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  • Pros and Cons of using SqlCommand Prepare in C#?

    - by MadBoy
    When i was reading books to learn C# (might be some old Visual Studio 2005 books) I've encountered advice to always use SqlCommand.Prepare everytime I execute SQL call (whether its' a SELECT/UPDATE or INSERT on SQL SERVER 2005/2008) and I pass parameters to it. But is it really so? Should it be done every time? Or just sometimes? Does it matter whether it's one parameter being passed or five or twenty? What boost should it give if any? Would it be noticeable at all (I've been using SqlCommand.Prepare here and skipped it there and never had any problems or noticeable differences). For the sake of the question this is my usual code that I use, but this is more of a general question. public static decimal pobierzBenchmarkKolejny(string varPortfelID, DateTime data, decimal varBenchmarkPoprzedni, decimal varStopaOdniesienia) { const string preparedCommand = @"SELECT [dbo].[ufn_BenchmarkKolejny](@varPortfelID, @data, @varBenchmarkPoprzedni, @varStopaOdniesienia) AS 'Benchmark'"; using (var varConnection = Locale.sqlConnectOneTime(Locale.sqlDataConnectionDetailsDZP)) //if (varConnection != null) { using (var sqlQuery = new SqlCommand(preparedCommand, varConnection)) { sqlQuery.Prepare(); sqlQuery.Parameters.AddWithValue("@varPortfelID", varPortfelID); sqlQuery.Parameters.AddWithValue("@varStopaOdniesienia", varStopaOdniesienia); sqlQuery.Parameters.AddWithValue("@data", data); sqlQuery.Parameters.AddWithValue("@varBenchmarkPoprzedni", varBenchmarkPoprzedni); using (var sqlQueryResult = sqlQuery.ExecuteReader()) if (sqlQueryResult != null) { while (sqlQueryResult.Read()) { //sqlQueryResult["Benchmark"]; } } } }

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  • How to perform COUNT() or COUNT(*)

    - by ninumedia
    I have a list of tags in a database. Ex: villan hero spiderman superman superman I wanted to obtain a sorted list of the tag names in ascending order and the number of times the unique tag appeared in the database. I wrote this code: Ex: SELECT hashtag.tag_name, COUNT( * ) AS number FROM hashtag GROUP BY hashtag.tag_name ORDER BY hashtag.tag_name ASC This yields the correct result: hero - 1 spiderman - 1 superman - 2 villan - 1 How can I obtain the full COUNT of this entire list. The answer should be 4 in this case because there are naturally 4 rows. I can't seem to get a correct COUNT() without the statement failing. Thanks so much for the help! :)

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  • How to retrieve MYSQL records as an INSERT statement.

    - by Aglystas
    I'm trying come up with the best method of synchronizing particular rows of 2 different database tables. So, for example there's 2 product tables in different databases as such... Origin Database product{ merchant_id, product_id, ... additional fields } Destination Database product{ merchant_id product_id ... additional fields } So, the database schema is the same for both. However I'm looking to select records with a particular merchant_id, remove all records from the destination table that have that merchant_id and replace those records with records from the origin database of the same merchant_id. My first thought was using mysqldump, parsing out the create table statements, and only running the Insert Statements. Seems like a pain though. So I was wondering if there is a better technique to do this. I would think mysql has some method of creating INSERT statements as output from a SELECT statement, so you can define how to insert specific record information into a new db. Any help would be appreciated, thank you much.

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  • Optimize LINQ Query for use with jQuery Autocomplete

    - by rockinthesixstring
    I'm working on building an HTTPHandler that will serve up plain text for use with jQuery Autocomplete. I have it working now except for when I insert the first bit of text it does not take me to the right portion of the alphabet. Example: If I enter Ne my drop down returns Nlabama Arkansas Notice the "N" from Ne and the "labama" from "Alabama" As I type the third character New, then the jQuery returns the "N" section of the results. My current code looks like this Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest ' the page contenttype is plain text' HttpContext.Current.Response.ContentType = "text/plain" ' store the querystring as a variable' Dim qs As Nullable(Of Integer) = Integer.TryParse(HttpContext.Current.Request.QueryString("ID"), Nothing) ' use the RegionsDataContext' Using RegionDC As New DAL.RegionsDataContext 'create a (q)uery variable' Dim q As Object ' if the querystring PID is not blank' ' then we want to return results based on the PID' If Not qs Is Nothing Then ' that fit within the Parent ID' q = (From r In RegionDC.bt_Regions _ Where r.PID = qs _ Select r.Region).ToArray ' now we loop through the array' ' and write out the ressults' For Each item In q HttpContext.Current.Response.Write(item & vbCrLf) Next End If End Using End Sub So where I'm at now is the fact that I stumbled on the "Part" portion of the Autocomplete method whereby I should only return information that is contained within the Part. My question is, how would I implement this concept into my HTTPHandler without doing a fresh SQLQuery on every character change? IE: I do the SQL Query on the QueryString("ID"), and then on every subsequent load of the same ID, we just filter down the "Part". http://www.example.com/ReturnRegions.axd?ID=[someID]&Part=[string]

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  • Sqlite. How to create an index in attached DB?

    - by kappa
    I have a problem with adding index to memory database attached to main database. 1) I open the database (F) from file 2) Attach the :memory: (M) database 3) Create tables in database M 4) Copy data from F to M I would also like to create an index in database M, but don't know how to do that. This code creates index but in F database: sQuery = "CREATE INDEX IF NOT EXISTS [INDID] ON [PANEL]([ID] ASC);"; I tried to add the name qualifier before table name like this: sQuery = "CREATE INDEX IF NOT EXISTS [INDID] ON [M.PANEL]([ID] ASC);"; but SQLite returns with message that column main.M.PANEL does not exist. What can I do?

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  • WebCenter Content Web Search Performance: Do you really need that folder path info?

    - by Nicolas Montoya
    End-users want content at their fingertips at the speed of thought if possible. When running search operations in the WebCenter Conter Web Interface every second or fraction of a second improvement does matter. When doing some trace analysis on the systemdatabase tracing on a customer environment, we came across some SQL queries that were unnecessarily being triggered! These were related to determining the folder path for every entry part of the search result set. However, this folder path was not even being used as part of the displayed information in the user interface.Why was the folder path information being collected when it was not even displayed in the UI? We found that the configuration parameter 'FolderPathInSearchResults' was set to 'true' under Administration > Admin Server > General Configuration > Additional Configuration Variables as shown below:When executing a quicksearch by keyword we were getting 100 out of 2280 entries in the first page of the result set.When thera 'FolderPathInSearchResults' configuration parameter is set to 'true', the following queries appear in the systemdatabase tracing:100 executions for a query on the FolderFiles table for each of the documents displayed in the first page:>systemdatabase/6       12.13 11:17:48.188      IdcServer-199   1.45 ms. SELECT * FROM FolderFiles WHERE dDocName='SLC02VGVUSORAC140641' AND fLinkRank=0[Executed. Returned row(s): true]382 executions for a query of the folders tables - most of the documents that match the keyword criteria are at a folder depth level of three or four:>systemdatabase/6       12.13 11:17:48.114      IdcServer-199   2.57 ms. SELECT FolderFolders.*,FolderMetaDefaults.* FROM FolderFolders,FolderMetaDefaults WHERE FolderFolders.fFolderGUID=FolderMetaDefaults.fFolderGUID(+) AND((FolderFolders.fFolderGUID = '1EB8E527E19B09ED3FE82EE310AEA13A' ) )[Executed.Returned row(s): true]By setting this 'FolderPathInSearchResults' configuration parameter to 'false', the above queries were no longer reported in the Server Output System Audit Information.Now, let's consider a practical scenario:Search result set page = 100Average folder depth der document in the search result set: 5The number of folder path related queries will be: 100 + 5*500 = 600If each query takes slightly over 3 ms. You would have 2000 ms (2 seconds) spent in server time to get this information.The overall performance impact goes beyond seerver time execution, as this information needs to travel from the server to the browser. If the documents are further nested into the folder hierarchy, additional hundreds of queries may be executed. If folder path is not being displayed in the end-user interface profile, your system may be better of with the 'FolderPathInSearchResults' configuration parameter disabled.

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  • STL find performs bettern than hand-crafter loop

    - by dusha
    Hello all, I have some question. Given the following C++ code fragment: #include <boost/progress.hpp> #include <vector> #include <algorithm> #include <numeric> #include <iostream> struct incrementor { incrementor() : curr_() {} unsigned int operator()() { return curr_++; } private: unsigned int curr_; }; template<class Vec> char const* value_found(Vec const& v, typename Vec::const_iterator i) { return i==v.end() ? "no" : "yes"; } template<class Vec> typename Vec::const_iterator find1(Vec const& v, typename Vec::value_type val) { return find(v.begin(), v.end(), val); } template<class Vec> typename Vec::const_iterator find2(Vec const& v, typename Vec::value_type val) { for(typename Vec::const_iterator i=v.begin(), end=v.end(); i<end; ++i) if(*i==val) return i; return v.end(); } int main() { using namespace std; typedef vector<unsigned int>::const_iterator iter; vector<unsigned int> vec; vec.reserve(10000000); boost::progress_timer pt; generate_n(back_inserter(vec), vec.capacity(), incrementor()); //added this line, to avoid any doubts, that compiler is able to // guess the data is sorted random_shuffle(vec.begin(), vec.end()); cout << "value generation required: " << pt.elapsed() << endl; double d; pt.restart(); iter found=find1(vec, vec.capacity()); d=pt.elapsed(); cout << "first search required: " << d << endl; cout << "first search found value: " << value_found(vec, found)<< endl; pt.restart(); found=find2(vec, vec.capacity()); d=pt.elapsed(); cout << "second search required: " << d << endl; cout << "second search found value: " << value_found(vec, found)<< endl; return 0; } On my machine (Intel i7, Windows Vista) STL find (call via find1) runs about 10 times faster than the hand-crafted loop (call via find2). I first thought that Visual C++ performs some kind of vectorization (may be I am mistaken here), but as far as I can see assembly does not look the way it uses vectorization. Why is STL loop faster? Hand-crafted loop is identical to the loop from the STL-find body. I was asked to post program's output. Without shuffle: value generation required: 0.078 first search required: 0.008 first search found value: no second search required: 0.098 second search found value: no With shuffle (caching effects): value generation required: 1.454 first search required: 0.009 first search found value: no second search required: 0.044 second search found value: no Many thanks, dusha. P.S. I return the iterator and write out the result (found or not), because I would like to prevent compiler optimization, that it thinks the loop is not required at all. The searched value is obviously not in the vector.

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  • How to shift pixels of a pixmap efficient in Qt4

    - by stanleyxu2005
    Hello, I have implemented a marquee text widget using Qt4. I painted the text content onto a pixmap first. And then paint a portion of this pixmap onto a paint device by calling painter.drawTiledPixmap(offsetX, offsetY, myPixmap) My Imagination is that, Qt will fill the whole marquee text rectangle with the content from myPixmap. Is there a ever faster way, to shift all existing content to left by 1px and than fill the newly exposed 1px wide and N-px high area with the content from myPixmap?

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  • can we use join inside join in mysql?

    - by I Like PHP
    i have 3 tables structure is below tbl_login login_id | login_name 1 | keshav tbl_role role_id | login_id( refer to tbl_login.login_id) 1 | 1 tbl_stuff stuff_id | role_id( refer to tbl_role.role_id) 1 | 1 i need data in follow format stuff_id | login_name 1 | keshav how to use JOIN to retrive the above data in mysql?

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  • fastest way to crawl recursive ntfs directories in C++

    - by Peter Parker
    I have written a small crawler to scan and resort directory structures. It based on dirent(which is a small wrapper around FindNextFileA) In my first benchmarks it is surprisingy slow: around 123473ms for 4500 files(thinkpad t60p local samsung 320 GB 2.5" HD). 121481 files found in 123473 milliseconds Is this speed normal? This is my code: int testPrintDir(std::string strDir, std::string strPattern="*", bool recurse=true){ struct dirent *ent; DIR *dir; dir = opendir (strDir.c_str()); int retVal = 0; if (dir != NULL) { while ((ent = readdir (dir)) != NULL) { if (strcmp(ent->d_name, ".") !=0 && strcmp(ent->d_name, "..") !=0){ std::string strFullName = strDir +"\\"+std::string(ent->d_name); std::string strType = "N/A"; bool isDir = (ent->data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) !=0; strType = (isDir)?"DIR":"FILE"; if ((!isDir)){ //printf ("%s <%s>\n", strFullName.c_str(),strType.c_str());//ent->d_name); retVal++; } if (isDir && recurse){ retVal += testPrintDir(strFullName, strPattern, recurse); } } } closedir (dir); return retVal; } else { /* could not open directory */ perror ("DIR NOT FOUND!"); return -1; } }

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  • table lock while creating table using select

    - by shal
    Using mysql version 5.0.18 I am creating a table TT, Client 1 set autocommit = false; start transaction Create table TT select * from PT; PT has tow columns pk bigint not null,name varchar(20) Client 2 set autocommit = false start transaction insert into PT values(123,'text'); While inserting a row in PT , it is waiting for the table Client 1 to commit. I am unable to insert the row. why? Is it possible to insert the row without waiting for Client 1 to commit.

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  • Python: how to run several scripts (or functions) at the same time under windows 7 multicore processor 64bit

    - by Gianni
    sorry for this question because there are several examples in Stackoverflow. I am writing in order to clarify some of my doubts because I am quite new in Python language. i wrote a function: def clipmyfile(inFile,poly,outFile): ... # doing something with inFile and poly and return outFile Normally I do this: clipmyfile(inFile="File1.txt",poly="poly1.shp",outFile="res1.txt") clipmyfile(inFile="File2.txt",poly="poly2.shp",outFile="res2.txt") clipmyfile(inFile="File3.txt",poly="poly3.shp",outFile="res3.txt") ...... clipmyfile(inFile="File21.txt",poly="poly21.shp",outFile="res21.txt") I had read in this example Run several python programs at the same time and i can use (but probably i wrong) from multiprocessing import Pool p = Pool(21) # like in your example, running 21 separate processes to run the function in the same time and speed my analysis I am really honest to say that I didn't understand the next step. Thanks in advance for help and suggestion Gianni

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  • Does the order of columns matter in a group by clause?

    - by Jeff Meatball Yang
    If I have two columns, one with very high cardinality and one with very low cardinality (unique # of values), does it matter in which order I group by? Here's an example: select dimensionName, dimensionCategory, sum(someFact) from SomeFact f join SomeDim d on f.dimensionKey = d.dimensionKey group by d.dimensionName, -- large number of unique values d.dimensionCategory -- small number of unique values Are there situations where it matters?

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  • Find the highest number of occurences in a column in SQL

    - by Ronnie
    Given this table: Order custName description to_char(price) A desa $14 B desb $14 C desc $21 D desd $65 E dese $21 F desf $78 G desg $14 H desh $21 I am trying to display the whole row where prices have the highest occurances, in this case $14 and $21 I believe there needs to be a subquery. So i started out with this: select max(count(price)) from orders group by price which gives me 3. after some time i didn't think that was helpful. i believe i needed the value 14 and 21 rather the the count so i can put that in the where clause. but I'm stuck how to display that. any help?

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  • .NET Data Provider for SqlServer

    - by DMcKenna
    Has anybody managed to get the ".NET Data Provider for SqlServer" to actually work within perfmon.exe. I have a .NET app that uses nhibernate to interact with sql server 2005 db. All I want to do is to view the NumberOfActiveConnectionPools, NumberOfActiveConnections and the NumberOfFreeConnections within perfmon.exe Can somebody explain to me how exactly I get this to work? Regards, David

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  • ~1 second TcpListener Pending()/AcceptTcpClient() lag

    - by cpf
    Probably just watch this video: http://screencast.com/t/OWE1OWVkO As you see, the delay between a connection being initiated (via telnet or firefox) and my program first getting word of it. Here's the code that waits for the connection public IDLServer(System.Net.IPAddress addr,int port) { Listener = new TcpListener(addr, port); Listener.Server.NoDelay = true;//I added this just for testing, it has no impact Listener.Start(); ConnectionThread = new Thread(ConnectionListener); ConnectionThread.Start(); } private void ConnectionListener() { while (Running) { while (Listener.Pending() == false) { System.Threading.Thread.Sleep(1); }//this is the part with the lag Console.WriteLine("Client available");//from this point on everything runs perfectly fast TcpClient cl = Listener.AcceptTcpClient(); Thread proct = new Thread(new ParameterizedThreadStart(InstanceHandler)); proct.Start(cl); } } (I was having some trouble getting the code into a code block) I've tried a couple different things, could it be I'm using TcpClient/Listener instead of a raw Socket object? It's not a mandatory TCP overhead I know, and I've tried running everything in the same thread, etc.

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  • Why is autorelease especially dangerous/expensive for iPhone applications?

    - by e.James
    I'm looking for a primary source (or a really good explanation) to back up the claim that the use of autorelease is dangerous or overly expensive when writing software for the iPhone. Several developers make this claim, and I have even heard that Apple does not recommend it, but I have not been able to turn up any concrete sources to back it up. SO references: autorelease-iphone Why does this create a memory leak (iPhone)? Note: I can see, from a conceptual point of view, that autorelease is slightly more expensive than a simple call to release, but I don't think that small penalty is enough to make Apple recommend against it. What's the real story?

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  • mysql display each day in a month

    - by Jason
    during a month, display the infor each date, order by date, but this infor is empty in some day. how can i still display each day as a row? Product date ----------------- 20 2008-01-01 10 2008-01-02 20 2008-01-03 10 2008-01-05 09 2008-01-08 30 2008-01-09 result: Product date ----------------- 20 2008-01-01 10 2008-01-02 20 2008-01-03 0 2008-01-04 10 2008-01-05 0 2008-01-06 0 2008-01-07 09 2008-01-08 30 2008-01-09

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  • ASP .NET page runs slow in production

    - by Brandi
    I have created an ASP .NET page that works flawlessly and quickly from Visual Studio. It does a very large database read from a database on our network to load a gridview inside of an update panel. It displays progress in an Ajax modalpopupextender. Of course I don't expect it to be instant what with the large db reads, but it takes on the order of seconds, not on the order of minutes. This is all working great until I put it up on the server - it is very, VERY slow when I access it via the internet - takes several minutes to load the database information into the gridview. I'm baffled why it would not perform the exact same as it had from Visual Studio. (It is in release mode and I have taken off the debug flag) I have since been trying things like eliminating unneeded update panels and throwing out the ajax tool. Nothing has made it any faster on production. It is not the database as far as I know, since it has been consistently fast from my computer (from visual studio) and consistently slow from the server. I am wondering, where do I look next? Has anyone else had this problem before? Could this be caused by update panels or Ajax modalpopupextenders in different parts of the application? Why would the live behaviour differ so much from the localhost behaviour? Both the server with the ASP .NET page and the server with the database are servers on our network. I'm using Visual Studio 2008. Thank you in advance for any insight or advice.

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  • Zend Framework table Relationships

    - by Uffo
    I have a table with over 4 million rows, I want to split this table in more tables, i.e one table with 50k rows. I also need to perform a search on these tables, whats the best way to do it? with JOIN, or? do you have some better ideas? Best Regards,

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