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  • How to Delete all data from a table which contain self referencing foreign key

    - by Shantanu Gupta
    I have a table which has employee relationship defined within itself. i.e. EmpID Name SeniorId ----------------------- 1 A NULL 2 B 1 3 C 1 4 D 3 and so on... Where Senior ID is a foreign key whose primary key table is same with refrence column EmpId I want to clear all rows from this table without removing any constraint. How can i do this? Deletion need to be performed like this 4, 3 , 2 , 1 How can I do this

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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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  • please help me to interpret the naive bayes result in weka..

    - by resmi
    Anybody please help me to interpret the following result generated in weka for classification using naive bayes.....Please explain clearly what is this Normal Distribution , Mean , StandardDev , WeightSum and Precision.Please help me.Am new in weka. ** Naive Bayes Classifier Class Normal: Prior probability = 0.5 1374195_at: Normal Distribution. Mean = 218.06 StandardDev = 6.0572 WeightSum = 3 Precision = 36.34333334 1373315_at: Normal Distribution. Mean = 1142.58 StandardDev = 21.1589 WeightSum = 3 Precision = 126.95333339999999

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  • Creating SQL table using Dynamic variable name

    - by megatoast
    I want to create backup SQL tables using variable names. something along the lines of DECLARE @SQLTable Varchar(20) SET @SQLTable = 'SomeTableName' + ' ' + '20100526' SELECT * INTO quotename(@SQLTable) FROM SomeTableName but i'm getting Incorrect syntax near '@SQLTable'. It's just part of a small script for maintence so i don't have to worry about injections.

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  • PostgreSQL 8.3 data types: xml vs varchar

    - by Sejanus
    There's xml data type in Postgres, I never used it before so I'd like to hear opinions. Downsides and upsides vs using regular varchar (or Text) column to store xml. The text I'm going to store is xml, well-formed, UTF-8. No need to search by it (I've read searching by xml is slow). This XML actually is data prepared for PDF generation with Apache FOP. XML can be generated dynamically from data found elsewhere (other Postgres tables), it's stored as is only so that I won't need to generate it twice. Kinda backup#2 for already generated PDF documents. Anything else to know? Good practices, performance, maintenance, etc?

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  • MySQL slow query

    - by andrhamm
    SELECT items.item_id, items.category_id, items.title, items.description, items.quality, items.type, items.status, items.price, items.posted, items.modified, zip_code.state_prefix, zip_code.city, books.isbn13, books.isbn10, books.authors, books.publisher FROM ( ( items LEFT JOIN bookitems ON items.item_id = bookitems.item_id ) LEFT JOIN books ON books.isbn13 = bookitems.isbn13 ) LEFT JOIN zip_code ON zip_code.zip_code = items.item_zip WHERE items.rid = $rid` I am running this query to get the list of a user's items and their location. The zip_code table has over 40k records and this might be the issue. It currently takes up to 15 seconds to return a list of about 20 items! What can I do to make this query more efficient?

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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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  • Concurency problem with Isolation - read-committed

    - by Ratn Deo--Dev
    I have to write a simple demo for amount withdrawl from a joint Bank amount .Andy and Jen holds a joint bank account with number 123 . Suppose they have 100$ in their account .Jen and Andy are operating their account at the same time and both are trying to withdraw 90$ at the time being .My transaction Isolation is set to read-committed and both are able to withdraw money leaving the balance to -(minus)80$ although I have constraint that balance should never be less than 0. I am using hibernate .Is versioning only way to solve this problem or I should go for another Isolation level ?

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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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  • Extract primary key from MySQL in PHP

    - by Parth
    I have created a PHP script and I am lacking to extract the primary key, I have given flow below, please help me in how can i modify to get primary key I am using MySQL DB, working for Joomla, My requirement is tracking the activity like insert/update/delete on any table and store it in another audit table using triggers, i.e. I am doing Auditing. DB's table structure: Few tables dont have any PK nor auto increment key Flow of my script is : I fetch out all table from DB. I check whether the table have any trigger or not. If yes then it moves to check nfor next table and so on. If it does'nt find any trigger then it creates the triggers for the table, such that, -it first checks if the table has any primary key or not(for inserting in Tracking audit table for every change made) if it has the primary key then it uses it further in creation of trigger. if it doesnt find any PK then it proceeds further in creating the trigger without inserting any id in audit table Now here, My problem is I need the PK every time so that I can record the id of any particular table in which the insert/update/delete is performed, so that further i can use this audit track table to replicate in production DB.. Now as I haave mentioned earlier that I am not available with PK/auto-incremented in some table, then what should I do get the particular id in which change is done? please guide me...GEEKS!!!

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  • Need help with SQL query on SQL Server 2005

    - by Avinash
    We're seeing strange behavior when running two versions of a query on SQL Server 2005: version A: SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = 1234 ORDER BY name ASC version B: DECLARE @Id AS INT; SET @Id = 1234; SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = @Id ORDER BY name ASC Both queries return 1000 rows; version A takes on average 15s; version B on average takes 4s. Could anyone help us understand the difference in execution times of these two versions of SQL? If we invoke this query via named parameters using NHibernate, we see the following query via SQL Server profiler: EXEC sp_executesql N'SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = @id ORDER BY name ASC', N'@id INT', @id=1234; ...and this tends to perform as badly as version A.

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  • Problem with duplicates in a SQL Join

    - by Chris Ballance
    I have the following result set from a join of three tables, an articles table, a products table, an articles to products mapping table. I would like to have the results with duplicates removed similar to a select distinct on content id. Current result set: [ContendId] [Title] [productId] 1 article one 2 1 article one 3 1 article one 9 4 article four 1 4 article four 10 4 article four 14 5 article five 1 6 article six 8 6 article six 10 6 article six 11 6 article six 13 7 article seven 14 Desired result set: [ContendId] [Title] [productId] 1 article one * 4 article four * 5 article five * 6 article six * 7 article seven * Here is condensed example of the relevant SQL: IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'tempdb.dbo.products') AND type = (N'U')) drop table tempdb.dbo.products go CREATE TABLE tempdb.dbo.products ( productid int, productname varchar(255) ) go IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articles') AND type = (N'U')) drop table tempdb.dbo.articles go create table tempdb.dbo.articles ( contentid int, title varchar(255) ) IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articles') AND type = (N'U')) drop table tempdb.dbo.articles go create table tempdb.dbo.articles ( contentid int, title varchar(255) ) IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articleproducts') AND type = (N'U')) drop table tempdb.dbo.articleproducts go create table tempdb.dbo.articleproducts ( contentid int, productid int ) insert into tempdb.dbo.products values (1,'product one'), (2,'product two'), (3,'product three'), (4,'product four'), (5,'product five'), (6,'product six'), (7,'product seven'), (8,'product eigth'), (9,'product nine'), (10,'product ten'), (11,'product eleven'), (12,'product twelve'), (13,'product thirteen'), (14,'product fourteen') insert into tempdb.dbo.articles VALUES (1,'article one'), (2, 'article two'), (3, 'article three'), (4, 'article four'), (5, 'article five'), (6, 'article six'), (7, 'article seven'), (8, 'article eight'), (9, 'article nine'), (10, 'article ten') INSERT INTO tempdb.dbo.articleproducts VALUES (1,2), (1,3), (1,9), (4,1), (4,10), (4,14), (5,1), (6,8), (6,10), (6,11), (6,13), (7,14) GO select DISTINCT(a.contentid), a.title, p.productid from articles a JOIN articleproducts ap ON a.contentid = ap.contentid JOIN products p ON a.contentid = ap.contentid AND p.productid = ap.productid ORDER BY a.contentid

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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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  • 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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  • 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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  • How do views reduce code duplication?

    - by Debuger
    Hi! I read something like this about db views: Views are incredibly powerful and useful for one reason that stands out above all the other very good reasons. They reduce code duplication. That is, in most cases, the bottom line. If a query will be used in three or more places, then a view will drastically simplify your changes if the schema or query parameters change. I once had to edit 22 stored procedures to change some query logic. If the original architecture had utilized views, then I would have had only three changes. Can anyone explain to me how it works, and maybe give me some examples? Best regards!

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  • html-encode output && incorrect string error

    - by fusion
    my data includes arabic characters which looks like garbage in mysql but displays correctly when run on browser. my questions: how do i html-encode the output? if i add this to all my files: <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> i get this error: Error: Incorrect string value: '\xE4\xEE\xC3\xD8\xEF\xE6...' for column 'cQuotes' at row 1 i'm working on php/mysql platform. insertion form in html: <!doctype html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Your Favorite Quotes</title> <link rel="stylesheet" type="text/css" href="style.css" /> <link rel="stylesheet" href="css/validationEngine.jquery.css" type="text/css" media="screen" charset="utf-8" /> <script type="text/javascript" src="scripts/jquery-1.4.2.js"></script> <script src="scripts/jquery.validationEngine-en.js" type="text/javascript"></script> <script src="scripts/jquery.validationEngine.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function() { $("#submitForm").validationEngine() }) </script> </head> <body> <div class="container"> <div class="center_div"> <h2>Submit Your Quote</h2> <fieldset> <form id="submitForm" action="qinsert.php" method="post"> <div class="field"> <label>Author: </label> <input id="author" name="author" type="text" class="validate[required,custom[onlyLetter],length[0,100]]"> </div><br /> <div class="field"> <label>Quote: </label> <textarea id="quote" name="quote" class="validate[required, length[0,1000]]"></textarea> <br /> </div> <input id="button1" type="submit" value="Submit" class="submit" /><br /> <input id="button2" type="reset" value="Reset" /> </form> </fieldset> </div> </div> </body> </html> ////////////////////// query in php: //<?php //header('Content-Type: text/html; charset=UTF-8'); //?> <!doctype html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <link rel="stylesheet" type="text/css" href="style2.css" /> <title>Your Quote Databank</title> </head> <body> <?php include 'config.php'; echo "Connected <br />"; //check for quotes and apostrophes $author = ''; $quote = ''; $author = $_POST['author']; $quote = $_POST['quote']; $author = mysql_real_escape_string(trim($author)); $quote = mysql_real_escape_string(trim($quote)); //************************** //validating data $query = "SELECT * FROM Quotes where cQuotes = '$quote' limit 1;"; $result = mysql_query($query, $conn); //now check that the number of rows is 0 if (mysql_num_rows($result) > 0 ) { header("Location: /error.html"); exit; } //inserting data //mysql_query("SET NAMES 'utf8'"); //mysql_query("SET CHARACTER SET utf8"); $sql="INSERT INTO Quotes (vauthor, cquotes) VALUES ('$author', '$quote')"; if (!mysql_query($sql,$conn)) { die('Error: ' . mysql_error()); } echo "<div class='container'><p><label class='lbl_record'> Record Added Successfully!</label>"; echo "<a href='qform.html'> Submit a New Quote!</a></p>"; //************************** //selecting data $result = mysql_query("SELECT * FROM Quotes ORDER BY idQuotes DESC"); echo "<div class='center_div'>"; echo "<table> <thead> <tr> <th>Author</th> <th>Quotes</th> </tr> </thead>"; while($row = mysql_fetch_array($result)) { echo "<tbody><tr>"; echo "<td width='150px'>" . $row['vAuthor'] . "</td>"; echo "<td>" . $row['cQuotes'] . "</td>"; echo "</tr>"; } echo "</tbody></table>"; echo "</div></div>"; //************************** include 'close_config.php'; ?> </body> </html>

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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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  • 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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