago, was new to me), but I am running across some questions that don't seem immediately obvious, so I was hoping to get some clarification. The question I have right is about foreign keys. As part of my design, I have a Company table. Originally, I had included address information directly within the table, but, as I was hoping to achieve 3NF, I broke out the address information into its own table, Address. In order to maintain data integrity, I created a row in Company called "addressId" as an INT and the Address table has a corresponding addressId as its primary key. What I'm a little bit confused about (or what I want to make sure I'm doing correctly) is determining which table should be the master (referenced) table and which should be the child (referencing) table. When I originally set this up, I made the Address table the master and the Company the child. However, I now believe this is wrong due to the fact that there should be only one address per Company and, if a Company row is deleted, I would want the corresponding Address to be removed as well (CASCADE deletion). I may be approaching this completely wrong, so I would appreciate any good rules of thumb on how to best think about the relationship between tables when using foreign keys. Thanks!

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  • how can I save/keep-in-sync an in-memory graph of objects with the database?

    - by Greg
    Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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  • SQL Server performance issue.

    - by Jit
    Hi Friends, I have been trying to analyze performance issue with SQL Server 2005. We have 30 jobs, one for each databases (30 databases, one per each client). The jobs run at early morning at an interval of 5 minutes. When I run the job individually for testing, for most of the databases it finishes in 7 to 9 minutes. But when these jobs run at early morning, I see few jobs taking 2 to 3 hours to finish and the same takes few minutes as mentioned above if ran independently. We dont have any other job scheduled during that time, other than these 30 jobs. If we restart the server then for 2 or so days all the jobs finishes in few minutes, but over the period of time (from 3rd day suddenly), few jobs start taking hours to finish. What could be the possible reason of performance degradation over the period of time? I verified all the SPs and we uses temp tables and I made sure none of the temp table is left without dropping at the end of SP. Let me know what are the possible reasons for such behavior. Appreciate your time and help. Thanks

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  • Core Data: Overkill for simple, static UITableView-based iPhone App?

    - by David Foster
    Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

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  • How to model parent to child pair in MySQL (SQL)

    - by mikeschuld
    I have a data model that includes element types Stage, Actor, and Form. Logically, Stages can be assigned pairs of ( Form <--- Actor ) which can be duplicated many times (i.e. same person and same form added to the same stage at a later date/time). Right now I am modeling this with these tables: Stage Form Actor Form_Actor _______________ |Id | |FormId | --> Id in Form |ActorId | --> Id in Actor Stage_FormActor __________________ |Id | |StageId | --> Id in Stage |FormActorId | --> Id in Form_Actor I am using CodeSmith to generate the data layer for this setup and none of the templates really know how to handle this type of relationship correctly when generating classes. Ideally, the ORM would have Stage.FormActors where FormActor would be the pair Form, Actor. Is this the correct way to model these relationships. I have tried using all three Ids in one table as well Stage_Form_Actor ______________ |Id | |StageId | --> Id in Stage |FormId | --> Id in Form |ActorId | --> Id in Actor This doesn't really get generated very well either. Ideas?

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  • Need some help with a MySQL subquery count

    - by Ferdy
    I'm running into my own limits of MySQL query skills, so I hope some SQL guru can help out on this one. The situation is as follow: I have images that can be tagged. As you might expect this is stored in three tables: Image Tag Tag_map (maps images to tags) I have a SQL query that calculates the related tags based on a tag id. The query basically checks what other tags were used for images for images using that tag. Example: Image1 tagged as "Bear" Image2 tagged as "Bear" and "Canada" If I throw "Bear" (or its tag id) at the query, it will return "Canada". This works fine. Here's the query: SELECT tag.name, tag.id, COUNT(tag_map.id) as cnt FROM tag_map,tag WHERE tag_map.tag_id = tag.id AND tag.id != '185' AND tag_map.image_id IN (SELECT tag_map.image_id FROM tag_map INNER JOIN tag ON tag_map.tag_id = tag.id WHERE tag.id = '185') GROUP BY tag_map.id LIMIT 0,100 The part I'm stuck with is the count. For each related tag returned, I want to know how many images are in that tag. Currently it always returns 1, even if there are for example 3. I've tried counting different columns all resulting in the same output, so I guess there is a flaw in my thinking.

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  • How can I properly handle 404s in ASP.NET MVC?

    - by Brian
    I am just getting started on ASP.NET MVC so bear with me. I've searched around this site and various others and have seen a few implementations of this. EDIT: I forgot to mention I am using RC2 Using URL Routing: routes.MapRoute( "Error", "{*url}", new { controller = "Errors", action = "NotFound" } //404s ); The above seems to take care of requests like this (assuming default route tables setup by initial MVC project): "/blah/blah/blah/blah" Overriding HandleUnknownAction() in the controller itself: //404s - handle here (bad action requested protected override void HandleUnknownAction(string actionName) { ViewData["actionName"] = actionName; View("NotFound").ExecuteResult(this.ControllerContext); } However the previous strategies do not handle a request to a Bad/Unknown controller. For example, I do not have a "/IDoNotExist", if I request this I get the generic 404 page from the web server and not my 404 if I use routing + override. So finally, my question is: Is there any way to catch this type of request using a route or something else in the MVC framework itself? OR should I just default to using Web.Config customErrors as my 404 handler and forget all this? I assume if I go with customErrors I'll have to store the generic 404 page outside of /Views due to the Web.Config restrictions on direct access. Anyway any best practices or guidance is appreciated.

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  • UITableView with Custom Cell only loads one row of data at a time

    - by Anton
    For my table, I've created a custom cell that has two labels. I also have two arrays with data, that I use to respectively assign each label in the cell. My problem, is that when the table is viewed, only the first row has data, and the rest of the data "sorta" loads when I start scrolling down. By "sorta", only the first row will load at a time. The only time I get to see all the data, is when I scroll to the bottom, then scroll up again. I've used the cellForRowAtIndexPath method to load the data into my cell. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CustomCellIdentifier = @"CustomCellIdentifier"; CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:CustomCellIdentifier]; if (cell == nil) { NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil]; for (id oneObject in nib) if ([oneObject isKindOfClass:[CustomCell class]]) cell = (CustomCell *)oneObject; } NSUInteger row = [indexPath row]; //I have two tables to fill up, hence the tag if statement if ([tableView tag] == 0) { cell.arriveTimeLabel.text = [homeBoundTimes objectAtIndex:row]; cell.departTimeLabel.text = [homeBoundTimes objectAtIndex:row]; } else if ([tableView tag] == 1) { cell.arriveTimeLabel.text = [workBoundTimes objectAtIndex:row]; cell.departTimeLabel.text = [workBoundTimes objectAtIndex:row]; } return cell; } Is it possible that its only getting called when the top cell is being called?

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  • Constructor and Destructors in C++ [Not a question] [closed]

    - by Jack
    I am using gcc. Please tell me if I am wrong - Lets say I have two classes A & B class A { public: A(){cout<<"A constructor"<<endl;} ~A(){cout<<"A destructor"<<endl;} }; class B:public A { public: B(){cout<<"B constructor"<<endl;} ~B(){cout<<"B destructor"<<endl;} }; 1) The first line in B's constructor should be a call to A's constructor ( I assume compiler automatically inserts it). Also the last line in B's destructor will be a call to A's destructor (compiler does it again). Why was it built this way? 2) When I say A * a = new B(); compiler creates a new B object and checks to see if A is a base class of B and if it is it allows 'a' to point to the newly created object. I guess that is why we don't need any virtual constructors. ( with help from @Tyler McHenry , @Konrad Rudolph) 3) When I write delete a compiler sees that a is an object of type A so it calls A's destructor leading to a problem which is solved by making A's destructor virtual. As user - Little Bobby Tables pointed out to me all destructors have the same name destroy() in memory so we can implement virtual destructors and now the call is made to B's destructor and all is well in C++ land. Please comment.

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  • SQL Server Express performance issue

    - by Developer IT
    Hi folks ! I know my questions will sound silly and probably nobody will have perfect answer but since I am in a complete dead-end with the situation it will make me feel better to post it here. So... I have a SQL Server Express database that's 500 Mb. It contains 5 tables and maybe 30 stored procedure. This database is use to store articles and is use for the Developer It web site. Normally the web pages load quickly, let's say 2 ou 3 sec. BUT, sqlserver process uses 100% of the processor for those 2 or 3 sec. I try to find which stored procedure was the problem and I could not find one. It seems like every read into the table dans contains the articles (there are about 155,000 of them and 20 or so gets added every 15 minutes). I added few index but without luck... It is because the table is full text indexed ? Should I have order with the primary key instead of date ? I never had any problems with ordering by dates.... Should I use dynamic SQL ? Should I add the primary key into the url of the articles ? Should I use mutiple indexes for seperate columns or one big index ? I you want more details or code bits, just ask for it. Basicly, every little hint is much apreciated. Thanks.

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  • Erlang ODBC parameter query with null parameters

    - by Schlomer
    Is it possible to pass null values to parameter queries? For example Sql = "insert into TableX values (?,?)". Params = [{sql_integer, [Val1]}, {sql_float, [Val2]}]. % Val2 may be a float, or it may be the atom, undefined odbc:param_query(OdbcRef, Sql, Params). Now, of course odbc:param_query/3 is going to complain if Val2 is undefined when trying to match to a sql_float, but my question is... Is it possible to use a parameterized query, such as: Sql = "insert into TableY values (?,?,?,?,?,?,?,?,?)". with any null parameters? I have a use case where I am dumping a large number of real-time data into a database by either inserting or updating. Some of the tables I am updating have a dozen or so nullable fields, and I do not have a guarantee that all of the data will be there. Concatenating a SQL together for each query, checking for null values seems complex, and the wrong way to do it. Having a parameterized query for each permutation is simply not an option. Any thoughts or ideas would be fantastic! Thank you!

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  • Overflow in table cells

    - by Ezdaroth
    I need to create a chat layout that uses all the available space and scales nicely, but has few fixed sizes. Here's the structure: <table style="width: 100%; height: 100%"> <tr> <td></td> <td style="width: 200px; background: red;"></td> </tr> <tr> <td style="height: 100px; background: blue"></td> <td></td> </tr> </table> However, I want to place a lot of content in the first table cell and I want it to scroll, so it won't expand the table. Is it possible to make it overflow properly, without having a fixed height for the cell? Simply adding overflow: auto doesn't seem to work. PS. I hate tables, but can't figure out a very clean and cross-browser way to do a layout like this with divs and css. If someone can come up with one, I'll gladly use it.

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  • Nhibernate: Stop it from joining to a table that is not needed

    - by Aaron
    I have two tables (tbArea, tbPost) that relate to the following classes. class Area { int ID string Name ... } class Post { int ID string Title Area Area ... } These two classes map up with Fluent Nhibernate. Below is the post mapping. public class PostMapping : ClassMap<Post> { public PostMapping() { Cache.NonStrictReadWrite(); this.Table("tbPost"); Id(x => x.ID) .Column("PostID") .GeneratedBy .Identity(); References(x => x.Area) .ForeignKey("AreaID") .Column("AreaID"); ... } } Any time I perform a query on the Post table "where AreaID = 1(any AreaId)", nhibernate will join to the area table. (What Nhibernate generates for a query) SELECT post fields , area fields (automatically added) FROM tbPost p LEFT JOIN tbArea a on p.areaid = a.areaid where p.areaid = 1 I have tried setting Area to LazyLoad, to Fetch.Select, ReadOnly, and any other setting on the reference and still it will always join to Area. I am trying to optimize the backend database queries, and since I don't need the area object loaded just filtered I would like to eliminate the unnecessary join to Area each time I Query post. What configurations do I need to change or mappings to get area to still be related to post in my objects, but not query it when I filter on AreaID?

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  • MS Query returns data inside itself but does not export it to Excel

    - by kappa
    Hi, I'm having a strange problem with Excel and MS Query: I'm using MS Query to run a T-SQL query against a Microsoft SQL Server 2000 and return the results to Excel. To do this, I open Excel, go to Data - Import external data - New database query, select my data source, paste the SQL script in MS Query and click File - Return data to Microsoft Office Excel, leaving all the query options to their defaults. This works fine for many other Excel files, but this time although MS Query shows the correct data when I paste the SQL script, after returning to Excel all I get is the query name in the upper left cell, with no data returned. I fear the cause could be the SQL script, as it contains some advanced functions like union all, UDFs and variables. Here's the script: declare @date smalldatetime set @date = dateadd(day, datediff(day, 0, getdate()), 0) select [date], sum([hours]) as [hours] from ( select [date], [hours] from [server].[dbo].[udf] (84, '2010-01-01', @date) union all select [date], [hours] from [server].[dbo].[udf] (89, '2010-01-01', @date) union all select [date], [hours] from [server].[dbo].[udf] (93, '2010-01-01', @date) ) as [a] group by [date] order by [date] asc I can't get rid of the UDF as inside them are done advanced groupings involving cursors and temporary tables, nor I can remove the variable as the UDF won't accept dateadd(day, datediff(day, 0, getdate()), 0) as parameter. Any ideas? Thanks in advance, Andrea.

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  • cakephp read and display from more than one related table

    - by z22
    I have 2 tables Users and Artists. User: id name password city_id state_id country_id Artist: id user_id description I wish to create add and edit form(single form acts as add and edit). But on click of edit link, I wish to fill in the form fields from user as well as artist table. How do i do that? Below is my controller code: public function artist_register() { $this->country_list(); if ($this->request->is('post')) { $this->request->data['User']['group_id'] = 2; if ($this->{$this->modelClass}->saveAll($this->request->data)) { $this->redirect(array('controller' => 'Users', 'action' => 'login')); } } $this->render('artist_update'); } public function artist_update($id) { $artist = $this->{$this->modelClass}->findByuser_id($id); $artist_id = $artist[$this->modelClass]['id']; if($this->request->is('get')) { $this->request->data = $this->{$this->modelClass}->read(null, $artist_id); $this->request->data = $this->{$this->modelClass}->User->read(null, $id); } else { if($this->{$this->modelClass}->save($this->request->data)) { $this->Session->setFlash('Your Profile has been updated'); $this->redirect(array('action' => 'index')); } } } The code doesnt work. how do i solve it?

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  • Oracle ODBC x64 - getting 0 when selecting a number(9) column

    - by MatsL
    I'm having a really weird problem with a third party web service that uses an ODBC connection to Oracle 10.2.0.3.0. I've written a .NET client that generates the same SQL as the web service so I can find out what's going on. The web service is hosted by IIS 6 that's in x64 mode so we use Oracle x64 client. The oracle client version is 10.2.0.1.0. I have a table that looks like this (I've removed some columns and names): SQL> describe tablename; Name Null? Type ----------------------------------------- -------- ---------------------------- KOD VARCHAR2(30) ORDNING NUMBER(5) AVGIFT NUMBER(9) I then in SQL*Plus issue the following statement: SELECT KOD as kod, AVGIFT as riskPoang FROM tablename Where upper(KODTYP) = 'OBJLIVSV_RISKVERKSAMTYP' ORDER BY ORDNING And I get the following result: KOD RISKPOANG ------------------------------ ---------- Hög risk 55 Mellan risk 35 Låg risk 15 Mycket låg risk 5 But when I execute the exact same SQL using the same DSN on the same machine I get this: Values Kod: Hög risk RiskPoäng: 0 Kod: Mellan risk RiskPoäng: 0 Kod: Låg risk RiskPoäng: 0 Kod: Mycket låg risk RiskPoäng: 0 If I first cast the number to varchar and then back again to number, like this: SELECT KOD as kod, to_number(to_char(AVGIFT, '99'), '9999999999') as riskPoang FROM tablename Where upper(KODTYP) = 'OBJLIVSV_RISKVERKSAMTYP' ORDER BY ORDNING I get the correct result: Values Kod: Hög risk RiskPoäng: 55 Kod: Mellan risk RiskPoäng: 35 Kod: Låg risk RiskPoäng: 15 Kod: Mycket låg risk RiskPoäng: 5 Has anyone else experiences this? It's incredibly annoying and I'm completely stuck and not sure what to do next. We have a third party web service that use these tables so I must get the original SQL-statement to work since I can't modify its code. And pointers are greatly appreciated! :-) Best regards, Mats

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  • using dummy row with NOT NULL to solve DEFAULT NULL

    - by Tony38
    I know having DEFAULT NULLS is not a good practice but I have many optional lookup values which are FK in the system so to solve this issue here is what i am doing: I use NOT NULL for every FK / lookup colunms. I have the first row in every lookup table which is PK id = 1 as a dummy row with just "none" in all the columns. This way I can use NOT NULL in my schema and if needed reference to the none row values PK =1 for FKs which do not have any lookup value. Is this a good design or any other work arounds? EDIT: I have: Neighborhood table Postal table. Every neighborhood has a city, so the FK can be NOT NULL. But not every postal code belongs to a neighborhood. Some do, some don't depending on the country. So if i use NOT NULL for the FK between postal and neighborhood then I will be screwed as there has to be some value entered. So what i am doing in essence is: have a row in every table to be a dummy row just to link the FKs. This way row one in neighborhood table will be: n_id = 1 name =none etc... In postal table I can have: postal_code = 3456A3 FK (city) = Moscow FK (neighborhood_id)=1 as a NOT NULL. If I don't have a dummy row in the neighborhood lookup table then I have to declare FK (neighborhood_id) as a Default null column and store blanks in the table. This is an example but there is a huge number of values which will have blanks then in many tables.

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  • Loading enumerations from database

    - by Mosh
    Hello, I have a problem with mapping .NET enumerations to database tables. Imagine I have a table called Statuses with the following values: StatusID | Name 1 Draft 2 Ready ... ... In the application layer, I can either use a Repository to get all Statuses as an IList object. However, the problem with this approach is that I cannot reference a certain status in my business logic. For example, how can I implement something like this? if (myObject.Status is Ready) do this else if (myObject.Status is Draft) do that... Since the statuses are loaded dynamically, I cannot tell for sure what particular Status object in the List represents the Draft or Ready status. Alternatively, I could just use an enumeration like public enum Statuses { Draft, Ready }; Then I could easily use an enumeration in my business logic. if (myObject.Status == Statuses.Draft) // do something... However, the problem with this approach is that every time the user wants to modify the list of Statuses (adding a new status, or renaming an existing status) the application has to be re-compiled. We cannot load the statuses dynamically from the database. Has anyone else come across a similar situation? Any solutions/patterns? Cheers, Mosh

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  • EF 6 Code First Many to many With Payload and self referencing many to many

    - by lesley86
    I Have the problem where i have a many to many relationship and on one of the tables there will be a self referencing many to many. So basically a school have zero or many groups and many groups can have 0 or many schools. The groups table will contain a parent child many to many with itself because a group can be a child of another group or it can have no children and that child can have a child, one child can also have many parents or a entity can have no parents. I created a mapping table with Payload to solvethe first many to many problem. code snippet public class School { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps } public class SchoolGroup { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps } public class SchoolGroupMap { public virtual School School public virtual SchoolGroup SchoolGroup } i Then tried modifying the code the following way for the the self referencing many to many public class SchoolGroup { public virtual ICollection<SchoolGroupMap> SchoolGroupMaps public virtual ICollection<SchoolGroup> Parents public virtual ICollection<SchoolGroup> Children } I changed the context with has many and an auto mapping table (forgive me i have been trying so many things today i do not have the exact code). I received an error the properties on the classes must match. Can anyone help please. I want to do create navigation properties on the self referencing many to many. Also a seed example would be appreciated regards

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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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  • Are document-oriented databases any more suitable than relational ones for persisting objects?

    - by Owen Fraser-Green
    In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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