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  • What are appropriate ways to represent relationships between people in a database table?

    - by Emilio
    I've got a table of people - an ID primary key and a name. In my application, people can have 0 or more real-world relationships with other people, so Jack might "work for" Jane and Tom might "replace" Tony and Bob might "be an employee of" Rob and Bob might also "be married to" Mary. What's the best way to represent this in the database? A many to many intersect table? A series of self joins? A relationship table with one row per relationship pair and type, where I insert records for the relationship in both directions?

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  • Remove Duplicates from List of HashMap Entries

    - by HonorGod
    I have a List<HashMap<String,Object>> which represents a database where each list record is a database row. I have 10 columns in my database. There are several rows where the values of 2 particular columns are equals. I need to remove the duplicates from the list after the list is updated with all the rows from database. What is the efficient way? FYI - I am not able to do distinct while querying the database, because the GroupName is added at a later stage to the Map after the database is loaded. And since Id column is not primary key, once you add GroupName to the Map. You will have duplicates based on Id + GroupName combination! Hope my question makes sense. Let me know if we need more clarification.

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  • Insert coding query in yii

    - by nerd
    I need to auto insert the next orders_id into an Orders table in a database. orders_id is not the primary Key, and it does not auto-increment I need to query the database, find the last (highest) id value, increment 1, and insert it in Orders table in database. Actually, I have a shipping action which will provide address of shipping of orders. So as soon as the user fills address form and move to payments page, I want to simultaneously fill my Orders table by max(orders_id)+1. I have built relations between Address table and Orders table but my orders Table is not getting populated. Please detail me correct codes to implement it in my controller in Yii

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  • using check contraint in MySQL for controlling string length not working

    - by ptrn
    Dear stackoverflow, I'm tumbled with a problem! I've set up my first check constraint using MySQL, but unfortunately I'm having a problem. When inserting a row that should fail the test, the row is inserted anyway. The structure: CREATE TABLE user ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, uname VARCHAR(10) NOT NULL, fname VARCHAR(50) NOT NULL, lname VARCHAR(50) NOT NULL, mail VARCHAR(50) NOT NULL, PRIMARY KEY (id), CHECK (LENGTH(fname) > 3) ); The insert statement: INSERT INTO user VALUES (null, 'user', 'Fname', 'Lname', '[email protected]'); I'm pretty sure I'm missing something basic here.

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  • I need free index/fund/stock end of day quotes in CSV

    - by Janne Mikkola
    Hello, I need (free or cheap) source for end of day stock/mutual funds/index values. Major world indexes & European stocks are primary intrest. I keep seeing that yahoo/ google/ MS offer this data, yet I cant find HOWTO doc (or similar) on getting the data. Reuters is an option - ~$300/month puts it out of my range. Sample of what I am looking for: WMX.IDX,20100326,54.49,54.6,54.17,54.41,0 XAH.IDX,20100326,52.39,52.77,52.33,52.54,0 XAL.IDX,20100326,37.34,38.4,37.34,37.59,0 XAO.IDX,20100326,4896.2998,4905.2002,4848.2998,4905.2002,0 I wish to get this data into txt file in an automated manner. My platform is Linux, (I also have pc with windows & emulator in for win in linux so windows is an option) http://www.eoddata.com/ is best site I have found so far. This is quite good yet I desire more info on european finances. Please advice! Sincerely, Janne

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  • C# winform Show form in second screen and vice versa

    - by Mohsan
    hi. I have an application in which there is a form which i wants to show on second screen. Mean If application is running on screen A and when i click on menu to show Form it should display on Screen B and same with if application is running on screen B and when i click on menu to show Form it should display on Screen A. please tell me how to do that. If you provide code then it will be better. i searched from net and found some articles to get primary and secondary screens. but unable to implement that.

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  • How to properly use Gearman with my PHP application?

    - by luckytaxi
    For now I just want to use Gearman for background processing. For example, I need to email a recipient that they have a private message waiting for them once the sender submits their message into the DB. I assume I can run the worker/client and server on my primary server but I have no problems offloading some of the tasks to a different web server. Anyways, my question is how do I handle multiple "functions?" Let's say I need a job that handles the email portion and a job to handle image manipulation. Can I have multiple functions in the worker? I've followed a couple of examples I found online but each example only shows one function being initialized. Do I have to start up multiple "workers" to handle multiple functions?

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  • sqlite ERROR no such column

    - by Richard
    Hi, Does anyone here have some experience with this error? Only If I use the WHERE clause, I get this error. I use php PDO to get the results. And this is my simple table $sql = "CREATE TABLE samenvatting ( stem_id INTEGER PRIMARY KEY AUTOINCREMENT, poll_id TEXT, stem_waarde_id TEXT, totaal INTEGER )"; $crud->rawQuery($sql); $poll_id = "somepoll"; $records = $crud->rawSelect('SELECT * FROM samenvatting WHERE poll_id=´.$poll_id); pdo abstract class public function conn() { isset($this->username); isset($this->password); if (!$this->db instanceof PDO) { $this->db = new PDO($this->dsn, $this->username, $this->password); $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } } public function rawSelect($sql) { $this->conn(); return $this->db->query($sql); } Thanks, Richard

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  • Retrieve Google Calendar Events

    - by Don
    Hi, I'm using the Java API for Google Calendar. The documents show the following example of how to retrieve events from a calendar: URL feedUrl = new URL("http://www.google.com/calendar/feeds/[email protected]/private/full"); CalendarService myService = new CalendarService("exampleCo-exampleApp-1"); myService.setUserCredentials("[email protected]", "mypassword"); // Send the request and receive the response: CalendarEventFeed myFeed = myService.getFeed(feedUrl, CalendarEventFeed.class); This will retrieve all events from the primary calendar of the [email protected] account. However, I need to retrieve events from a secondary calendar. I already have a reference the CalendarEntry object that represents the secondary calendar, but I still can't figure out how to get events from it. I suspect I can do this using the same code as above, but I just need to change the URL to something else. Thanks, Donal

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  • doctrine2: many-to-one with non default referencedColumnName does not persist entity

    - by timaschew
    I'm using symfony 2.1.2 with FOSUserBundle. I extend the User from FOS and define a many-to-one (bidirectional) association to a Customer entity. I don't want to use primary key for the association (referencedColumnName). I will use another integer uniqe column: customer_no use FOS\UserBundle\Entity\User as BaseUser; /** * @ORM\Entity * @ORM\Table(name="t_myuser") */ class MyUser extends BaseUser { /** * @ORM\ManyToOne(targetEntity="Customer", inversedBy="user") * @ORM\JoinColumn(name="customer_no", referencedColumnName="customer_no", nullable=false) */ $public $customer; } /** * @ORM\Entity * @ORM\Table(name="t_customer") */ class Customer extends BaseEntity // provides an id (pk) { /** * @ORM\Column(type="integer", unique=true, nullable=false) */ public $customer_no; /** * @ORM\OneToMany(targetEntity="MyUser", mappedBy="customer") */ public $user; } When I try to persist (via a form) a new MyUser entity with an (already in db existing and) loaded Customer entity from db, I get this error: Notice: Undefined index: customer_no in ...\vendor\doctrine\orm\lib\Doctrine\ORM\Persisters\BasicEntityPersister.php line 608 The schema on the db is all right. //update: I fix the inversedBy and mappedBy stuff, but this is not the problem.

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  • Apache .htaccess

    - by Peter
    Hi! I have a htaccess problem. My directory structure look like this: / HEADER.html README.html /stackoverflow/ /stackoverflow/.htaccess .htaccess ServerSignature Off Options +Indexes HeaderName /HEADER.html IndexIgnore HEADER.html ReadmeName /README.html IndexIgnore /README.html IndexOptions +FancyIndexing AddCharset UTF-8 .txt IndexIgnore *.xml IndexIgnore *.php My primary directory is /stackoverflow/, when I navigate to this directory via browser I have included HEADER.html and README.html on every site/directories under /stackoverflow/, this works fine. I added some php code to my HEADER.html (which is in the root directory / ), I am trying to add to htaccess: AddType application/x-httpd-php .html .php .htm This not working, I think because the HEADER.html is in the root. If I try add the AddType... to the /.htaccess (and not to the /stackoverflow/.htaccess) it is overwriting my /stackoverflow/.htaccess rules. Why? How I can add AddType rule to my /stackoverflow/.htaccess to Apache parse html file as php file?

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  • Are there any kata for practice VIM?

    - by Grzegorz Gierlik
    I've used VIM for many years as my primary text editor. And I am still learning how to use VIM for various editing tasks. The problem is that even if I learn something and use it once a week I forgot soon how I did it -- classic case is search and replace in many buffers using bufdo :(. I was wondering if there is any kata to daily VIM practice including many VIM commands: open existing files, create new files, edit files and move around: move cursor (beginning & end of line/function/block/screen, top & bottom of screen, move screen line up/down, etc.), mark, copy & paste, insert & remove characters/words/lines, move between buffers, move between windows, arrange windows, search & replace, repeat last command, formatting (=), probably some more (bookmarks, macros). save files, create/update/save an open projects (mksession and source). Do you know any kata for VIM of tutorial which could help to practice all above (and more) VIM commands?

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  • optimal memory layout for read-only/write memory segments.

    - by aaa
    hello. Suppose I have two memory segments (equal size each, approximately 1kb in size) , one is read-only (after initialization), and other is read/write. what is the best layout in memory for such segments in terms of memory performance? one allocation, contiguous segments or two allocations (in general not contiguous). my primary architecture is linux Intel 64-bit. my feeling is former (cache friendlier) case is better. is there circumstances, where second layout is preferred? Thanks

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  • Why does Sql Server recommends creating an index when it already exist?

    - by Pierre-Alain Vigeant
    I ran a very basic query against one of our table and I noticed that the execution plan query processor is recommending that we create an index on a column The query is SELECT SUM(DATALENGTH(Data)) FROM Item WHERE Namespace = 'http://some_url/some_namespace/' After running, I get the following message // The Query Processor estimates that implementing the following index could improve the query cost by 96.7211%. CREATE NONCLUSTERED INDEX [<Name of Missing Index, sysname,>] ON [dbo].[Item] ([Namespace]) My problem is that I already have such index on that column: CREATE NONCLUSTERED INDEX [IX_ItemNamespace] ON [dbo].[Item] ( [Namespace] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] Why is Sql Server recommending me to create such index when it already exist?

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  • SQL Server: collect values in an aggregation temporarily and reuse in the same query

    - by Erwin Brandstetter
    How do I accumulate values in t-SQL? AFAIK there is no ARRAY type. I want to reuse the values like demonstrated in this PostgreSQL example using array_agg(). SELECT a[1] || a[i] AS foo ,a[2] || a[5] AS bar -- assuming we have >= 5 rows for simplicity FROM ( SELECT array_agg(text_col ORDER BY text_col) AS a ,count(*)::int4 AS i FROM tbl WHERE id between 10 AND 100 ) x How would I best solve this with t-SQL? Best I could come up with are two CTE and subselects: ;WITH x AS ( SELECT row_number() OVER (ORDER BY name) AS rn ,name AS a FROM #t WHERE id between 10 AND 100 ), i AS ( SELECT count(*) AS i FROM x ) SELECT (SELECT a FROM x WHERE rn = 1) + (SELECT a FROM x WHERE rn = i) AS foo ,(SELECT a FROM x WHERE rn = 2) + (SELECT a FROM x WHERE rn = 5) AS bar FROM i Test setup: CREATE TABLE #t( id INT PRIMARY KEY ,name NVARCHAR(100)) INSERT INTO #t VALUES (3 , 'John') ,(5 , 'Mary') ,(8 , 'Michael') ,(13, 'Steve') ,(21, 'Jack') ,(34, 'Pete') ,(57, 'Ami') ,(88, 'Bob') Is there a simpler way?

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  • MySQL Volleyball Standings

    - by Torez
    I have a database table full of game by game results and want to know if I can calculate the following: GP (games played) Wins Loses Points (2 points for each win, 1 point for each lose) Here is my table structure: CREATE TABLE `results` ( `id` int(10) unsigned NOT NULL auto_increment, `home_team_id` int(10) unsigned NOT NULL, `home_score` int(3) unsigned NOT NULL, `visit_team_id` int(10) unsigned NOT NULL, `visit_score` int(3) unsigned NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ; And a few testing results: INSERT INTO `results` VALUES(1, 1, 21, 2, 25); INSERT INTO `results` VALUES(2, 3, 21, 4, 17); INSERT INTO `results` VALUES(3, 1, 25, 3, 9); INSERT INTO `results` VALUES(4, 2, 7, 4, 22); INSERT INTO `results` VALUES(5, 1, 19, 4, 20); INSERT INTO `results` VALUES(6, 2, 24, 3, 26); Here is what a final table would look like: +-------------------+----+------+-------+--------+ | Team Name | GP | Wins | Loses | Points | +-------------------+----+------+-------+--------+ | Spikers | 4 | 4 | 0 | 8 | | Leapers | 4 | 2 | 2 | 6 | | Ground Control | 4 | 1 | 3 | 5 | | Touch Guys | 4 | 0 | 4 | 4 | +-------------------+----+------+-------+--------+

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  • How do you get average of sums in SQL (multi-level aggregation)?

    - by paxdiablo
    I have a simplified table xx as follows: rdate date rtime time rid integer rsub integer rval integer primary key on (rdate,rtime,rid,rsub) and I want to get the average (across all times) of the sums (across all ids) of the values. By way of a sample table, I have (with consecutive identical values blanked out for readability): rdate rtime rid rsub rval ------------------------------------- 2010-01-01 00.00.00 1 1 10 2 20 2 1 30 2 40 01.00.00 1 1 50 2 60 2 1 70 2 80 02.00.00 1 1 90 2 100 2010-01-02 00.00.00 1 1 999 I can get the sums I want with: select rdate,rtime,rid, sum(rval) as rsum from xx where rdate = '2010-06-01' group by rdate,rtime,rid which gives me: rdate rtime rid rsum ------------------------------- 2010-01-01 00.00.00 1 30 (10+20) 2 70 (30+40) 01.00.00 1 110 (50+60) 2 150 (70+80) 02.00.00 1 190 (90+100) as expected. Now what I want is the query that will also average those values across the time dimension, giving me: rdate rtime ravgsum ---------------------------- 2010-01-01 00.00.00 50 ((30+70)/2) 01.00.00 130 ((110+150)/2) 02.00.00 190 ((190)/1) I'm using DB2 for z/OS but I'd prefer standard SQL if possible.

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  • Alright to truncate database tables when also using Hibernate?

    - by Marcus
    Is it OK to truncate tables while at the same time using Hibernate to insert data? We parse a big XML file with many relationships into Hibernate POJO's and persist to the DB. We are now planning on purging existing data at certain points in time by truncating the tables. Is this OK? It seems to work fine. We don't use Hibernate's second level cache. One thing I did notice, which is fine, is that when inserting we generate primary keys using Hibernate's @GeneratedValue where Hibernate just uses a key value one greater than the highest value in the table - and even though we are truncating the tables, Hibernate remembers the prior value and uses prior value + 1 as opposed to starting over at 1. This is fine, just unexpected. Note that the reason we do truncate as opposed to calling delete() on the Hibernate POJO's is for speed. We have gazillions of rows of data, and truncate is just so much faster.

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  • SQL for selecting only the last item from a versioned table

    - by Jeremy
    I have a table with the following structure: CREATE TABLE items ( id serial not null, title character varying(255), version_id integer DEFAULT 1, parent_id integer, CONSTRAINT items_pkey PRIMARY KEY (id) ) So the table contains rows that looks as so: id: 1, title: "Version 1", version_id: 1, parent_id: 1 id: 2, title: "Version 2", version_id: 2, parent_id: 1 id: 3, title: "Completely different record", version_id: 1, parent_id: 3 This is the SQL code I've got for selecting out all of the records with the most recent version ids: select * from items inner join ( select parent_id, max(version_id) as version_id from items group by parent_id) as vi on items.version_id = vi.version_id and items.parent_id = vi.parent_id Is there a way to write that SQL statement so that it doesn't use a subselect?

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  • How to rewrite the URL

    - by Kalpana
    I have a small application built using Seam 2.2, Richfaces 3.3, JBoss 5.1. Most of the page navigation adds the request parameters to the target URL. I would like to hide parameters to be hidden to the customer who is using the application (e.g. I would expect the URL to be something like "http://localhost:8080/books/Book.seam". The parameters (userId, orderId and cmId) are currently mapped to the backend bean via Book.page.xml. How do I prevent the request parameters from showing up in the browser URL, as it also allows the customer to manipulate the URL. We did look at seam URL re-writing feature, it talked about manipulating say the primary key id in a REST format, not sure how to accomplish something more complex like the above use case in a elegant fashion.

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  • SQL - How can I apply a "semi-unique" constraint?

    - by Erin Drummond
    Hi, I have a (simplified) table consisting of three columns: id INT PRIMARY KEY NOT NULL AUTO_INCREMENT, foreignID INT NOT NULL, name VARCHAR NOT NULL Basically, I would like to add a constraint (at the database level rather than at the application level) where it only possible for one unique 'name' to exist per foreignID. For example, given the data (id, foreignid, name): 1,1,Name1 2,1,Name2 3,1,Name3 4,2,Name1 5,2,Name2 I want the constraint to fail if the user tries to insert another 'Name3' under foreignId 1, but succeed if the user tries to insert 'Name3' under foreignId 2. For this reason I cannot simply make the whole column UNIQUE. I am having difficulty coming up with a SQL expression to achieve this, can anybody help me? Thanks

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  • Efficiency of checking for null varbinary(max) column ?

    - by Moe Sisko
    Using SQL Server 2008. Example table : CREATE table dbo.blobtest (id int primary key not null, name nvarchar(200) not null, data varbinary(max) null) Example query : select id, name, cast((case when data is null then 0 else 1 end) as bit) as DataExists from dbo.blobtest Now, the query needs to return a "DataExists" column, that returns 0 if the blob is null, else 1. This all works fine, but I'm wondering how efficient it is. i.e. does SQL server need to read in the whole blob to its memory, or is there some optimization so that it just does enough reads to figure out if the blob is null or not ? (FWIW, the sp_tableoption "large value types out of row" option is set to OFF for this example).

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  • Generic Method to find the tuples used for computation in Postgres?

    - by Rahul
    If I have a table col1 | name | pay ------+------------------+------ 1 | Steve Jobs | 1006 2 | Mike Markkula | 1007 3 | Mike Scott | 1978 4 | John Sculley | 1983 5 | Michael Spindler | 1653 The user executes a sum query which sums the pay of people getting paid more than $1500. Is there a way to also implicitly know which tuples have been used which satisfy the condition for sum ? I know you can separately write another query to just return the primary key ids which satisfy the condition. But, Is there any other way to do that in the same query ? probably rewrite the query in some way ? or... any suggestion ?

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  • Transactional isolation level needed for safely incrementing ids

    - by Knut Arne Vedaa
    I'm writing a small piece of software that is to insert records into a database used by a commercial application. The unique primary keys (ids) in the relevant table(s) are sequential, but does not seem to be set to "auto increment". Thus, I assume, I will have to find the largest id, increment it and use that value for the record I'm inserting. In pseudo-code for brevity: id = select max(id) from some_table id++ insert into some_table values(id, othervalues...) Now, if another thread started the same transaction before the first one finished its insert, you would get two identical ids and a failure when trying to insert the last one. You could check for that failure and retry, but a simpler solution might be setting an isolation level on the transaction. For this, would I need SERIALIZABLE or a lower level? Additionally, is this, generally, a sound way of solving the problem? Are the any other ways of doing it?

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  • What's the best self-tracking software for Linux?

    - by trench
    I'm looking for a way to track myself and receive quality data upon which I can write future scripts/programs. For example, I use Google Reader a lot. I'd like to track the hrefs that garner my clicks. Further, I'd like to drop all of the words of each href into a database where they can be stacked in a hierarchical manner. At the end of the week I want to know that "Ubuntu" garnered 448 clicks and "Cheetos" garnered 2. :) That's just one example... I'd like this tracking and data-collecting to extend beyond my browser. I know writing something to do this myself wouldn't be too awfully difficult but if something already exists I'd happily use it. Thanks in advance. Primary OS: Ubuntu 10.04

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