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• Using Closure Properties to prove Regularity

  - by WATWF

  Here's a homework problem: Is L_4 Regular? Let L_4 = L*, where L={0^i1^i | i>=1}. I know L is non-regular and I know that Kleene Star is a closed operation, so my assumption is that L_4 is non-regular. However my professor provided an example of the above in which L = {0^p | p is prime}, which he said was regular by proving that L* was equal to L(000* + e) by saying each was a subset of one another (e in this case means the empty word). So his method involved forming a regex of 0^p, but how I can do that when I essentially have one already?

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• Is It Safe to Cast Away volatile?

  - by Yan Cheng CHEOK

  Most of the time, I am doing this way. class a { public: ~ a() { i = 100; // OK delete (int *)j; // Compiler happy. But, is it safe? // Error : delete j; } private: volatile int i; volatile int *j; }; int main() { a aa; } However, I saw an article here: https://www.securecoding.cert.org/confluence/display/seccode/EXP32-C.+Do+not+access+a+volatile+object+through+a+non-volatile+reference Casting away volatile allows access to an object through a non-volatile reference. This can result in undefined and perhaps unintended program behavior. So, what will be the workaround for my above code example?

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• rails 3, active record: any way to tell how many unique values match a "x LIKE ?" query

  - by jpwynn

  I have a query to find all the phone numbers that match a partial expression such as "ends with 234" @matchingphones = Calls.find :all, :conditions => [ "(thephonenumber LIKE ?)", "%234"] The same phone number might be in the database several times, and so might be returned multiple times by this query if it matches. What I need is to know is UNIQUE phone numbers the query returns. For example if the database contains 000-111-1234 * 000-111-3333 000-111-2234 * 000-111-1234 * 000-111-4444 the existing query will return the 3 records marked with * (eg returns one phone number -1234 twice since it's in the database twice) what I need is a query that returns just once instance of each match, in this case 000-111-1234 * 000-111-2234 *

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• How to create and restore a backup from SqlAlchemy?

  - by swilliams

  I'm writing a Pylons app, and am trying to create a simple backup system where every table is serialized and tarred up into a single file for an administrator to download, and use to restore the app should something bad happen. I can serialize my table data just fine using the SqlAlchemy serializer, and I can deserialize it fine as well, but I can't figure out how to commit those changes back to the database. In order to serialize my data I am doing this: from myproject.model.meta import Session from sqlalchemy.ext.serializer import loads, dumps q = Session.query(MyTable) serialized_data = dumps(q.all()) In order to test things out, I go ahead and truncation MyTable, and then attempt to restore using serialized_data: from myproject.model import meta restore_q = loads(serialized_data, meta.metadata, Session) This doesn't seem to do anything... I've tried calling a Session.commit after the fact, individually walking through all the objects in restore_q and adding them, but nothing seems to work. What am I missing? Or is there a better way to do what I'm aiming for? I don't want to shell out and directly touch the database, since SqlAlchemy supports different database engines.

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• Login implementation for windows mobile

  - by pdiddy

  What is a good approach for credential checks for windows mobile app. Knowing that it is an occasionally connected device. Should I keep the user credential into the local database? If the credential doesn't exist in the db, try to see if it has internet access and do the check through a web service? If both fails then display an error message ? If logins is successful then store the credential to the local database store then upon next login go against the database first? Is this a good approach?

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• Using Linq to SQL change events with attribute-based mapping

  - by R Mene

  I'm writing a new ASP.NET MVC2 application using Linq to SQL. This application depends on an existing SQL database. I am using attribute-based mapping to map my database fields to my Linq to SQL entities. I also need to make use of Linq to SQL's On[Property]Changed methods so I can perform change-auditing of database tables within my application. Whereas the documentation explains how to do this when using Linq to SQL's ORM and dbml files (i.e. by writing partial classes), it is not clear how to do with when using attribute-based mapping or when using XML-based mapping. It would be very helpful if someone could describe how to do this.

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• Error OEM (oracle Enterprise Manager)

  - by user137520

  Dear Friends I was trying to configure OEM today. Everything seemed fine. I could login the OEM but when I tried to lauch DBA studio from there, I could not and it said no database has been discovered yet. I don't understand why since I created a database already. Has anyone experienced that? Thank You

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• How can i attach data to a JTA transaction? (or uniquely identify it)

  - by kwyjibo

  I have a getStockQuote() function that will get a current stock quote for a symbol from the stock market. My goal is that within a JTA transaction, the first call to getStockQuote() will fetch a stock quote, but all subsequent calls within the same transaction will reuse the same stock quote (e.g.: it will not try to fetch a new quote). If a different transaction starts, or another transaction runs concurrently, i would expect the other transaction to fetch its own stock quote on its first call. This would be similar to how you can configure JPA providers to only fetch a database row from the database once, and use the cached value for subsequent access to the same database row within the transaction. Does anyone have tips on how this can be achieved?

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• MySQLi insert into prepare error

  - by JPM

  Hi I inserted a lot of stuff into a mysql databse. But now I get an error in the prepare statement. I see Database prepare error. What am I doing wrong? This is my Code: $sql = "INSERT INTO Contact (IP,To,Name,Email,Subject,Text) VALUES ( ?, ?, ?, ?, ?, ? ) "; if (!$stmt = $db->prepare($sql)) { echo 'Database prepare error'; exit; } $stmt->bind_param('ssssss', $ip_contact, $to_contact, $name_contact, $email_contact, $subject_contact, $text_contact); if (!$stmt->execute()) { echo 'Database execute error'; exit; } $stmt->close(); My SQL table looks like this: Contact: - ID int(11) auto_increment primary key - IP varchar(15) - To varchar(5) - Name varchar(20) - Email varchar(20) - Subject varchar(20) - Text varchar(600)

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• C++ streams question (explanation of comment in code)

  - by skyeagle

  I am playing around with the fastCGI application found here. The following comment is in the code: if (content) delete []content; // If the output streambufs had non-zero bufsizes and // were constructed outside of the accept loop (i.e. // their destructor won't be called here), they would // have to be flushed here. My knowledge of C++ streams is rather weak. Could someone please explain the following: which streambufs are being referred to in the comment? under what conditions would the streambufs had non-zero bufsizes? last but not the least, can someone point to a resource (pun intended) online that provides a clear but gentle introduction to C++ IO streams?

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• Why I cannot create DB in MySQL throw PHP?

  - by Roman

  I have this code: $link = mysql_connect("localhost", "ctman", "blablabla"); if ( ! $link ) die ("I cannot connect to MySQL.<br>\n"); else print "Connection is established.<br>\n"; // Create the "ct" database. mysql_query("create database ct", $link) or die("I cannot create the DB: ".mysql_error()."<br>\n"); And I get this error message: I cannot create the DB: Access denied for user 'ctmanager'@'%' to database 'ct' Does anybody have any idea why I cannot create a DB and why I have '@%' symbols in the error message?

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• How to analyse Wikipedia article's data base with R?

  - by Tal Galili

  Hi all, This is a "big" question, that I don't know how to start, so I hope some of you can give me a direction. And if this is not a "good" question, I will close the thread with an apology. I wish to go through the database of Wikipedia (let's say the English one), and do statistics. For example, I am interested in how many active editors (which should be defined) Wikipedia had at each point of time (let's say in the last 2 years). I don't know how to build such a database, how to access it, how to know which types of data it has and so on. So my questions are: What tools do I need for this (besides basic R) ? MySQL on my computer? RODBC database connection? How do you start planning for such a project?

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• Creating Test Sites

  - by Robert

  I have a website running off site. When we hire someone I would like to create a test site (a copy of live site) for the new employee to tinker with. I will need to take fresh copies of the Files and Database (basically a snapshot) and allow them to access these copied files and database so they could edit and upload them to see the changes they made as if it was the live site Basically what is the best practice for creating a copy of a website for testing? Server is running Linux, PHP, mySQL

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• ASP, My SQL & case sensitity suddenly broken

  - by user131812

  Hi There, We have an old ASPsite that has been working fine for years with a MY SQL database. All of a sudden last week lots fo SQL queries stopped working. The database has a table called 'members' but the code calls 'Members'. It appears the queries used to work regardless of case sensitivity on the table names, but something has changed recently somewhere to enforce case. This has me stumped as the site has not been touched in years, the server config hasn't changed & the database provide has not changed anything. Is there any simple way to ignore case for an ASP site (without editing lots fo files :) Thanks Ben

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• wrong data type in mysql for grails byte[] property

  - by srkiNZ84

  Hi, I have an application which is trying to save a photo to the database. I've created a grails domain class with a byte[] property and this was working well when using HSQLDB (the default in grails). However, when I changed the database to MySQL I ended up getting the following error: Data truncation: Data too long for column 'photo' at row 1 I then had a look at the schema and found that the byte[] was being created as a TINYBLOB field, which was causing the error. How can I specify that this property should correspond to a BLOB/LONGBLOB type in the database?

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• User.Identity.Name returning NT AUTHORITY\NETWORK SERVICE i want Domain\USER

  - by Jalvemo

  in my asp.net MVC project i have an database connection with connectionstring: Data Source=.;Initial Catalog=dbname;Integrated Security=True All users can execute Stored Procedures on that connection and i want to log those users. so after each execution I store "User.Identity.Name" to another database. This work great on my development machine but after deployment, to access the site i have to go through a VPN-connention and then remote desktop to the same server that the IIS is running on and use a web-browser there. Then i get User.Identity.Name: "NT AUTHORITY\NETWORK SERVICE". i would expect it to be the credentials i entered in remote desktop that have access to the database. any idea how i can get this to work? iis6 authentication: "windows authentication: enabled" web.config:

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• GUID not being generated automatically when db.submitchanges()

  - by BlindingDawn

  I have a couple of tables I ported over to a new database. Everything is exactly the same from the legacy one to the new one. The back-end code that submits the user generated data to the database is also the same. When I submit changes to the database, all of the submitted information populates the correct columns but the column that stores the GUID populates with all 0's. When I enter in the columns manually using SQL Server Management Studio, the GUID gets populated as it does in the legacy version. Am I missing something?

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• DDD Infrastructure services

  - by Zygimantas

  Hello, I am learning DDD and I am a little bit lost in Infrastructure layer: As I understand, "all good DDD applications" should have 4 layers: Presentation, Application, Domain and Infrastructure. Database should be accessed using Repositories. Repository interfaces should be in Domain layer and repository implementation - in Infrastructure (reference http://stackoverflow.com/questions/693221/ddd-where-to-keep-domain-interfaces-the-infrastructure). Application, Domain and Infrastructure layer should/may have services (reference www.lostechies.com/blogs/jimmy_bogard/archive/2008/08/21/services-in-domain-driven-design.aspx), in example EmailService in Infrastructure layer which sends Email messages. BUT, inside Infrastructure layer we have repository implementations, which are used to access database. So, in this case, repositories are database services? What is the difference between Infrastructure service and repository? Thanks in advance!

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• creating a custom odbc driver for application

  - by neddy

  Ok, i have a simple database engine (its a proprietary product written in vb6) for one of my applications... i'd like to create an ODBC driver for it so i can use some of my other applications (which require a database) with my database engine rather than microsoft sql (which they are currently using).... Does anyone have any heads up on how to develop an ODBC driver (preferably in vb6) ... i'v spent the last few hours googling it and havnt had much luck... about the best thing i have found so far is: http://www.datadirect.com/products/openaccess/index.ssp but i dont exactly want to go buying an SDK to write an ODBC driver... Cheers in advance,

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• Scraping html WITHOUT uniquie identifiers using python

  - by Nicholas Law

  I would like to design an algorithm using python that scrapes thousands of pages like this one and this one, gathers all the data and inserts it into a MySQL database. The script will be run on a weekly or bi-weekly basis to update the database of any new information added to each individual page. Ideally I would like a scraper that is easy to work with for table structured data but also data that does not have unique identifiers (ie. id and classes attributes). Which scraper add-on should I use? BeautifulSoup, Scrapy or Mechanize? Are there any particular tutorials/books I should be looking at for this desired result? In the long-run I will be implementing a mobile app that works with all this data through querying the database.

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• What's the simplest way to let the user download a file in ASP.NET MVC ?

  - by drasto

  In an ASP.NET MVC I have a database table. I want to have a button on some view page, if some user clicks that button I my application will generate XML file containing all rows in the database. Then the file containing XML should be sent to the client so that the user will see a download pop-up window. Similarly I want to allow user to upload an XML file whose content will be added to the database. What's the simplest way to let the user upload and download file ? Thanks for all the answers

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• SQL Server Mapping a user to a login and adding roles programmatically

  - by user163457

  In my SQL Server 2005 server I create databases and logins using Management Studio. My application requires that I give a newly created user read and write permissions to another database. To do this I right-click the newly created login, select properties and go to User Mapping. I put a check beside the database to map this login to the db and select db_datareader and db_datawriter as the roles to map. Can this be done programmatically? I've read about using Alter User and sp_change_users_login but I'm having problems getting these to work, since sp_change_users_login has been deprecated so I'd prefer to use Alter User. Please note my understanding of SQL Server database users/logins/roles is basic

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• How to make sure no scripts except those under my own domain, can include the db connection file?

  - by Jack

  I would like to ensure that any scripts that are trying to "include" my database connection file are located under my own domain. I don't want a hacker to include the database connection file to their malicious script and gain access to my database that way. My connection file's name is pretty easy to guess, it's called "connect.php". So without renaming it and taking the security through obscurity route, how can I protect it by making sure all connection requests are made by scripts residing under my own domain name? How can this be checked using PHP?

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• Does an HTTPS SharePoint Site Need to Use HTTPS-Compliant Web Parts?

  - by bporter

  I am new to SharePoint, so this question may be a little naive. However, I sincerely appreciate any help with this. We are planning to create a new sub-site within our company's intranet site, which is built on SharePoint 2007. We want to add a 3rd-party weather web part (which is just a widget to display the local weather forecast) to the home page of the new intranet site. Since the intranet site uses HTTPS, do we need to find an HTTPS-compliant web part? Or, is it possible to use any web part and then configure it to use HTTPS? I'm assuming that if we use a non-HTTPS web part, then users will get some sort of "This page contains both secure and non-secure items" error message when they load the page.

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• display format for gridview

  - by peter

  I have a grid named 'GridView1' contains two columns 'Date' and 'Session Deatils' i am displaying like this way only <asp:GridView ID="GridView1" OnRowCommand="ScheduleGridView_RowCommand" runat="server" AutoGenerateColumns="False" Height="60px" Style="text-align: center" Width="869px" EnableViewState="False"> <Columns> <asp:BoundField HeaderText="Date" DataField="Date"><HeaderStyle Width="80px" /></asp:BoundField> <asp:BoundField DataField="" HeaderText="Session Detais" /> </Columns> But here i need to display 3 column sections downside Session details without any column borders for each dates,,how can i achive like this wasy Date SessionDetails 06-04-2010 Time-(value from database) Topic-(value from database) Head-(value from database) ------- ------------------ ------------------- ----------------------

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