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  • How to reserve a set of primary key identifiers for preloading bootstrap data

    - by Joshua
    We would like to reserve a set of primary key identifiers for all tables (e.g. 1-1000) so that we can bootstrap the system with pre-loaded system data. All our JPA entity classes have the following definition for the primary key. @Id @GeneratedValue(strategy = IDENTITY) @Column(name = "id", unique = true, nullable = false, insertable = false, updatable = false) private Integer id; is there a way to tell the database that increments should start happening from 1000 (i.e. customer specific data will start from 1000 onwards). We support (h2, mysql, postgres) in our environment and I would prefer a solution which can be driven via JPA and reverse engineering DDL tools from Hibernate. Let me know if this is the correct approach

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  • ManyToMany Relation does not create the primary key

    - by Javi
    Hello, I have a ManyToMany relationship between two classes: ClassA and ClassB, but when the table for this relationship (table called objectA_objectB) there is no primary key on it. In my ClassA I have the following: @ManyToMany(fetch=FetchType.LAZY) @OrderBy(value="name") @JoinTable(name="objectA_objectB", joinColumns= @JoinColumn(name="idObjectA", referencedColumnName="id"), inverseJoinColumns= @JoinColumn(name="idObjectB", referencedColumnName="id") ) private List<ClassB> objectsB; and in my ClassB I have the reversed relation @ManyToMany List<ClassA> objectsA; I just want to make a primary key of both id's but I need to change the name of the columns as I do. Why is the PK missing? How can I define it? I use JPA 2.0 Hibernate implementation, if this helps. Thanks.

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  • Very long strings as primary keys in a database for caching

    - by Bill Zimmerman
    Hi, I am working on a web app that allows users to create dynamic PDF files based on what they enter into a form (it is not very structured data). The idea is that User 1 enters several words (arbitrary # of words, practically capped of course), for example: A B C D E There is no such string in the database, so I was thinking: Store this string as a primary key in a MySQL database (it could be maybe around 50-100k of text, but usually probably less than 200 words) Generate the PDF file, and create a link to it in the database When the next user requests A B C D E, then I can just serve the file instead of recreating it each time. (simple cache) The PDF is cpu intensive to generate, so I am trying to cache as much as I can... My questions are: Does anyone have any alternative ideas to my approach What will the database performance be like? Is there a better way to design the schema than using the input string as the primary key?

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  • Getting the primary key back from a SQL insert with SQLLite

    - by Paul Nathan
    Hi, I have a SQL table set that looks like this create table foo ( id int primary key asc, data datatype ); create table bar ( id int primary key asc, fk_foo int, foreign key(foo_int) references foo(id)); Now, I want to insert a record set. insert into table foo (data) values (stuff); But wait - to get Bar all patched up hunkydory I need the PK from Foo. I know this is a solved problem. What's the solution?

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  • When should I consider representing the primary-key ...?

    - by JMSA
    When should I consider representing the primary-key as classes? Should we only represent primary keys as classes when a table uses composite-key? For example: public class PrimaryKey { ... ... ...} Then private PrimaryKey _parentID; public PrimaryKey ParentID { get { return _parentID; } set { _parentID = value; } } And public void Delete(PrimaryKey id) {...} When should I consider storing data as comma-separated values in a column in a DB table rather than storing them in different columns?

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  • NHibernate - get List<long> representing primary keys?

    - by Nathan
    I have a situation where I definitely don't want to get the whole domain object. Basically, the entity has a primary key of long (.NET)/bigint(sql server 2005). I simply need to pass the primary key to an external system which will access the database directly - and since the list of ids could be large, I don't want to rehydrate the entire domain object just to get the Id. In linq2sql, I could accomplish this with a projection, but I am restricted to NHibernate 1.2.1.4000, which doesn't support Linq. Is there a way to accomplish this using NHibernate 1.2.1.4000? (I am open to using a named-query if that will work)

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  • Rails 3: habtm migration, primary key issue

    - by Brian Wigginton
    I'm trying to setup a migration file for a habtm relationship, however when I run the migration I'm getting the following error: Primary key is not allowed in a has_and_belongs_to_many join table (parts_vehicles). Here is my migration file (20110111035950_create_parts_vehicles.rb): class CreatePartsVehiclesJoinTable < ActiveRecord::Migration def self.up create_table :parts_vehicles, :id => false do |t| t.integer :part_id t.integer :vehicle_id end end def self.down drop_table :parts_vehicles end end The documentation example states to use :id => false to disable a primary key from being generated, but I'm still getting the error.

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  • Drupal limit number of menu items in primary links

    - by ninusik
    Is there a way to set a limit on how many menu items users can add to Primary Links menu? I'm working on a Drupal site and I have a horizontal primary links nav bar. There is only room for no more than 7-8 links in the nav bar. I don't want the future maintainer of the site to add more than 8 items to the menu. Is there a way I can set a limit on that? Some module or override function? Thanks,

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  • Composite Primary and Cardinality

    - by srini.venigalla
    I have some questions on Composite Primary Keys and the cardinality of the columns. I searched the web, but did not find any definitive answer, so I am trying again. The questions are: Context: Large (50M - 500M rows) OLAP Prep tables, not NOSQL, not Columnar. MySQL and DB2 1) Does the order of keys in a PK matter? 2) If the cardinality of the columns varies heavily, which should be used first. For example, if I have CLIENT/CAMPAIGN/PROGRAM where CLIENT is highly cardinal, CAMPAIGN is moderate, PROGRAM is almost like a bitmap index, what order is the best? 3) What order is the best for Join, if there is a Where clause and when there is no Where Clause (for views) Thanks in advance.

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  • Hibernate without primary keys generated by db?

    - by Michael Jones
    I'm building a data warehouse and want to use InfiniDB as the storage engine. However, it doesn't allow primary keys or foreign key constraints (or any constraints for that matter). Hibernate complains "The database returned no natively generated identity value" when I perform an insert. Each table is relational, and contains a unique integer column that was previously used as the primary key - I want to keep that, but just not have the constraint in the db that the column is the primary key. I'm assuming the problem is that Hibernate expects the db to return a generated key. Is it possible to override this behaviour so I can set the primary key field's value myself and keep Hibernate happy? -- edit -- Two of the mappings are as follows: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jun 1, 2010 2:49:51 PM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="com.example.project.Visitor" table="visitor" catalog="orwell"> <id name="id" type="java.lang.Long"> <column name="id" /> <generator class="identity" /> </id> <property name="firstSeen" type="timestamp"> <column name="first_seen" length="19" /> </property> <property name="lastSeen" type="timestamp"> <column name="last_seen" length="19" /> </property> <property name="sessionId" type="string"> <column name="session_id" length="26" unique="true" /> </property> <property name="userId" type="java.lang.Long"> <column name="user_id" /> </property> <set name="visits" inverse="true"> <key> <column name="visitor_id" /> </key> <one-to-many class="com.example.project.Visit" /> </set> </class> </hibernate-mapping> and: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jun 1, 2010 2:49:51 PM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="com.example.project.Visit" table="visit" catalog="orwell"> <id name="id" type="java.lang.Long"> <column name="id" /> <generator class="identity" /> </id> <many-to-one name="visitor" class="com.example.project.Visitor" fetch="join" cascade="all"> <column name="visitor_id" /> </many-to-one> <property name="visitId" type="string"> <column name="visit_id" length="20" unique="true" /> </property> <property name="startTime" type="timestamp"> <column name="start_time" length="19" /> </property> <property name="endTime" type="timestamp"> <column name="end_time" length="19" /> </property> <property name="userAgent" type="string"> <column name="user_agent" length="65535" /> </property> <set name="pageViews" inverse="true"> <key> <column name="visit_id" /> </key> <one-to-many class="com.example.project.PageView" /> </set> </class> </hibernate-mapping>

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  • Creating a db driven primary navigation in django?

    - by Fedor
    I find that it's pretty common most people hardcode the navigation into their templates, but I'm dealing with a pretty dynamic news site which might be better off if the primary nav was db driven. So I was thinking of having a Navigation model where each row would be a link. link_id INT primary key link_name varchar(255) url varchar(255) order INT active boolean If anyone's done something similar in the past, would you say this sort of schema is good enough? I also wanted for there to be an optional dropdown in the admin near the url field so that a user could choose a Category model's slug since category links would be common, but I'm not quite sure how that would be possible.

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  • Set primary key on hibernate generated sequence table

    - by bungrudi
    setup: hibernate 3.3, MySQL 5 I have an hibernate entity that have its PK generated using a sequence table. The annotation looks like this: @GenericGenerator(name = "SCENARIO_TABLE_GEN", strategy = "org.hibernate.id.enhanced.TableGenerator", parameters = { @Parameter(name = "initial_value", value = "5"), @Parameter(name = "force_table_use", value = "true"), @Parameter(name = "table_name", value = "SEQ_TABLE"), @Parameter(name = "value_column_name", value = "VALUE_COL"), @Parameter(name = "segment_column_name", value = "KEY_COL"), @Parameter(name = "segment_value", value = "SCENARIO") }) The problem is, that hibernate generated sequence table (SEQ_TABLE in my case, generated using hbm2ddl) does not have a primary keys. How do I tell hibernate that I want to have the primary key for the sequence table set on KEY_COL ?

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  • SQL Server Express: Failed to add primary key after creating a database table

    - by Syd
    Scenario: I have created a database table. And when I tried to add a primary key (using the SQL Server Management Studiio) to the table, it failed with an error message "Saving changes is not permitted. The changes you have made requrie the following tables to be dropped and re-created. You have either made changes to a table that can't be recreated or enabled the option Prevent savign changes that require the table to be re-created." The environment is Windows 7. I have earlier installed it on a Windows XP SP2 and it worked. And yes, my table is empty (freshly created). My current workaround is to run the "Drop and Create" script. The other alternative is to create the primary key before I save the table. Is this a bug or a limitation with the Express version?

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  • Copying Primary key to another field in Access.

    - by BashLover
    Hey, I'm struggling to copy the Primary Key to another field in Access. This is irrelevant , but clarifying on what I'm comparing. ... WHERE Tunniste=" & [Tarkiste] & "" Tunniste = Primary Key , Autonumber , ID (Generated by Access.) Tarkiste = This is the field I want to copy it to compare it. I'm open to suggestions, I've already try'ed with Form_Load, using the following code. Private Sub Form_Load() DoCmd.RunSQL "UPDATE Korut SET [Tarkiste]=('" & Tunniste & "');" End Sub But this copied the same key to all the entries in "Tarkiste" field. In simplicity I want 1:1 copy of field "Tunniste" to "Tarkiste" , whichever method it takes. Started from this question. File Picker Replaces All Rows With The Same Choice.

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  • is it a good idea to change a recovery partition from primary to logical? [HP laptop]

    - by DiegoDD
    I have a new HP laptop, model dv6-6c85la, with 1TB hard drive, and it has 4 primary partitions, like this: |<- system [199 MB] -|<- c: [899.8 GB] -|<- d:(recovery) [27.5 GB] -|<- e:(hp_tools) [4 GB] -| I wanted to make another partition, splitting "C" which is the main partition, into TWO partitions, and leave the rest as it is. but it doesn't let me because they are already 4 primary partitions (the ones in the diagram). I read somewhere, that i could in fact split C into 2 partitions, but only if the adjacent partition (in this case d:(recovery) is converted into a "logical" partition. That way, the new unallocated part taken from C, and the recovery partition, would each be logical, "inside" an extended partition (right???) As i understand, the resulting partitions would be: primary (system, no letter), primary (c:), extended [ logical (x:) | logical(d:recovery) ], primary (e: hp_tools) "x" being the new one. am i correct? My question is, if i do convert the recovery partition to logical (and thus, it is inside an extended partition adjacent to the new "x:" one), would i have any problems when in case of a disaster i would like to restore the system using the now logical instead of primary RECOVERY partition? Or it is completely safe to change it to logical? My main concern is because i think i may need to be primary so the recovery can proceed in boot time? Or i am completely wrong? how does the recovery process happens? I also understand that i can simply create recovery media, in DVDs, and then even i would be able to delete that recovery partition completely, but as of now, i don't want to do that. I may create the disks, but i don't want to delete the partition, simply because it would be a lot faster and easier to recover from a hard drive than disks. Wrapping up: if i change a recovery partition from primary to logical, will the system still be capable of using it to recover? or it NEEDS to be primary to work? The whole point is that i want to split C:, but as things are, i cant directly, i'd need to change the recovery partition to logical. Or is there another way? thanks.

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  • Keycodes of function keys with F-lock off?

    - by ak
    Many recent keyboard from Microsoft and Logitech have a so-called F-Lock key, which toggles the function keys F1 to F12 between their traditional keycodes and new meanings that are printed onto the keys: F1=Help F2=Undo F3=Redo F4=Open ... . (See also http://en.wikipedia.org/wiki/F-Lock.) This means that long-established shortcuts such as Alt+F4 no longer work if the F-lock is off, and googling shows that quite a few people are unhappy about this. So I'm wondering, what virtual key (VK) codes do the function keys send when F-lock is off? VK_F13 to VK_F24 perhaps? Or do they not trigger standard keyboard events at all? (I haven't got such a keyboard to try and find out myself, and didn't manage to dig up anything on MSDN about this.)

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  • ActiveRecord fundamentally incompatible with composite keys?

    - by stimms
    I have been attempting to use subsonic for a project on which I'm working. All was going quite well until I encountered a link table with a composite primary key. That is a key made up of the primary keys of the two tables it joins. Subsonic failed to recognize both keys which was problematic. I was going to adjust subsonic to support compound keys but I stopped and though "Maybe there is a reason for this". Normally active record relies on a single primary key field for every record, even in link tables. But is this necessary? Should I just give up on active record for this project or continue with my modifications?

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  • JDO in Google App Engine: order of keys in unowned one-to-many relationship

    - by Kel
    I'm implementing web application with JDO in Google App Engine. According to documentation, in owned one-to-many relationships, order of elements in "owner" object collection is determined either by automatically created index field, or by information given in explicit ordering clause. For example: @PersistenceCapable public class Person { // ... @Order(extensions = @Extension(vendorName="datanucleus", key="list-ordering", value="country asc, city asc")) private List<ContactInfo> contacts = new List<ContactInfo>(); In unowned relationships, "owner" object contains collection of keys of "nested" objects, for example: @PersistenceCapable public class Author { // ... @Persistent private List<Key> books; Is order of keys preserved, if I use List<Key> collection in "owner" object for storing keys of "nested" elements? I could not find answer neither in JDO relationships article, nor in Data Classes article :(

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  • Make Arrow and delete keys work in Korn shell Command line

    - by user66854
    Hi all, I am new to unix and am using sun solaris (v10 i think) . I have my shell set as korn shell . i am wondering how to make the arrow keys and delete key work in the command line . I have done set -o emacs and the backspace works , but not the arrow keys and the delete keys . Also is it possible to set the up and down arrow key to cycle through the command line history ? . any help is appreciated .

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  • mysql add auto increment and a additional key

    - by Lee
    Hey all I am trying to alter a table with adding a new column setting it as auto increment and with a key. The table already has one key and this one will be an addition. The error I get is the following. error : Multiple primary key defined My code is: alter table user add column id int (11) NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST; I have also tries wrapping the key name ie alter table user add column id int (11) NOT NULL AUTO_INCREMENT PRIMARY (id) KEY FIRST; But still no luck. How can it be done ?

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