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  • lambda expression for a query on two tables that returns records from one table

    - by peetee
    I have two tables TableA (articles) int id int Type string name and TableB (compatibles) int linked_ID int tableA_ID TableA records: id=1, Type=0, name="ArticleA" id=2, Type=1, name="ArticleB" id=3, Type=2, name="ArticleC" id=4, Type=1, name="ArticleD" TableB records: linked_ID= 1, tableA_ID=2 linked_ID= 1, tableA_ID=3 linked_ID= 1, tableA_ID=4 TableB has a list of arcicels that are compatible to a certain article. I am quite new to queries (didn't need them in my projects yet). But as C# and WPF allow some pretty cool automation with Binding I would like to add a binding that returns the following: Give me all articles that are of Type 1 and compatible to my selected article (id=1). The simple part of it works well (articles has a list of all articles): private ObservableCollection<Article> _articles = new ObservableCollection<Article>(); [fill it with the available articles] and then: comboBoxArticles.ItemsSource = _articles.AsBindable().Where( c => c.Typ == 0 ); How can I extend the Where clause to query another table? Thanks a lot in advance.

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  • C# mysqlreader on same connection error

    - by dominiquel
    Hi, I must find a way to do this in C#, if possible... I must loop on my folder list (mysql table), and for each folder I instanciate I must do another query, but when I do this it says : "There is already an open DataReader associated with this Connection" and I am inside a mysqlreader loop already. Note that I have oversimplified the code just to show you, the fact is that I must do queries inside a mysqlreader loop, and it looks to be impossible as they are on the same connection? MySqlConnection cnx = new MySqlConnection(connexionString); cnx.Open(); MySqlCommand command= new MySqlCommand("SELECT * FROM folder WHERE folder_id = " + id, cnx); MySqlDataReader reader= commande.ExecuteReader(); while (reader.Read()) { this.folderList[this.folderList.Length] = new CFolder(reader.GetInt32"folder_id"), cnx); } reader.Close(); cnx.Close();

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  • Android: making a custom ListView independent of adapters ?

    - by wei
    I am adding a local database as a cache to a remote web service in my android application to answer queries. I used ArrayAdapters before for list views to display the results from the web service. Now with a database cache, the result could be either a Cursor(from database) or a List(from web), which means the adapter can be CursorAdapter or ArrayAdapter too. Creating two adapters for one query doesn't seem to be a good idea. So I am wondering what would be the best way to refactor my current code to add this database feature? Thanks,

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  • PHP - Frameworks, ORM, Encapsulation.

    - by Ian
    Programming languages/environments aside, are there many developers who are using a framework in PHP, ORM and still abide by encapsulation for the DAL/BLL? I'm managing a team of a few developers and am finding that most of the frameworks require me to do daily code inspection because my developers are using the built in ORM. Right now, I've been using a tool to generate the classes and CRUD myself, with an area for them to write additional queries/functions. What's been happening though, is they are creating vulnerabilities by not doing proper checks on data permission, or allowing the key fields to be manipulated in the form. Any suggestions, other than get a new team and a new language (I've seen Python/Ruby frameworks have the same issues).

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  • Using indexes on/through a MySQL view

    - by Peeja
    We've got a MySQL table in which rows are never updated, but instead new rows are added and the old ones marked obsolete. Think Rails' acts_as_paranoid, but for every update. To make working with Rails sane, we've got a view which selects only the rows which are "current". That makes a much better "table" for our ActiveRecord model. The snag: our indexes aren't being used anymore. Queries on the view don't use the underlying tables' indexes. You can't add an index to a view. Without indexes, the app is unbearably slow. The only solution we've come up with is to build a materialized view, but that's a pain in MySQL because they're not natively supported. Is there a better way to do this?

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  • Find overdrawn accounts in SQL

    - by mazzzzz
    Hey guys, I have a program that allows me to run queries against a large database. I have two tables that are important right now, Deposits and withdraws. Each contains a history of every user. I need to take each table, add up every deposit and withdraws (per user), then subtract the withdraws from the deposits. I then need to return every user whos result is negative (aka they withdrew more then they deposited). Is this possible in one query? Example: Deposit Table: |ID|UserName|Amount| |1 | Use1 |100.00| |2 | Use1 |50.00 | |3 | Use2 |25.00 | |4 | Use1 | 5.00 | WithDraw Table: |ID|UserName|Amount| |2 | Use2 | 5.00 | |1 | Use1 |100.00| |4 | Use1 | 5.00 | |3 | Use2 |25.00 | So then the result would output: |OverWithdrawers| | Use2 | Is this possible (I sure don't know how to do it)? Thanks for any help, Max

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  • MS Access CrossTab query - across 3 tables

    - by Prembo
    Hi, I have the following 3 tables: 1) Sweetness Table FruitIndex CountryIndex Sweetness 1 1 10 1 2 20 1 3 400 2 1 50 2 2 123 2 3 1 3 1 49 3 2 40 3 3 2 2) Fruit Name Table FruitIndex FruitName 1 Apple 2 Orange 3 Peaches 3) Country Name Table CountryIndex CountryName 1 UnitedStates 2 Canada 3 Mexico I'm trying to perform a CrossTab SQL query to end up with: Fruit\Country UnitedStates Canada Mexico Apple 10 20 400 Orange 50 123 1 Peaches 49 40 2 The challenging part is to label the rows/columns with the relevant names from the Name tables. I can use MS Access to design 2 queries, create the joins the fruit/country names table with the Sweetness table perform crosstab query However I'm having trouble doing this in a single query. I've attempted nesting the 1st query's SQL into the 2nd, but it doesn't seem to work. Unfortunately, my solution needs to be be wholly SQL, as it is an embedded SQL query (cannot rely on query designer in MS Access, etc.). Any help greatly appreciated. Prembo.

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  • HQL multiple updates. Is there a better way?

    - by folone
    I have a Map, that I want to persist. The domain object is something like this: public class Settings { private String key; private String value; public String getKey() { ... } public String getValue() { ... } public void setKey() { ... } public void setValue() { ... } } The standard approach is to generate a Setting for each pair, and saveOrUpdate() it. But it generates way too much queries, because I need to save lots of settings at a time, and it really affects perfomance. Is there a way to do this using one update query?

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  • toplink prefixes table with TL_ while update operation

    - by Dewfy
    I have very simple named query on JPA (toplink ): UPDATE Server s SET s.isECM = 0 I don't carry about cache or validity of already preloaded entities. But database connection is performed from restricted account (only INSERT/UPDATE/DELETE). It is appeared that toplink on this query executes (and failed since TL_Server is not exists) very strange SQL: INSERT INTO TL_Server (elementId, IsECM) SELECT t0.ElementId, ? FROM Element t0, Server t1 WHERE ((t1.elementId = t0.ElementId) AND (t0.elementType = ?)) bind => [0, Server] What is this? How the simple UPDATE appears an INSERT? Why toplink queries TL_?

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  • OOP App Architecture: Which layer does a lazy loader sit in?

    - by JW
    I am planning the implemention an Inheritance Mapper pattern for an application component http://martinfowler.com/eaaCatalog/inheritanceMappers.html One feature it needs to have is for a domain object to reference a large list of aggreageted items (10,000 other domain objects) So I need some kind of lazy loading collection to be passed out of the aggregate root domain object to other domain objects. To keep my (php) model scripts organised i am storing them in two folders: MyComponent\ controllers\ models\ domain\ <- domain objects, DDD repository, DDD factory daccess\ <- PoEAA data mappers, SQL queries etc views\ But now I am racking my brains wondering where my lazy loading collection sits. Any suggestions / justifications for putting it in one place over another another? DDD = Domain Driven Design Patterns, Eric Evans - book PoEAA = Patterns of Application Architecture Patterns, Martin Fowler - book

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  • ResultSet and aggregation

    - by kachanov
    Ok, I admit my situation is special There is a data system that supports SQL-92 and JDBC interface However the SQL requets are pretty expensive, and in my application I need to retreive the same data multiple times and aggregate it ("group by") on different fields to show different dimensions of the same data. For example on one screen I have three tables that show the same set or records but aggregated by City (1st grid), by Population (2nd grid), by number of babies (3rd grid) This amounts to 3 SQL queries (which is very slow), UNLESS anyone of you can suggest any idea any library from apache commons or from google code, so that I can select all records into ResultSet and get 3 arrays of data group by different fields from this single ResultSet. Am I'm missing some obvious and unexpected solution to this problem?

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  • VendInvoiceJour.InvoiceAccount <- VendTable.AccountNum relation

    - by vukis
    Hi. I have following situation: I need to join VendInvoiceJour.InvoiceAccount <- VendTable.AccountNum and take VendTable.Vendgroup. In all cases (queries,or even views) Dynamics ax joins tables VendInvoiceJour.OrderAccount<- VendTable.AccountNum not VendInvoiceJour.InvoiceAccount <- VendTable.AccountNum. I`m trying to use this kind of query: qBdSVendJour = element.query().dataSourceTable(tablenum(VendInvoiceJour)); qBdSVendTbl = qBdSVendJour.addDataSource(tablenum(VendTable)); qBdSVendTbl.relations(true); qBdSVendTbl.joinMode(JoinMOde::InnerJoin); qBdSVendTbl.fetchMode(QueryFetchMode::One2One); qBdSVendTbl.addLink(FieldNum(VendInvoiceJour,InvoiceAccount),FieldNum(VendTable,AccountNum));//(Dynamics ax automaticaly corrects InvoiceAccount to orderaccount in reports if trying this link in morphx)

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  • Use LINQ to count the number of combinations existing in two lists

    - by Ben McCormack
    I'm trying to create a LINQ query (or queries) that count the total number of occurences of a combinations of items in one list that exist in a different list. For example, take the following lists: CartItems DiscountItems ========= ============= AAA AAA AAA BBB AAA BBB BBB CCC CCC DDD The result of the query operation should be 2 since I can find two combinations of AAA and BBB (from DiscountItems) within the contents of CartItems. My thinking in approaching the query is to join the lists together to shorten CartItems to only include items from DiscountItems. The solution would be to find the CartItem in the resulting query that occurs the least amount of times, thus indicating how many combinations of items exist in CartItems. How can this be done? Here's the query I already have, but it's not working. query results in an enumeration with 100 items, far more than I expected. Dim query = From cartItem In Cart.CartItems Group Join discountItem In DiscountGroup.DiscountItems On cartItem.SKU Equals discountItem.SKU Into Group Select SKU = cartItem.SKU, CartItems = Group Return query.Min(Function(x) x.CartItems.Sum(Function(y) y.Quantity))

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  • Best data store for billions of rows

    - by Jody Powlette
    I need to be able to store small bits of data (approximately 50-75 bytes) for billions of records (~3 billion/month for a year). The only requirement is fast inserts and fast lookups for all records with the same GUID and the ability to access the data store from .net. I'm a SQL server guy and I think SQL Server can do this, but with all the talk about BigTable, CouchDB, and other nosql solutions, it's sounding more and more like an alternative to a traditional RDBS may be best due to optimizations for distributed queries and scaling. I tried cassandra and the .net libraries don't currently compile or are all subject to change (along with cassandra itself). I've looked into many nosql data stores available, but can't find one that meets my needs as a robust production-ready platform. If you had to store 36 billion small, flat records so that they're accessible from .net, what would choose and why?

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  • Help Forming An SQL Query That Selects The Max Difference Of Two Fields

    - by Frank
    I'm trying to select a record with the most effective votes. Each record has an id, the number of upvotes (int) and the number of downvotes (int) in a MySQL database. I know basic update, select, insert queries but I'm unsure of how to form a query that looks something like: SELECT * FROM topics WHERE MAX(topic.upvotes - topic.downvotes). Please excuse my made up SQL. The tutorials on SQL I find on the internet cover very basic stuff. Does anyone recommend a good book on this subject?

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  • Access DoCmd.OpenForm Not Working

    - by user961743
    Looking for a second set of eyes to figure out my problem with an Access form filter. I created a search form, when filled in, appends search criteria to a string variable (strQuery) that is put in place to the [WhereCondition] for opening a form. However, when the script is ran, nothing comes up except for a filtered form with no records. Here is the line that opens the form: DoCmd.OpenForm "ADD_NEW_NCMR", , , strQuery Before the line is ran, strQuery equals: 1=1 AND [NCMR].[NCMR_NUM] = '12-129' The form name, and table.column combination are all correct. In fact, using the DCount function returns the result of 1, which is correct for this query, and returns the correct number for other queries as well. This makes me think that there is nothing wrong with the where condition. DCount("[NCMR_NUM]", "NCMR", strQuery)

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  • is there a tool to see the difference between two database tables in mssql?

    - by reinier
    What is a good tool to see the differences between 2 tables (or even better, the datasets returned by 2 queries). EDIT: I'm not interested in the schema changes. Just assume that the schemas are the same. background as to why: I'm porting some legacy code which can fill a database with some pre-calced data. The easiest way to see if I got everything right, is to check the output of the old program, with the new one. I was thinking that if there is some kind of 'diff' tool for databases, this might be great.

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  • How to estimate memory need by XPathDocument for a specific xml file

    - by bill seacham
    Is there any way to estimate the memory requirement for creating an XpathDocument instance based on the file size of the xml? XpathDocument xdoc = new XpathDocument(xmlfile); Is there any way to programmatically stop the process of creating the XpathDocument if memory drops to a very low level? Since it loads the entire xml into memory, it would be nice to know ahead of time if the xml is too big. What I have found is that when I create a new XpathDocument with a big xml file, an outofmemory exception is never fired, but that the process slows to a crawl, only 5 Mb of memory remains a available and the Task Manager reports it is not responding. This happened with a 266 Mb xml file when there was 584 Mb of ram. I was able to load a 150 Mb file with no problems in 18. After loading the xml, I want to do xpath queries using an XpathNavigator and an XpathNodeIterator. I am using .net 2.0, xp sp3.

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  • Any Google API in perl working with OAuth

    - by Julien
    Hello, I've looked at Net::Google, and 90% of the modules use AuthSub with a mandatory login/password. The right way for a web application to interact with Google applications on behalf of a customer is to use OAuth. That way, the authentication is done by Google, and the application does not know the user's password. This is supported by Net::Google::DocumentsList for example. Are you aware of modules that can work well with Picasa and Blogger, for example, using OAuth. The current Net::Google::PicasaWeb handles read-only queries, no add/remove/update actions.

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  • MySQL: Get only count of result set.

    - by Varun
    I am using MVC with PHP/MySQL. Suppose I am using 10 functions with different queries for fetching details from the database. But at other times I may want to get only the count of the result that will be returned by the query. What is the standard way to handle such situation. Should I write 10 more functions which duplicate almost whole query and return only the count. Or Should I always return the count also with the result set Or I can pass a flag to indicate that the function should return count only, and then based on the flag I will dynamically generate the (select part of) query. Or Is there a better way?

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  • What's the best way to capture output from SQL Management Studio and paste it into an Outlook email?

    - by Decker
    I'm constantly executing ad-hoc queries in SQL Management Studio and need to send the results to people via email. This happens several times a day so I'm looking for the best way to copy the results of the query from the results window into an Outlook email body so that it can be formatted in a reader friendly manner. I haven't come up with anything that works well for me. When it really matters, I end up going into Excel, executing the query from within there and then attaching the resulting spreadsheet. I'm looking for something that I can do without involving Excel if possible. Any ideas?

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  • two where conditions in a mysql query

    - by Kaartz
    I have a table like below |date|dom|guid|pid|errors|QA|comm| |2010-03-22|xxxx.com|jsd3j234j|ab|Yes|xxxxxx|bad| |2010-03-22|xxxx.com|jsd3j234j|ab|No|xxxxxx|| |2010-03-22|xxxx.com|jsd3j234j|if|Yes|xxxxxx|bad| |2010-03-22|xxxx.com|jsd3j234j|if|No|xxxxxx|| |2010-03-22|xxxx.com|jsd3j234j|he|Yes|xxxxxx|bad| |2010-03-22|xxxx.com|jsd3j234j|he|No|xxxxxx|| I want to retrieve the total count of "dom" referred to each "QA" and also I need the count of "errors" detected by the "QA" SELECT date, count(dom), QA FROM reports WHERE date="2010-03-22" GROUP BY QA |2010-03-22|2|ab| |2010-03-22|2|if| |2010-03-22|2|he| SELECT date, count(dom), count(errors), QA FROM reports WHERE errors="Yes" GROUP BY QA |2010-03-22|1|ab| |2010-03-22|1|if| |2010-03-22|1|he| I want to combine the above two queries, is it possible. If I use the below query, I am not getting the desired result. SELECT date, count(dom), QA, count(errors) FROM reports WHERE date="2010-03-22" AND errors="Yes" GROUP BY QA I want the below output |2010-03-22|2|ab|1| |2010-03-22|2|if|1| |2010-03-22|2|he|1| Please help me.

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  • Ruby implementation of conversion between Latitude/Longitude and OS National Grid Reference point?

    - by Harry Wood
    For converting between Latitude/Longitude and UK's Ordnance Survey National Grid eastings and northings, this seems to be the most popular explanation and reference implementation in JavaScript: http://www.movable-type.co.uk/scripts/latlong-gridref.html The web is littered with other implementations in different languages. Making the conversion via PostGIS queries is another alternative. ...but did anyone implement this maths in ruby? OSGridToLatLong is the direction I'm looking for just at this moment, but I would have thought a library for converting in both directions must surely be available in a gem somewhere. I'm just not searching for the right thing.

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  • Mysql - multiple values and between

    - by realshadow
    Hey, I need to select 10 products and display them. Each product has 3 different prices. The select to get the prices looks like this: SELECT * FROM products_loans WHERE CODE IN('10X15/12', '10X15/Q10-10', '10X15/Q20-10') AND 550 BETWEEN PRICE_FROM AND PRICE_TO; Where 550 is the base price. Now this select returns 3 rows, but I want to modify it so it will return 30 results. I dont like the idea to execute 10 queries at once. I know I can easily achieve that with "OR", but I would like to ask if there is some other more elegant way to this. The select "should" look like this: SELECT * FROM products_loans WHERE KOD IN('10X15/12', '10X15/Q10-10', '10X15/Q20-10') AND (550, 325, 780) BETWEEN CENA_OD AND CENA_DO; Note that there is no "price" column or anything in the table which I could use to do a JOIN and I cant modify the table.

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  • LINQ to Entity, joining on NOT IN tables

    - by SlackerCoder
    My brain seems to be mush right now! I am using LINQ to Entity, and I need to get some data from one table that does NOT exist in another table. For example: I need the groupID, groupname and groupnumber from TABLE A where they do not exist in TABLE B. The groupID will exist in TABLE B, along with other relevant information. The tables do not have any relationship. In SQL it would be quite simply (there is a more elegant and efficient solution, but I want to paint a picture of what I need) SELECT GroupID, GroupName, GroupNumber, FROM TableA WHERE GroupID NOT IN (SELECT GroupID FROM TableB) Is there an easy/elegant way to do this? Right now I have a bunch of queries hitting the db, then comparing, etc. It's pretty messy. Thanks.

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