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  • Avoiding Duplicate Data in DB (for use with Rails)

    - by ants
    I have five tables that I am trying to get to work nicely together but may need some help. I have three main tables: accounts members and roles. With two join tables account_members and account_member_roles. The accounts and members table are joined by account_members (fk account_id and member_id) table. The other 2 tables are the problem (roles and account_member_roles). A member of an account can have more than one role and I have the account_member_roles (fk account_member_id and role_id) table joining the account_members join table and the roles table. That seems logical but can you have a relationship with a join table? What I'd like to be able to do is when creaeting an account, for instance, I would like @account.save to include the roles and update the account_member_roles table neatly ..... but through the account_members join table. I've tried ..... accept_nested_attributes_for :members, :account_member_roles in the account.rb but I get ..... ActiveRecord::HasManyThroughCantAssociateThroughHasManyReflection (Cannot modify association 'Account#account_member_roles' because the source reflection class 'AccountMemberRole' is associated to 'AccountMember' via :has_many.) upon trying to save a record. Any advice on how I should approach this? CIA -ants

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  • bidirectional habtm linking

    - by Alexey Poimtsev
    Hi, all. I have application with 2 groups of models - content based (news, questions) and "something" based (devices, applications etc). I need to link all models between groups - for example question may belongs to 3 different things - one application and 2 devices. The same - for news. From other side - i need to see all news articles and questions related to some application or device. Any idea how to develop this in rails? I have only one idea - mixins that will add methods content_id and thing_id to models and join table.

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  • NHibernate - Stream large result sets?

    - by Dan Black
    Hi, I have to read in a large record set, process it, then write it out to a flat file. The large result set comes from a Stored Proc in SQL 2000. I currently have: var results = session.CreateSQLQuery("exec usp_SalesExtract").List(); I would like to be able to read the result set row by row, to reduce the memory foot print Thanks

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  • MySQL, C++: Retrieving auto-increment ID

    - by Thomas Matthews
    I have a table with an auto-incrementing ID. After inserting a new row, I would like to retrieve the new ID. I found an article that used the MySQL function LAST_INSERT_ID(). The article says to create a new query and submit it. I'm using MySQL Connector C++, Windows XP and Vista, and Visual Studio 9. Here are my questions: Is there an API, for the connector, that will fetch the ID out of the record? Does the result set, after an insert/append, contain the new ID? The LAST_INSERT_ID is MySQL specific. Is there an SQL standard method for obtaining the new ID?

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  • Autoincrement uniqueidentifier in C#

    - by drasto
    Basically I want to use uniqueidentifier in similar way as identity. I don't want to insert values into it, It should just insert values automatically, different value for each row. I'm not able to set autoincrement on columns of type uniqueidentifier(the property 'autoincrement' is set to false and is not editable).

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  • SQL Compact import DB from SQL Server Express with Server Management Studio

    - by Sasha
    Hi! I try to import sql script, generated with Server Management Studio, into SQL Compact 3.5 and get a lot of error. What I am doing wrong? I generate script with "Task/Generate Script" context menu. Part of my script: CREATE TABLE [LogMagazines]( [IdUser] [int] NOT NULL, [Text] [nvarchar](500) NULL, [TypeLog] [int] NOT NULL, [DateAndTime] [datetime] NOT NULL, [DetailMessage] [nvarchar](max) NULL, [Id] [int] IDENTITY(1,1) NOT NULL, CONSTRAINT [PK_LogMagazines] PRIMARY KEY ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] Knowledge Base: http://stackoverflow.com/questions/1525063/how-to-import-data-in-sql-compact-edition http://stackoverflow.com/questions/1515969/exporting-data-in-sql-server-as-insert-into/1515975

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  • Looking for detailed explanation of Hibernate UserType methods for mutable objects

    - by Tom
    I am creating a custom UserType class in Hibernate. The specific case is for an HL7v3 clinical document (I work in health IT). It is a mutable object and most of the documentation around the Hibernate UserType interface seems to center around immutable types. I want a better understanding of how and when the interface methods are used, specifically: assemble - why two parameters (one Serializable, one Object)? What is the use case for this method? disassemble - should I just implement this method to return a serializable form (e.g. String representation)? When and how is this method invoked? equals - is this for update? read? contention? dirty reads? What are the consequences of simply returning false in most cases? replace - I really don't understand where the three Object parameters come from, when this method is invoked, and what Hibernate expects to return, or how that return value is used. Any pointers would be appreciated. I've searched and read all I can find on the subject, but have not found much documentation at all explaining how these methods are used for mutable objects.

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  • Non-Relational DBMS Design Resources

    - by Matt Luongo
    Hey guys, As a personal project, I'm looking to build a rudimentary DBMS. I've read the relevant sections in Elmasri & Navathe (5ed), but could use a more focused text. The rub is that I want to play with novel non-relational data models. While a lot of E&N was great- indexing implementation details in particular- the more advanced DBMS implementation was only targeted to a relational model. I could also use something a bit more practical and detail-oriented, with real-world recommendations. I'd like to defer staring at DBMS source for a while if I can. Any ideas?

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  • KD-Trees and missing values (vector comparison)

    - by labratmatt
    I have a system that stores vectors and allows a user to find the n most similar vectors to the user's query vector. That is, a user submits a vector (I call it a query vector) and my system spits out "here are the n most similar vectors." I generate the similar vectors using a KD-Tree and everything works well, but I want to do more. I want to present a list of the n most similar vectors even if the user doesn't submit a complete vector (a vector with missing values). That is, if a user submits a vector with three dimensions, I still want to find the n nearest vectors (stored vectors are of 11 dimensions) I have stored. I have a couple of obvious solutions, but I'm not sure either one seem very good: Create multiple KD-Trees each built using the most popular subset of dimensions a user will search for. That is, if a user submits a query vector of thee dimensions, x, y, z, I match that query to my already built KD-Tree which only contains vectors of three dimensions, x, y, z. Ignore KD-Trees when a user submits a query vector with missing values and compare the query vector to the vectors (stored in a table in a DB) one by one using something like a dot product. This has to be a common problem, any suggestions? Thanks for the help.

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  • I am not able to create foreign key in mysql Error 150. Please help

    - by Shantanu Gupta
    i am trying to create a foreign key in my table. But when i executes my query it shows me error 150 Error Code : 1005 Can't create table '.\vts#sql-6ec_1.frm' (errno: 150) (0 ms taken) My Queries are Query to create a foreign Key alter table `vts`.`tblguardian` add constraint `FK_tblguardian` FOREIGN KEY (`GuardianPickPointId`) REFERENCES `tblpickpoint` (`PickPointId`) Primary Key table CREATE TABLE `tblpickpoint` ( `PickPointId` int(4) NOT NULL auto_increment, `PickPointName` varchar(500) default NULL, `PickPointLabel` varchar(500) default NULL, `PickPointLatLong` varchar(100) NOT NULL, PRIMARY KEY (`PickPointId`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 CHECKSUM=1 DELAY_KEY_WRITE=1 ROW_FORMAT=DYNAMIC Foreign Key Table CREATE TABLE `tblguardian` ( `GuardianId` int(4) NOT NULL auto_increment, `GuardianName` varchar(500) default NULL, `GuardianAddress` varchar(500) default NULL, `GuardianMobilePrimary` varchar(15) NOT NULL, `GuardianMobileSecondary` varchar(15) default NULL, `GuardianPickPointId` varchar(100) default NULL, PRIMARY KEY (`GuardianId`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1

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  • Join one row to multiple rows in another table

    - by Ghostrider
    I have a table to entities (lets call them people) and properties (one person can have an arbitrary number of properties). Ex: People Name Age -------- Jane 27 Joe 36 Jim 16 Properties Name Property ----------------- Jane Smart Jane Funny Jane Good-looking Joe Smart Joe Workaholic Jim Funny Jim Young I would like to write an efficient select that would select people based on age and return all or some of their properties. Ex: People older than 26 Name Properties Jane Smart, Funny, Good-looking Joe Smart, Workaholic It's also acceptable to return one of the properties and total property count. The query should be efficient: there are millions of rows in people table, hundreds of thousands of rows in properties table (so most people have no properties). There are hundreds of rows selected at a time. Is there any way to do it?

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  • Which is better practice: complex SQL statements or Recordset manipulation in Access VBA?

    - by mazi
    I'm doing some VBA development and I found creating SQLs quite efficient way of getting everything done (selecting and updating). But I got to this stage where my SQL statements contain complex Switches and WHERE conditions where I have another Selects to update appropriate records. Therefore, I create this SQLs and I simply run it via "CurrentDb.Execute strSQL" and it does everything fine. The question is, why would I declare ADODB.connections etc, set recordsets, loop through it and manipulate the data one by one?

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  • Zend_Auth using multiple tables

    - by Christian
    What I'm trying to do is use Zend_Auth for authentication with the issuing being that the 'identity' is stored in a different table then then 'credential.' I'm able to pass an array for the credential and the identity but when it comes to the actual tables I'm not able to get it to accept the array. It ignores the 2nd table name. I was wondering if anyone has ever made this work in this way without extending the Zend_Auth class or if I will need to do so. Thanks in advance.

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  • How to move an element in a sorted list and keep the CouchDb write "atomic"

    - by karlthorwald
    I have elements of a list in couchdb documents. Let's say these are 3 elements in 3 documents: { "id" : "783587346", "type" : "aList", "content" : "joey", "sort" : 100.0 } { "id" : "358734ff6", "type" : "aList", "content" : "jill", "sort" : 110.0 } { "id" : "abf587346", "type" : "aList", "content" : "jack", "sort" : 120.0 } A view retrieves all "aList" documents and displays them sorted by "sort". Now I want to move the elements, when I want to move "jack" to the middle, I could do this atomic in one write and change it's sort key to 105.0. The view now returns the documents in the new sort order. After a lot of sorting I could end up with sort keys like 50.99999 and 50.99998 after some years and in extreme situations run out of digits? What can you recommend, is there a better way to do this? I'd rather keep the elements in seperate documents. Different users might edit different elements in parallel (which also can get tricky). Maybe there is a much better way?

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  • SQL: How do I INSERT primary key values from two tables INTO a master table.

    - by Stefan
    Hello, I would appreciate some help with an SQL statement I really can't get my head around. What I want to do is fairly simple, I need to take the values from two different tables and copy them into an master table when a new row is inserted into one of the two tables. The problem is perhaps best explained like this: I have three tables, productcategories, regioncategories and mastertable. --------------------------- TABLE: PRODUCTCATEGORIES --------------------------- COLUMNS: CODE | DESCRIPTION --------------------------- VALUES: BOOKS | Books --------------------------- --------------------------- TABLE: REGIONCATEGORIES --------------------------- COLUMNS: CODE | DESCRIPTION --------------------------- VALUES: EU | European Union --------------------------- --------------------------- TABLE: MASTERTABLE --------------------------- COLUMNS: REGION | PRODUCT --------------------------- VALUES: EU | BOOKS --------------------------- I want the values to be inserted like this when a new row is created in either productcategories or regioncategories. New row is created. --------------------------- TABLE: PRODUCTCATEGORIES --------------------------- COLUMNS: CODE | DESCRIPTION --------------------------- VALUES: BOOKS | Books --------------------------- VALUES: DVD | DVDs --------------------------- And a SQL statement copies the new values into the mastertable. --------------------------- TABLE: MASTERTABLE --------------------------- COLUMNS: REGION | PRODUCT --------------------------- VALUES: EU | BOOKS --------------------------- VALUES: EU | DVD --------------------------- The same goes if a row is created in the regioncategories. New row. --------------------------- TABLE: REGIONCATEGORIES --------------------------- COLUMNS: CODE | DESCRIPTION --------------------------- VALUES: EU | European Union --------------------------- VALUES: US | United States --------------------------- Copied to the mastertable. --------------------------- TABLE: MASTERTABLE --------------------------- COLUMNS: REGION | PRODUCT --------------------------- VALUES: EU | BOOKS --------------------------- VALUES: EU | DVD --------------------------- VALUES: US | BOOKS --------------------------- VALUES: US | DVD --------------------------- I hope it makes sense. Thanks, Stefan

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  • importing a large txt file in MySQL ?

    - by Taz
    Hi I am loading a text data in MySQL using the following command 'mysql> Load Data local Infile 'C:\\Documents and Settings\\Scan\\My Documents\\D ownloads\\instance_types_en.nt\\Copy of instance_types_en.txt' into table dbpedi aentities.resources fields terminated by ' ' lines terminated by 'rn';' Data is like (actually there is a newline after '.') <a> <b> <c> . <a> <b> <c> . <a> <b> <c> . <a> <b> <c> .<a> <b> <c> . <a> <b> <c> . Table has and auto increment ID field and then text fields for all three values. File size is about 750MB The problems are 1. appears to be in first text field 2. only 2MB data is imported

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  • Porting join from Oracle to Postgres

    - by Grasper
    INSERT INTO MISSION_OBJECTIVE( MSN_INT_ID, MO_INT_ID, MO_MSN_CLASS_NM, MO_MSN_CLASS_CD, MO_MSN_TYPE, MO_PRIORITY, MO_COMMENT, MO_START_DT, MO_END_DT, ASP_AIRSPACE_NM, MO_OBJ_LOCATION, MO_ALO_LEG_ID, MO_ALO_ARRIVE_LOC) SELECT '1025', '1', 'AIRDROP', 'ADP', 'LAPES', NULL, COALESCE( NULL, ' '), TO_TIMESTAMP( '1002260900', 'YYMMDDHH24MI'), TO_TIMESTAMP( '1002260915', 'YYMMDDHH24MI'), 'TRANSIT ALPHA', 'TRANSIT ALPHA', '1', 'TRANSIT ALPHA' FROM AIRSPACE ASP, apsmain .MISSION_CLASS MC WHERE ASP.ASP_AIRSPACE_NM(+)= 'TRANSIT ALPHA' AND MC.MCS_MISSION_CLASS_NAME= 'AIRDROP' AND 'TRANSIT ALPHA' IS NOT NULL Is that exactly the same as: INSERT INTO MISSION_OBJECTIVE( MSN_INT_ID, MO_INT_ID, MO_MSN_CLASS_NM, MO_MSN_CLASS_CD, MO_MSN_TYPE, MO_PRIORITY, MO_COMMENT, MO_START_DT, MO_END_DT, ASP_AIRSPACE_NM, MO_OBJ_LOCATION, MO_ALO_LEG_ID, MO_ALO_ARRIVE_LOC) SELECT '1025', '1', 'AIRDROP', 'ADP', 'LAPES', NULL, COALESCE( NULL, ' '), TO_TIMESTAMP( '1002260900', 'YYMMDDHH24MI'), TO_TIMESTAMP( '1002260915', 'YYMMDDHH24MI'), 'TRANSIT ALPHA', 'TRANSIT ALPHA', '1', 'TRANSIT ALPHA' FROM AIRSPACE ASP, apsmain .MISSION_CLASS MC WHERE ASP.ASP_AIRSPACE_NM = 'TRANSIT ALPHA' AND MC.MCS_MISSION_CLASS_NAME= 'AIRDROP' AND 'TRANSIT ALPHA' IS NOT NULL I just deleted the (+). The part that is confusing me is that ASP.ASP_AIRSPACE_NM is being right joined to a constant.

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  • Struggling to create correct relationships in MS Access

    - by Yandawl
    http://img714.imageshack.us/img714/7820/croppercapture1.png Basically: an award(course) has many units, which can be either optional or core(mandatory), depending on the award. So for example: the unit 'Advanced Software Engineering' maybe a core unit for the award 'Software Engineering BSc' but only an optional unit for the course 'Web Technology BSc'. I've used flags for that purpose. A student is enrolled on an award so I need to get a complete list of core and optional units (bearing in mind that a student chooses 1 out of many possible optional units). Also, these units have events, e.g, a lecture, workshop or seminar, etc. and those events have sessions or instances of events where students enrolled on that particular unit are required to attend, and those attendances are stored in a separate table to form a register. So I need a hierarchy of expanding the tables something like this I guess: Awards - Students - Units - Sessions - Attendances Any help with this would be appreciated... It's blowing my mind and I'm really close to going insane! My tutor didn't spot I'd got it wrong when I showed my original data model to him and it's due in next week! Thank you :D

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  • How to select top n rows from a datatable/dataview in asp.net

    - by skamale
    How to select top n rows from a datatable/dataview in asp.net.currently I am using the following code by passing the table and number of rows to get the records but is there a better way. public DataTable SelectTopDataRow(DataTable dt, int count) { DataTable dtn = dt.Clone(); for (int i = 0; i < count; i++) { dtn.ImportRow(dt.Rows[i]); } return dtn; }

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  • How can I remove rows with unique values? As in only keeping rows with duplicate values?

    - by user1456405
    Here's the conundrum, I'm a complete and utter noob when it comes to programming. I understand the basics, but am still learning javascript. I have a spreadsheet of surveys, in which I need to see how particular users have varied over time. As such, I need to disregard all rows with unique values in a particular column. The data looks like this: Response Date Response_ID Account_ID Q.1 10/20/2011 12:03:43 PM 23655956 1168161 8 10/20/2011 03:52:57 PM 23660161 1168152 0 10/21/2011 10:55:54 AM 23672903 1166121 7 10/23/2011 04:28:16 PM 23694471 1144756 9 10/25/2011 06:30:52 AM 23732674 1167449 7 10/25/2011 07:52:28 AM 23734597 1087618 5 I've found a way to do so in VBA, which sucks as I have to use excel, per below: Sub Del_Unique() Application.ScreenUpdating = False Columns("B:B").Insert Shift:=xlToRight Columns("A:A").Copy Destination:=Columns("B:B") i = Application.CountIf(Range("A:A"), "<>") + 50 If i > 65536 Then i = 65536 Do If Application.CountIf(Range("B:B"), Range("A" & i)) = 1 Then Rows(i).Delete End If i = i - 1 Loop Until i = 0 Columns("B:B").Delete Application.ScreenUpdating = True End Sub But that requires mucking about. I'd really like to do it in Google Spreadsheets with a script that won't have to be changed. Closest I can get is retrieving all duplicate user ids from the range, but can't associate that with the row. That code follows: function findDuplicatesInSelection() { var activeRange = SpreadsheetApp.getActiveRange(); var values = activeRange.getValues(); // values that appear at least once var once = {}; // values that appear at least twice var twice = {}; // values that appear at least twice, stored in a pretty fashion! var final = []; for (var i = 0; i < values.length; i++) { var inner = values[i]; for (var j = 0; j < inner.length; j++) { var cell = inner[j]; if (cell == "") continue; if (once.hasOwnProperty(cell)) { if (!twice.hasOwnProperty(cell)) { final.push(cell); } twice[cell] = 1; } else { once[cell] = 1; } } } if (final.length == 0) { Browser.msgBox("No duplicates found"); } else { Browser.msgBox("Duplicates are: " + final); } } Anyhow, sorry if this is the wrong place or format, but half of what I've found so far has been from stack, I thought it was a good place to start. Thanks!

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