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  • How to do @OneToMany mapping on the field using @transient

    - by hemal
    I am using JPA annotations here , I want to do @OneToMany mapping on filed declared as @Transient. is it possible to do mapping on @transient field ? SimpleTagGroup.java @Entity @Table(name = "TagGroup") public class SimpleTagGroup { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private long id = -1; @NotNull private String tagGroupName; @OneToMany(fetch = FetchType.EAGER) @JoinTable(name = "TagMapping", joinColumns = @JoinColumn(name = "id"), inverseJoinColumns = @JoinColumn(name = "tagId")) @Transient private List<SimpleTag> tags; SimpleTag.java @Entity @Table(name = "Tag") public class SimpleTag implements Tag{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private long id = -1; @NotNull private String tagValue;

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  • Circular database relationships. Good, Bad, Exceptions?

    - by jim
    I have been putting off developing this part of my app for sometime purely because I want to do this in a circular way but get the feeling its a bad idea from what I remember my lecturers telling me back in school. I have a design for an order system, ignoring the everything that doesn't pertain to this example I'm left with: CreditCard Customer Order I want it so that, Customers can have credit cards (0-n) Customers have orders (1-n) Orders have one customer(1-1) Orders have one credit card(1-1) Credit cards can have one customer(1-1) (unique ids so we can ignore uniqueness of cc number, husband/wife may share cc instances ect) Basically the last part is where the issue shows up, sometimes credit cards are declined and they wish to use a different one, this needs to update which their 'current' card is but this can only change the current card used for that order, not the other orders the customer may have on disk. Effectively this creates a circular design between the three tables. Possible solutions: Either Create the circular design, give references: cc ref to order, customer ref to cc customer ref to order or customer ref to cc customer ref to order create new table that references all three table ids and put unique on the order so that only one cc may be current to that order at any time Essentially both model the same design but translate differently, I am liking the latter option best at this point in time because it seems less circular and more central. (If that even makes sense) My questions are, What if any are the pros and cons of each? What is the pitfalls of circular relationships/dependancies? Is this a valid exception to the rule? Is there any reason I should pick the former over the latter? Thanks and let me know if there is anything you need clarified/explained. --Update/Edit-- I have noticed an error in the requirements I stated. Basically dropped the ball when trying to simplify things for SO. There is another table there for Payments which adds another layer. The catch, Orders can have multiple payments, with the possibility of using different credit cards. (if you really want to know even other forms of payment). Stating this here because I think the underlying issue is still the same and this only really adds another layer of complexity.

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  • MySQL - Join as zero if record Not IN

    - by Zurahn
    To explain by example, take two tables, A and B Table A id foo 1 x 2 y 3 z Table B id aid bar 1 3 50 2 1 100 An example join SELECT foo, bar FROM a, b WHERE a.id = b.aid; Garners a result of foo bar z 50 x 100 What I would like to do is get all values of foo and for any instances where there isn't a corresponding bar value, return 0 for that column. My best guess was something along the lines of SELECT foo, bar AS br FROM a, b WHERE a.id = b.aid OR a.id NOT IN (SELECT aid FROM b); But that returns duplicates and non-zero values for bar. Possible?

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  • Java JPA @OneToMany neededs to reciprocate @ManyToOne?

    - by bguiz
    Create Table A ( ID varchar(8), Primary Key(ID) ); Create Table B ( ID varchar(8), A_ID varchar(8), Primary Key(ID), Foreign Key(A_ID) References A(ID) ); Given that I have created two tables using the SQL statements above, and I want to create Entity classes for them, for the class B, I have these member attributes: @Id @Column(name = "ID", nullable = false, length = 8) private String id; @JoinColumn(name = "A_ID", referencedColumnName = "ID", nullable = false) @ManyToOne(optional = false) private A AId; In class A, do I need to reciprocate the many-to-one relationship? @Id @Column(name = "ID", nullable = false, length = 8) private String id; @OneToMany(cascade = CascadeType.ALL, mappedBy = "AId") private List<B> BList; //<-- Is this attribute necessary? Is it a necessary or a good idea to have a reciprocal @OneToMany for the @ManyToOne? If I make the design decision to leave out the @OneToMany annotated attribute now, will come back to bite me further down.

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  • Link a sequence with to an identity in hsqldb

    - by Candy Chiu
    In PostgreSql, one can define a sequence and use it as the primary key of a table. In HsqlDB, one can still accomplish creating an auto-increment identity column which doesn't link to any user defined sequence. Is it possible to use a user defined sequence as the generator of an auto-increment identity column in HsqlDB? Sample sql in PostgreSql: CREATE SEQUENCE seq_company_id START WITH 1; CREATE TABLE company ( id bigint PRIMARY KEY DEFAULT nextval('seq_company_id'), name varchar(128) NOT NULL CHECK (name < '') ); What's the equivalent in HsqlDB? Thanks.

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  • How to return the value from MySql Stored Proc ??

    - by karthik
    I am using the below storedproc to generate the Insert statements of a specified table It is build-ed without any errors. Now i want to return the result set in "V_string" as output of the SP DELIMITER $$ DROP PROCEDURE IF EXISTS `demo`.`InsertGenerator` $$ CREATE DEFINER=`root`@`localhost` PROCEDURE `InsertGenerator`() SWL_return: BEGIN -- SQLWAYS_EVAL# to retrieve column specific information -- SQLWAYS_EVAL# table DECLARE v_string NATIONAL VARCHAR(3000); -- SQLWAYS_EVAL# first half -- SQLWAYS_EVAL# tement DECLARE v_stringData NATIONAL VARCHAR(3000); -- SQLWAYS_EVAL# data -- SQLWAYS_EVAL# statement DECLARE v_dataType NATIONAL VARCHAR(1000); -- SQLWAYS_EVAL# -- SQLWAYS_EVAL# columns DECLARE v_colName NATIONAL VARCHAR(50); DECLARE NO_DATA INT DEFAULT 0; DECLARE cursCol CURSOR FOR SELECT column_name,data_type FROM `columns` -- WHERE table_name = v_tableName; WHERE table_name = 'tbl_users'; DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN SET NO_DATA = -2; END; DECLARE CONTINUE HANDLER FOR NOT FOUND SET NO_DATA = -1; OPEN cursCol; SET v_string = CONCAT('INSERT ',v_tableName,'('); SET v_stringData = ''; SET NO_DATA = 0; FETCH cursCol INTO v_colName,v_dataType; IF NO_DATA <> 0 then -- NOT SUPPORTED print CONCAT('Table ',@tableName, ' not found, processing skipped.') close cursCol; LEAVE SWL_return; end if; WHILE NO_DATA = 0 DO IF v_dataType in('varchar','char','nchar','nvarchar') then SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(',v_colName,'SQLWAYS_EVAL# ''+'); ELSE if v_dataType in('text','ntext') then -- SQLWAYS_EVAL# -- SQLWAYS_EVAL# else SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(cast(',v_colName,'SQLWAYS_EVAL# 00)),'''')+'''''',''+'); ELSE IF v_dataType = 'money' then -- SQLWAYS_EVAL# doesn't get converted -- SQLWAYS_EVAL# implicitly SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# y,''''''+ isnull(cast(',v_colName,'SQLWAYS_EVAL# 0)),''0.0000'')+''''''),''+'); ELSE IF v_dataType = 'datetime' then SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# time,''''''+ isnull(cast(',v_colName, 'SQLWAYS_EVAL# 0)),''0'')+''''''),''+'); ELSE IF v_dataType = 'image' then SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(cast(convert(varbinary,',v_colName, 'SQLWAYS_EVAL# 6)),''0'')+'''''',''+'); ELSE SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(cast(',v_colName,'SQLWAYS_EVAL# 0)),''0'')+'''''',''+'); end if; end if; end if; end if; end if; SET v_string = CONCAT(v_string,v_colName,','); SET NO_DATA = 0; FETCH cursCol INTO v_colName,v_dataType; END WHILE; END $$ DELIMITER ;

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  • Sound not working with Ubuntu 12.10 clean install

    - by ZooRocket
    Did a clean install of Ubuntu 12.10 from 12.04 and the sound is not working now. In 12.04 it worked out of the box. I ran hwinfo --sound > hal.1: read hal dataprocess 4222: arguments to dbus_move_error() were incorrect, assertion "(dest) == NULL || !dbus_error_is_set ((dest))" failed in file ../../dbus/dbus-errors.c line 282. This is normally a bug in some application using the D-Bus library. libhal.c 3483 : Error unsubscribing to signals, error=The name org.freedesktop.Hal was not provided by any .service files 10: PCI 1b.0: 0403 Audio device [Created at pci.318] Unique ID: u1Nb.ekgK5auW5RA SysFS ID: /devices/pci0000:00/0000:00:1b.0 SysFS BusID: 0000:00:1b.0 Hardware Class: sound Model: "Intel 82801G (ICH7 Family) High Definition Audio Controller" Vendor: pci 0x8086 "Intel Corporation" Device: pci 0x27d8 "82801G (ICH7 Family) High Definition Audio Controller" SubVendor: pci 0x1028 "Dell" SubDevice: pci 0x01de Revision: 0x01 Memory Range: 0xfdffc000-0xfdffffff (rw,non-prefetchable) IRQ: 11 (no events) Module Alias: "pci:v00008086d000027D8sv00001028sd000001DEbc04sc03i00" Driver Info #0: Driver Status: snd_hda_intel is active Driver Activation Cmd: "modprobe snd_hda_intel" Config Status: cfg=new, avail=yes, need=no, active=unknown Not sure how to proceed to fix this. Has also worked prior to this version.

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  • What causes this error..please run "exec sp_register_custom_scripting 'CUSTOM_SCRIPT', your_script???

    - by larryr
    Configuration SQL 2005 (Server A) replicates to SQL 2008(Server B) which replicates to SQL 2008(Server C). I recently added a column (to Server A) to a replicated table via script & the DDL change replicated to Server B with out a problem. When the DDL change replicated to Server C, I received the error below. 'DDL replication failed to refresh custom procedures, please run "exec sp_register_custom_scripting 'CUSTOM_SCRIPT', your_script, 'EDI from xx', 'table_name_here' "and try again (Source: MSSQLServer, Error number: 21814)' These subscriptions (on Server B to Server C) were created via a script below. **exec sp_addsubscription @publication = N'EDI to XLOCX', @subscriber = N'RXLOCXS-SQLA', @destination_db = N'EDI', @subscription_type = N'Push', @sync_type = N'replication support only', @article = N'all', @update_mode = N'read only', @subscriber_type = 0 exec sp_addpushsubscription_agent @publication = N'EDI to XLOCX (Merge)', @subscriber = N'RXLOCXS-SQLA', @subscriber_db = N'EDI', @job_login = N'ROUSES.COM\RXLOCXSQLREPL', @job_password = N'XPASSWORDX', @subscriber_security_mode = 1, @frequency_type = 4, @frequency_interval = 1, @frequency_relative_interval = 1, @frequency_recurrence_factor = 1, @frequency_subday = 8, @frequency_subday_interval = 1, @active_start_time_of_day =3300, @active_end_time_of_day = 235959, @active_start_date = 20070923, @active_end_date = 99991231, @enabled_for_syncmgr = N'False', @dts_package_location = N'Distributor'** GO So the million dollar question is, why do I get the error 'exec sp_register_custom_scripting 'CUSTOM_SCRIPT', your_script' when I add a column to a table in the EDI to XLOCX publication??? AHIA, LarryR...

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  • MySQL join headaches, please help!

    - by Andrew Heath
    Ok, I've hit the wall here and need some help. Sample tables are as follows: SCENARIO_NATIONS [scenID] [side] [nation] scen001 1 Germany scen001 2 Britain scen001 2 Canada SCENARIO_NEEDUNITS [scenID] [unitID] scen001 0001 scen001 0003 scen001 0107 scen001 0258 scen001 0759 UNIT_BASIC_DATA [unitID] [nation] [name] 0001 Germany Mortars 0003 Germany Infantry 0107 Britain Lt 0258 Britain Infantry 0759 Canada Kilted Yaksmen Goal: given a scenID, pull a list of units from the database sorted by side, nation, name. I can do everything except for the side inclusion with: SELECT scenario_needunits.scenID, unit_basic_data.nation, unit_basic_data.name FROM scenario_needunits LEFT OUTER JOIN unit_basic_data ON scenario_needunits.unitID=unit_basic_data.unitID WHERE scenario_needunits.scenID='scen001' ORDER BY unit_basic_data.nation ASC, unit_basic_data.name ASC I've tried just dropping the SCENARIO_NATIONS table in as a LEFT OUTER JOIN on scenID but what ends up happening is that ALL units come back with a side of 1 because that's always the first side listed for the scenID in the SCENARIO_NATIONS table. Conceptually, what I think needs to happen is SCENARIO_NATIONS must be joined to both the scenID (to restrict it to just that scenario) and to each unit's nation but I don't have any idea how to do that and my Google-fu is inadequate. :-/

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  • Error 3032 during EF 4.0 validation

    - by Mohammadreza
    Hi guys. I have a table that has a column called "rowguid" with default value of newguid(). After I delete the generated property in the Entity Framework 4.0 designer, whenever I try to build or validate the model I receive the following error message. Error 3023: Problem in mapping fragments starting at line 1460:Column People.rowguid in table People must be mapped: It has no default value and is not nullable. It's an obvious error message but the problem is that the column HAS default value. Does anyone knows what the problem is? Thanks.

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  • In a virtual machine monitor such as VMware's ESXi Server, how are shadow page tables implemented?

    - by ali01
    My understanding is that VMMs such as VMware's ESXi Server maintain shadow page tables to map virtual page addresses of guest operating systems directly to machine (hardware) addresses. I've been told that shadow page tables are then used directly by the processor's paging hardware to allow memory access in the VM to execute without translation overhead. I would like to understand a bit more about how the shadow page table mechanism works in a VMM. Is my high level understanding above correct? What kind of data structures are used in the implementation of shadow page tables? What is the flow of control from the guest operating system all the way to the hardware? How are memory access translations made for a guest operating system before its shadow page table is populated? How is page sharing supported? Short of straight up reading the source code of an open source VMM, what resources can I look into to learn more about hardware virtualization?

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  • How do I specify a null relation in SQLAlchemy?

    - by Jesse
    Not sure what the correct title for this question should be. I have the following schema: Matters have a one-many relationship to WorkItems. WorkItems have a one-one (or one-zero) relationship to LineItems. I am trying to create the following relation between Matters and WorkItems Matter.unbilled_work_items = orm.relation(WorkItem, primaryjoin = (Matter.id == WorkItem.matter_id) and (WorkItem.line_item_id == None), foreign_keys = [WorkItem.matter_id, WorkItem.line_item_id], viewonly=True ) This throws: AttributeError: '_Null' object has no attribute 'table' That seems to be saying that the second clause in the primaryjoin returns an object of type _Null, but it seems to be expecting something with a "table" attribute. This seems like it should be pretty straightforward to me, am I missing something obvious?

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  • Select records from XML column (SQL Server 2005) based on node order

    - by jdoe
    I have a column in a SQL Server 2005 table defined as an XML column. Is there a way to select records from this table based on the order of two nodes in that column? For example, we have the following structure in our XML: <item> <latitude/> <longitude/> </item> I want to see if there are any records that have latitude/longitude in the opposite order i.e. <longitude/> then <latitude/>. I've tried some XPath expressions but with no luck.

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  • Wix Installer - How to customize FatalError dialog based on server actions

    - by Paul
    I need to display different messages in the FatalError dialog depending on what caused the installation to fail. My first attempt was to make the FatalError description text point to a property, and then set this property's value when an error appeared. The problem is that this dialog runs in the InstallUISequence table and the problematic actions in the InstallExecuteSequence table, and apparently the values that are set during InstallExecuteSequence are not copied back to the UI, and thus I'm losing them when the dialog is created. Any ideas on how to solve this? Thanks!

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  • Is a many-to-many relationship with extra fields the right tool for my job?

    - by whichhand
    Previously had a go at asking a more specific version of this question, but had trouble articulating what my question was. On reflection that made me doubt if my chosen solution was correct for the problem, so this time I will explain the problem and ask if a) I am on the right track and b) if there is a way around my current brick wall. I am currently building a web interface to enable an existing database to be interrogated by (a small number of) users. Sticking with the analogy from the docs, I have models that look something like this: class Musician(models.Model): first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) dob = models.DateField() class Album(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) class Instrument(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) Where I have one central table (Musician) and several tables of associated data that are related by either ForeignKey or OneToOneFields. Users interact with the database by creating filtering criteria to select a subset of Musicians based on data the data on the main or related tables. Likewise, the users can then select what piece of data is used to rank results that are presented to them. The results are then viewed initially as a 2 dimensional table with a single row per Musician with selected data fields (or aggregates) in each column. To give you some idea of scale, the database has ~5,000 Musicians with around 20 fields of related data. Up to here is fine and I have a working implementation. However, it is important that I have the ability for a given user to upload there own annotation data sets (more than one) and then filter and order on these in the same way they can with the existing data. The way I had tried to do this was to add the models: class UserDataSets(models.Model): user = models.ForeignKey(User) name = models.CharField(max_length=100) description = models.CharField(max_length=64) results = models.ManyToManyField(Musician, through='UserData') class UserData(models.Model): artist = models.ForeignKey(Musician) dataset = models.ForeignKey(UserDataSets) score = models.IntegerField() class Meta: unique_together = (("artist", "dataset"),) I have a simple upload mechanism enabling users to upload a data set file that consists of 1 to 1 relationship between a Musician and their "score". Within a given user dataset each artist will be unique, but different datasets are independent from each other and will often contain entries for the same musician. This worked fine for displaying the data, starting from a given artist I can do something like this: artist = Musician.objects.get(pk=1) dataset = UserDataSets.objects.get(pk=5) print artist.userdata_set.get(dataset=dataset.pk) However, this approach fell over when I came to implement the filtering and ordering of query set of musicians based on the data contained in a single user data set. For example, I could easily order the query set based on all of the data in the UserData table like this: artists = Musician.objects.all().order_by(userdata__score) But that does not help me order by the results of a given single user dataset. Likewise I need to be able to filter the query set based on the "scores" from different user data sets (eg find all musicians with a score 5 in dataset1 and < 2 in dataset2). Is there a way of doing this, or am I going about the whole thing wrong?

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  • Selecting two field in MySQL with PHP

    - by Crays
    Hi guys, i'm relatively new to php and mysql and would like to know how to select two value in mysql with php. What i have is $query = sprintf("SELECT COUNT(id) FROM table WHERE UPPER(username) = UPPER('%s') AND password='%s'"... in this case, i'm only selecting and count if the id exist and i use list($count) = mysql_fetch_row($result); if($count == 1) and by using cookies, i would like to retrieve two value from the database, namely user (the user's name) and power (which has value of 1,2 or 3, indicating the menu they would be able to see) basically it is to differentiate if you're admin or normal user, but i wonder if i could do SELECT COUNT(id) AND power FROM table WHERE ... is this possible? or is there any other way? Please guide me, thanks.

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  • Calculate open timeslots given availability and existing appointments - by day

    - by Andre
    Overview: I have a table which stores a persons "availability" for a current day, e.g. Mon - 8:00am - 11:30am Mon - 1:30pm - 6:00pm A second table stores appointments that this person already has for the same day, e.g. Mon - 8:30am - 11:00am Mon - 2:30pm - 4pm Desired result: Doing calculationsI'd like to have the following result - e.g. "this person has availability on the given day": Mon - 8:00am - 8:30am Mon - 11:00am - 11:30am Mon - 1:30pm - 2:30pm Mon - 4:00pm - 6:00pm Any ideas on how to calculate the output given the two inputs (e.g. availability, existing appointments) would be greatly appreciated. Preferably I'd use javascript on the client to do the calculating as I would believe that doing it within the DB (I'm using MSSQL) would be slow for many records, persons, etc. Hope this is enough information to illustrate the problem at hand - Many thanks in advance.

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  • Customizing Bugzilla 4.0.2 Bug ID numbers

    - by Marcus Polk
    Is it possible to customize Bugzilla bug numbers and add a letter designator, to immediately know it came from Bugzilla? My company is evaluating Bugzilla and has now added many new bugs. We also use 2 other bug databases. This wasn't my decision and I believe they were trying to incorporate better reporting, etc. I read an answer here about "seeding" Bugzilla bug numbers, by setting the "AUTO_INCREMENT" field in the "bugs" table to a different value. I wish I would've thought about this sooner and found this board. Setting that value to start at 9000 or some extraordinary value would have ensured that we knew exactly which bugs came from Bugzilla. However, would it be possible to change the field in the "bugs" table to accept letters, as well? Of course that would probably just mess up the whole auto incrementing of the numbers. Any help or advice is greatly appreciated. Thank you.

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  • sql jdbc getgeneratedkeys with mysql returns column "id" not found

    - by iamrohitbanga
    I want to retrieve the most recently updated value in the table using an insert query. these are the datatypes in my sql table. int(11) // primary key auto increment, not being assigned by sqlQuery varchar(30) timestamp // has a default value. but i am explicit assigning it using CURRENT_TIMESTAMP varchar(300) varchar(300) varchar(300) int(11) varchar(300) // java code statement.executeUpdate(sqlQuery, Statement.RETURN_GENERATED_KEYS); ResultSet rs = statement.getGeneratedKeys(); System.out.println("here: " + rs.getMetaData().getColumnCount()); System.out.println("here1: " + rs.getMetaData().getColumnName(1)); // none of the following 3 works System.out.println("id: " + rs.getInt(1)); System.out.println("id: " + rs.getInt("GENERATED_KEY")); System.out.println("id: " + rs.getInt("id")); for a bit of background see this

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  • will_paginate without use of activerecord

    - by truthSeekr
    I apologize if this is a trivial question or my understanding of rails is weak. I have 2 actions in my controller, index and refine_data. index fetches and displays all the data from a database table. refine_data weeds out unwanted data using regex and returns a subset of the data. Controller looks like: def index Result.paginate :per_page => 5, :page => params[:page], :order => 'created_at DESC' end def refine_data results = Result.all new_results = get_subset(results) redirect_to :action => 'index' end I would like to redirect the refine_data action to the same view (index) with new_results. As new_results are not from the database table (or model), how do I go about constructing my paginate?

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  • Hibernate, alter identifier/primary key

    - by Schildmeijer
    I receive the following exception when Im trying to alter my @ID in an @Entity. identifier of an instance of com.google.search.pagerank.ItemEntity was altered from 1 to 2. I know that im altering the primary key in my table. Im using JPA-annotations. I solved this by using this single HQL query: update Table set name=:newName where name=:oldName instead of using the more oo approach: beginTransaction(); T e = session.load(...); e.setName(newName); session.saveOrUdate(e); commit(); Any idea what the diff is?

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  • [JQuery] Highlight a Radio field and then pop up an input text box field

    - by kwokwai
    Hi all, I am trying to make some dynamic effect to a HTML page using JQuery. 1. When the user clicks a Radio feild, the field will be highlighted. 2. When the user clicks the Radio 'Man', a Input text box will be provided immeditely just below it. Here is my simple HTML page, but I don't know how to do with the JQuery part: <Table> <TR> <TD>Gender</TD> <TD> Man: <INPUT type=radio name="gender" value="M"><Br/> Woman: <INPUT type=radio name="gender" value="F"> </TD> </TR> <?Table>

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  • What is the effect on record size of reordering columns in PostgreSQL?

    - by Summer
    Since Postgres can only add columns at the end of tables, I end up re-ordering by adding new columns at the end of the table, setting them equal to existing columns, and then dropping the original columns. So, what does PostgreSQL do with the memory that's freed by dropped columns? Does it automatically re-use the memory, so a single record consumes the same amount of space as it did before? But that would require a re-write of the whole table, so to avoid that, does it just keep a bunch of blank space around in each record? Thanks! ~S

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  • Need help optimizing MYSQL query with join

    - by makeee
    I'm doing a join between the "favorites" table (3 million rows) the "items" table (600k rows). The query is taking anywhere from .3 seconds to 2 seconds, and I'm hoping I can optimize it some. Favorites.faver_profile_id and Items.id are indexed. Instead of using the faver_profile_id index I created a new index on (faver_profile_id,id), which eliminated the filesort needed when sorting by id. Unfortunately this index doesn't help at all and I'll probably remove it (yay, 3 more hours of downtime to drop the index..) Any ideas on how I can optimize this query? In case it helps: Favorite.removed and Item.removed are "0" 98% of the time. Favorite.collection_id is NULL about 80% of the time. SELECT `Item`.`id`, `Item`.`source_image`, `Item`.`cached_image`, `Item`.`source_title`, `Item`.`source_url`, `Item`.`width`, `Item`.`height`, `Item`.`fave_count`, `Item`.`created` FROM `favorites` AS `Favorite` LEFT JOIN `items` AS `Item` ON (`Item`.`removed` = 0 AND `Favorite`.`notice_id` = `Item`.`id`) WHERE ((`faver_profile_id` = 1) AND (`collection_id` IS NULL) AND (`Favorite`.`removed` = 0) AND (`Item`.`removed` = '0')) ORDER BY `Favorite`.`id` desc LIMIT 50;

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  • How do I choose a database?

    - by liamzebedee
    I need a comparison table of some sort for database varieties (MySQL, SQLite etc.). I can't find one. My use case is, I am implementing storage of objects in a distributed hash table. I need a database solution that is: Fast for sorting Simplistic (no users, preferably no additional structures like multiple tables etc.) Concurrent (if possible) Multi-platform File based (not stored in memory primarily) Centralized I will be programming in Go. As I understand, I believe I need what is called a Document Orientated Database, because I am storing objects, identified by keys. EDIT: While I am implementing a DHT, I will also be storing metadata about the objects, such as access counts etc. It would also be preferable to have TLL (time to live)

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