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  • Querying with foreign key

    - by theactiveactor
    Say I have 2 tables whose structures are as follows: tableA id | A1 | A2 tableB id | tableA_id (foreign key) | B1 Entries in A have a one-to-many relationship with entries in B. What kind of query operation would I need to achieve "something like this: select all objects from table B where A1="foo""? Basically, apply a query on tableA and from those result, find corresponding dependent objects in tableB

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  • How do I restrict foreign keys choices to related objects only in django

    - by Jeff Mc
    I have a two way foreign relation similar to the following class Parent(models.Model): name = models.CharField(max_length=255) favoritechild = models.ForeignKey("Child", blank=True, null=True) class Child(models.Model): name = models.CharField(max_length=255) myparent = models.ForeignKey(Parent) How do I restrict the choices for Parent.favoritechild to only children whose parent is itself? I tried class Parent(models.Model): name = models.CharField(max_length=255) favoritechild = models.ForeignKey("Child", blank=True, null=True, limit_choices_to = {"myparent": "self"}) but that causes the admin interface to not list any children.

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  • Upgrading Entity Framework 1.0 to 4.0 to include foreign keys

    - by duthiega
    Currently I've been working with Entity Framework 1.0 which is located under a service façade. Below is one of the save methods I've created to either update or insert the device in question. This currently works but, I can't help feel that its a bit of a hack having to set the referenced properties to null then re-attach them just to get an insert to work. The changedDevice already holds these values, so why do I need to assign them again. So, I thought I'll update the model to EF4. That way I can just directly access the foreign keys. However, on doing this I've found that there doesn't seem to be an easy way to add the foreign keys except by removing the entity from the diagram and re-adding it. I don't want to do this as I've already been through all the entity properties renaming them from the DB column names. Can anyone help? /// <summary> /// Saves the non network device. /// </summary> /// <param name="nonNetworkDeviceDto">The non network device dto.</param> public void SaveNonNetworkDevice(NonNetworkDeviceDto nonNetworkDeviceDto) { using (var context = new AssetNetworkEntities2()) { var changedDevice = TransformationHelper.ConvertNonNetworkDeviceDtoToEntity(nonNetworkDeviceDto); if (!nonNetworkDeviceDto.DeviceId.Equals(-1)) { var originalDevice = context.NonNetworkDevices.Include("Status").Include("NonNetworkType").FirstOrDefault( d => d.DeviceId.Equals(nonNetworkDeviceDto.DeviceId)); context.ApplyAllReferencedPropertyChanges(originalDevice, changedDevice); context.ApplyCurrentValues(originalDevice.EntityKey.EntitySetName, changedDevice); } else { var maxNetworkDevice = context.NonNetworkDevices.OrderBy("it.DeviceId DESC").First(); changedDevice.DeviceId = maxNetworkDevice.DeviceId + 1; var status = changedDevice.Status; var nonNetworkType = changedDevice.NonNetworkType; changedDevice.Status = null; changedDevice.NonNetworkType = null; context.AttachTo("DeviceStatuses", status); if (nonNetworkType != null) { context.AttachTo("NonNetworkTypes", nonNetworkType); } changedDevice.Status = status; changedDevice.NonNetworkType = nonNetworkType; context.AddToNonNetworkDevices(changedDevice); } context.SaveChanges(); } }

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  • How to create an entity with a composite primary key containing a generated value.

    - by David
    Using Hibernate + annotations, I'm trying to do the following: Two entities, Entity1 and Entity2. Entity1 contains a simple generated value primary key. Entity2 primary key is composed by a simple generated value + the id of entity one (with a many to one relationship) Unfortunately, I can't make it work. Here is an excerpt of the code: @Entity public class Entity1 { @Id @GeneratedValue private Long id; private String name; ... } @Entity public class Entity2 { @EmbeddedId private Entity2PK pk = new Entity2PK(); private String miscData; ... } @Embeddable public class Entity2PK implements Serializable { @GeneratedValue private Long id; @ManyToOne private Entity1 entity; } void test() { Entity1 e1 = new Entity1(); e1.setName("nameE1"); Entity2 e2 = new Entity2(); e2.setEntity1(e1); e2.setMiscData("test"); Transaction transaction = session.getTransaction(); try { transaction.begin(); session.save(e1); session.save(e2); transaction.commit(); } catch (Exception e) { transaction.rollback(); } finally { session.close(); } } When I run the test method I get the following errors: Hibernate: insert into Entity1 (id, name) values (null, ?) Hibernate: call identity() Hibernate: insert into Entity2 (miscData, entity_id, id) values (?, ?, ?) 07-Jun-2010 10:51:11 org.hibernate.util.JDBCExceptionReporter logExceptions WARNING: SQL Error: 0, SQLState: null 07-Jun-2010 10:51:11 org.hibernate.util.JDBCExceptionReporter logExceptions SEVERE: failed batch 07-Jun-2010 10:51:11 org.hibernate.event.def.AbstractFlushingEventListener performExecutions SEVERE: Could not synchronize database state with session org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103) at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43) at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:254) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:266) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:167) at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1001) at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:339) at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106) at test.App.main(App.java:32) Caused by: java.sql.BatchUpdateException: failed batch at org.hsqldb.jdbc.jdbcStatement.executeBatch(Unknown Source) at org.hsqldb.jdbc.jdbcPreparedStatement.executeBatch(Unknown Source) at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:48) at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:247) ... 8 more Note that I use HSQLDB. Any ideas about what is wrong ?

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  • Add a foreign key to existing tables in Rails (MySQL)

    - by randombits
    What's the best way to add foreign keys to my existing tables in Rails with an underlying MySQL database? clearly the solution should be done in a migration, as I want this versioned. Otherwise I'd create the constraints myself. I can't seem to find one, conducive response to they above. Again, the tables have already been created with previous migrations. I'm just going back now and adding referential integrity wherever it's applicable.

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  • Foreign Keys Duplicated in DataGridView

    - by John Doe
    I created a Windows Forms Application to which I added a DataGridView and LINQ to SQL Classes from one of my databases. I can successfully bind one of my database's tables to my DataGridView: var dataSource = from c in _db.NetworkedEquipments select c; dataGridView1.DataSource = dataSource; However, the foreign keys get duplicated, that is, the columns appear twice. How can I prevent this?

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  • Is there a C++ cross platform key/value API or library for C++?

    - by Tim
    We want to persist some user settings int he GUI part of our code. I used to do Win32 programming exclusively and the typical way this was done was with registry settings. I assume that this should be done with configuration files, but was wondering if there was a library or cross platform wrapper that made key/value pair persistence very easy.

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  • How do I update my primary key in MySQL?

    - by Wesley
    Ok, this is probably really simple, but I just can't figure it out. I have a primary key in a table that goes from 1-5,000. I need to manually update that id (for other table update purposes) so that it says 5,000-10,000. Can't I manually update this column? Please help!!! Thank you

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  • Foreign keys and NULL in mySQL

    - by Industrial
    Hi everyone, Can I have a column in my values table (value) referenced as a foreign key to knownValues table, and let it be NULL whenever needed, like in the example: Table: values product type value freevalue 0 1 NULL 100 1 2 NULL 25 3 3 1 NULL Table: types id name prefix 0 length cm 1 weight kg 2 fruit NULL Table: knownValues id Type name 0 2 banana Note: The types in the table values & knownValues are of course referenced into the types table. Thanks!

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  • Hibernate subclass with foreign key relationships

    - by shikarishambu
    I need some help defining the following object hierarchy/ database relationship in Hibernate From the object sense – Agent is inherited from Person and Agency is inherited from Organization. they are inherited from Party which can have multiple Addresses associated with it The database consists of Agent - ID - Name -PartyID (references Party.ID) Agency -ID -Name -PartyID (references Party.ID) Address -AddrID -PartyID (references Party.ID) -Street Party. -PartyID

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  • Is it okay to use array[key] in PHP?

    - by terrani
    Hi, I have a simple question. Is it okay to use array without single or double quotion like $array[key]? I thought it is bad because PHP look for constant first if I don't use single or doulbe quotion. One of my colleagues told me that it does not matter. WHat do you guys think?

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  • Postgres: Find table foreign keys (Faster alternative)

    - by Najera
    Is there faster alternative to this: Take almost 1 minute in our server. SELECT tc.constraint_name, tc.table_name, kcu.column_name, ccu.table_name AS foreign_table_name, ccu.column_name AS foreign_column_name FROM information_schema.table_constraints AS tc JOIN information_schema.key_column_usage AS kcu ON tc.constraint_name = kcu.constraint_name JOIN information_schema.constraint_column_usage AS ccu ON ccu.constraint_name = tc.constraint_name WHERE constraint_type = 'FOREIGN KEY' AND tc.table_name='mytable'; Maybe using pg_class metadata?, thanks.

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  • inserting new relationship data in core-data

    - by michael
    My app will allow users to create a personalised list of events from a large list of events. I have a table view which simply displays these events, tapping on one of them takes the user to the event details view, which has a button "add to my events". In this detailed view I own the original event object, retrieved via an NSFetchedResultsController and passed to the detailed view (via a table cell, the same as the core data recipes sample). I have no trouble retrieving/displaying information from this "event". I am then trying to add it to the list of MyEvents represented by a one to many (inverse) relationship: This code: NSManagedObjectContext *context = [event managedObjectContext]; MyEvents *myEvents = (MyEvents *)[NSEntityDescription insertNewObjectForEntityForName:@"MyEvents" inManagedObjectContext:context]; [myEvents addEventObject:event];//ERROR And this code (suggested below): //would this add to or overwrite the "list" i am attempting to maintain NSManagedObjectContext *context = [event managedObjectContext]; MyEvents *myEvents = (MyEvents *)[NSEntityDescription insertNewObjectForEntityForName:@"MyEvents" inManagedObjectContext:context]; NSMutableSet *myEvent = [myEvents mutableSetValueForKey:@"event"]; [myEvent addObject:event]; //ERROR Bot produce (at the line indicated by //ERROR): *** -[NSComparisonPredicate evaluateWithObject:]: message sent to deallocated instance Seems I may have missed something fundamental. I cant glean any more information through the use of debugging tools, with my knowledge of them. 1) Is this a valid way to compile and store an editable list like this? 2) Is there a better way? 3) What could possibly be the deallocated instance in error? -- I have now modified the Event entity to have a to-many relationship called "myEvents" which referrers to itself. I can add Events to this fine, and logging the object shows the correct memory addresses appearing for the relationship after a [event addMyEventObject:event];. The same failure happens right after this however. I am still at a loss to understand what is going wrong. This is the backtrace #0 0x01f753a7 in ___forwarding___ () #1 0x01f516c2 in __forwarding_prep_0___ () #2 0x01c5aa8f in -[NSFetchedResultsController(PrivateMethods) _preprocessUpdatedObjects:insertsInfo:deletesInfo:updatesInfo:sectionsWithDeletes:newSectionNames:treatAsRefreshes:] () #3 0x01c5d63b in -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] () #4 0x0002e63a in _nsnote_callback () #5 0x01f40005 in _CFXNotificationPostNotification () #6 0x0002bef0 in -[NSNotificationCenter postNotificationName:object:userInfo:] () #7 0x01bbe17d in -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] () #8 0x01c1d763 in -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] () #9 0x01ba25ea in -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] () #10 0x01bdfb3a in -[NSManagedObjectContext processPendingChanges] () #11 0x01bd0957 in _performRunLoopAction () #12 0x01f4d252 in __CFRunLoopDoObservers () #13 0x01f4c65f in CFRunLoopRunSpecific () #14 0x01f4bc48 in CFRunLoopRunInMode () #15 0x0273878d in GSEventRunModal () #16 0x02738852 in GSEventRun () #17 0x002ba003 in UIApplicationMain () solution I managed to get to the bottom of this. I was fetching the event in question using a NSFetchedResultsController with a NSPredicate which I was releasing after I had the results. Retrieving values from the entities returned was no problem, but when I tried to update any of them it gave the error above. It should not have been released. oustanding part of my question What is a good way to create this sub list from a list of existing items in terms of a core data model. I don't believe its any of the ways I tried here. I need to show/edit it in another table view. Perhaps there is a better way than a boolean property on each event entity? The relationship idea above doesn't seem to work here (even though I can now create it). Cheers.

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  • Entity Framework model and foreign key property

    - by verror
    I have 2 tables that I import to EF model. First table has a property [section] that acts as foreign key to the second table. When I map this property in model to the table and try to compile I get this error: Problem in Mapping Fragments starting at lines 158, 174: Non-Primary-Key column(s) [Section] are being mapped in both fragments to different conceptual side properties - data inconsistency is possible because the corresponding conceptual side properties can be independently modified. If i remove this property from the model it passes, but when I query the data I don't have the section field. I know that I can get it by using the navigation field and reading this property from the second table, but to make it work I must include the other table in my query. var res = from name in Context.Table1.Include("Table2")... Why do I need to include the association just for one field?

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  • how can i set up a uniqueness constraint in mysql for columns that can be null?

    - by user299689
    I know that in MySQL, UNIQUE constraits don't treat NULL values as equal. So if I have a unique constraint on ColumnX, then two separate rows can have values of NULL for ColumnX and this wouldn't violate the constraint. How can I work around this? I can't just set the value to an arbitrary constant that I can flag, because ColumnX in my case is actually a foreign key to another table. What are my options here? Please note that this table also has an "id" column that is its primary key. Since I'm using Ruby on Rails, it's important to keep this id column as the primary key. Note 2: In reality, my unique key encompasses many columns, and some of them have to be null, because they are foreign keys, and only one of them should be non-null. What I'm actually trying to do is to "simulate" a polymorphic relationship in a way that keep referential integrity in the db, but using the technique outlined in the first part of the question asked here: http://stackoverflow.com/questions/922184/why-can-you-not-have-a-foreign-key-in-a-polymorphic-association

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  • Clustered index on frequently changing reference table of one or more foreign keys

    - by Ian
    My specific concern is related to the performance of a clustered index on a reference table that has many rapid inserts and deletes. Table 1 "Collection" collection_pk int (among other fields) Table 2 "Item" item_pk int (among other fields) Reference Table "Collection_Items" collection_pk int, item_pk int (combined primary key) Because the primary key is composed of both pks, a clustered index is created and the data physically ordered in the table according to the combined keys. I have many users creating and deleting collections and adding and removing items to those collections very frequently affecting the "Collection_Items" table, and its clustered index. QUESTION PART: Since the "Collection_Items" table is so dynamic, wouldn't there be a big performance hit on constantly resorting the table rows because of the clustered index ? If yes, what should I do to minimize this ?

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  • Automatically starting svnserve on Snow Leopard

    - by Cleggy
    Note: I originally asked this question on Server Fault (http://serverfault.com/questions/148052/automatically-starting-svnserve-on-snow-leopard), but I thought this may be a more appropriate place to ask. I have installed Subversion onto my iMac running Snow Leopard, but am having trouble getting svnserve to start up automatically. As I understand it (I'm still fairly green with OSX), the best way to do that is to utilize launchd. To that end, I have created the following .plist file in the /Library/LaunchDaemons folder. If I use launchctl to execute this file, svnserve starts as expected, but it doesn't automatically start when the system starts up or I log in. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Disabled</key> <false/> <key>Label</key> <string>org.tigris.subversion.svnserve</string> <key>UserName</key> <string>Dave</string> <key>ProgramArguments</key> <array> <string>/opt/subversion/bin/svnserve</string> <string>--inetd</string> <string>--root=/Users/Shared/SVNrep</string> </array> <key>ServiceDescription</key> <string>Subversion Standalone Server</string> <key>Sockets</key> <dict> <key>Listeners</key> <array> <dict> <key>SockFamily</key> <string>IPv4</string> <key>SockServiceName</key> <string>svn</string> <key>SockType</key> <string>stream</string> </dict> <dict> <key>SockFamily</key> <string>IPv6</string> <key>SockServiceName</key> <string>svn</string> <key>SockType</key> <string>stream</string> </dict> </array> </dict> <key>inetdCompatibility</key> <dict> <key>Wait</key> <false/> </dict> </dict> </plist> I have tried many different configs in the .plist, including auto-starting, simplifying the listeners section, removing dependence on inetd, but they all show the same symptom. The files work when started using launchctl load, but do not automatically start up svnserve if the iMac is rebooted. If anyone here could provide any suggestions as to how to get this to work, I'd really appreciate it.

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