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  • Best way to handle Many-to-Many relationships in PHP MySQL

    - by Jayrox
    I am looking for the best way to handle a database of many-to-many relationships in PHP and MySQL. Right now I have 2 tables: Users (id, user_name, first_name, last_name) Connections (id_1, id_2) In the User table id is auto incremented on add and user_name is unique, but can be changed. Unfortunately, I don't have control over the user_name and its ability to be changed, but I must account for it. The Connections table is obviously, user1 and user2's id. The connection table needs to account for these possible relations: user1 --> user2 (user 1 friends with user 2 but not user2 friends with user1) user2 --> user1 (user 2 friends with user 1 but not user1 friends with user2) user1 <--> user2 (user 1 and user 2 mutually friends) user1 <-!-> user2 (user 1 and user 2 not friends) That part is not the problem, The problem I am having with is keeping these relations unique when and if they change in batches. Possible solution 1: delete all of user 1's relations and readd them with the updated list. I think this might be too slow for my needs. Solution 2? Anyone else encounter this problem? How should I best handle this? update: distinguishing relationships: i handle relationships like this: user1, user2 user1, user3 user2, user1 in that example the following is true: user1 follows user2 and user3 user2 only follows user1 but doesn't follow user3 user3 doesn't follow either user1 or user2

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  • Help with SQL Query

    - by djfrear
    With regards to the following statement: Select * From explorer.booking_record booking_record_ Inner Join explorer.client client_ On booking_record_.labelno = client_.labelno Inner Join explorer.tour_hotel tour_hotel_ On tour_hotel_.tourcode = booking_record_.tourrefcode Inner Join explorer.hotelrecord hotelrecord_ On tour_hotel_.hotelcode = hotelrecord_.hotelref Where booking_record_.bookingdate Not Like '0000-00-00' And booking_record_.tourdeparturedate Not Like '0000-00-00' And hotelrecord_.hotelgroup = "LPL" And Year(booking_record_.tourdeparturedate) Between Year(AddDate(Now(), Interval -5 Year)) And Year(Now()) My MySQL skills are certainly not up to scratch, the actual result set I wish to find is "a customer who has been to 5 or more LPL hotels in the past 5 years". So far I havent got as far as dealing with the count as I'm getting a huge number of results with some 250+ per customer. I assume this is to do with the way I'm joining tables. Schema wise the booking_record table contains a tour reference code, which links to tour_hotel which then contains a hotelcode which links to hotelrecord. This hotelrecord table contains the hotelgroup. The client table is joined to the booking_record via a booking reference and a client may have many bookings. If anyone could suggest a way for me to do this I'd be very grateful and hopefully learn enough to do it myself next time! I've been scratching my head over this one for a few hours now! Customers may have many bookings within booking_record Daniel.

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  • Use an audio/video file from a Linux laptop via USB to be played by Magic Sing ET-23H

    - by AisIceEyes
    I am one of the technical directors of a regular karaoke contest event. For the karaoke contest itself, due to tight budget, we are using what one of the sponsors are providing - Magic Sing ET-23H . The video output of the Magic Sing ET-23H are broadcasted at two big screens that are being shown to the audience and event attendees. When a karaoke contestant provides his / her karaoke video, the video itself is in a readable USB flashdrive and is attached to the USB input of Magic Sing ET-23H. What really bugs me is that the interface of Magic Sing ET-23H are also being broadcasted at the big screen video feeds. The interface of choosing the video file is being seen in the Magic Sing ET-23H - also to the big video screens that are seen by the audience and event goers. I will post in the comments ( if my less than 10 reputation would allow me) the picture of Magic Sing ET-23KH USB input of the device. I always bring my laptop, Acer AS5742-7653, during the regular karaoke event. I'm using my laptop also for tallying of scores from the judges, and also playing audio files from contestants that did not provide a karaoke video. I personally am using different Linux distros, but I next to all the time use my Ubuntu Studio 12.04.3 64bit partition during the regular karaoke contest event. My question is this: Is there a way I can share a temporary video/audio file directly from the laptop I'm using, going to the Magic Sing ET-23H that can broadcast both the video/audio file? Just like how in Window's Avisynth AVS files, or VirtualDub's temporary avi file, or like using ffplay (of ffmpeg), etc. I have researched somewhat the matter and found links in SuperUser.com. Though I can only provide the links at the comments section of this post if my reputation of less than 10 would allow me. I have a hunch it is possible, but I have not fully understood the device being used at the event, Magic Sing ET-23H, if there are other ways for it to broadcast video and audio files besides its USB input. Any help to my current predicament is highly appreciated. Thank you. PS: Since I need at least 10 reputation to post more than 2 links and also post images, I will try to post the image & links at the comments (if my below 10 reputation would allow me).

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  • Schema design: many to many plus additional one to many

    - by chrisj
    Hi, I have this scenario and I'm not sure exactly how it should be modeled in the database. The objects I'm trying to model are: teams, players, the team-player membership, and a list of fees due for each player on a given team. So, the fees depend on both the team and the player. So, my current approach is the following: **teams** id name **players** id name **team_players** id player_id team_id **team_player_fees** id team_players_id amount send_reminder_on Schema layout ERD In this schema, team_players is the junction table for teams and players. And the table team_player_fees has records that belong to records to the junction table. For example, playerA is on teamA and has the fees of $10 and $20 due in Aug and Feb. PlayerA is also on teamB and has the fees of $25 and $25 due in May and June. Each player/team combination can have a different set of fees. Questions: Are there better ways to handle such a scenario? Is there a term for this type of relationship? (so I can google it) Or know of any references with similar structures?

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  • How can I automatically delete /tmp folder on shared drive?

    - by Matt
    We have a /tmp folder that people use for temporary stuff. It can be anything and any file. We want to make it so that this automatically deletes (or preferably MOVES to another folder on the same shared drive) all the files that haven't been accessed in the last two weeks. This should happen weekly on a schedule that I don't have to manually do. Is there software out there that does this? Anyone have a script possibly? Server 2008R2

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  • Nhibernate - stuck with detached criteria (asp.net mvc 1 with nhibernate 2) c#

    - by Jen
    OK so I can't find a good example of this so I can better understand how to use detached criteria (assuming that's what I want to use in the first place). I have 2 tables. Placement and PlacementSupervisor My PlacementSupervisor table has a FK of PlacementID which relates to Placement.PlacementID - though my nhibernate model class has PlacementSupervisor . Placement (rather than specifically specifying a property of placement ID - not sure if this is important). What I am trying to do is - if values are passed through for the supervisor ID I want to restrict placements with that supervisor id. Have tried: ICriteria query = m_PlacementRepository.QueryAlias("p") .... if (criteria.SupervisorId > 0 && !string.IsNullOrEmpty(criteria.SupervisorTypeId)) { DetachedCriteria entityQuery = DetachedCriteria.For<PlacementSupervisor>("sup") .Add(Restrictions.And( Restrictions.Eq("sup.supervisorId", criteria.SupervisorId), Restrictions.Eq("sup.supervisorTypeId", criteria.SupervisorTypeId) )) .SetProjection(Projections.ProjectionList() .AddPropertyAlias("Placement.PlacementId", "PlacementId") ); query.Add(Subqueries.PropertyIn("p.PlacementId", entityQuery)); } Which just gives me the error: Could not find a matching criteria info provider to: (sup.supervisorId = 5 and sup.supervisorTypeId = U) Firstly supervisorTypeId is a string. Secondly I don't understand how to achieve what I'm trying to do so have just been trying various combinations of projections, and property aliases and subquery options..as I don't get how I'm supposed to join to another table/entity when the FK key sits in the second table. Can someone point me in the right direction. It seems like such an easy thing to do from a data perspective that hopefully I'm just missing something obvious!!

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  • Core Data: Overkill for simple, static UITableView-based iPhone App?

    - by David Foster
    Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

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  • Display a ranking grid for game : optimization of left outer join and find a player

    - by Jerome C.
    Hello, I want to do a ranking grid. I have a table with different values indexed by a key: Table SimpleValue : key varchar, value int, playerId int I have a player which have several SimpleValue. Table Player: id int, nickname varchar Now imagine these records: SimpleValue: Key value playerId for 1 1 int 2 1 agi 2 1 lvl 5 1 for 6 2 int 3 2 agi 1 2 lvl 4 2 Player: id nickname 1 Bob 2 John I want to display a rank of these players on various SimpleValue. Something like: nickname for lvl Bob 1 5 John 6 4 For the moment I generate an sql query based on which SimpleValue key you want to display and on which SimpleValue key you want to order players. eg: I want to display 'lvl' and 'for' of each player and order them on the 'lvl' The generated query is: SELECT p.nickname as nickname, v1.value as lvl, v2.value as for FROM Player p LEFT OUTER JOIN SimpleValue v1 ON p.id=v1.playerId and v1.key = 'lvl' LEFT OUTER JOIN SimpleValue v2 ON p.id=v2.playerId and v2.key = 'for' ORDER BY v1.value This query runs perfectly. BUT if I want to display 10 different values, it generates 10 'left outer join'. Is there a way to simplify this query ? I've got a second question: Is there a way to display a portion of this ranking. Imagine I've 1000 players and I want to display TOP 10, I use the LIMIT keyword. Now I want to display the rank of the player Bob which is 326/1000 and I want to display 5 rank player above and below (so from 321 to 331 position). How can I achieve it ? thanks.

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  • Mysql select - improve performance

    - by realshadow
    Hey, I am working on an e-shop which sells products only via loans. I display 10 products per page in any category, each product has 3 different price tags - 3 different loan types. Everything went pretty well during testing time, query execution time was perfect, but today when transfered the changes to the production server, the site "collapsed" in about 2 minutes. The query that is used to select loan types sometimes hangs for ~10 seconds and it happens frequently and thus it cant keep up and its hella slow. The table that is used to store the data has approximately 2 milion records and each select looks like this: SELECT * FROM products_loans WHERE KOD IN("X17/Q30-10", "X17/12", "X17/5-24") AND 369.27 BETWEEN CENA_OD AND CENA_DO; 3 loan types and the price that needs to be in range between CENA_OD and CENA_DO, thus 3 rows are returned. But since I need to display 10 products per page, I need to run it trough a modified select using OR, since I didnt find any other solution to this. I have asked about it here, but got no answer. As mentioned in the referencing post, this has to be done separately since there is no column that could be used in a join (except of course price and code, but that ended very, very badly). Here is the show create table, kod and CENA_OD/CENA_DO very indexed via INDEX. CREATE TABLE `products_loans` ( `KOEF_ID` bigint(20) NOT NULL, `KOD` varchar(30) NOT NULL, `AKONTACIA` int(11) NOT NULL, `POCET_SPLATOK` int(11) NOT NULL, `koeficient` decimal(10,2) NOT NULL default '0.00', `CENA_OD` decimal(10,2) default NULL, `CENA_DO` decimal(10,2) default NULL, `PREDAJNA_CENA` decimal(10,2) default NULL, `AKONTACIA_SUMA` decimal(10,2) default NULL, `TYP_VYHODY` varchar(4) default NULL, `stage` smallint(6) NOT NULL default '1', PRIMARY KEY (`KOEF_ID`), KEY `CENA_OD` (`CENA_OD`), KEY `CENA_DO` (`CENA_DO`), KEY `KOD` (`KOD`), KEY `stage` (`stage`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 And also selecting all loan types and later filtering them trough php doesnt work good, since each type has over 50k records and the select takes too much time as well... Any ides about improving the speed are appreciated.

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  • Avoid loading unnecessary data from db into objects (web pages)

    - by GmGr
    Really newbie question coming up. Is there a standard (or good) way to deal with not needing all of the information that a database table contains loaded into every associated object. I'm thinking in the context of web pages where you're only going to use the objects to build a single page rather than an application with longer lived objects. For example, lets say you have an Article table containing id, title, author, date, summary and fullContents fields. You don't need the fullContents to be loaded into the associated objects if you're just showing a page containing a list of articles with their summaries. On the other hand if you're displaying a specific article you might want every field loaded for that one article and maybe just the titles for the other articles (e.g. for display in a recent articles sidebar). Some techniques I can think of: Don't worry about it, just load everything from the database every time. Have several different, possibly inherited, classes for each table and create the appropriate one for the situation (e.g. SummaryArticle, FullArticle). Use one class but set unused properties to null at creation if that field is not needed and be careful. Give the objects access to the database so they can load some fields on demand. Something else? All of the above seem to have fairly major disadvantages. I'm fairly new to programming, very new to OOP and totally new to databases so I might be completely missing the obvious answer here. :)

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  • Correlate GROUP BY and LEFT JOIN on multiple criteria to show latest record?

    - by Sunbird
    In a simple stock management database, quantity of new stock is added and shipped until quantity reaches zero. Each stock movement is assigned a reference, only the latest reference is used. In the example provided, the latest references are never shown, the stock ID's 1,4 should have references charlie, foxtrot respectively, but instead show alpha, delta. How can a GROUP BY and LEFT JOIN on multiple criteria be correlated to show the latest record? http://sqlfiddle.com/#!2/6bf37/107 CREATE TABLE stock ( id tinyint PRIMARY KEY, quantity int, parent_id tinyint ); CREATE TABLE stock_reference ( id tinyint PRIMARY KEY, stock_id tinyint, stock_reference_type_id tinyint, reference varchar(50) ); CREATE TABLE stock_reference_type ( id tinyint PRIMARY KEY, name varchar(50) ); INSERT INTO stock VALUES (1, 10, 1), (2, -5, 1), (3, -5, 1), (4, 20, 4), (5, -10, 4), (6, -5, 4); INSERT INTO stock_reference VALUES (1, 1, 1, 'Alpha'), (2, 2, 1, 'Beta'), (3, 3, 1, 'Charlie'), (4, 4, 1, 'Delta'), (5, 5, 1, 'Echo'), (6, 6, 1, 'Foxtrot'); INSERT INTO stock_reference_type VALUES (1, 'Customer Reference'); SELECT stock.id, SUM(stock.quantity) as quantity, customer.reference FROM stock LEFT JOIN stock_reference AS customer ON stock.id = customer.stock_id AND stock_reference_type_id = 1 GROUP BY stock.parent_id

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  • Swipe left/right to push next/previous details view

    - by Youssef
    I am working on a ios application, using storyboard. I have a simple table view with rows. Each row has a "key" string to identify it. When the user clicks on a row I push the next view "DetailsViewController" and pass the "key" as a parameter in the prepareForSegue method. The data in the second view will change based on the "key" passed. In the "DetailsViewController" I want to add a swipe gesture, when the user swipes right, I want to push the next details view. It will be as if he clicked on the next row in the table view. So to rephrase, the user has 2 ways of switching between items: he can click the item in the table view and the details view will show, he can then go back and select another item. Or he can click on a row, and in the details view he can swipe left and right to see the previous/next item. i added the uigesture recognizer: UISwipeGestureRecognizer *recognizer; recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)]; [recognizer setDirection:UISwipeGestureRecognizerDirectionRight]; [[self view] addGestureRecognizer:recognizer]; - (void) handleSwipe:(UISwipeGestureRecognizer *) sender { //I want to go to the next item in the tableview } I hope I was clear. Thank you.

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  • Mysterious OS X FileVault-related home directory

    - by Nick
    I recently enabled FileVault on Snow Leopard, and after doing so, found a directory /Users/<myusername>.4529809818604982560, containing the original (unencrypted) contents of my home directory, owned by root:wheel with permissions 700, side-by-side with my normal home directory. Does anyone know why this was created (maybe a temporary backup that didn't get erased), or whether deleting it will be harmful?

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  • what is a RoR best practice? match by id or different column?

    - by Omnipresent
    I had a terrible morning. Lots of emails floating around about why things don't work. Upon investigating I found that there is a data mismatch which is causing errors. Scenario Customer and Address are two tables. Customer contains class Customer < ActiveRecord::Base has_one :address, :foreign_key => "id" end Address Contains class Address < ActiveRecord::Base belongs_to :customer, :foreign_key => "cid" end So the two tables match on id which is the default and that column is auto incremented. Problem on the edit Page we have some code like this. params[:line1] = @customer.first.address.line1 It fails because no matching record is found for a customer in the address table. I don't know why this is happening. It seems that over time a lot of records did not get added to Address table. Now problem is that when a new Customer is added (say with id 500) the Address will be added with some other id (say 425) ...now you don't know which address belongs to which customer. Question Being new to Rails, I am asking whether it is always considered good to create an extra column for joining of the records, rather than depending on the column that is automatically incremented? If I had a seperate column in Address table where I would manually insert the recently added customers id then this issue would not have come up.

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  • How can I automatically generate sql update scripts when some data is updated ?

    - by Brann
    I'd like to automatically generate an update script each time a value is modified in my database. In other words, if a stored procedure, or a query, or whatever updates column a with value b in table c (which as a pk column (i,j...k), I want to generate this : update c set a=b where i=... and j=... and k=... and store it somewhere (for example as a raw string in a table). To complicate things, I want the script to be generated only if the update has been made by a specific user. Good news is that I've got a primary key defined for all my tables. I can see how to do this using a trigger, but I would need to generate specific triggers for each table, and to update them each and every-time my schema changes. I guess there are some built-in ways to do this as SQL server sometimes need to store this kind of things (while using transactional replication for example), but couldn't find anything so far ... any ideas ? I'm also interested in ways to automatically generate triggers (probably using triggers - meta triggers, huh? - since I will need to update triggers automatically when the schema change)

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  • Import CSV to mysql

    - by 404error
    I have created a database and table. I have also created all the fields i will be needing. I have created 46 fields including 1 that is my ID for the row. The CSV doesn't contain the id field, nor does it contain the headers for the columns. I am new to all of this but have been trying to figure this out. I'm not on here being lazy asking for the answer, but looking for direction. I'm trying to figure out how to import the CSV but have it start importing data starting at the 2nd field, since I'm hoping the auto_increment will fill in the ID field, which is the first field i created. I tried these instructions with now luck. Can anyone offer some insight? your cvs file's column name must match your table column name browse your required .csv file select CSV using LOAD DATA options Check box 'ON' for Replace table data with file in Fields terminated by box type , in Fields enclosed by box " in Fields escaped by box \ in Lines terminated by box auto in Column names box type column name seperated by , like column1,column2,column3 10 check box ON for Use LOCAL keyword.

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  • Eclipselink: Create objects from JOIN query

    - by Raven
    Hi, I have a SQL query SELECT * FROM Thing AS a JOIN Thing_Property AS b ON a.id=b.Thing_ID JOIN Property AS c ON b.properties_ID = c.id JOIN Item AS d ON c.item_ID = d.id ORDER BY a.name, d.name and I Eclipselink to create my object model with it. Here is the model: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end but I can not figure out, how to make Eclipselink create the model from that query. Can you help?

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  • Atomically maintaining a counter using Sub-sonic ActiveRecord

    - by cantabilesoftware
    I'm trying to figure out the correct way to atomically increment a counter in one table and use that incremented value as an pseudo display-only ID for a record in another. What I have is a companies table and a jobs table. I want each company to have it's own set of job_numbers. I do have an auto increment job_id, but those numbers are shared across all companies. ie: the job numbers should generally increment without gaps for each company. ie: companies(company_id, next_job_number) jobs(company_id, job_id, job_number) Currently I'm doing this (as a method on the partial job class): public void SaveJob() { using (var scope = new System.Transactions.TransactionScope()) { if (job_id == 0) { _db.Update<company>() .SetExpression("next_job_number").EqualTo("next_job_number+1") .Where<company>(x => x.company_id == company_id) .Execute(); company c = _db.companies.SingleOrDefault(x => x.company_id == company_id); job_number = c.next_job_number; } // Save the job this.Save(); scope.Complete(); } } It seems to work, but I'm not sure if there are pitfalls here? It just feels wrong, but I'm not sure how else to do it. Any advice appreciated.

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  • TSQL Help (SQL Server 2005)

    - by Mick Walker
    I have been playing around with a quite complex SQL Statement for a few days, and have gotten most of it working correctly. I am having trouble with one last part, and was wondering if anyone could shed some light on the issue, as I have no idea why it isnt working: INSERT INTO ExistingClientsAccounts_IMPORT SELECT DISTINCT cca.AccountID, cca.SKBranch, cca.SKAccount, cca.SKName, cca.SKBase, cca.SyncStatus, cca.SKCCY, cca.ClientType, cca.GFCID, cca.GFPID, cca.SyncInput, cca.SyncUpdate, cca.LastUpdatedBy, cca.Deleted, cca.Branch_Account, cca.AccountTypeID FROM ClientsAccounts AS cca INNER JOIN (SELECT DISTINCT ClientAccount, SKAccount, SKDesc, SKBase, SKBranch, ClientType, SKStatus, GFCID, GFPID, Account_Open_Date, Account_Update FROM ClientsAccounts_IMPORT) AS ccai ON cca.Branch_Account = ccai.ClientAccount Table definitions follow: CREATE TABLE [dbo].[ExistingClientsAccounts_IMPORT]( [AccountID] [int] NOT NULL, [SKBranch] [varchar](2) NOT NULL, [SKAccount] [varchar](12) NOT NULL, [SKName] [varchar](255) NULL, [SKBase] [varchar](16) NULL, [SyncStatus] [varchar](50) NULL, [SKCCY] [varchar](5) NULL, [ClientType] [varchar](50) NULL, [GFCID] [varchar](10) NULL, [GFPID] [varchar](10) NULL, [SyncInput] [smalldatetime] NULL, [SyncUpdate] [smalldatetime] NULL, [LastUpdatedBy] [varchar](50) NOT NULL, [Deleted] [tinyint] NOT NULL, [Branch_Account] [varchar](16) NOT NULL, [AccountTypeID] [int] NOT NULL ) ON [PRIMARY] CREATE TABLE [dbo].[ClientsAccounts_IMPORT]( [NEWClientIndex] [bigint] NOT NULL, [ClientGroup] [varchar](255) NOT NULL, [ClientAccount] [varchar](255) NOT NULL, [SKAccount] [varchar](255) NOT NULL, [SKDesc] [varchar](255) NOT NULL, [SKBase] [varchar](10) NULL, [SKBranch] [varchar](2) NOT NULL, [ClientType] [varchar](255) NOT NULL, [SKStatus] [varchar](255) NOT NULL, [GFCID] [varchar](255) NULL, [GFPID] [varchar](255) NULL, [Account_Open_Date] [smalldatetime] NULL, [Account_Update] [smalldatetime] NULL, [SKType] [varchar](255) NOT NULL ) ON [PRIMARY] The error message I get is: Msg 8152, Level 16, State 14, Line 1 String or binary data would be truncated. The statement has been terminated.

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  • copy rows before updating them to preserve archive in Postgres

    - by punkish
    I am experimenting with creating a table that keeps a version of every row. The idea is to be able to query for how the rows were at any point in time even if the query has JOINs. Consider a system where the primary resource is books, that is, books are queried for, and author info comes along for the ride CREATE TABLE authors ( author_id INTEGER NOT NULL, version INTEGER NOT NULL CHECK (version > 0), author_name TEXT, is_active BOOLEAN DEFAULT '1', modified_on TIMESTAMP DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (author_id, version) ) INSERT INTO authors (author_id, version, author_name) VALUES (1, 1, 'John'), (2, 1, 'Jack'), (3, 1, 'Ernest'); I would like to be able to update the above like so UPDATE authors SET author_name = 'Jack K' WHERE author_id = 1; and end up with 2, 1, Jack, t, 2012-03-29 21:35:00 2, 2, Jack K, t, 2012-03-29 21:37:40 which I can then query with SELECT author_name, modified_on FROM authors WHERE author_id = 2 AND modified_on < '2012-03-29 21:37:00' ORDER BY version DESC LIMIT 1; to get 2, 1, Jack, t, 2012-03-29 21:35:00 Something like the following doesn't really work CREATE OR REPLACE FUNCTION archive_authors() RETURNS TRIGGER AS $archive_author$ BEGIN IF (TG_OP = 'UPDATE') THEN -- The following fails because author_id,version PK already exists INSERT INTO authors (author_id, version, author_name) VALUES (OLD.author_id, OLD.version, OLD.author_name); UPDATE authors SET version = OLD.version + 1 WHERE author_id = OLD.author_id AND version = OLD.version; RETURN NEW; END IF; RETURN NULL; -- result is ignored since this is an AFTER trigger END; $archive_author$ LANGUAGE plpgsql; CREATE TRIGGER archive_author AFTER UPDATE OR DELETE ON authors FOR EACH ROW EXECUTE PROCEDURE archive_authors(); How can I achieve the above? Or, is there a better way to accomplish this? Ideally, I would prefer to not create a shadow table to store the archived rows.

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  • Help with HTML hyperlink please

    - by liz
    Hello, Can someone help me with this problem: I have a table in a jsp page, with the text in one column being hyperlinks. Whenever anyone of these hyperlinks is clicked the whole table should refresh and repopulate based on the value of the hyperlink clicked. My problem is currently when the hyperlink is clicked the page refreshes with an empty table. I have the following line of HTML code for performing this in my jsp page: <TD><A href="http://localhost:8080/pmweb/gui.jsp" onclick="getResults(param)">hyperlinktext</A></TD>; Below is my getResults function in javascript in the same JSP page: <script type="text/javascript"> var httpRequest; function getResults(param) { var url = "http://localhost:8080/pmweb/api/GetResultsByParam?param=" + param; httpRequest = new XMLHttpRequest(); httpRequest.open("GET", url, true); httpRequest.onreadystatechange = function() {processRequest(); } ; httpRequest.send(null); } I have verified that the getResults function above is working fine itself. When I debugged it I noticed that this getResults function is not entered when the hyperlink is clicked. Anyone know how to get the hyperlink calling the javascript function properly? Thanks very much in advance!

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  • Same query has nested loops when used with INSERT, but Hash Match without.

    - by AaronLS
    I have two tables, one has about 1500 records and the other has about 300000 child records. About a 1:200 ratio. I stage the parent table to a staging table, SomeParentTable_Staging, and then I stage all of it's child records, but I only want the ones that are related to the records I staged in the parent table. So I use the below query to perform this staging by joining with the parent tables staged data. --Stage child records INSERT INTO [dbo].[SomeChildTable_Staging] ([SomeChildTableId] ,[SomeParentTableId] ,SomeData1 ,SomeData2 ,SomeData3 ,SomeData4 ) SELECT [SomeChildTableId] ,D.[SomeParentTableId] ,SomeData1 ,SomeData2 ,SomeData3 ,SomeData4 FROM [dbo].[SomeChildTable] D INNER JOIN dbo.SomeParentTable_Staging I ON D.SomeParentTableID = I.SomeParentTableID; The execution plan indicates that the tables are being joined with a Nested Loop. When I run just the select portion of the query without the insert, the join is performed with Hash Match. So the select statement is the same, but in the context of an insert it uses the slower nested loop. I have added non-clustered index on the D.SomeParentTableID so that there is an index on both sides of the join. I.SomeParentTableID is a primary key with clustered index. Why does it use a nested loop for inserts that use a join? Is there a way to improve the performance of the join for the insert?

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  • PHP: What is an efficient way to parse a text file containing very long lines?

    - by Shaun
    I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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  • Mapping enum with fluent nhibernate

    - by Puneet
    I am following the http://wiki.fluentnhibernate.org/Getting%5Fstarted tutorial to create my first NHibernate project with Fluent NHibernate I have 2 tables 1) Account with fields Id AccountHolderName AccountTypeId 2) AccountType with fields Id AccountTypeName Right now the account types can be Savings or Current So the table AccountTypes stores 2 rows 1 - Savings 2 - Current For AccoutType table I have defined enum public enum AccountType { Savings=1, Current=2 } For Account table I define the entity class public class Account { public virtual int Id {get; private set;} public virtual string AccountHolderName {get; set;} public virtual string AccountType {get; set;} } The fluent nhibernate mappings are: public AgencyMap() { Id(o => o.Id); Map(o => o.AccountHolderName); Map(o => o.AccountType); } When I try to run the solution, it gives an exception - InnerException = {"(XmlDocument)(2,4): XML validation error: The element 'class' in namespace 'urn:nhibernate-mapping-2.2' has incomplete content. List of possible elements expected: 'meta, subselect, cache, synchronize, comment, tuplizer, id, composite-id' in namespace 'ur... I guess that is because I have not speciofied any mapping for AccountType. The questions are: How can I use AccountType enum instead of a AccountType class? Maybe I am going on wrong track. Is there a better way to do this? Thanks!

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  • how to retrieve informatin from deleted row

    - by JM
    How can I retrie infromation from delete rows. I delete some rows from table in dataset, then I use method GetChanges(DataRowState.Deleted) to get deleted rows. I try delete rows in original table on server side, but it finished with this errors. System.Data.DeletedRowInaccessibleException: Deleted row information cannot be accessed through the row. What is correct way? Here is my code, any advice? Thank you everybody Dataset ds = //get dataset from client side //get changes DataTable delRows = ds.Tables[0].GetChanges(DataRowState.Deleted); //try delete rows in table in DB if (delRows != null) { string connStr = WebConfigurationManager.ConnectionStrings["Employees"].ConnectionString; conn = new SqlConnection(connStr); conn.Open(); for (int i = 0; i < delRows.Rows.Count; i++) { string cmdText = string.Format("DELETE Tab1 WHERE Surname=@Surname"); cmd = new SqlCommand() { Connection = conn, CommandText = cmdText }; //here is problem, I need get surnames from rows which was deleted var sqlParam = new SqlParameter(@"Surname", SqlDbType.VarChar) { Value = delRows.Rows[i][1].ToString() }; cmd.Parameters.Add(sqlParam); cmd.CommandText = cmdText; cmd.Connection = conn; cmd.ExecuteNonQuery(); } }

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