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  • Rails: Modeling an optional relation in ActiveRecord

    - by Hassinus
    I would like to map a relation between two Rails models, where one side can be optionnal. Let's me be more precise... I have two models: Profile that stores user profile information (name, age,...) and User model that stores user access to the application (email, password,...). To give you more information, User model is handled by Devise gem for signup/signin. Here is the scenario of my app: 1/ When a user register, a new row is created in User table and there is an equivalent in Profile table. This leads to the following script: class User < ActiveRecord::Base belongs_to :profile end 2/ A user can create it's profile without registering (kind of public profile with public information), so a row in Profile doesn't have necessarily a User row equivalent (here is the optional relation, the 0..1 relation in UML). Question: What is the corresponding script to put in class Profile < AR::Base to map optionally with User? Thanks in advance.

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  • In SQL, a Join is actually an Intersection? And it is also a linkage or a "Sideway Union"?

    - by Jian Lin
    I always thought of a Join in SQL as some kind of linkage between two tables. For example, select e.name, d.name from employees e, departments d where employees.deptID = departments.deptID In this case, it is linking two tables, to show each employee with a department name instead of a department ID. And kind of like a "linkage" or "Union" sideway". But, after learning about inner join vs outer join, it shows that a Join (Inner join) is actually an intersection. For example, when one table has the ID 1, 2, 7, 8, while another table has the ID 7 and 8 only, the way we get the intersection is: select * from t1, t2 where t1.ID = t2.ID to get the two records of "7 and 8". So it is actually an intersection. So we have the "Intersection" of 2 tables. Compare this with the "Union" operation on 2 tables. Can a Join be thought of as an "Intersection"? But what about the "linking" or "sideway union" aspect of it?

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  • Clean install of 12.04 won't boot from HDD

    - by MarchingKazoo
    Downloaded 12.04.2. Made CD. Machine boots from CD as expected. Installed onto HD. Upon reboot, "Read error" message appears. Upon booting from CD, the HD appears as expected: One partition for Ubuntu, taking up about 12 gig, the rest empty. Lather, rinse, repeat five times. Results of "sudo fdisk -l": Disk /dev/sda: 200.0 GB, 200049647616 bytes 255 heads, 63 sectors/track, 24321 cylinders, total 390721968 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000dfa3e Device Boot Start End Blocks Id System /dev/sda1 * 2048 386596863 193297408 83 Linux /dev/sda2 386598910 390721535 2061313 5 Extended /dev/sda5 386598912 390721535 2061312 82 Linux swap / Solaris Should this be complicate? Seems no.

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  • DataSet XML export is empty

    - by Shaine
    I've got in-memory dataset with couple of tables that is populated in code. Data-bound grids on the gui show table contents without a problem. Then I try to export the dataset into XML: ds.WriteXml(fdSave.FileName, XmlWriteMode.WriteSchema); and get empty XML (with couple of lines regarding dataset names but without any tables) If I export table directly I've got all the data but dataset name is obviously wrong: ds.Fields.WriteXml(fdSave.FileName, XmlWriteMode.WriteSchema); What am I missing? Is there any reasonable way to write the whole dataset into file?

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  • related categories - database design

    - by mike
    Hello! I'm looking for a little database design advice... I have a spreadsheet with a few columns in it. Column 1 being a list of categories and the rest being related categories(to the category in column 1). I'm trying to figure out what the best way to setup the tables would be... My thought so far is to have a table that just lists the categories then have a table with 2 columns that holds the id of the category and the id of a related category.... Would this be the best way to do this? Any better ideas?

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  • Make recovery disk for customers

    - by alexander7567
    I hear about other computer shops that sells customers recovery disks that they have created. I'm assuming all that they do is make a image and uses an automation script that allows this to be done. I have seen where clonezilla does this, but it has to be the same HDD size or they might have problems down the road. Is there any other freeware that I could do this with that allows you to use on any size disk. Ghost is really good for this because it automatically fills up empty space with the partition and never needs any user input or "Expert Mode" like clonezilla. But it is not freeware.

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  • Run a proc on several different values of one parameter

    - by WEFX
    I have the following query that gets run within a proc. The function MyFunction returns a table, and this query joins on that table. This proc works great when a @MyArg value is supplied. However, I’m wondering if there’s a way to run this on all @MyArg values in the database. I’m sure there’s a way to do it within a loop, but I know that loops are generally to be avoided at the db layer. I really just need to perform this for the sake of checking (and possibly cleansing) some bad data. SELECT ColumnA, ColumnB, ColumnC FROM ( SELECT a.ColumnA, a.ColumnB, a.ColumnC, ROW_NUMBER() over(partition by a.ColumnD order by f.ColumnX) as RowNum FROM dbo.MyTableA AS a INNER JOIN dbo.MyFunction(@MyArg) f ON f.myID = a.myID WHERE (a.myBit = 1 OR a.myID = @MyArg) ) AS x WHERE x.rownum = 1;

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  • Create "INSERT" statements from mySQL database in Java

    - by girdus
    Does anyone know of any good libraries or scripts out there which will allow me to point to any mySQL table and automatically get a list of all the INSERT statements for the data in the table? DdlUtils allows me to create an XML file from a database model but I would like to have it in INSERT statements format and preferably the ability to choose a couple of tables instead of dumping the entire database. Thanks. EDIT: I need it to be a Java API because I want to programatically call it from my Java method.

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  • Tree data structure in php

    - by Piyush
    in my application user starts a new tree or get added under a child-user and keep on adding users in branches in such a way- >there are 10 level of tree type structure. >root node contain 1 user and each node(user) can have max 5 child-user in this way tree will be like level 0 = 1 user , level 1 = 5 user, level 2 = 25 user , level 3 = 125 user and so on. I created one MySQL table having columns like- User_id , level, super_id, child1_id, child2_id, child3_id, child4_id, child5_id my question is How can I get all child-user(child to child also) of a particular user at any level do I need to add some more columns in my table??

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  • mysql select multiple rows in join

    - by julio
    Hi-- I have a simple mySQL problem-- I have two tables, one is a user's table, and one is a photos table (each user can upload multiple photos). I'd like to write a query to join these tables, so I can pull all photos associated with a user (up to a certain limit). However, when I do something obvious like this: SELECT *.a, *.b FROM user_table a JOIN photos_table b ON a.id = b.userid it returns a.id, a.name, a.email, a.address, b.id, b.userid, b.photo_title, b.location but it only returns a single photo. Is there a way to return something like: a.id, a.name, a.email, a.address, b.id, b.userid, b.photo_title, b.location, b.id2, b.photo_title2, b.location2 etc. . . for a given LIMIT of photos? Thanks for any ideas.

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  • how to write xsd for the following xml?

    - by Venkats
    <?xml version="1.0"?> <datatype xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" xs:noNamespaceSchemaLocation="sampletype.xsd"> <table name="emp"> <columns> <column> <name>emp_id</name> <data_type>int(200) </data_type> </column> </columns> </table> </datatype> Here i generate the xsd for above xml, but it was not correct. can you help me generate the xsd for the xml? thanks in advance.

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  • No panels at all after upgrading from 10.04 to 12.04

    - by user86330
    After upgrading to 12.4 from 10.4 on an AMD64 the situation is as follows: After booting I see the Xubuntu logo splash screen and when I log in I get an error that there is a system crash somewhere (it suggest to click on the notification icon, but no info appears then). FInally I can only see my initial 10.04 Desktop but I have no panels at all, so I can only click on my Desktop objects. Question: Will a clean re intall solve the problem? In such case will my multi partition configuration (Vista+XP+ubuntu partitions) be affected?

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  • Dynamically created textboxes and changes plus jQuery in ASP.NET?

    - by gazeebo
    Hi all, I was wondering how to read off a value from a textbox that resides in a partialview and output the value into a textbox within the initial window. Here's my code... <script type="text/javascript"> $(document).ready(function (e) { // Calculate the sum when the document has been loaded. var total = 0; $("#fieldValues :input.fieldKronor").each(function (e) { total += Number($(this).val()); }); // Set the value to the correspondent textbox $("#fieldSummation").text(total); // Re-calculate on change $("#fieldValues :input.fieldKronor").change(function (e) { var total = 0; $("#fieldValues :input.fieldKronor").each(function (e) { total += Number($(this).val()); }); $("#fieldSummation").text(total); }); }); </script> Here's the table where in info is... <table id="fieldValues" style="width: 60%; margin-bottom: 2em"> <thead> <tr> <th>Rubrik, t.ex. teknik*</th> <th>Kronor (ange endast siffror)*</th> </tr> </thead> <asp:Panel ID="pnlStaffRows" runat="server"></asp:Panel> <tfoot> <tr> <th></th> <th>Total kostnad</th> </tr> <tr> <td></td> <td><input type="text" value="" class="fieldSummation" style="width:120px" /></td> </tr> </tfoot> </table> And here's the partialview... <tr> <td class="greyboxchildsocialsecuritynumberheading4" style="padding-bottom:1em"> <asp:TextBox ID="txtRubrikBox" ToolTip="Rubrik" runat="server" Width="120"></asp:TextBox> </td> <td class="greyboxchildnameheading3" style="padding-bottom:1em"> <asp:TextBox ID="txtKronorBox" class="fieldKronor" ToolTip="Kronor" runat="server" Width="120"></asp:TextBox> </td> </tr>

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  • Are conditional subqueries optimized out, if the condition is false?

    - by Tobias Schulte
    I have a table foo and a table bar, where each foo might have a bar (and a bar might belong to multiple foos). Now I need to select all foos with a bar. My sql looks like this SELECT * FROM foo f WHERE [...] AND ($param IS NULL OR (SELECT ((COUNT(*))>0) FROM bar b WHERE f.bar = b.id)) with $param being replaced at runtime. The question is: Will the subquery be executed even if param is null, or will the dbms optimize the subquery out? We are using mysql, mssql and oracle. Is there a difference between these regarding the above?

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  • Doctrine: Mixing YAML markup and db manager (navicat) editing?

    - by ropstah
    I think the answer to this question should be: No. However I hope to be corrected. I'd like to edit our database using a mixture of YAML markup + Doctrine createTables() and Navicat editing. Can I maintain the inheritance which is marked up? Example (4 steps, at step 4, Doctrine is in no way able to re-create the inheritance schema... or is it?): Step 1: Create YAML with inheritance --- Entity: columns: username: string(20) password: string(16) created_at: timestamp updated_at: timestamp User: inheritance: extends: Entity type: column_aggregation keyField: type keyValue: 1 Group: inheritance: extends: Entity type: column_aggregation keyField: type keyValue: 2 Step 2: Create tables using Doctrine (and drop/create db if nessecary) Created sql: CREATE TABLE entity (id BIGINT AUTO_INCREMENT, username VARCHAR(20), password VARCHAR(16), created_at DATETIME, updated_at DATETIME, type VARCHAR(255), PRIMARY KEY(id)) ENGINE = INNODB Step 3: Edit table using Navicat Step 4: Refresh YAML file because of 'external' edits...

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  • How do I ensure data consistency in this concurrent situation?

    - by MalcomTucker
    The problem is this: I have multiple competing threads (100+) that need to access one database table Each thread will pass a String name - where that name exists in the table, the database should return the id for the row, where the name doesn't already exist, the name should be inserted and the id returned. There can only ever be one instance of name in the database - ie. name must be unique How do I ensure that thread one doesn't insert name1 at the same time as thread two also tries to insert name1? In other words, how do I guarantee the uniqueness of name in a concurrent environment? This also needs to be as efficient as possible - this has the potential to be a serious bottleneck. I am using MySQL and Java. Thanks

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  • Hibernate Query - Get latest versions by timestamp?

    - by Slim
    I have a database that is being used as a sort of version control system. That is, instead of ever updating any rows, I add a new row with the same information. Each row also contains a version column that is a date timestamp, so the only difference is the new row will have a more recent timestamp. What I'm having trouble with is writing an efficient hibernate query to return the latest version of these rows. For the sake of example, these are rows in a table called Product, the timestamped column is version. There are multiple versions of multiple products in the table. So there may be multiple versions (rows) of ProductA, multiple versions of ProductB, etc. And I would like to grab the latest version of each. Can I do this in just a single hibernate query? session.createQuery("select product from Product product where...?"); Or would this require some intermediate steps?

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  • Unknown file system: grub Rescue

    - by samba
    I deleted the partition which contains the Ubuntu 12.0.4 OS. I have windows one other drive. When I reboot the system, It shows the following. unknown filesystem. grub rescue I read the previous questions about this topic and I tried to install Linux again using usb flash drive but was unable to boot from flash drive. I do not have a DVD ROM... what Shall I do now to boot from windows...? thank you in advance....

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  • How to fast rendering UITableView

    - by pubudu
    In my program has two view controller. first one has one button.and second one has tableview with custom cell. in this cell has 5 textviews. when i click button of first tableview.it shows second view controller. Its is very slow rendering table view with 5 , 6 rows.it is working well with simulator.but it is very slow with actual i pad. when i click the button i have to wait 2,3 second with button pressed status.and after it view the second view controller it also very slow rendering.i can see it render rows. [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; this one also i used.when i comment this table from my second view.it navigate first view controller to second view controller very fast. how can i solve this issue?

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  • SQL Query takes about 10 - 20 minutes

    - by masfenix
    I have a select from (nothing to complex) Select * from VIEW This view has about 6000 records and about 40 columns. It comes from a Lotus Notes SQL database. So my ODBC drive is the LotusNotesSQL driver. The query takes about 30 seconds to execute. The company I worked for used EXCEL to run the query and write everything to the worksheet. Since I am assuming it writes everything cell by cell, it used to take up to 30 - 40 minutes to complete. I then used MS access. I made a replica local table on Access to store the data. My first try was INSERT INTO COLUMNS OF LOCAL TABLE FROM (SELECT * FROM VIEW) note that this is pseudocode. This ran successfully, but again took up to 20 - 30 minutes. Then I used VBA to loop through the data and insert it in manually (using an INSERT statement) for each seperate record. This took about 10 - 15 minutes. This has been my best case yet. What i need to do after: After i have the data, I need to filter through it by department. The thing is if I put a where clause in the SQL query (the time jumps from 30 seconds to execute the query, to about 10 minutes + the time to write to local table/excel). I dont know why. MAYBE because the columns are all text columns? If we change some of the columns to integer, would that make it faster in terms of the where clause? I am looking for suggestions on how to approach this. My boss has said we could employ some Java based solution. Will this help? I am not a java person but a c#, and maybe I'll convince them to use c# as well, but i am mainly looking for suggestions on how to cut down the time. I've already cut it down from 40 minutes to 10 minutes, but the want it under 2 minutes. Just to recap: Query takes about 30 seconds to exceute Query takes about 15 - 40 minutes to be used locally in excel/acess Need it under 2 minutes Could use java based solution You may suggest other solutions instead of java.

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  • How to concatinate text on existing database entry?

    - by Starx
    I am a table, whose structure is somewhat like this id, name, link the link holds the name of the page like "link" = "index.php". Now I want to update this field and add "page=" in front of "index.php". Using this method I would like to update every entry in my table. My desired SQL syntax need to be something like this UPDATE mytable set link= 'page=' + <existing value of link> WHERE 1; I am using Where 1; to denote every other rows Anyone know what to accomplish this?

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  • Help with MySQL and CASE WHEN with a range of values

    - by kickdaddy
    I have an accounts table and a records table where accounts have multiple records. I would like to break down the account totals by "count of records" range. i.e. show the breakdown of Count of Records | Count 0-25 | 100 25 - 50 | 122 50 - 100 | 300 etc. I am using the following query, but I can't get it to group by "grp" which is what I want, any help on the best way to modify query? Thanks! SELECT count(*) as ct, CASE WHEN COUNT(*) < 25 THEN '1-25' WHEN COUNT(*) >= 25 < 50 THEN '25-50' WHEN COUNT(*) >= 50 < 100 THEN '50-100' WHEN COUNT(*) >= 100 < 250 THEN '100-250' WHEN COUNT(*) >= 250 < 500 THEN '250-500' WHEN COUNT(*) >= 500 < 1000 THEN '500-1000' ELSE '1000+' END AS grp FROM records r,accounts a WHERE r.account_id=a.id ORDER BY ct

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  • Problem using mysql joins

    - by mariomario
    I'm fairly new to mysql and I have no idea if I'm heading in the right direction but I'm having trouble with a mysql query. I basically have a table of users id name ---- -------- 1 user1 2 user2 3 user3 4 user4 as well as a table of user attributes id userid attribute ---- ----- ------ 1 1 5 2 1 6 3 2 5 4 3 4 I want to be able to select users that have both the attribute 5 and the attribute 6, so in this case I want to return id name ---- -------- 1 user1 I tried using a join like this. SELECT u.id, u.name FROM users u LEFT JOIN attributes a ON (a.userid = u.id) WHERE a.attribute = 5 AND a.attribute = 6 But obviously that won't work, what is the best way of doing this?

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  • Jquery question : maintain focus upon appending a row?

    - by PoppySeedsAndAppleJuice
    The function below checks whether the id entered is already in the database, and if it is, then it adds some html to the table. I'm not sure if it's directly related to my issue or not, but, essentially, a user will place the focus on the id input field and enters an id. Using ajax, it posts to a php script and returns data if rows are found and nothing if it doesn't. If the user then tabs over to the next input field (zipcode), or clicks in another input field, they essentially have to do so twice. The cursor "flashes" in the field briefly and then focuses out. I tried adding in a focus(), but the behavior didn't change. So, the html looks like this: <table id="tableSearchData" class="searchlist" style="width: 789px;"> <thead> <tr> <th>ID</th> <th>Zip Code</th> <th>Radius (in miles)</th> </tr> </thead> <tbody> <tr class="odd"> <!-- PROBLEM is described below --> <!-- User clicks in <input name="id[]"> and ID is checked --> <!-- User presses "tab" or clicks in <input name="zipcode[] (in the *same* row) and cursor flashes, then goes out of focus so that the user has to click in the field again --> <td class="center sorting_1"><input type="text" value="" name="id[]"></td> <td class="center"><input type="text" value="" name="zipcode[]"></td> <td class="center"><input type="text" value="" name="radius[]"></td> </tr> </tbody> </table> Here's the jquery function... Like I said, I'm not sure if it's directly related to the problem I'm having, but, thought I should include it because I suppose it's likely there is something happening there... $("#tableSearchData > tbody > tr > td > input[name=id[]]").focusout(function() { var row = $(this).closest("tr").get(0); var sData = $(this).serialize(); $.ajax({ type: "POST", url: "checkid.php", data: sData, success: function(html) { $(row).replaceWith(html); $(".preset").each(function() { $(this).attr("disabled", true); }); $(row).closest("input[name=zipcode[]]").focus(); } }); });

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  • getting values by time difference in SQL

    - by Maestro1024
    I want to get the difference of two values within a time frame. so I have a table like this Data Table TimeStamp DataValue 2010-06-01 21 2010-06-03 33 2010-06-05 44 So I want to first get all data over the last month which I can do with something like. ([TimeStamp] < GETDATE()-0 and ([TimeStamp] > GETDATE()-31) But I want to see how much value added on over the course of the month. So it started at 21 and went to 44. So I would expect this example to to return 23 (as in 44-21). How would I build a query like this?

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