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  • Ruby on Rails ActiveRecord: eager loading issue with foreign and primary key

    - by Krishnaswamy Subramanian
    The eager loading on Ruby on Rails is not working properly for the following scenario. First we had a model called marks which has the following fields id, student, subject, mark the student is a string column which has the active directory login value, later on for reporting functionality we introduce another table called user which has the following fields id, ad_name, full_name Now on the Mark model, we have added the belongs to class belongs_to :student_details, :class_name = "User", :foreign_key = "student", :primary_key = "ad_name" and when loading using the ActiveRecord's find method we are passing in the include conditon for eager loading Marks.find(:all, :include = :reserved_user) but when the find is executed, for each and every mark a student select query executed. Is this a known bug in ROR? or am i missing something?

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  • PostgreSQL insert on primary key failing with contention, even at serializable level

    - by Steven Schlansker
    I'm trying to insert or update data in a PostgreSQL db. The simplest case is a key-value pairing (the actual data is more complicated, but this is the smallest clear example) When you set a value, I'd like it to insert if the key is not there, otherwise update. Sadly Postgres does not have an insert or update statement, so I have to emulate it myself. I've been working with the idea of basically SELECTing whether the key exists, and then running the appropriate INSERT or UPDATE. Now clearly this needs to be be in a transaction or all manner of bad things could happen. However, this is not working exactly how I'd like it to - I understand that there are limitations to serializable transactions, but I'm not sure how to work around this one. Here's the situation - ab: => set transaction isolation level serializable; a: => select count(1) from table where id=1; --> 0 b: => select count(1) from table where id=1; --> 0 a: => insert into table values(1); --> 1 b: => insert into table values(1); --> ERROR: duplicate key value violates unique constraint "serial_test_pkey" Now I would expect it to throw the usual "couldn't commit due to concurrent update" but I'm guessing since the inserts are different "rows" this does not happen. Is there an easy way to work around this?

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  • How to import text file to table with primary key as auto-increment

    - by webworm
    I have some bulk data in a text file that I need to import into a MySQL table. The table consists of two fields .. ID (integer with auto-increment) Name (varchar) The text file is a large collection of names with one name per line ... (example) John Doe Alex Smith Bob Denver I know how to import a text file via phpMyAdmin however, as far as I understand, I need to import data that has the same number of fields as the target table. Is there a way to import the data from my text file into one field and have the ID field auto-increment automatically? Thank you in advance for any help.

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  • Naming convention for the primary key in a Table

    - by kwokwai
    Hi all, I am learning the Model relationship types in cakephp. I have built twotables and in one of the Table A, I got these fields in it: Table A {postID, topic, content} Table B {replyID, content, postID} And when I ran the web page, a bunch of error related to SQL popped up saying that cakephp couldn't find post_id. It is weird that I have already declared the $primaryKey to be using postID in the tableA.php under Models folder, but cakephp seemed want me to change the ID field to post_id instead of postID, because the error disappeared after I have changed the primaryKey to post_id. ANy ideas?

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  • automatic id generation which is a primary key

    - by abhi
    in vb.net while entering a new entry i want to assign a record a unique id like in case of numeric i do this way Dim ItemID As Integer KAYAReqConn.Open() SQLCmd = New SqlCommand("SELECT ISNULL(MAX(ItemID),0) AS ItemID from MstItem", ReqConn) Dim dr As SqlDataReader dr = SQLCmd.ExecuteReader If dr.HasRows Then dr.Read() ItemID = dr("ItemID") + 1 End If dr.Close() in this case m using itemid as a unique id and the format is 1,2,3... and m finding out the max and assigning to a new record but how to assign if the previous id is of the a00001,a00002,a00003,a00004...so on. how i do i produce a unique id in this case

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  • Rails - Override primary key on has_one

    - by Ben Hall
    I have the following associations, basically I want to link via userid and not the id of the object. class Tweet < ActiveRecord::Base has_one :user_profile, :primary_key = 'userid', :foreign_key = 'twitter_userid' class UserProfile < ActiveRecord::Base belongs_to :tweet, :foreign_key = 'userid' However the following spec fails as twitter_userid is reset to the id of the object it "should have the user's twitter id set on their user profile" do t = Tweet.new(:twitter_id = 1, :status = 'Tester', :userid = 'personA', :user_profile = UserProfile.new(:twitter_userid = 'personA', :avatar = 'abc')) t.save! t.user_profile.twitter_userid.should == 'personA' end should have the user's twitter id set on their user profile expected: "personA", got: 216 (using ==) However, the following does pass: it "should return the correct avatar after being saved" do t = Tweet.new(:twitter_id = 1, :status = 'Tester', :userid = 'personA', :user_profile = UserProfile.new(:twitter_userid = 'personA', :avatar = 'abc')) t.save! t.user_profile.avatar.should == 'abc' end How can I force it to use userid and not id? Thanks Ben

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  • Java Applet Deployment, ClassNotFoundException (primary class)

    - by Matt
    This is driving me up the wall. I have checked and rechecked spelling and paths. I have tried just about every combination of paths, including relative, absolute, and full http paths. I continue to get the following error when trying to load a Java applet: java.lang.ClassNotFoundException: AppletClient.class at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source) at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source) at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Exception: java.lang.ClassNotFoundException: AppletClient.class The HTML used to load the applet: <applet width="100" height="100" archive="applet/myapplet.jar, applet/applet_dependency.jar" code="AppletClient.class"> <param value="blahblah" name="username"> <param value="false" name="codebase_lookup"> </applet> The applet is in a relative directory, "applet", from the path of the current page. I have unzipped the jar file and can see AppletClient.class. Also, in the source of the project, it is spelled that way (casing and all). I have tried with/without the parameters. I have changed the names of the archive jars in the applet include tag just to see if I get a different error for bad file names (same error). I have manually done GETs on the jars to make sure the server is responding to the requests (it is). I have tried with and without the codebase tag, with all different varieties of paths (start getting bad "magic number" errors on those). I know that this error sometimes pops up when a dependency fails to load, so it can be misleading, but all dependencies are present, accounted for, and are fetchable via manual GETs. Between each and every attempt I always clear my cache in FireFox. These problems are reproduced in IE8 and Chrome as well. Per my Java Console from the browser, I am running Java Plug-in 1.6.0_20. This is from the same machine that I develop the applet on, which runs fine via Eclipse. Finally, I kicked on Fiddler2, and I don't see a single request for the jar files anywhere The host site is running from my Visual Studio debugger, so it's running on localhost. But I see the requests for all the other resources on Fiddler. Just... no Jars. ANYWHERE. I clear the log, cleared my browser cache, and did a ctrl-R refresh. And still, not a single Jar request on the Fiddler log. I even did a delayed write (with JS) of the applet tag after the page loaded, once all the Fiddler activity slowed down. The element gets written to the document (and I can see the 100x100 Java error window), but not a single request shows up on Fiddler. Any suggestions, before I go crawl into the corner and cry myself to sleep? EDIT: From the Java console, if I hit "l" (el) to "dump classloader list", I see something that looks like this: Live entry: key=http://localhost:55446/BaseWebSite/,http://localhost:55446/BaseWebSite/applet/myappliet.jar, http://localhost:55446/BaseWebSite/applet/applet_dependency.jar, refCount=1, threadGroup=sun.plugin2.applet.Applet2ThreadGroup[name=http://localhost:55446/BaseWebSite/-threadGroup,maxpri=4]

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  • Host Primary Domain from a subfolder

    - by TandemAdam
    I am having a problem making a sub directory act as the public_html for my main domain, and getting a solution that works with that domains sub directories too. My hosting allows me to host multiple sites, which are all working great. I have set up a subfolder under my ~/public_html/ directory called /domains/, where I create a folder for each separate website. e.g. public_html domains websiteone websitetwo websitethree ... This keeps my sites nice and tidy. The only issue was getting my "main domain" to fit into this system. It seems my main domain, is somehow tied to my account (or to Apache, or something), so I can't change the "document root" of this domain. I can define the document roots for any other domains ("Addon Domains") that I add in cPanel no problem. But the main domain is different. I was told to edit the .htaccess file, to redirect the main domain to a subdirectory. This seemed to work great, and my site works fine on it's home/index page. The problem I'm having is that if I try to navigate my browser to say the images folder (just for example) of my main site, like this: www.yourmaindomain.com/images/ then it seems to ignore the redirect and shows the entire server directory in the url, like this: www.yourmaindomain.com/domains/yourmaindomain/images/ It still actually shows the correct "Index of /images" page, and show the list of all my images. Here is an example of my .htaccess file that I am using: RewriteEngine on RewriteCond %{HTTP_HOST} ^(www.)?yourmaindomain.com$ RewriteCond %{REQUEST_URI} !^/domains/yourmaindomain/ RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ /domains/yourmaindomain/$1 RewriteCond %{HTTP_HOST} ^(www.)?yourmaindomain.com$ RewriteRule ^(/)?$ domains/yourmaindomain/index.html [L] Does this htaccess file look correct? I just need to make it so my main domain behaves like an addon domain, and it's subdirectories adhere to the redirect rules.

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  • Ruby on Rails - Primary and Foreign key

    - by Eef
    Hey, I am creating a site in Ruby on Rails, I have two models a User model and a Transaction model. These models both belong to an account so they both have a field called account_id I am trying to setup a association between them like so: class User < ActiveRecord::Base belongs_to :account has_many :transactions end class Transaction < ActiveRecord::Base belongs_to :account belongs_to :user end I am using these associations like so: user = User.find(1) transactions = user.transactions At the moment the application is trying to find the transactions with the user_id, here is the SQL it generates: Mysql::Error: Unknown column 'transactions.user_id' in 'where clause': SELECT * FROM `transactions` WHERE (`transactions`.user_id = 1) This is incorrect as I would like the find the transactions via the account_id, I have tried setting the associations like so: class User < ActiveRecord::Base belongs_to :account has_many :transactions, :primary_key => :account_id, :class_name => "Transaction" end class Transaction < ActiveRecord::Base belongs_to :account belongs_to :user, :foreign_key => :account_id, :class_name => "User" end This almost achieves what I am looking to do and generates the following SQL: Mysql::Error: Unknown column 'transactions.user_id' in 'where clause': SELECT * FROM `transactions` WHERE (`transactions`.user_id = 104) The number 104 is the correct account_id but it is still trying to query the transaction table for a user_id field. Could someone give me some advice on how I setup the associations to query the transaction table for the account_id instead of the user_id resulting in a SQL query like so: SELECT * FROM `transactions` WHERE (`transactions`.account_id = 104) Cheers Eef

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  • Can't Insert Data Into Tables Containing Auto Increment Primary Key Using PHP Prepared Statements

    - by Drew
    I know I have that my connection to the database works, and a test I did using no auto-increment id worked fine for me. The code below refuses to work and I can't find a a way around it. My table has 3 columns, ID (auto increment), name and value. What do I need to change in order to get this to work? Thanks in advance //create placeholder query $query = "INSERT INTO prepared_test (name, value) VALUES (?,?)"; //prepare the query $stmt = mysqli_prepare($connection, $query); $name = 'steve'; $value = 45; mysqli_bind_param($stmt, array(MYSQLI_BIND_STRING, MYSQLI_BIND_INT), $name, $value); mysqli_execute($stmt); if(mysqli_stmt_affected_rows($stmt) != 1) die("issues"); mysqli_stmt_close($stmt); $connection-close();

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  • Vertically Merge Multiple Tables in MySQL by Joint Primary Key

    - by world
    Hello, I'll attempt to make my question as clear as possible. I'm fairly unexperienced with SQL, only know the really basic queries. In order to have a better idea I'd been reading the MySQL manual for the past few days, but I couldn't really find a concrete solution and my needs are quite specific. I've got 3 MySQL MyISAM tables: table1, table2 and table3. Each table has an ID column (ID, ID2, ID3 respectively), and different data columns. For example table1 has [ID, Name, Birthday, Status, ...] columns, table2 has [ID2, Country, Zip, ...], table3 has [ID3, Source, Phone, ...] you get the idea. The ID, ID2, ID3 columns are common to all three tables... if there's an ID value in table1 it will also appear in table2 and table3. The number of rows in these tables is identical, about 10m rows in each table. What I'd like to do is create a new table that contains (most of) the columns of all three tables and merge them into it. The dates, for instance, must be converted because right now they're in VARCHAR YYYYMMDD format. Reading the MySQL manual I figured STR_TO_DATE() would do the job, but I don't know how to write the query itself in the first place so I have no idea how to integrate the date conversion. So basically, after I create the new table (which I do know how to do), how can I merge the three tables into it, integrating into the query the date conversion?

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  • Should i really use integer primary IDs [sql]

    - by arthurprs
    For example, i always generate an auto-increment field for the users table, but i also specifies an UNIQUE index on their usernames. There is situations that i first need to get the userId for a given username and then execute the desired query. Or use a JOIN in the desired query. It's 2 trips to the database or a JOIN vs. a varchar index The above is just an example There is a real performance benefit on INT over small VARCHAR indexes? Thanks in advance!

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  • SQLAlchemy: an efficient/better select by primary keys?

    - by hadrien
    Yet another newbie question.. Let's say I have an user table in declarative mode: class User(Base): __tablename__ = 'user' id = Column(u'id', Integer(), primary_key=True) name = Column(u'name', String(50)) When I have a list of users identifiers, I fetch them from db with: user_ids = [1, 2, 3, 4, 5] users = Session.query(User).filter(User.id.in_(user_ids)).all() I dislike using in_ because I think I learned it has bad performance on indexed fields (is that true/false?). Anyway, is there a better way doing that query? Thanks!

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  • Database Design Composite Keys

    - by guazz
    I am going to use a contrived example: one headquarter has one-or-many contacts. A contact can only belong to one headquarter. TableName = Headquarter Column 0 = Id : Guid [PK] Column 1 = Name : nvarchar(100) Column 2 = IsAnotherAttribute: bool TableName = ContactInformation Column 0 = Id : Guid [PK] Column 1 = HeadquarterId: Guid [FK] Column 2 = AddressLine1 COlumn 3 = AddressLine2 Column 4 = AddressLine3 I would like some help setting the table primary keys and foreign keys here? How does the above look? Should I use a composite key for ContactInformation on [Column 0 and Column1]? Is it ok to use surrogate key all of the time?

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  • jqGrid : "All in One" approach width jqGridEdit Class > how to set a composite primary key ?

    - by Qualliarys
    Hello, How to set a composite primary key for a "All in One" approach (grid defined in JS file, and data using jqGridEdit Class in php file) ? Please, for me a composite primary key of a table T, is a elementary primary key that is defined with some fields belong to this table T ! Here is my test, but i get no data and cannot use the CRUD operations : In my JS file i have this lines code: ... colModel":[ {"name":"index","index":"index","label":"index"}, // <= THAT'S JUST THE INDEX OF MY TABLE {"name":"user","index":"user","label":"user","key":true}, // <= A PART OF MY COMPOSITE PRIMARY KEY {"name":"pwd","index":"pwd","label":"pwd","key":true}, // <= A PART OF MY COMPOSITE PRIMARY KEY {"name":"state","index":"state","label":"state","key":true}, // <= A PART OF MY COMPOSITE PRIMARY KEY ... <= AND SO ON "url":"mygrid_crud.php", "datatype":"json", "jsonReader":{repeatitems:false}, "editurl": "mygrid_crud.php", "prmNames":{"id":"index"} // <= WHAT I NEED TO WRITE HERE ??? ... In my php file (mygrid_crud.php) : ... $grid = new jqGridEdit($conn); $query = "SELECT * FROM mytable WHERE user='$user' and pwd='$pwd' and state='$state'..."; // <= SELECT * it's ok or i need to specify all fields i need ? $grid->SelectCommand = $query; $grid->dataType = "json"; $grid->table = 'mytable'; $grid->setPrimaryKeyId('index'); // <= WHAT I NEED TO WRITE HERE ??? ... $grid->editGrid(); Please, say me what is wrong, and how to do to set a composite primary key in this approach !? Thank you so much for tour responses.

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  • MySQL: updating a row and deleting the original in case it becomes a duplicate

    - by Silvio Donnini
    I have a simple table made up of two columns: col_A and col_B. The primary key is defined over both. I need to update some rows and assign to col_A values that may generate duplicates, for example: UPDATE `table` SET `col_A` = 66 WHERE `col_B` = 70 This statement sometimes yields a duplicate key error. I don't want to simply ignore the error with UPDATE IGNORE, because then the rows that generate the error would remain unchanged. Instead, I want them to be deleted when they would conflict with another row after they have been updated I'd like to write something like: UPDATE `table` SET `col_A` = 66 WHERE `col_B` = 70 ON DUPLICATE KEY REPLACE which unfortunately isn't legal in SQL, so I need help finding another way around. Also, I'm using PHP and could consider a hybrid solution (i.e. part query part php code), but keep in mind that I have to perform this updating operation many millions of times. thanks for your attention, Silvio Reminder: UPDATE's syntax has problems with joins with the same table that is being updated

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  • MySQL ALTER TABLE on very large table - is it safe to run it?

    - by Timothy Mifsud
    I have a MySQL database with one particular MyISAM table of above 4 million rows. I update this table about once a week with about 2000 new rows. After updating, I then perform the following statement: ALTER TABLE x ORDER BY PK DESC i.e. I order the table in question by the primary key field in descending order. This has not given me any problems on my development machine (Windows with 3GB memory), but, even though 3 times I have tried it successfully on the production Linux server (with 512MB RAM - and achieving the resulted sorted table in about 6 minutes each time), the last time I tried it I had to stop the query after about 30 minutes and rebuild the database from a backup. I have started to wonder whether a 512MB server can cope with that statement (on such a large table) as I have read that a temporary table is created to perform the ALTER TABLE command?! And, if it can be safely run, what should be the expected time for the alteration of the table? Thanks in advance, Tim

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  • Database Design Question: GUID + Natural Numbers

    - by Alan
    For a database I'm building, I've decided to use natural numbers as the primary key. I'm aware of the advantages that GUID's allow, but looking at the data, the bulk of row's data were GUID keys. I want to generate XML records from the database data, and one problem with natural numbers is that I don't want to expose my database key's to the outside world, and allow users to guess "keys." I believe GUID's solve this problem. So, I think the solution is to generate a sparse, unique iD derived from the natural ID (hopefully it would be 2-way), or just add an extra column in the database and store a guid (or some other multibyte id) The derived value is nicer because there is no storage penalty, but it would be easier to reverse and guess compared to a GUID. I'm (buy) curious as to what others on SO have done, and what insights they have.

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  • MySql Query to return number of photos in each album

    - by GivenPie
    MY table is set up like this, all I need to do is call a query to my Photos table. I have PhotoID as the primary key and GalleryID as the foreign key to Gallery. How can I could the number of unique PhotoID's for each multiple GalleryIDs. So to speak there are may duplicate GalleryIDs because there are many photos in a gallery. So I just need to could the number of unique PhotoIDs associated with that GalleryID. Can it be done in one query?

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