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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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  • 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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  • Python - Using "Google AJAX Search" API's Local Search Objects

    - by user330739
    Hi! I've just started using Google's search API to find addresses and the distances between those addresses. I used geopy for this, but, I often had the problem of not getting the correct addresses for my queries. I decided to experiment, therefore, with Google's "Local Search" (http://code.google.com/apis/ajaxsearch/local.html). Anyway, I wanted to ask if I could use the "Local Search" objects provided by the API within python. Something tells me that I can't and that I have to use json. Does anyone know if there is a work around? PS: Im trying to make something like this: http://www.google.com/uds/samples/random/lead.html ... except a matrix type deal where the insides will be filled with distances between the addresses. Thanks for reading!

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  • Valid Email Addresses - XSS and SQL Injection

    - by PAAMAYIM_NEKUDOTAYIM
    Since there are so many valid characters for email addresses, are there any valid email addresses that can in themselves be XSS attacks or SQL injections? I couldn't find any information on this on the web. The local-part of the e-mail address may use any of these ASCII characters: Uppercase and lowercase English letters (a–z, A–Z) Digits 0 to 9 Characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~ Character . (dot, period, full stop) provided that it is not the last character, and provided also that it does not appear two or more times consecutively (e.g. [email protected]). http://en.wikipedia.org/wiki/E-mail_address#RFC_specification I'm not asking how to prevent these attacks (I'm already using parametrized queries and HTML purifier), this is more a proof-of-concept. The first thing that came to mind was 'OR [email protected], except that spaces are not allowed. Do all SQL injections require spaces?

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  • nHibernate query by example with multiple associated objects

    - by BurnWithLife
    I'm trying to use nhibernate's query by example to build dynamic queries. I'm stuck on how to code for an example object with multiple associations. Here's an example from NHibernate in Action. Its a User object with Items. Example exampleUser = Example.Create(u).IgnoreCase().EnableLike(MatchMode.Anywhere); Example exampleItem = Example.Create(i).IgnoreCase().EnableLike(MatchMode.Anywhere); return GetSession().CreateCriteria(typeof(User)) .Add( exampleUser ) .CreateCriteria("Items") .Add( exampleItem ) .List<User>(); If the User object has let's say a Category object as a property, how could I add that in to the above example? If i put another CreateCriteria at the end it refers to the Items, not the User.

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  • Understanding Plesk Watchdog statistics

    - by weotch
    We have Plesk 8.3 installed. I've started using their Watchdog module to track server useage. Our server routinely has trouble with the amount of traffic we have and I think our MySQL queries need to be smarter. Anyway, looking at the stats from Watchdog, it seems like MySQL usage is low compared to so something else making up the "overall" usage. See this: I was hoping someone with a lot of Plesk exeprience could help me understand what I'm seeing here. Can I not trust Watchdog's reports or am I missing something?

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  • Reuse select query in a procedure in Oracle

    - by Jer
    How would I store the result of a select statement so I can reuse the results with an in clause for other queries? Here's some pseudo code: declare ids <type?>; begin ids := select id from table_with_ids; select * from table1 where id in (ids); select * from table2 where id in (ids); end; ... or will the optimizer do this for me if I simply put the sub-query in both select statements?

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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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  • Accessing database problem

    - by anarche
    Ok, so I've got an SQLiteOpenHelper that prepares and returns a SQLiteDatabase object; this is written singleton-pattern, so the database is opened once and only closed when the Activity closes. From there I have three database wrappers encapsulating the queries (some returning cursors to datasets, some inserting data) used by the Activity. I want to insert data from one View, then have that automatically update in another View on the same Dialogue. I'm writing this on a notepad and testing on the phone (since the emulator crashes the notepad...), so I can't pull up stacktraces atm. So questions: 1) are there limitations to writing to a database, when there are cursors open on the database? 2) Does a Cursor.requery()? call update the ListView with the cursor as a data connector?

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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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  • Storing search result for paging and sorting

    - by Mattias
    I've been implementing MS Search Server 2010 and so far its really good. Im doing the search queries via their web service, but due to the inconsistent results, im thinking about caching the result instead. The site is a small intranet (500 employees), so it shouldnt be any problems, but im curious what approach you would take if it was a bigger site. I've googled abit, but havent really come over anything specific. So, a few questions: What other approaches are there? And why are they better? How much does it cost to store a dataview of 400-500 rows? What sizes are feasible? Other points you should take into consideration. Any input is welcome :)

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  • Custom SQL Server driver

    - by hoodoos
    I had a crazy thought about writing my own SQL Server driver to make it work something like non-blocking http client, so it won't be thread thirsty and could handle lots of db queries within one thread. I tried to look over google for some guidelines about implementing SQL Server client protocol, but found none really, where do those guys get information about it when they write own implementations for PHP or python? I need a really low level to be documented so I can implement all phases of working with a connection through sockets. And would be really nice to have a an example in c# language. :)

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  • HQL updates and domain objects

    - by CaptainAwesomePants
    I have what may be a pretty elementary Hibernate question. Do HQL (and/or Criteria) update queries cause updates to live domain objects? And do they automatically flush now-invalid domain objects from the first-level cache? Example: Player playerReference1 = session.get(Player.class,1); session.createQuery("update players set gold = 100").executeUpdate(); //Question #1 -- does playerReference1.getGold() now return 100? Player playerReference2 = session.get(Player.class,1); //Question #2 -- does playerReference2.getGold() return 100, or is it the same exact object? Should I make a practice of evicting all objects that are affected by an HQL update if there's a chance some code will need it later?

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  • Database Design Question

    - by deniz
    Hi, I am designing a database for a project. I have a table that has 10 columns, most of them are used whenever the table is accessed, and I need to add 3 more rows; View Count Thumbs Up (count) Thumbs Down (Count) which will be used on %90 of the queries when the table is accessed. So, my question is that whether it is better to break the table up and create new table which will have these 3 columns + Foreign ID, or just make it 13 columns and use no joins? Since these columns will be used frequently, I guess adding 3 more columns is better, but if I need to create 10 more columns which will be used %90 of the time, should I add them as well, or create a new table and use joins? I am not sure when to break the table if the columns are used very frequently. Do you have any suggestions? Thanks in advance,

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  • Can I expect a performance gain from removing this JOIN?

    - by makeee
    I have a "items" table with 1 million rows and a "users" table with 20,000 rows. When I select from the "items" table I do a join on the "users" table (items.user_id = user.id), so that I can grab the "username" from the users table. I'm considering adding a username column to the items table and removing the join. Can I expect a decent performance increase from this? It's already quite fast, but it would be nice to decrease my load (which is pretty high). The downside is that if the user changes their username, items will still reflect their old username, but this is okay with me if I can expect a decent performance increase. I'm asking stackoverflow because benchmarks aren't telling me too much. Both queries finish very quickly. Regardless, I'm wondering if removing the join would lighten load on the database to any significant degree.

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  • SQL to get range of results in alphabetical order

    - by Tom Gullen
    I have a table, tblTags which works in much the same way as StackOverflows tagging system. When I view a tags page, let's say the tag Tutorial I want to display the 10 tags before and after it in alphabetical order. So if we are given the tag Tutorial of ID 30 how can we return a record set in the order resembling: Tap Tart > Tutorial Umbrellas Unicorns Xylaphones I have thought of ways of doing this, badly, in my opinion as they involve retrieving ugly amounts of data. I'm not sure if it's possible to do something along the lines of (pseudo): SELECT RANGE(0 - 30) FROM tblTags ORDER BY Name ASC But how do you know the position of the tutorial tag in the list in an efficient manner without traversing the entire list until you find it? I'm using SQL Server 2008 R2 Express with LINQ if it makes any difference, SQL queries or LINQ would be great answers, thanks!

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  • PHP - Too many mysql_query("SELECT .. ") .. ?

    - by Mike
    Hey, I'm making an e-shop and to display the tree of categories and all the products with their multiple variations of prices I made like more than 150 mysql_query("SELECT ..."); queries on one page. (If I count the "while" loops). Is it too many, and if yes, can it have any negative effect? (ofc. it takes longer to load the data ..) Also can I anyhow achieve the effect of this code without doing it that way? $result2 = mysql_query("SELECT * FROM ceny WHERE produkt_id='$id' ORDER BY gramaz"); $result3 = mysql_query("SELECT * FROM ceny WHERE produkt_id='$id' ORDER BY gramaz"); $result4 = mysql_query("SELECT * FROM ceny WHERE produkt_id='$id' ORDER BY gramaz"); $result5 = mysql_query("SELECT * FROM ceny WHERE produkt_id='$id' ORDER BY gramaz"); while( $row2 = mysql_fetch_array( $result2 )) { } while( $row3 = mysql_fetch_array( $result2 )) { } while( $row4 = mysql_fetch_array( $result2 )) { } while( $row5 = mysql_fetch_array( $result2 )) { } Thanks, Mike.

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  • Update query with conditional?

    - by dmontain
    I'm not sure if this possible. If not, let me know. I have a PDO mysql that updates 3 fields. $update = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2, field3=:field3 WHERE key=:key"); But I want field3 to be updated only when $update3 = true; (meaning that the update of field3 is controlled by a conditional statement) Is this possible to accomplish with a single query? I could do it with 2 queries where I update field1 and field2 then check the boolean and update field3 if needed in a separate query. //run this query to update only fields 1 and 2 $update_part1 = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2 WHERE key=:key"); //if field3 should be update, run a separate query to update it separately if ($update3){ $update_part2 = $mypdo->prepare("UPDATE tablename SET field3=:field3 WHERE key=:key"); } But hopefully there is a way to accomplish this in 1 query?

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  • Proper abstraction of the database tier in a 3 tier system?

    - by Earlz
    Hello, I am creating a 3 tier application. Basically it goes Client - (through optional server to be a thin-client) - Business Logic - Database Layer And basically making it so that there is never any skipping around. As such, I want for all of the SQL queries and such to be in the Database Layer. Well, now I'm a bit confused. I made a few static classes to start off the database tier but what should I do for the database connections? Should I just create a new database connection anytime I enter the Database Layer or would that be wasteful? Does Connection.Open() take time whenever you have a ConnectionPool? To me, it just feels wrong for the Business tier to have to pass in a IdbConnection object to the Database tier. It seems like the Database tier should handle all of that DB-specific code. What do you think? How can I do it the proper way while staying practical?

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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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  • ASP.NET Thread Safety in aspx.cs code behind file

    - by Tim Michalski
    I am thinking of adding a DataContext as a member variable to my aspx.cs code-behind class for executing LinqToSql queries. Is this thread safe? I am not sure if a new instance of this code-behind class is created for each HTTP request, or if the instance is shared amongst all request threads? My fear is that I will get 10 simultaneous concurrent http requests that will be using the same database session. public partial class MyPage : System.Web.UI.Page { private DataContext myDB = new DataContext(); protected void MyAction_Click(object sender, EventArgs e) { myDB.DoWork(); } }

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  • Parsing HTML with XPath and PHP

    - by Peter
    Is there a way (using XPath and PHP) to do the following (WITHOUT external XSLT files)? Remove all tables and their contents Remove everything after the first h1 tag Keep only paragraphs (INCLUDING their inner HTML (links, lists, etc)) I received an XSLT answer here, but I'm looking for XPATH queries that don't require external files. Currently, I've got the HTML in question loaded into a SimpleXmlElement via: $doc = @DOMDocument::loadHTML($xml); $data = simplexml_import_dom($doc); Now I need help with: $data = $data->xpath('??????'); Been working with this one for several days to no avail. I really appreciate the help. Edit: I don't particularly care what's inside the paragraphs, as I can use strip_tags to eliminate what I don't want. All I need to do is to isolate the paragraphs from the rest of the source. I suppose a more specific, accurate requirement would be this: Return only paragraphs (and their html contents) that aren't contained in tables, and only before the first h1 tag

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  • Custom keys for Google App Engine models (Python)

    - by Cameron
    First off, I'm relatively new to Google App Engine, so I'm probably doing something silly. Say I've got a model Foo: class Foo(db.Model): name = db.StringProperty() I want to use name as a unique key for every Foo object. How is this done? When I want to get a specific Foo object, I currently query the datastore for all Foo objects with the target unique name, but queries are slow (plus it's a pain to ensure that name is unique when each new Foo is created). There's got to be a better way to do this! Thanks.

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  • Aggregate functions in ANSI SQL

    - by morpheous
    I want to use multiple aggregate functions in a query. All the examples i have seem on aggregate functions however, are trivial. Typically, they are of the form: SELECT field1,agg_func1, agg_func2 GROUP BY SOME_COLUMNS HAVING agg_func1 OP SOME_SCALAR Where: OP: is a boolean operator (e.g. <, = etc) SOME_SCALAR: is a scalar (i.e. a constant number) What I want to know is if it is possible to write (IN ANSI SQL) queries like: SELECT field1,agg_func1, agg_func2, agg_func3 GROUP BY SOME_COLUMNS HAVING (agg_func1 OP1 agg_func2) OP2 (agg_func2 OP3 agg_func3) Where: OP[N] are boolean operators or ANSI SQL clause operators like 'BETWEEN', 'LIKE', 'IN' etc. Also, assuming this is possible (I have not seen any documentation saying otherwise) are there any efficiency/performance considerations (i.e. penalties) when the HAVING clause consists of a boolean expression combining the output of the aggregate functions - instead of the normal comparison of the output of the aggregate with a constant number (e.g. min('salary') 100 ) - which is often used in the most banal examples involving aggregate functions?

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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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