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  • Best way to create a SPARQL endpoint for a RDBMS (MySQL database)

    - by Ankur
    I am doing (want to do) some experiments with Linked Open Datasets particularly those put out by governments. I have a RDBMS (more specifically MySQL). I designed it with semantic web ideas in mind i.e. I have a information stored as objects, predicates and classes which define objects. In turn all objects are related to each other though statements of the form subject -- predicate -- object (where the subjects are from the objects table). I want to be able to query other RDF triple stores from my application and let other triple stores query my data. Is it possible to "set something up" so that this is possible? I have looked at Jena. Using Jena seems to mean I have to it as a storage application rather than MySQL - the only problem with this is that I include a new concept called a category (which I don't think is part of the semantic web languages). I will use categories to help with displaying information (they don't have any other meaning) but using Jena seems to mean that I can't organise predicates under categories for more convenient viewing. I am using Java so a JAVA API is preferred. It's also possible I misunderstood the purpose of Jena, and maybe that can be of use, but I am not sure how. I am sure four days from now this question will seem rather silly, but at the moment I am somewhat confused about how to proceed.

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  • db4o problem with graph of objects

    - by Staszek28
    I am a new to db4o. I have a big problem with persistance of a graph of objects. I am trying to migrate from old persistance component to new, using db4o. Before I peristed all objects its graph looked like below (Take a look at Zrodlo.Metadane.abstrakt string field with focused value) [its view from eclipse debuger] with a code: ObjectContainer db=Db4o.openFile(DB_FILE); try { db.store(encja); db.commit(); } finally{ db.close(); } After that, I tried to read it with a code: ObjectContainer db=Db4o.openFile((DB_FILE)); try{ Query q = db.query(); q.constrain(EncjaDanych.class); ObjectSet<Object> objectSet = q.execute(); logger.debug("objectSet.size" + objectSet.size()); EncjaDanych encja = (EncjaDanych) objectSet.get(0); logger.debug("ENCJA" + encja.toString()); return encja; }finally{ db.close(); } and I got it (picture below) - string field "abstrakt" is null now !!! I take a look at it using ObjectManager (picture below) and abstrakt field has not-null value there!!! The same value, that on the 1st picture. Please help me :) It is my second day with db4o. Thanks in advance! I am attaching some code with structure of persisted class: public class EncjaDanych{ Map mapaIdRepo = new HashMap(); public Map mapaNazwaRepo = new HashMap(); }

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  • MYSQL JOIN WHERE ISSUES - need some kind of if condition

    - by Breezer
    Hi Well this will be hard to explain but ill do my best The thing is i have 4 tables all with a specific column to relate to eachother. 1 table with users(agent_users) , 1 with working hours(agent_pers), 1 with sold items(agent_stat),1 with project(agent_pro) the user and the project table is irrelevant in the issue at hand but to give you a better understanding why certain tables is included in my query i decided to still mention them =) The thing is that I use 2 pages to insert data to the working hour and the sold items during that time tables, then i have a third page to summarize everything for current month, the query for that is as following: SELECT *, SUM(sv_p_kom),SUM(sv_p_gick),SUM(sv_p_lunch) FROM (( agent_users LEFT JOIN agent_pers ON agent_users.sv_aid = agent_pers.sv_p_uid) LEFT JOIN agent_stat ON agent_pers.sv_p_uid = agent_stat.sv_s_uid) LEFT JOIN agent_pro ON agent_pers.sv_p_pid=agent_pro.p_id WHERE MONTH(agent_pers.sv_p_datum) =7 GROUP BY sv_aname so the problem is now that i dont want sold items from previous months to get included in the data received, i know i could solve that by simple adding in the WHERE part MONTH(agent_stat.sv_s_datum) =7 but then if no items been sold that month no data at all will show up not the time or anything. Any aid on how i could solve this is greatly appreciated. if there's something that's not so clear dont hesitate to ask and ill try my best to answer. after all my english isn't the best out there :P regards breezer

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  • When should we use Views, Temporary Tables and Direct Queries ? What are the Performance issues in a

    - by Shantanu Gupta
    I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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  • Serializable object in intent returning as String

    - by B_
    In my application, I am trying to pass a serializable object through an intent to another activity. The intent is not entirely created by me, it is created and passed through a search suggestion. In the content provider for the search suggestion, the object is created and placed in the SUGGEST_COLUMN_INTENT_EXTRA_DATA column of the MatrixCursor. However, when in the receiving activity I call getIntent().getSerializableExtra(SearchManager.EXTRA_DATA_KEY), the returned object is of type String and I cannot cast it into the original object class. I tried making a parcelable wrapper for my object that calls out.writeSerializable(...) and use that instead but the same thing happened. The string that is returned is like a generic Object toString(), i.e. com.foo.yak.MyAwesomeClass@4350058, so I'm assuming that toString() is being called somewhere where I have no control. Hopefully I'm just missing something simple. Thanks for the help! Edit: Some of my code This is in the content provider that acts as the search authority: //These are the search suggestion columns private static final String[] COLUMNS = { "_id", // mandatory column SearchManager.SUGGEST_COLUMN_TEXT_1, SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA }; //This places the serializable or parcelable object (and other info) into the search suggestion private Cursor getSuggestions(String query, String[] projection) { List<Widget> widgets = WidgetLoader.getMatches(query); MatrixCursor cursor = new MatrixCursor(COLUMNS); for (Widget w : widgets) { cursor.addRow(new Object[] { w.id w.name w.data //This is the MyAwesomeClass object I'm trying to pass }); } return cursor; } This is in the activity that receives the search suggestion: public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Object extra = getIntent().getSerializableExtra(SearchManager.EXTRA_DATA_KEY); //extra.getClass() returns String, when it should return MyAwesomeClass, so this next line throws a ClassCastException and causes a crash MyAwesomeClass mac = (MyAwesomeClass)extra; ... }

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  • Not loading associations without proxies in NHibernate

    - by Alice
    I don't like the idea of proxy and lazy loading. I don't need that. I want pure POCO. And I want to control loading associations explicitly when I need. Here is entity public class Post { public long Id { get; set; } public long OwnerId { get; set; } public string Content { get; set; } public User Owner { get; set; } } and mapping <class name="Post"> <id name="Id" /> <property name="OwnerId" /> <property name="Content" /> <many-to-one name="Owner" column="OwnerId" /> </class> However if I specify lazy="false" in the mapping, Owner is always eagerly fetched. I can't remove many-to-one mapping because that also disables explicit loading or a query like from x in session.Query<Comment>() where x.Owner.Title == "hello" select x; I specified lazy="true" and set use_proxy_validator property to false. But that also eager loads Owner. Is there any way to load only Post entity?

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  • Puppet exported resource naming

    - by Tim Brigham
    I am working on setting up a collection of Splunk nodes to be deployed by Puppet. One of the steps in this process is importing the trusts to allow these nodes to automatically find each other. I've looked over several options and it appears that exported resources are the only ready way to go for this to work. The files I need to create are under /opt/splunk/etc/auth/distServerKeys//trusted.pem. The source for each of these files should be /opt/splunk/etc/auth/distServerKeys/trusted.pem, one per node. What syntax do I need to make this work? The samples I've looked at all appear to have the same source and destination file name.

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  • SqlServer slow on production environment

    - by Lieven Cardoen
    I have a weird problem in a production environment at a customer. I can't give any details on the infrastructure except that sql server runs on a virtual server and the data, log and filestream file are on another storage server (data and filestream together and log on a seperate server). Now, there's this query that when we run it gives these durations (first we clear the cache): 300ms, 20ms, 15ms, 17ms,... First time it takes longer, but from then on it is cached. At the customer, on a sql server that is more powerfull, these are the durations (I didn't have the rights to clear the cache. Will try this tomorrow). 2500ms, 2600ms, 2400ms, ... The query can be improved, that's right, but that's not the question here. How would you tackle this? I don't know where to go from here. The servers at this customer are really more powerfull but they do have virtual servers (we don't). What could be the cause... - Not enough memory? - Fragmentation? - Physical storage? I know it can be a lot of things, but maybe some of you have got some info for me on how to go on with this issue...

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  • MYSQL: Limit Word Length for MySql Insert

    - by elmaso
    Hi, every search query is saved in my database, but I want to Limit the Chracterlength for one single word: odisafuoiwerjsdkle -- length too much -- dont write in the database my actually code is: $search = $_GET['q']; if (!($sql = mysql_query ('' . 'SELECT * FROM `history` WHERE `Query`=\'' . $search . '\''))) { exit ('<b>SQL ERROR:</b> 102, Cannot write history.'); ; } while ($row = mysql_fetch_array ($sql)) { $ID = '' . $row['ID']; } if ($ID == '') { mysql_query ('' . 'INSERT INTO history (Query) values (\'' . $search . '\')'); } if (!($sql = mysql_query ('SELECT * FROM `history` ORDER BY `ID` ASC LIMIT 1'))) { exit ('<b>SQL ERROR:</b> 102, Cannot write history.'); ; } while ($row = mysql_fetch_array ($sql)) { $first_id = '' . $row['ID']; } if (!($sql = mysql_query ('SELECT * FROM `history`'))) { exit ('<b>SQL ERROR:</b> 102, Cannot write history.'); ; }

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  • All symbols after & stripped

    - by user300413
    My query: mysql::getInstance()->update('requests', array('response' => mysql_real_escape_string($_POST['status'])), array('secret' => $_POST['secret'])); ?> If i wand to add string with "&" symbol, all symbols after "&" stripped. Example: string: !"?;%:?*()_+!@#$%^&*()_+ in database i see only: !"?;%:?*()_+!@#$%^ How to fix this? update function, if anyone need: function update($table, $updateList, $whereConditions) { $updateQuery = ''; foreach ($updateList as $key => $newValue) { if (!is_numeric($newValue)) { $newValue = "'" . $newValue . "'"; } if (strlen($updateQuery) == 0) { $updateQuery .= '`' . $key . '` = ' . $newValue; } else { $updateQuery .= ', `' . $key . '` = ' . $newValue; } } return $this->query('UPDATE ' . $table . ' SET ' . $updateQuery . $this->buildWhereClause($whereConditions)); }

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  • How is timezone handled in the lifecycle of an ADO.NET + SQL Server DateTime column?

    - by stimpy77
    Using SQL Server 2008. This is a really junior question and I could really use some elaborate information, but the information on Google seems to dance around the topic quite a bit and it would be nice if there was some detailed elaboration on how this works... Let's say I have a datetime column and in ADO.NET I set it to DateTime.UtcNow. 1) Does SQL Server store DateTime.UtcNow accordingly, or does it offset it again based on the timezone of where the server is installed, and then return it offset-reversed when queried? I think I know that the answer is "of course it stores it without offsetting it again" but want to be certain. So then I query for it and cast it from, say, an IDataReader column to a DateTime. As far as I know, System.DateTime has metadata that internally tracks whether it is a UTC DateTime or it is an offsetted DateTime, which may or may not cause .ToLocalTime() and .ToUniversalTime() to have different behavior depending on this state. So, 2) Does this casted System.DateTime object already know that it is a UTC DateTime instance, or does it assume that it has been offset? Now let's say I don't use UtcNow, I use DateTime.Now, when performing an ADO.NET INSERT or UPDATE. 3) Does ADO.NET pass the offset to SQL Server and does SQL Server store DateTime.Now with the offset metadata? So then I query for it and cast it from, say, an IDataReader column to a DateTime. 4) Does this casted System.DateTime object already know that it is an offset time, or does it assume that it is UTC?

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  • Find element all of whose children have a given value

    - by cru3l
    for example, i have this xml <elements> <a> <b>6</b> <b>5</b> <b>6</b> </a> <a> <b>5</b> <b>5</b> <b>6</b> </a> <a> <b>5</b> <b>5</b> <b>5</b> <b>5</b> </a> </elements> i need a xpath query, which must return me parent tag, only if all its children are equal to 5 (a[3] in this case). Something like that //b[text()="5"]/.. but with check of all children's tags. Please note that number of children tags can be different from node to node. It's possible with only xpath query? thanks

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  • Best way to migrate export/import from SQL Server to oracle

    - by matao
    Hi guys! I'm faced with needing access for reporting to some data that lives in Oracle and other data that lives in a SQL Server 2000 database. For various reasons these live on different sides of a firewall. Now we're looking at doing an export/import from sql server to oracle and I'd like some advice on the best way to go about it... The procedure will need to be fully automated and run nightly, so that excludes using the SQL developer tools. I also can't make a live link between databases from our (oracle) side as the firewall is in the way. The data needs to be transformed in the process from a star schema to a de-normalised table ready for reporting. What I'm thinking about is writing a monster query for SQL Server (which I mostly have already) that will denormalise and read out the data from SQL Server into a flat file using the sql server equivalent of sqlplus as a scheduled task, dump into a Well Known Location, then on the oracle side have a cron job that copies down the file and loads it with sql loader and rebuilds indexes etc. This is all doable, but very manual. Is there one or a combination of FOSS or standard oracle/SQL Server tools that could automate this for me? the Irreducible complexity is the query on one side and building indexes on the other, but I would love to not have to write the CSV dumping detail or the SQL loader script, just say dump this view out to CSV on one side, and on the other truncate and insert into this table from CSV and not worry about mapping column names and all other arcane sqlldr voodoo... best practices? thoughts? comments? edit: I have about 50+ columns all of varying types and lengths in my dataset, which is why I'd prefer to not have to write out how to generate and map each single column...

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  • Sonata Media Bundle sortBy created_at

    - by tony908
    I use SonataMediaBundle and i would like sort Gallery by created_at field. In repository class i have (without orderBy working good!): $qb = $this->createQueryBuilder('m') ->orderBy('j.expires_at', 'DESC'); $query = $qb->getQuery(); return $query->getResult(); and this throw error: An exception has been thrown during the rendering of a template ("[Semantical Error] line 0, col 80 near 'created_at D': Error: Class Application\Sonata\MediaBundle\Entity\Gallery has no field or association named created_at") so i add this field to Gallery class: /** * @var \DateTime */ private $created_at; /** * Set created_at * * @param \DateTime $createdAt * @return Slider */ public function setCreatedAt($createdAt) { $this->created_at = $createdAt; return $this; } /** * Get created_at * * @return \DateTime */ public function getCreatedAt() { return $this->created_at; } but now i have error: FatalErrorException: Compile Error: Declaration of Application\Sonata\MediaBundle\Entity\Gallery::setCreatedAt() must be compatible with Sonata\MediaBundle\Model\GalleryInterface::setCreatedAt(DateTime $createdAt = NULL) in /home/tony/www/test/Application/Sonata/MediaBundle/Entity/Gallery.php line 32 GalleryInterface: https://github.com/sonata-project/SonataMediaBundle/blob/master/Model/GalleryInterface.php So... how can i use sortBy in my example?

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  • How do I learn algorithms?

    - by Panthe
    Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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  • HELP ME !! I am Not able to update form data to mysql using php and jquery

    - by Jimson Jose
    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 jquery 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 jquery 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 function called from index.php to delete record from mysql database (function calling delete.php works fine) - Update is an 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. some thing is missing in calling update.php page it is not entering into that page I am new bee in programming i had collected this script from many forums and made this one.So i was limited in solving this problem i cam to know that this is good platform for me and many where we get a help to create new things.. please guide me with your help to complete my effors !!!!! i will be greatfull to all including ths site which gave me an oppurtunity to present my self..... please find the link below to download all files which is of 35kb (virus free assurance) download mysmallform files in ZIPped format, including mysql query thanks a lot in advance, May GOD bless YOU and THIS SITE

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  • SQLAlchemy sessions - DetachedInstanceError?

    - by benjaminhkaiser
    I have a function that attempts to take a list of usernames, look each one up in a user table, and then add them to a membership table. If even one username is invalid, I want the entire list to be rolled back, including any users that have already been processed. I thought that using sessions was the best way to do this but I'm running into a DetachedInstanceError: DetachedInstanceError: Instance <Organization at 0x7fc35cb5df90> is not bound to a Session; attribute refresh operation cannot proceed Full stack trace is here. The error seems to trigger when I attempt to access the user (model) object that is returned by the query. From my reading I understand that it has something to do with there being multiple sessions, but none of the suggestions I saw on other threads worked for me. Code is below: def add_members_in_bulk(organization_eid, users): """Add users to an organization in bulk - helper function for add_member()""" """Returns "success" on success and id of first failed student on failure""" session = query_session.get_session() session.begin_nested() users = users.split('\n') for u in users: try: user = user_lookup.by_student_id(u) except ObjectNotFoundError: session.rollback() return u if user: membership.add_user_to_organization( user.entity_id, organization_eid, '', [] ) session.flush() session.commit() return 'success' here's the membership.add_user_to_organization: def add_user_to_organization(user_eid, organization_eid, title, tag_ids): """Add a User to an Organization with the given title""" user = user_lookup.by_eid(user_eid) organization = organization_lookup.by_eid(organization_eid) new_membership = OrganizationMembership( organization_eid=organization.entity_id, user_eid=user.entity_id, title=title) new_membership.tags = [get_tag_by_id(tag_id) for tag_id in tag_ids] crud.add(new_membership) and here is the lookup by ID query: def by_student_id(student_id, include_disabled=False): """Get User by RIN""" try: return get_query_set(include_disabled).filter(User.student_id == student_id).one() except NoResultFound: raise ObjectNotFoundError("User with RIN %s does not exist." % student_id)

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  • What characters are NOT escaped with a mysqli prepared statement?

    - by barfoon
    Hey everyone, I'm trying to harden some of my PHP code and use mysqli prepared statements to better validate user input and prevent injection attacks. I switched away from mysqli_real_escape_string as it does not escape % and _. However, when I create my query as a mysqli prepared statement, the same flaw is still present. The query pulls a users salt value based on their username. I'd do something similar for passwords and other lookups. Code: $db = new sitedatalayer(); if ($stmt = $db->_conn->prepare("SELECT `salt` FROM admins WHERE `username` LIKE ? LIMIT 1")) { $stmt->bind_param('s', $username); $stmt->execute(); $stmt->bind_result($salt); while ($stmt->fetch()) { printf("%s\n", $salt); } $stmt->close(); } else return false; Am I composing the statement correctly? If I am what other characters need to be examined? What other flaws are there? What is best practice for doing these types of selects? Thanks,

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  • PHP - dynamic page via subdomain

    - by Phil Jackson
    Hi, im creating profile pages based on a subdomains using the wildcard DNS setting. Problem being, if the subdomain is incorrect, I want it to redirect to the same page but without the subdomain infront ie; if ( preg_match('/^(www\.)?([^.]+)\.domainname\.co.uk$/', $_SERVER['HTTP_HOST'], $match)) { $DISPLAY_NAME = $match[2]; $query = "SELECT * FROM `" . ACCOUNT_TABLE . "` WHERE DISPLAY_NAME = '$DISPLAY_NAME' AND ACCOUNT_TYPE = 'premium_account'"; $q = mysql_query( $query, $CON ) or die( "_error_" . mysql_error() ); if( mysql_num_rows( $q ) != 0 ) { }else{ mysql_close( $CON ); header("location: http://www.domainname.co.uk"); exit; } } I get a browser error: Firefox has detected that the server is redirecting the request for this address in a way that will never complete. I think its because when using header("location: http://www.domainname.co.uk"); it still puts the sub domain infront i.e. ; header("location: http://www.sub.domainname.co.uk"); Does anyone know how to sort this and/or what is the problem. Regards, Phil

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  • Ruby-on-Rails: Multiple has_many :through possible?

    - by williamjones
    Is it possible to have multiple has_many :through relationships that pass through each other in Rails? I received the suggestion to do so as a solution for another question I posted, but have been unable to get it to work. Friends are a cyclic association through a join table. The goal is to create a has_many :through for friends_comments, so I can take a User and do something like user.friends_comments to get all comments made by his friends in a single query. class User has_many :friendships has_many :friends, :through => :friendships, :conditions => "status = #{Friendship::FULL}" has_many :comments has_many :friends_comments, :through => :friends, :source => :comments end class Friendship < ActiveRecord::Base belongs_to :user belongs_to :friend, :class_name => "User", :foreign_key => "friend_id" end This looks great, and makes sense, but isn't working for me. This is the error I'm getting in relevant part when I try to access a user's friends_comments: ERROR: column users.user_id does not exist : SELECT "comments".* FROM "comments" INNER JOIN "users" ON "comments".user_id = "users".id WHERE (("users".user_id = 1) AND ((status = 2))) When I just enter user.friends, which works, this is the query it executes: : SELECT "users".* FROM "users" INNER JOIN "friendships" ON "users".id = "friendships".friend_id WHERE (("friendships".user_id = 1) AND ((status = 2))) So it seems like it's entirely forgetting about the original has_many through friendship relationship, and then is inappropriately trying to use the User class as a join table. Am I doing something wrong, or is this simply not possible?

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  • rsync : Read input from a file and sync accordingly

    - by Dheeraj
    I have a text file which contains the list of files and directories that I want to copy (one on a line). Now I want rsync to take this input from my text file and sync it to the destination that I provide. I've tried playing around with "--include-from=FILE" and "--file-from=FILE" options of rsync but is is just not working I also tried pre-fixing "+" on each line in my file but still it is not working. I have tried coming with various filter PATTERNs as outlined in the rsync man page but it is not working. Could someone provide me correct syntax for this use case. I've tried above things on Fedora 15, RHEL 6.2 and Ubuntu 10.04 and none worked. So i am definitely missing something. Many thanks.

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  • Form validation

    - by kielie
    Hi guys, I need to create a form that has many of the same fields, that have to be inserted into a database, but the problem I have is that if a user only fills in one or two of the rows, the form will still submit the blank data of the empty fields along with the one or two fields the user has filled in. How can I check for the rows that have not been filled in and leave them out of the query? or check for those that have been filled in and add them to the query. . . The thank_you.php file will capture the $_POST variables and add them to the database. <form method="post" action="thank_you.php"> Name: <input type="text" size="28" name="name1" /> E-mail: <input type="text" size="28" name="email1" /> <br /> Name: <input type="text" size="28" name="name2" /> E-mail: <input type="text" size="28" name="email2" /> <br /> Name: <input type="text" size="28" name="name3" /> E-mail: <input type="text" size="28" name="email3" /> <br /> Name: <input type="text" size="28" name="name4" /> E-mail: <input type="text" size="28" name="email4" /> <input type="image" src="images/btn_s.jpg" /> </form> I am assuming that I could use javascript or jQuery to accomplish this, how would I go about doing this? Thanx in advance for the help.

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  • Use MySQL trigger to update another table when duplicate key found

    - by Jason
    Been scratching my head on this one, hoping one of you kind people and direct me towards solving this problem. I have a mysql table of customers, it contains a lot of data, but for the purpose of this question, we only need to worry about 4 columns 'ID', 'Firstname', 'Lastname', 'Postcode' Problem is, the table contains a lot of duplicated customers. A new table is being created where each customer is unique and for us, we decide a unique customer is based on 'Firstname', 'Lastname' and 'Postcode' However, (this is the important bit) we need to ensure each new "unique" customer record also can be matched to the original multiple entries of that customer in the original table. I believe the best way to do this is to have a third table, that has 'NewUniqueID', 'OldCustomerID'. So we can search this table for 'NewUniqueID' = '123' and it would return multiple 'OldCustomerID' values where appropriate. I am hoping to make this work using a trigger and the on duplicate key syntax. So what would happen is as follows: An query is run taking the old customer table and inserting it in to the new unique table. (A standard Insert Select query) On duplicate key continue adding records, but add one entry in to the third table noting the 'NewUniqueID' that duped along with the 'OldCustomerID' of the record we were trying to insert. Hope this makes sense, my apologies if it isn't clear. I welcome and appreciate any thoughts on this one! Many thanks Jason

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  • Is the following valid XHTML 1.0 Transitional?

    - by willem
    The w3c validator service complains that the following html is invalid. It does not like the ampersand(&) in my javascript. But ampersands are allowed in javascript strings, aren't they? <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Page Title</title> </head> <body> <script type="text/javascript"> function search(query) { redir = "http://search.mysite.com/search?s=FIN&ref=&q=" + query; window.location.href = redir return false; } </script> <span>This is all valid HTML</span> </body> </html>

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  • How can I determine when an InnoDB table was last changed?

    - by David M
    I've had success in the past storing the (heavily) processed results of a database query in memcached, using the last update time of the underlying tables(s) as part of the cache key. For MyISAM tables, that last changed time is available in SHOW TABLE STATUS. Unfortunately, that's usually NULL for InnoDB tables. In MySQL 4.1, the ctime for an InnoDB in its SHOW TABLE STATUS line was usually its actual last update time, but that doesn't seem to be true for MySQL 5.1. There is a DATETIME field in the table, but it only shows when a row has been modified - it cannot show the deletion time of a row that's not there anymore! So, I really cannot use MAX(update_time). Here's the really tricky part. I have a number of replicas that I do reads from. Can I figure out the state of the table that doesn't rely on when the changes have actually been applied? My conclusion after working on this for a while is that it's not going to be possible to get this information as cheaply as I'd like. I'm probably going to cache data until the time that I expect the table to change (it's updated once a day), and let the query cache help out where it can.

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