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• could not execute a stored procedure(using DAAB) from a client(aspx page) to a wcf service

  - by user1144695

  i am trying to store data to sql database from a asp.net client website through a stored procedure(using DAAB) in a wcf service hosted in a asp.net empty website.When i try to store data to the DB i get the following error: ** - The server was unable to process the request due to an internal error. For more information about the error, either turn on IncludeExceptionDetailInFaults (either from ServiceBehaviorAttribute or from the <serviceDebug> configuration behavior) on the server in order to send the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework SDK documentation and inspect the server trace logs. ** When i try to debug i get the following exception: Activation error occured while trying to get instance of type Database, key "" in the code-- Database db = EnterpriseLibraryContainer.Current.GetInstance<Database>("MyInstance"); where my app.config is <?xml version="1.0"?> <configuration> <configSections> <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true"/> </configSections> <dataConfiguration defaultDatabase="MyInstance"/> <connectionStrings> <add name="MyInstance" connectionString="Data Source=BLRKDAS307581\KD;Integrated Security=True;User ID=SAPIENT\kdas3;Password=ilove0LINUX" providerName="System.Data.SqlClient" /> </connectionStrings> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/> </startup> </configuration> Can anyone help me with it? Thanks in advance...

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• Are there any NOSQL-compatible CMS projects?

  - by Michael

  This question is partially related to an older question (Any CMS is Google App Engine compatible?) , but is slightly more general. It seems that in most CMS systems, the most fragile failure point is the database. Traditional database implementations scale poorly and will never be able to handle unforeseen spikes of traffic. Since Google App Engine was designed to help even small businesses overcome that problem, I had the same question that was asked earlier this year with less than satisfactory answers. But more generally, where are the CMS projects that support NOSQL databases? Looking over Wikipedia's list of CMS platforms, I see without much effort that only traditional RDBMS are supported by every single vendor on the list. I would have expected to see at least one or two projects handling CouchDB or similar engines. I understand the complexities of implementing a NOSQL solution to a problem that is typically solved using the relations cleanly expressed in any RDBMS, but there seems to be a rather wide market gap. Since databases are, today, easily outsourced to Google, Amazon, and others which use NOSQL models, I am amazed that there are not more projects actively pursuing this path. Am I simply not aware? Can someone please point me to projects that have real momentum that are developing on this path? I'm looking for two things: a CMS that has as its backbone a NOSQL database enabling easy database outsourcing (hosted MySQL clusters and similar solutions are not what I'm looking for) a project that is built to run on either a PaaS architecture like Google App Engine or an IaaS architecture like Amazon EC2 Any pointers in that direction would be most welcome.

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• How lucene indexing ?

  - by user312140

  Hello I read some document about lucene ; also i read the document in this link ( http://lucene.sourceforge.net/talks/pisa ) . I don't really understand how lucene index documents and don't understand lucene work with which algorithm for indexing ? On above link , said lucene use this algorithm for indexing : * incremental algorithm: o maintain a stack of segment indices o create index for each incoming document o push new indexes onto the stack o let b=10 be the merge factor; M=8 for (size = 1; size < M; size *= b) { if (there are b indexes with size docs on top of the stack) { pop them off the stack; merge them into a single index; push the merged index onto the stack; } else { break; } } How this algorithm help us to have an optimize indexing ? Does lucene use B-tree algorithm or any other algorithm like that for indexing or have a paticular algorithm ? Thank you for reading my post .

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• Java convert time format to integer or long

  - by behrk2

  Hello, I'm wondering what the best method is to convert a time string in the format of 00:00:00 to an integer or a long? My ultimate goal is to be able to convert a bunch of string times to integers/longs, add them to an array, and find the most recent time in the array... I'd appreciate any help, thanks! Ok, based on the answers, I have decided to go ahead and compare the strings directly. However, I am having some trouble. It is possible to have more than one "most recent" time, that is, if two times are equal. If that is the case, I want to add the index of both of those times to an ArrayList. Here is my current code: days[0] = "15:00:00"; days[1] = "17:00:00"; days[2] = "18:00:00"; days[3] = "19:00:00"; days[4] = "19:00:00"; days[5] = "15:00:00"; days[6] = "13:00:00"; ArrayList<Integer> indexes = new ArrayList<Integer>(); String curMax = days[0]; for (int x = 1; x < days.length1; x++) { if (days[x].compareTo(curMax) > 0) { curMax = days[x]; indexes.add(x); System.out.println("INDEX OF THE LARGEST VALUE: " + x); } } However, this is adding index 1, 2, and 3 to the ArrayList... Can anyone help me?

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• problem with a very simple tile based game

  - by newbieguy

  Hello, I am trying to create a pacman-like game. I have an array that looks like this: array: 1111111111111 1000000000001 1111110111111 1000000000001 1111111111111 1 = Wall, 0 = Empty space I use this array to draw tiles that are 16x16 in size. The Game character is 32x32. Initially I represented the character's position in array indexes, [1,1] etc. I would update his position if array[character.new_y][charater.new_x] == 0 Then I translated these array coordinates to pixels, [y*16, x*16] to draw him. He was lining up nicely, wouldn't go into walls, but I noticed that since I was updating him by 16 pixels each, he was moving very fast. I decided to do it in reverse, to store the game character's position in pixels instead, so that he could use less than 16 pixels per move. I thought that a simple if statement such as this: if array[(character.new_pixel_y)/16][(character.new_pixel_x)/16] == 0 would prevent him from going into walls, but unfortunately he eats a bit of the bottom and right side walls. Any ideas how would I properly translate pixel position to the array indexes? I guess this is something simple, but I really can't figure it out :(

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• How to speed up a slow UPDATE query

  - by Mike Christensen

  I have the following UPDATE query: UPDATE Indexer.Pages SET LastError=NULL where LastError is not null; Right now, this query takes about 93 minutes to complete. I'd like to find ways to make this a bit faster. The Indexer.Pages table has around 506,000 rows, and about 490,000 of them contain a value for LastError, so I doubt I can take advantage of any indexes here. The table (when uncompressed) has about 46 gigs of data in it, however the majority of that data is in a text field called html. I believe simply loading and unloading that many pages is causing the slowdown. One idea would be to make a new table with just the Id and the html field, and keep Indexer.Pages as small as possible. However, testing this theory would be a decent amount of work since I actually don't have the hard disk space to create a copy of the table. I'd have to copy it over to another machine, drop the table, then copy the data back which would probably take all evening. Ideas? I'm using Postgres 9.0.0. UPDATE: Here's the schema: CREATE TABLE indexer.pages ( id uuid NOT NULL, url character varying(1024) NOT NULL, firstcrawled timestamp with time zone NOT NULL, lastcrawled timestamp with time zone NOT NULL, recipeid uuid, html text NOT NULL, lasterror character varying(1024), missingings smallint, CONSTRAINT pages_pkey PRIMARY KEY (id ), CONSTRAINT indexer_pages_uniqueurl UNIQUE (url ) ); I also have two indexes: CREATE INDEX idx_indexer_pages_missingings ON indexer.pages USING btree (missingings ) WHERE missingings > 0; and CREATE INDEX idx_indexer_pages_null ON indexer.pages USING btree (recipeid ) WHERE NULL::boolean; There are no triggers on this table, and there is one other table that has a FK constraint on Pages.PageId.

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• Stored procedure for generic MERGE

  - by GilliVilla

  I have a set of 10 tables in a database (DB1). And there are 10 tables in another database (DB2) with exact same schema on the same SQL Server 2008 R2 database server machine. The 10 tables in DB1 are frequently updated with data. I intend to write a stored procedure that would run once every day for synchronizing the 10 tables in DB1 with DB2. The stored procedure would make use of the MERGE statement. Now, my aim is to make this as generic and parametrized as possible. That is, accommodate for more tables down the line... and accommodate different source and target DB names. Definitely no hard coding is intended. This is my algorithm so far: Have the database names as parameters Have the first query within the stored procedure... result in giving the names of the 10 tables from a lookup table (this can be 10, 20 or whatever) Have a generic MERGE statement that does the sync for each of the above set of tables (based on primary key?) This is where I need more inputs on. What is the best way to achieve this stored procedure? SQL syntax would be helpful.

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• Failed to specialize function template

  - by citizencane

  This is homework, although it's already submitted with a different approach. I'm getting the following from Visual Studio 2008 error C2893: Failed to specialize function template 'void std::sort(_RanIt,_RanIt,_Pr)' The code is as follows main.cpp Database<> db; db.loadDatabase(); db.sortDatabase(sort_by_title()); Database.cpp void Database<C>::sortDatabase(const sort_by &s) { std::sort(db_.begin(), db_.end(), s); } And the function objects are defined as struct sort_by : public std::binary_function<const Media *, const Media *, bool> { virtual bool operator()(const Media *l, const Media *r) const = 0; }; struct sort_by_title : public sort_by { bool operator()(const Media *l, const Media *r) const { ... } }; ... What's the cure here? [Edit] Sorry, maybe I should have made the inheritance clear template <typename C = std::vector<Media *> > class Database : public IDatabase<C> [/Edit]

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• Android: New app not showing on a sprint phone...

  - by Allan

  I uploaded my app to the Android Market last week and people have been purchasing it with no problems. My carrier is T-Mobile. As soon as I uploaded my app to the Market I got on my phone (Nexus One), searched for it, and there it was - instantly! (Is that because I have a google phone?) My friends G1 found it instantly also. BUT, another friend has a Sprint Moment phone and when he tried to search for it - it just wasn't there - like it didn't exist. I then called T-Mobile and Sprint representatives and found some information that I didn't know. The Sprint dude said that Sprint goes to some sort of massive Android Market Database and that's how Sprint knows about new apps and is then able to list them. New apps are not instantly shown on Sprint phones, you have to wait till their database updates to Android's database. At least that is what I thought they were trying to say to me. Has anyone else come across this issue and/or does anyone know how long Sprint takes to update their database for new Android apps? Do other carriers follow these methods?

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• Asynchronous SQL Operations

  - by Paul Hatcherian

  I've got a problem I'm not sure how best to solve. I have an application which updates a database in response to ad hoc requests. One request in particular is quite common. The request is an update that by itself is quite simple, but has some complex preconditions. For this request the business layer first requests a set of data from the data layer. The business logic layer evaluated the data from the database and parameters from the request, from this the action to be performed is determined, and the request's response message(s) are created. The business layer now executes the actual update command that is the purpose of the request. This last step is the problem, this command is dependent on the state of the database, which might have changed since the business logic ran. Locking down the data read in this operation across several round-trips to the database doesn't seem like a good idea either. Is there a 'best-practice' way to accomplish something like this? Thanks!

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• Login failed for user ''. The user is not associated with a trusted SQL Server connection

  - by Tony_Henrich

  My web service app on my Windows XP box is trying to log in to my sql server 2005 database on the same box. The machine is part of a domain. I am logged in in the domain and I am an admin on my machine. I am using Windows Authentication in my connection string as in "Server=myServerAddress;Database=myDataBase;Trusted_Connection=True". SQLServer is configured for both types of authentication (mixed mode) and accepts remote connections and accepts tcp and named pipes protocols. Integrated authentication is enabled in IIS and with and without anonymous access. 'Everyone' has access to computer from network setting in local security settings. ASPNET is a user in the sql server and has access to the daatabase. user is mapped to the login. The app works fine for other developers which means the app shouldn't be changed (It's not new code). So it seems it's my machine which has an issue. I am getting the error "Login failed for user ''. The user is not associated with a trusted SQL Server connection" Note the blank user name. Why am I getting this error when both the app and database are on my machine? I can use SQL Server authentication but don't want to. I can connect to the database using SSMS and my Windows credentials. It might be related to setspn, kerberos, delegation, AD. I am not sure what further checks to make?

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• Array's index and argc signedness

  - by tusbar

  Hello, The C standard (5.1.2.2.1 Program startup) says: The function called at program startup is named main. [...] It shall be de?ned with a return type of int and with no parameters: int main(void) { /* ... */ } or with two parameters [...] : int main(int argc, char *argv[]) { /* ... */ } And later says: The value of argc shall be nonnegative. Why shouldn't argc be defined as an unsigned int, argc supposedly meaning 'argument count'? Should argc be used as an index for argv? So I started wondering if the C standard says something about the type of array's index. Is it signed? 6.5.2.1 Array subscripting: One of the expressions shall have type ‘‘pointer to object type’’, the other expression shall have integer type, and the result has type ‘‘type’’. It doesn't say anything about its signedness (or I didn't find it). It is pretty common to see codes using negatives array indexes (array[-1]) but isn't it undefined behavior? Should array's indexes be unsigned?

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• Custom PHP Framework Feedback

  - by Jascha

  I've been learning OOP programming for about a year and a half now and have developed a fairly standard framework to which I generally abide by. I'd love some feedback or input on how I might improve some functionality or if there are some things I'm overlooking. VIEW MODE 1) Essentially everything starts at the Index.php page. The first thing I do is require my "packages.php" file that is basically a config file that imports all of the classes and function lists I'll be using. 2) I have no direct communication between my index.php file and my classes, what I've done is "pretty them up" with my viewfunctions.php file which is essentially just a conduit to the classes so that in my html I can write <?php get_title('page'); ?> instead of <?php echo $pageClass->get_title('page'); ?> Plus, I can run a couple small booleans and what not in the view function script that can better tailor the output of the class. 3) Any information brought in via the database is started from it's corresponding class that has direct communication with the database class, the only class that is allowed direct to communicate with the database (allowed in the sense that I run all of my queries with custom class code). INPUT MODE 1) Any user input is sent to my userFunctions.php. 2) My security class is then instantiated where I send whatever user input that has been posted for verification and validation. 3) If the input passes my security check, I then pass it to my DB class for input into my Database. FEEDBACK I'm wondering if there are any glaringly obvious pitfalls to the general structure, or ways I can improve this. Thank you in advance for your input. I know there is real no "right" answer for this, but I imagine a couple up votes would be in order for some strong advice regarding building frameworks. -J

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• Could I return a FileStream as a generic interface to a file?

  - by Eric

  I'm writing a class interface that needs to return references to binary files. Typically I would provide a reference to a file as a file path. However, I'm considering storing some of the files (such as a small thumbnail) in a database directly rather then on a file system. In this case I don't want to add the extra step of reading the thumbnail out of the database onto the disc and then returning a path to the file for my program to read. I'd want to stream the image directly out of the database into my program and avoid writing anything to the disc unless the user explicit wants to save something. Would having my interface return a FileStreamor even a Imagemake sense? Then it would be up to the implementing class to determine if the source of the FileStream or Image is a file on a disc or binary data in a database. public interface MyInterface { string Thumbnail {get;} string Attachment {get;} } vs public interface MyInterface { Image Thumbnail {get;} FileStream Attachment {get;} }

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• PHP and storing stats

  - by John

  Using PHP5 and the latest version of MySQL I want to be able to track impressions and clicks for business listings. My question is if I did this myself what would be the best method in storing it so I can run reports? Before I just had a table that had the listing id, user ip address and if it was a click or impression as well as the date it was tracked. However the database itself is approaching 2GB of data and its very slow, part of the problem is its a pretty simple script that includes impressions and clicks from anyone including search engines and basically anyone or anything that accesses the listing page. Is there an api or file out there that has an update to date list that can detect if the person viewing is a actually person and not a spider so I dont fill up the database with unneeded stats? Just looking for suggestions, do I just have a raw database that gets just the hits then a cron job at night tally up for the day for each listing for each ip and store the cumulative stats in a different table? Also what type of database should it be? Innodb? MyISAM?

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• How can i test my TSQL syntax?

  - by acidzombie24

  Quick question: How do i get some kind of database to use to test my sql syntax and create basic data. I have Sqlite Code which i'll soon put on a server. I have sql server 2008 installed with visual studio 2010. I tried connecting to the database and had no luck. I also tried using a .mdf file instead thinking its a file and i wont have connectivity issues. Wrong, i still couldnt connect and i used this site to help me (i'm aware its 2005) In that case i used var conn = new SqlConnection(@"Server=.\SQLExpress;AttachDbFilename=C:\dev\src\test\SQL_DB_VS_Test\test.mdf;Database=dbo;Trusted_Connection=Yes;"); exception Unable to open the physical file "C:\dev\src\test\SQL_DB_VS_Test\test.mdf". Operating system error 5: "5(Access is denied.)". Cannot attach the file 'C:\dev\src\test\SQL_DB_VS_Test\test.mdf' as database 'dbo'. with trusted = no i get Login failed for user ''. (What user am i suppose to set...). I created the .mdf with visual studio somehow.

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• Storing large numbers of varying size objects on disk

  - by Foredecker

  I need to develop a system for storing large numbers (10's to 100's of thousands) of objects. Each object is email-like - there is a main text body, and several ancillary text fields of limited size. A body will be from a few bytes, to several KB in size. Each item will have a single unique ID (probably a GUID) that identifies it. The store will only be written to when an object is added to it. It will be read often. Deletions will be rare. The data is almost all human readable text so it will be readily compressible. A system that lets me issue the I/Os and mange the memory and caching would be ideal. I'm going to keep the indexes in memory, using it to map indexes to the single (and primary) key for the objects. Once I have the key, then I'll load it from disk, or the cache. The data management system needs to be part of my application - I do not want to depend on OS services. Or separately installed packages. Native (C++) would be best, but a manged (C#) thing would be ok. I believe that a database is an obvious choice, but this needs to be super-fast for look up and loading into memory of an object. I am not experienced with data base tech and I'm concerned that general relational systems will not handle all this variable sized data efficiently. (Note, this has nothing to do with my job - its a personal project.) In your experience, what are the viable alternatives to a traditional relational DB? Or would a DB work well for this?

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• Data not transfred from form to mysql table (updating of data is not happening)

  - by Jimson

  Hi all and thanks in advance to all for this I tired and was unable to find the answer i am looking for an answer. my problem is that i am unable to update the values enterd in the form. I have attached all the files i'm using MYSQL database to fetch data. what happens is that i'm able to add and delete records from form using ajax and PHP scripts to MYSQL database, but i am not able to update data which was retrived from database. the file structure is as follows index.php is a file with ajax functions where it displays form for adding new data to MYSQL using save.php file and list of all records are view without refrishing page (calling load-list.php to view all records from index.php works fine, and save.php to save data from form) - *Delete*is an ajax function called from index.php to delete record from mysql database (function calling delete.php works fine) - Update is an ajax function called from index.php to update data using update-form.php by retriving specific record from mysql tabel, (works fine) Problem lies in updating data from update-form.php to update.php (in which update query is wrriten for mysql) i had tried in many ways at last i had figured out that data is not being transfred from update-form.php to update.php there is a small problem in jquery ajax function where it is not transfering data to update.php page. can any one correct this ????? i will be greatfull to them..... please find the link below for all files link to get my form files

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• How to speed-up a simple method (preferably without changing interfaces or data structures)?

  - by baol

  I have some data structures: all_unordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::tr1::unordered_map<size_t, size_t> position_m; const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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• How do I introspect on a SQL Server?

  - by MetaHyperBolic

  I have a server with a vendor application which is heavily database-reliant. I need to make some minor changes to the data in a few tables in the database in an automated fashion. Just INSERTs and UPDATEs, nothing fancy. Vendors being vendors, I can never be quite sure when they change the schema of a database during upgrade. To that end, how do I ask the SQL server, in some scriptable fashion, "Hey, does this table still exist? Yeah, cool, okay, but does it have this column? What's the data type and size on that? Is it nullable? Could you give me a list of tables? In this table, could you give me a list of columns? Any primary keys there?" I do not need to do this for the whole schema, only part of it, just a quick check of the database before I launch into things. We have Microsoft SQL Server 2005 on it currently, but it might easily move to Microsoft SQL Server 2008. I am probably not using the correct terminology when searching. I do know that ORM is not only too much overhead for this sort of thing, but also that I have no chance of pitching it to my coworkers.

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• Redirecting Pages with PHP causing problems

  - by psp

  I have a page which has a link to a php page which takes data from $_GET and updates a database. After that it returns the user to the homepage with: header("Location: http://localhost/"); The thing is that this seems to "interrupt" the mysql part of the code. If I remove this redirect, everything in the database is updated, but when I put it back, nothing gets updated... This is the database update code, I am using a class of mine as a mysql wrapper: $conn->where('hash',$data1['hash']); $conn->update(TABLE_ITEMS,$newData1); $conn->where('hash',$data2['hash']); $conn->update(TABLE_ITEMS,$newData2); Notes: -There is no text or echo()'s on the page and no space before the <?php tag Order of Code: Data received from $_SESSION and $_GET Data processed and placed into arrays Data placed into mysql database header(); used to redirect page Code <?php require_once('config.php'); import(); if ( isset ( $_GET['g'] ) && isset ( $_SESSION['itemA'] ) && isset ( $_SESSION['itemB'] ) ) { $itemA = $_SESSION['gameA']; $itemB = $_SESSION['gameB']; $newData1 = processData($itemA); $newData2 = processData($itemB); $conn->update(TABLE_ITEMS,$newData1); $conn->update(TABLE_ITEMS,$newData2); header('Location: http://localhost/'); } else { header('Location: http://localhost/'); }

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• Altering sql tables based on condition

  - by Parker

  Is there any possible way to add a row of data to only some of the tables in a database? I am not sure what parameter I could use amongst the tables to compare them to each other. Any Ideas? For Example: My database has tables that are (let's say) group A tables, and tables that are group B. I want to add a row to only the group B tables while leaving the group A tables untouched. Sorry I should have been a bit more specific. The tables that need to have a row added will change. My application monitors inventory in different store locations(each table in my database represents a store). When I need to add an item to inventory(the items are rows in the tables) I don't want to have to manually add the row to all the store tables. My problem is: Not all the tables in the database represent stores. For instance one table stores the user login data. Obviously I do not want to add the new row to this table. How do I update only the tables that represent stores?

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• How to speed-up a simple method? (possibily without changing interfaces or data structures)

  - by baol

  Hello. I have some data structures: all_unordered_mordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::map<size_t, size_t> position_m; // positions of strings in ordered_m const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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• MySQL Join/Comparison on a DATETIME column (<5.6.4 and > 5.6.4)

  - by Simon

  Suppose i have two tables like so: Events ID (PK int autoInc), Time (datetime), Caption (varchar) Position ID (PK int autoinc), Time (datetime), Easting (float), Northing (float) Is it safe to, for example, list all the events and their position if I am using the Time field as my joining criteria? I.e.: SELECT E.*,P.* FROM Events E JOIN Position P ON E.Time = P.Time OR, even just simply comparing a datetime value (taking into consideration that the parameterized value may contain the fractional seconds part - which MySQL has always accepted) e.g. SELECT E.* FROM Events E WHERE E.Time = @Time I understand MySQL (before version 5.6.4) only stores datetime fields WITHOUT milliseconds. So I would assume this query would function OK. However as of version 5.6.4, I have read MySQL can now store milliseconds with the datetime field. Assuming datetime values are inserted using functions such as NOW(), the milliseconds are truncated (<5.6.4) which I would assume allow the above query to work. However, with version 5.6.4 and later, this could potentially NOT work. I am, and only ever will be interested in second accuracy. If anyone could answer the following questions would be greatly appreciated: In General, how does MySQL compare datetime fields against one another (consider the above query). Is the above query fine, and does it make use of indexes on the time fields? (MySQL < 5.6.4) Is there any way to exclude milliseconds? I.e. when inserting and in conditional joins/selects etc? (MySQL 5.6.4) Will the join query above work? (MySQL 5.6.4) EDIT I know i can cast the datetimes, thanks for those that answered, but i'm trying to tackle the root of the problem here (the fact that the storage type/definition has been changed) and i DO NOT want to use functions in my queries. This negates all my work of optimizing queries applying indexes etc, not to mention having to rewrite all my queries. EDIT2 Can anyone out there suggest a reason NOT to join on a DATETIME field using second accuracy?

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• Why won't JPA delete owned entities when the owner entity loses the reference to them?

  - by Nick

  Hi! I've got a JPA entity "Request", that owns a List of Answers (also JPA entities). Here's how it's defined in Request.java: @OneToMany(cascade= CascadeType.ALL, mappedBy="request") private List<Answer> answerList; And in Answer.java: @JoinColumn(name = "request", referencedColumnName="id") @ManyToOne(optional = false) private Request request; In the course of program execution, the Request's List of Answers may have Answers added or removed from it, or the actual List object may be replaced. My problem is thus: when I merge a Request to the database, the Answer objects that used to be in the List are kept in the database -- that is, Answer objects that the Request no longer holds a reference to (indirectly, via a List) are not deleted. This is not the behaviour I desire, as if I merge a Request to the database, and then fetch it again, its Answers List may not be the same. Am I making some programming mistake? Is there an annotaion or setting that will ensure that the Answers in the database are exactly the Answers in the Request's List? A solution is to keep references to the original Answers List and then use the EntityManager to remove each old Answer before merging the Request, but it seems like there should be a cleaner way. Thank you!

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