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  • Hibernate MappingException Unknown entity: $Proxy2

    - by slynn1324
    I'm using Hibernate annotations and have a VERY basic data object: import java.io.Serializable; import javax.persistence.Entity; import javax.persistence.Id; @Entity public class State implements Serializable { /** * */ private static final long serialVersionUID = 1L; @Id private String stateCode; private String stateFullName; public String getStateCode() { return stateCode; } public void setStateCode(String stateCode) { this.stateCode = stateCode; } public String getStateFullName() { return stateFullName; } public void setStateFullName(String stateFullName) { this.stateFullName = stateFullName; } } and am trying to run the following test case: public void testCreateState(){ Session s = HibernateUtil.getSessionFactory().getCurrentSession(); Transaction t = s.beginTransaction(); State state = new State(); state.setStateCode("NE"); state.setStateFullName("Nebraska"); s.save(s); t.commit(); } and get an org.hibernate.MappingException: Unknown entity: $Proxy2 at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:628) at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1366) at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121) .... I haven't been able to find anything referencing the $Proxy part of the error - and am at a loss.. Any pointers to what I'm missing would be greatly appreciated. hibernate.cfg.xml <property name="hibernate.connection.driver_class">org.hsqldb.jdbcDriver</property> <property name="connection.url">jdbc:hsqldb:hsql://localhost/xdb</property> <property name="connection.username">sa</property> <property name="connection.password"></property> <property name="current_session_context_class">thread</property> <property name="dialect">org.hibernate.dialect.HSQLDialect</property> <property name="show_sql">true</property> <property name="hbm2ddl.auto">update</property> <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> <mapping class="com.test.domain.State"/> in HibernateUtil.java public static SessionFactory getSessionFactory(boolean testing ) { if ( sessionFactory == null ){ try { String configPath = HIBERNATE_CFG; AnnotationConfiguration config = new AnnotationConfiguration(); config.configure(configPath); sessionFactory = config.buildSessionFactory(); } catch (Exception e){ e.printStackTrace(); throw new ExceptionInInitializerError(e); } } return sessionFactory; }

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  • @OneToOne and @JoinColumn, auto delete null entity , doable?

    - by smallufo
    I have two Entities , with the following JPA annotations : @Entity @Table(name = "Owner") public class Owner implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id") private long id; @OneToOne(fetch=FetchType.EAGER , cascade=CascadeType.ALL) @JoinColumn(name="Data_id") private Data Data; } @Entity @Table(name = "Data") public class Data implements Serializable { @Id private long id; } Owner and Data has one-to-one mapping , the owning side is Owner. The problem occurs when I execute : owner.setData(null) ; ownerDao.update(owner) ; The "Owner" table's Data_id becomes null , that's correct. But the "Data" row is not deleted automatically. I have to write another DataDao , and another service layer to wrap the two actions ( ownerDao.update(owner) ; dataDao.delete(data); ) Is it possible to make a data row automatically deleted when the owning Owner set it to null ?

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  • Customize MS dynamic CRM entity in visua studio 2008

    - by Lalit
    Hi, I have installed the MS dynamic CRM on my windows server 2003. I want to add the javascript to the one of entity that has drop down control. let say Opportunity entity. But I don't know how to open the CRM in visual studio so that i can make changes. I have installed CRM explorer as well as Install the CRM Solution Framework(under folder\CRMSolutionFrameworkTemplate\Setup.cmd) Using command prompt to install: Setup.cmd {InstallDir} {ProjectName} {Project Long Name} {Organization Name} How to make the chanes, how to get the CRM in VS for edit. While opening the soution from "C:\Projects\MyCrmSolution\SourceCode\MyCrmSolution" It giving error as :"Mcrosoft.sourceanalysis.target not found error so it can not open the solution". please guide I am new in this stuff....

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  • Effective Entity Update In Hibernate ?

    - by Tony
    I've always wanted to know How can I update an entity effectively in hibernate just as by using SQL. For example : I have a product entity , has a field name createTime , when I use session.saveOrUpdate(product) ; I have to get this field from database and then set to product then update , actually whenever I use session.saveOrUpdate() , I updated ALL fileds , even if I just need update only one field. but most time the value object we passed to DAO layer can't contain all fileds information , like the createDate in Product , we seldom need to update this field. How to just update selected fields ? Of course I can use HQL , but that will separate save and update logic . It would be better If Hibernate has a method like this : session.updateOnlyNotNullFields(product); How can I do this in Hibernate ?

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  • how to configure hibernate not to update @Version on each access to entity

    - by radai
    i have a simple query that returns an entity, and when i look at hibernate SQL output i see that when i execute this query hibernate updates the @Version field (on each consecutive read the @version field is updated). i dont modify anything in the entity i fetch, and i dont pass is as an argument to either persist or merge. this effectively means every read i make turns into a read+write. i've tried setting the lock mode t oboth NONE (jpa 2) and READ (jpa 1) to no avail. is there any way to achieve this? if so, is there any way to set this as the default behavior in persistence.xml in some way ? im using jpa2 over hibernate 3.6

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  • Have an external java application by notified of changes to Entity EJBs in JBoss AS

    - by John
    I'm trying to connect an external application to a JBoss AS container. The external application is a Java application that is currently being notified of changes to database entities through a JMS topic. I've added an EntityLifecycleListener class to all my entities that publishes a serialized (and unwrapped) copy of the entity to the JMS topic. The problem is that this implementation ignores the transaction boundaries of the JBoss container. For example, the @PostUpdate event can be fire, generating the JMS message for that entity, but the transaction could be rolled back causing the external application to be notified of an invalid change and become unsync'd. I need my external application to only be notified of successful commits to the database, but I need to be able to publish the entire java POJO to the external application. Is there an official way of doing this?

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  • In JPA, a Map of embeddable values, that have an embedded entity used as the key

    - by Schmuli
    I'm still new to JPA (and Hibernate, which I'm using as my provider), so maybe this just can't be done, but anyway... Consider the following code: @Entity class Root { @Id private long id; private String name; @ElementCollection private Map<ResourceType, Resource> resources; ... } @Entity class ResourceType { @Id private long id; private String name; } @Embeddable class Resource { private ResourceType resourceType; private long value; } In the database, there is a collection table, 'Root_resources', that stores the values of the map, but the resource type appears twice (actually, the resource type ID does), once as the KEY of the map, and once as part of the value. Is there a way, similar to, say, the @MapKey annotation, to indicate that the key is one of the columns of the value (i.e. embedded)?

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  • Criteria: search for two different entity classes...

    - by RoCMe
    Hi! I have a "super entity" SuperEntity and three entities ChildEntity1, ..., ChildEntity3 which extends the super class. It's easy to search for all entities in the database, i.e. we could use session.createCriteria(SuperEntity.class); It's no problem to search for one specific entity type, too, just replace the SuperEntity with any of the children to look for entities of that type. But I have a problem when allowing 'multiple choice' for the types. I.e., it could be neccessary to search all entities of type 1 and 2, but not of type 3. A first idea was to create two independent queries and join the results in a final list - but that would destroy the paging which uses offset and limit functionality of the database... Is there a possibility in Criteria to join two different queries in one single result list? Kind regards, RoCMe

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  • West Palm Beach Developers&rsquo; Group Celebrates its Fifth Anniversary as a Member of INETA

    - by Sam Abraham
    Earlier this week marked our fifth anniversary as an INETA group, a fact that we had forgotten but thankfully INETA remembered. In celebrating our membership, INETA sent us a certificate recognizing our membership which we will be sharing with our members at our upcoming meeting. It‘s been a great two-year tenure for me as group co-coordinator working with Venkat Subramanian who had been involved with the group since its inception. Moving into the future we hope to grow both group membership and leadership. We continue to strive to bring added value to our membership which can only happen with your ideas, feedback and involvement in our community-driven group. Our next almost sold-out meeting will be taking place on 8/28/2012 6:30PM (Register at: http://www.fladotnet.com/Reg.aspx?EventID=607) . Will Strohl, DotNetNuke’s Technical Evangelist will be presenting to us an overview on getting started with DNN’s latest 6.2 version all while taking us on a deep dive into its built-in social networking integration features. There is still time to register, but don’t procrastinate! Our September meeting will feature Jonas Stawski, Microsoft MVP sharing with us on SignalR while October will bring us the much anticipated visit by our Microsoft Developer Evangelist Joe Healy who will be talking to us about the latest with Windows 8. Joe will be also presenting in Miami the next day after our event in case you miss his West Palm appearance. We look forward to meeting you at our upcoming meetings. All the best --Sam Abraham

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  • Post SQL 2008 R2 Launch Thurs 15th London - UK SQL Server User Group is having a Social Event @ the

    - by tonyrogerson
    The UK SQL Server User Group is organising a Social event for SQL and SQL Server professionals, the event will be held after the SQL Server 2008 R2 launch event and is a short walk from that venue. See site for more information: http://sqlserverfaq.com/events/222/Social-for-SQL-and-SQL-Server-professionals-SQL-quiz-meet-your-peers-ask-the-group-Q-A.aspx We are putting some light bites on, if you are coming then do let us know through the site. Neil Hambly who is the London UK SQL Server User Group...(read more)

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  • [EF + ORACLE] Updating and Deleting Entities

    - by JTorrecilla
    Prologue In previous chapters we have seen how to insert data through EF, with and without sequences. In this one, we are going to see how to Update and delete Data from the DB. Updating data The update of the Entity Data (properties) is a very common and easy action. Before of change any of the properties of the Entity, we can check the EntityState property, and we can see that is EntityState.Unchanged.   For making an update it is needed to get the Entity which will be modified. In the following example, I use the GetEmployeeByNumber to get a valid Entity: 1: EMPLEADOS emp=GetEmployeeByNumber(2); 2: emp.Name="a"; 3: emp.Phone="2"; 4: emp.Mail="aa"; After modifying the desired properties of the Entity, we are going to check again Entitystate property, which now has the EntityState.Modified value. To persist the changes to the DB is necessary to invoke the SaveChanges function of our context. 1: context.SaveChanges(); After modifying the desired properties of the Entity, we are going to check again Entitystate property, which now has the EntityState.Modified value. To persist the changes to the DB is necessary to invoke the SaveChanges function of our context. If we check again the EntityState property we will see that the value will be EntityState.Unchanged.   Deleting Data Another easy action is to delete an Entity.   The first step to delete an Entity from the DB is to select the entity: 1: CLIENTS selectedClient = GetClientByNumber(15); 2: context.CLIENTES.DeleteObject(clienteSeleccionado); Before invoking the DeleteObject function, we will check EntityStet which value must be EntityState.Unchanged. After deleting the object, the state will be changed to EntitySate.Deleted. To commit the action we have to invoke the SaveChanges function. Aftar that, the EntityState property will be EntityState.Detached. Cascade Entity Framework lets cascade updates and deletes, although I never see cascade updates. What is a cascade delete? A cascade delete is an action that allows to delete all the related object to the object we desire to delete. This option could be established in the DB manager, or it could be in the EF model designer. For example: With a given relation (1-N) between clients and requests. The common situation must be to let delete those clients whose have no requests. If we select the relation between both entities, and press the second mouse button, we can see the properties panel of the relation. The props are: This grid shows the relations indicating the Master table(Clients) and the end point (Cabecera or Requests) The property “End 1 OnDelete” indicates the action to do when a Entity from the Master will be deleted. There are two options: - None: No action will be done, it is said, if a Entity has details entities it could not be deleted. - Cascade: It will delete all related entities to the master Entity. If we enable the cascade delete in a relation, and we invoke the DeleteObject function of the set, we could observe that all the related object indicates a Entitystate.Deleted state. Like an update, insert or common delete, until we commit the changes with SaveChanges function, the data would not be commited. Si habilitamos el borrado en cascada de una relación, e invocamos a la función DeleteObject del conjunto, podremos observar que todas las entidades de Detalle (de la relación indicada) presentan el valor EntityState.Deleted en la propiedad EntityState. Del mismo modo que en el borrado, inserción o actualización, hasta que no se invoque al método SaveChanges, los cambios no van a ser confirmados en la Base de Datos. Finally In this chapter we have seen how to update a Entity, how to delete an Entity and how to implement Cascade Deleting through EF. In next chapters we will see how to query the DB data.

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  • Azure : Mobiles Services et Web Sites entrent en production, l'infrastructure stocke 8,5 trillions d'objets et gère 900 000 transactions par seconde

    Windows Azure : Mobiles Services et Web Sites entrent en production L'infrastructure stocke 8,5 trillions d'objets et gère 900 000 transactions par secondeDisponible en Preview depuis août 2012, Windows Azure Mobiles Services est passé en disponibilité générale (GA) avec Windows Azure Web Sites. Une étape qui marque l'entrée de ces services en phase de production. Pour rappel, Windows Azure Mobile Services est une plateforme Backend as a service (BaaS), qui fournit une solution clef en main dans le Cloud, permettant d'accélérer le développement d'applications connectées côté client.

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  • Queyring container with Linq + group by ?

    - by Prix
    public class ItemList { public int GuID { get; set; } public int ItemID { get; set; } public string Name { get; set; } public entityType Status { get; set; } public class Waypoint { public int Zone { get; set; } public int SubID { get; set; } public int Heading { get; set; } public float PosX { get; set; } public float PosY { get; set; } public float PosZ { get; set; } } public List<Waypoint> Routes = new List<Waypoint>(); } I have a list of items using the above class and now I need to group it by ItemID and join the first entry of Routes of each iqual ItemID. So for example, let's say on my list I have: GUID ItemID ListOfRoutes 1 23 first entry only 2 23 first entry only 3 23 first entry only 4 23 first entry only 5 23 first entry only 6 23 first entry only 7 23 first entry only Means I have to group entries 1 to 7 as 1 Item with all the Routes entries. So I would have one ItemID 23 with 7 Routes on it where those routes are the first element of that given GUID Routes List. My question is if it is possible using LINQ to make a statment to do something like that this: var query = from ItemList entry in myList where status.Contains(entry.Status) group entry by entry.ItemID into result select new { items = new { ID = entry.ItemID, Name = entry.Name }, routes = from ItemList m in entry group m.Routes.FirstOrDefault() by n.NpcID into m2 }; So basicly I would have list of unique IDS information with a inner list of all the first entry of each GUID route that had the same ItemID. <<< UPDATE: This would be an example of public List<ItemList> myList = new List<ItemList>(); data: GUID ItemID ListOfRoutes 1 20 Routes[1] 2 20 Routes[2] 3 20 Routes[3] 4 20 Routes[4] 5 20 Routes[5] 6 55 Routes[6] 7 55 Routes[7] 8 55 Routes[8] 9 1 Routes[9] 10 1 Routes[10] As you can see GUID is unique, ItemID can reapeat it self. Each GUID has a Routes list and all routes list have a minimum of 1 entry and above. Routes example. Routes[1] have: Entry Zone SubID Heading PosX PosY PosZ 1 1200 0 100 1029.32 837.21 29.10 2 1200 0 120 1129.32 537.21 29.10 3 1200 0 180 1229.32 137.21 29.10 4 1200 0 360 1329.32 437.21 29.10 5 1200 0 100 1429.32 637.21 29.10 Routes[2] have: Entry Zone SubID Heading PosX PosY PosZ 1 100 0 10 129.32 437.21 29.10 So what I want to do is a list of all entries I have on myList grouped by ItemID maintainning the fields ItemID and Name ... and a new field or item that will have all the first elements of Routes of those GUIDs. For example ItemID 20 would produce the follow result: ItemID, Name, ListOfRoutes This ItemID ListOfRoutes would contain Routes[1] first entry: Entry Zone SubID Heading PosX PosY PosZ 1 1200 0 100 1029.32 837.21 29.10 Routes[2] first entry: Entry Zone SubID Heading PosX PosY PosZ 1 100 0 10 129.32 437.21 29.10 Routes[3], Routes[4], Routes[5] first entries. Example of how myList is feeded: ItemList newItem = new ItemList(); newItem.GUID = GUID; newItem.ItemID = ItemID; newItem.Name = Name; newItem.Status = Status; // Item location ItemList.Waypoint itemLocation = new ItemList.Waypoint(); itemLocation.SubID = SubID; itemLocation.Zone = Zone; itemLocation.Heading = convertHeading(Heading); itemLocation.PosX = PosX; itemLocation.PosY = PosY; itemLocation.PosZ = PosZ; itemLocation.Rest = Rest; newItem.Routes.Add(itemLocation); myList.Add(newItem);

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  • Efficient representation of Hierarchies in Hibernate.

    - by Alison G
    I'm having some trouble representing an object hierarchy in Hibernate. I've searched around, and haven't managed to find any examples doing this or similar - you have my apologies if this is a common question. I have two types which I'd like to persist using Hibernate: Groups and Items. * Groups are identified uniquely by a combination of their name and their parent. * The groups are arranged in a number of trees, such that every Group has zero or one parent Group. * Each Item can be a member of zero or more Groups. Ideally, I'd like a bi-directional relationship allowing me to get: * all Groups that an Item is a member of * all Items that are a member of a particular Group or its descendants. I also need to be able to traverse the Group tree from the top in order to display it on the UI. The basic object structure would ideally look like this: class Group { ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { ... } /** @return all direct children of this group */ Set<Group> getChildren() { ... } ... } class Item { ... /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { ... } ... } Originally, I had just made a simple bi-directional many-to-many relationship between Items and Groups, such that fetching all items in a group hierarchy required recursion down the tree, and fetching groups for an Item was a simple getter, i.e.: class Group { ... private Set<Item> items; private Set<Group> children; ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { Set<Item> allItems = new HashSet<Item>(); allItems.addAll(this.items); for(Group child : this.getChildren()) { allItems.addAll(child.getAllItems()); } return allItems; } /** @return all direct children of this group */ Set<Group> getChildren() { return this.children; } ... } class Item { ... private Set<Group> groups; /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { return this.groups; } ... } However, this resulted in multiple database requests to fetch the Items in a Group with many descendants, or for retrieving the entire Group tree to display in the UI. This seems very inefficient, especially with deeper, larger group trees. Is there a better or standard way of representing this relationship in Hibernate? Am I doing anything obviously wrong or stupid? My only other thought so far was this: Replace the group's id, parent and name fields with a unique "path" String which specifies the whole ancestry of a group, e.g.: /rootGroup /rootGroup/aChild /rootGroup/aChild/aGrandChild The join table between Groups and Items would then contain group_path and item_id. This immediately solves the two issues I was suffering previously: 1. The entire group hierarchy can be fetched from the database in a single query and reconstructed in-memory. 2. To retrieve all Items in a group or its descendants, we can select from group_item where group_path='N' or group_path like 'N/%' However, this seems to defeat the point of using Hibernate. All thoughts welcome!

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  • Facebook Invalid OAuth access token signature trying to post an attachment to group wall from PHP

    - by Volodymyr B
    I am an administrator (manager role) of a Facebook Group. I created an app, and stored its id and secret. I want my app to be able to post something on the Facebook group's feed. But when I attempt to post, I get the error 190 Invalid OAuth access token signature, even though I able to successfully obtain the access_token with publish_stream and offline_access scopes. It has the form of NNNNNNNNNNNNNNN|XXXXXXXXXXXXXXXXXXXXXXXXXXX, where N is a number (15) and X is a letter or a number (27). What should I do more to get this accomplished? Here is the code I am using: public static function postToFB($message, $image, $link) { //Get App Token $token = self::getFacebookToken(); // Create FB Object Instance $facebook = new Facebook(array( 'appId' => self::fb_appid, 'secret' => self::fb_secret, 'cookie' => true )); //$token = $facebook->getAccessToken(); //Try to Publish on wall or catch the Facebook exception try { $attachment = array('access_token' => $token, 'message' => $message, 'picture' => $image, 'link' => $link, //'name' => '', //'caption' => '', 'description' => 'More...', //'actions' => array(array('name' => 'Action Text', 'link' => 'http://apps.facebook.com/xxxxxx/')) ); $result = $facebook->api('/'.self::fb_groupid.'/feed/', 'post', $attachment); } catch (FacebookApiException $e) { //If the post is not published, print error details echo '<pre>'; print_r($e); echo '</pre>'; } } Code which returns the token //Function to Get Access Token public static function getFacebookToken($appid = self::fb_appid, $appsecret = self::fb_secret) { $args = array( 'grant_type' => 'client_credentials', 'client_id' => $appid, 'client_secret' => $appsecret, 'redirect_uri' => 'https://www.facebook.com/connect/login_success.html', 'scope' => 'publish_stream,offline_access' ); $ch = curl_init(); $url = 'https://graph.facebook.com/oauth/access_token'; curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_HEADER, false); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_POST, true); curl_setopt($ch, CURLOPT_POSTFIELDS, $args); try { $data = curl_exec($ch); } catch (Exception $exc) { error_log($exc->getMessage()); } return json_encode($data); } If I uncomment $token = $facebook->getAccessToken(); in the posting code, it gives me yet another error (#200) The user hasn't authorized the application to perform this action. The token I get using developers.facebook.com/tools/explorer/ is of another form, much longer and with it I am able to post to the group page feed. How do I do it without copy/paste from Graph API Explorer and how do I post as a group instead of posting as a user? Thanks.

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  • Listing issue, GROUP mysql

    - by SethCodes
    Here is a mock-up example of Mysql table: | ID | Country | City | ________________________________ | 1 | Sweden | Stockholm | | 2 | Sweden | Stockholm | | 3 | Sweden | Lund | | 4 | Sweden | Lund | | 5 | Germany | Berlin | | 6 | Germany | Berlin | | 7 | Germany | Hamburg | | 8 | Germany | Hamburg | Notice how both rows Country and city have repeated values inside them. Using GROUP BY country, city in my PDO query, the values will not repeat while in loop. Here is PDO for this: $query = "SELECT id, city, country FROM table GROUP BY country, city"; $stmt = $db->query($query); while($row = $stmt->fetch(PDO::FETCH_ASSOC)) : The above code will result in an output like this (some editing in-between). GROUP BY works but the country repeats: Sweden - Stockholm Sweden - Lund Germany - Berlin Germany - Hamburg Using bootstrap collapse and above code, I separate the country from the city with a simple drop down collopase. Here is code: <li> <a data-toggle="collapse" data-target="#<?= $row['id']; ?>" href="search.php?country=<?= $row['country']; ?>"> <?= $row['country']; ?> </a> <div id ="<?= $row['id']; ?>" class="collapse in"> //collapse div here <a href="search.php?city=<?= $row['city']; ?>"> <?= $row['city']; ?><br></a> </div> //end </li> It then looks something like this (once collapse is initiated): Sweden > Stockholm Sweden > Lund Germany >Berlin Germany >Hamburg Here is where I face the problem. The above lists the values Sweden and Germany 2 times. I want Sweden and Germany to only list one time, and the cities listed below, so the desired look is to be this: Sweden // Lists one time > Stockholm > Lund Germany // Lists one time >Berlin >Hamburg I have tried using DISTINCT, GROUP_CONTACT and other methods, yet none get my desired output (above). Suggestions? Below is my current full code in action: <? $query = "SELECT id, city, country FROM table GROUP BY country, city"; $stmt = $db->query($query); while($row = $stmt->fetch(PDO::FETCH_ASSOC)) : ?> <li> <a data-toggle="collapse" data-target="#<?= $row['id']; ?>" href="search.php?country=<?= $row['country']; ?>"> <?= $row['country']; ?> </a> <div id ="<?= $row['id']; ?>" class="collapse in"> //collapse div here <a href="search.php?city=<?= $row['city']; ?>"> <?= $row['city']; ?><br></a> </div> //end </li> <? endwhile ?>

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  • SQL - Count grouped entries and then get the max values grouped by date

    - by Marcus
    hello, I am out of any logic how to write the right sql statment. I've got a sqlite table holding every played track in a row with played date/time Now I will count the plays of all artists, grouped by day and then find the artist with the max playcount per day. I used this Query SELECT COUNT(ARTISTID) AS artistcount, ARTIST AS artistname,strftime('%Y-%m-%d', playtime) AS day_played FROM playcount GROUP BY artistname to get this result "93"|"The Skygreen Leopards"|"2010-06-16" "2" |"Arcade Fire" |"2010-06-15" "2" |"Dead Kennedys" |"2010-06-15" "2" |"Wolf People" |"2010-06-15" "3" |"16 Horsepower" |"2010-06-15" "3" |"Alela Diane" |"2010-06-15" "46"|"Motorama" |"2010-06-15" "1" |"Ariel Pink's Haunted" |"2010-06-14" I tried then to query this virtual table but I always get false results in artistname. SELECT MAX(artistcount), artistname , day_played FROM ( SELECT COUNT(ARTISTID) AS artistcount, ARTIST AS artistname,strftime('%Y-%m-%d', playtime) AS day_played FROM playcount GROUP BY artistname ) GROUP BY strftime('%Y-%m-%d',day_played) result in this "93"|"lilium" |"2010-06-16" "46"|"Wolf People"|"2010-06-15" "30"|"of Montreal"|"2010-06-14" but the artist name is false. I think through the grouping by day, it just use the last artist, or so. I tested stuff like INNER JOIN or GROUP BY ... HAVING in trial and error, I read examples of similar issues but always get lost in columnnames and stuff (I am a bit burned out) I hope someone can give me a hint. thanks m

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  • Lost Update Anomaly in Sql Server Update Command

    - by Javed
    Hi, I am very much confused. I have a transaction in ReadCommitted Isolation level. Among other things I am also updating a counter value in it, something similar to below: Update tblCount set counter = counter + 1 My application is a desktop application and this transaction happens to occur quite frequently and concurrently. We recently noticed an error that sometimes the counter value doesn't get updated or is missed. We also insert one record on each counter update so we are sure that records have been inserted but somehow counter fails to update. This happens once in 2000 simulaneous transactions. I seriously doubt it is a lost update anomaly I am facing but if you look at the command above, it's just update the counter from its own value: if I have started a transaction and the transaction has reached this statement, it should have locked the row. This should not cause lost update, but it's happening somehow. Is the thing that this update command works in two parts? Like first it reads the counter value (during which it doesn't get the exclusive lock) and then writes the new calculated value (when it does get an exclusive lock)? Please help, I have got really confused.

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  • Delivery of JMS message before the transaction is committed

    - by ewernli
    Hi, I have a very simple scenario involving a database and a JMS in an application server (Glassfish). The scenario is dead simple: 1. an EJB inserts a row in the database and sends a message. 2. when the message is delivered with an MDB, the row is read and updated. The problem is that sometimes the message is delivered before the insert has been committed in the database. This is actually understandable if we consider the 2 phase commit protocol: 1. prepare JMS 2. prepare database 3. commit JMS 4. ( tiny little gap where message can be delivered before insert has been committed) 5. commit database I've discussed this problem with others, but the answer was always: "Strange, it should work out of the box". My questions are then: How could it work out-of-the box? My scenario sounds fairly simple, why isn't there more people with similar troubles? Am I doing something wrong? Is there a way to solve this issue correctly? Here are a bit more details about my understanding of the problem: This timing issue exist only if the participant are treated in this order. If the 2PC treats the participants in the reverse order (database first then message broker) that should be fine. The problem was randomly happening but completely reproducible. I found no way to control the order of the participants in the distributed transactions in the JTA, JCA and JPA specifications neither in the Glassfish documentation. We could assume they will be enlisted in the distributed transaction according to the order when they are used, but with an ORM such as JPA, it's difficult to know when the data are flushed and when the database connection is really used. Any idea?

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  • how to atomically claim a row or resource using UPDATE in mysql

    - by Igor
    i have a table of resources (lets say cars) which i want to claim atomically. if there's a limit of one resource per one user, i can do the following trick: UPDATE cars SET user = 'bob' WHERE user IS NULL LIMIT 1 SELECT * FROM cars WHERE user IS bob that way, i claim the resource atomically and then i can see which row i just claimed. this doesn't work when 'bob' can claim multiple cars. i realize i can get a list of cars already claimed by bob, claim another one, and then SELECT again to see what's changed, but that feels hackish. What I'm wondering is, is there some way to see which rows i just updated with my last UPDATE? failing that, is there some other trick to atomically claiming a row? i really want to avoid using SERIALIZABLE isolation level. If I do something like this: 1 SELECT id FROM cars WHERE user IS NULL 2 <here, my PHP or whatever picks a car id> 3 UPDATE cars SET user = 'bob' WHERE id = <the one i picked> would REPEATABLE READ be sufficient here? in other words, could i be guaranteed that some other transactions won't claim the row my software has picked during step 2?

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  • Blocking on DBCP connection pool (open and close connnection). Is database connection pooling in OpenEJB pluggable?

    - by topchef
    We use OpenEJB on Tomcat (used to run on JBoss, Weblogic, etc.). While running load tests we experience significant performance problems with handling JMS messages (queues). Problem was localized to blocking on database connection pool getting or releasing connection to the pool. Blocking prevented concurrent MDB instances (threads) from running hence performance suffered 10-fold and worse. The same code used to run on application servers (with their respective connection pool implementations) with no blocking at all. Example of thread blocked: Name: JMS Resource Adapter-worker-23 State: BLOCKED on org.apache.commons.pool.impl.GenericObjectPool@1ea6b4a owned by: JMS Resource Adapter-worker-19 Total blocked: 18,426 Total waited: 0 Stack trace: org.apache.commons.pool.impl.GenericObjectPool.returnObject(GenericObjectPool.java:916) org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:91) - locked org.apache.commons.dbcp.PoolableConnection@1bcba8 org.apache.commons.dbcp.managed.ManagedConnection.close(ManagedConnection.java:147) com.xxxxx.persistence.DbHelper.closeConnection(DbHelper.java:290) .... Couple of questions. I am almost certain that some transactional attributes and properties contribute to this blocking, but MDBs are defined as non-transactional (we use both annotations and ejb-jar.xml). Some EJBs do use container-managed transactions though (and we can observe blocking there as well). Are there any DBCP configurations that may fix blocking? Is DBCP connection pool implementation replaceable in OpenEJB? How easy (difficult) to replace it with another library? Just in case this is how we define data source in OpenEJB (openejb.xml): <Resource id="MyDataSource" type="DataSource"> JdbcDriver oracle.jdbc.driver.OracleDriver JdbcUrl ${oracle.jdbc} UserName ${oracle.user} Password ${oracle.password} JtaManaged true InitialSize 5 MaxActive 30 ValidationQuery SELECT 1 FROM DUAL TestOnBorrow true </Resource>

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  • PostgreSQL insert on primary key failing with contention, even at serializable level

    - by Steven Schlansker
    I'm trying to insert or update data in a PostgreSQL db. The simplest case is a key-value pairing (the actual data is more complicated, but this is the smallest clear example) When you set a value, I'd like it to insert if the key is not there, otherwise update. Sadly Postgres does not have an insert or update statement, so I have to emulate it myself. I've been working with the idea of basically SELECTing whether the key exists, and then running the appropriate INSERT or UPDATE. Now clearly this needs to be be in a transaction or all manner of bad things could happen. However, this is not working exactly how I'd like it to - I understand that there are limitations to serializable transactions, but I'm not sure how to work around this one. Here's the situation - ab: => set transaction isolation level serializable; a: => select count(1) from table where id=1; --> 0 b: => select count(1) from table where id=1; --> 0 a: => insert into table values(1); --> 1 b: => insert into table values(1); --> ERROR: duplicate key value violates unique constraint "serial_test_pkey" Now I would expect it to throw the usual "couldn't commit due to concurrent update" but I'm guessing since the inserts are different "rows" this does not happen. Is there an easy way to work around this?

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