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  • mysql error #1452 appearing when trying to add a constraint

    - by user1701484
    I am trying to alter a table so That I can add a foreign key constraint in mysql database: ALTER TABLE `Question` ADD CONSTRAINT `FK_question` FOREIGN KEY (`QuestionId`) REFERENCES `Image_Question` (`QuestionId`) ON DELETE CASCADE ; Problem is that it is giving me this error: 1452 - Cannot add or update a child row: a foreign key constraint fails (mobile_app. '#sql-4517_15241', CONSTRAINT FK_question FOREIGN KEY (QuestionId) REFERENCES Image_Question (QuestionId) ON DELETE CASCADE) What does this error actually mean and what are the possible solutions I might have to undertake in order to fix this?

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  • Enity framework not loading relationship even when using include

    - by dilbert789
    I have this code: Category selectedCategory = (from c in DB.Category.Include("SubCategory") join a in DB.Accessory on c.AccCatUID equals a.Category.AccCatUID where a.AccUID == currentAccessory.AccUID select c).FirstOrDefault(); It works fine, selectedCategory gets populated as expected. BUT selectedCategory has a child table 'SubCategory' which does not get loaded even though there is the include there. It is not loaded until I do this: selectedCategory.SubCategory.Load(); Why do I have to call load explicitly in order to load the child table?

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  • SQL Query with conditional JOIN

    - by mariki
    The scenario: Table1 CatId|Name|Description Table2 ItId|Title|Date|CatId (foreign key) I want to return all rows from Table1 and Title,Date from Table2, where The returned from Table 2 must be the Latest one by the date column. (in second table there many items with same CatId and I need just the latest) I have 2 queries but can't merge them together: Query 1: SELECT Table1.Name, Table1.Description, Table2.Title, Table2.Date FROM Table1 LEFT JOIN Table2 ON Table1.CatId=Table2.CatId Query2: SELECT TOP 1 Table2.Title, Table2.Date FROM Table2 WHERE Table2.CatId = @inputParam ORDER BY Table2.Date DESC

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  • SQL Server Merge statement issue

    - by George2
    Hello everyone, I am learning and using SQL Server 2008 new Merge statement, merge statement will compare/operate source table and destination table row by row ("operate" I mean operations performed for when matched or not-matched conditions). My question is whether the whole merge process will be one transaction or each row comparison/operation will be one transaction? Appreciate if any document to prove it. thanks in advance, George

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  • Foreign key pointing to different tables

    - by Álvaro G. Vicario
    I'm implementing a table per subclass design I discussed in a previous question. It's a product database where products can have very different attributes depending on their type, but attributes are fixed for each type and types are not manageable at all. I have a master table that holds common attributes: product_type ============ product_type_id INT product_type_name VARCHAR E.g.: 1 'Magazine' 2 'Web site' product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id valid_since DATETIME valid_to DATETIME E.g. 1 'Foo Magazine' 1 '1998-12-01' NULL 2 'Bar Weekly Review' 1 '2005-01-01' NULL 3 'E-commerce App' 2 '2009-10-15' NULL 4 'CMS' 2 '2010-02-01' NULL ... and one subtable for each product type: item_magazine ============= item_magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id issue_number INT pages INT copies INT close_date DATETIME release_date DATETIME E.g. 1 'Foo Magazine Regular Issue' 1 89 52 150000 '2010-06-25' '2010-06-31' 2 'Foo Magazine Summer Special' 1 90 60 175000 '2010-07-25' '2010-07-31' 3 'Bar Weekly Review Regular Issue' 2 12 16 20000 '2010-06-01' '2010-06-02' item_web_site ============= item_web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id bandwidth INT hits INT date_from DATETIME date_to DATETIME E.g. 1 'The Carpet Store' 3 10 90000 '2010-06-01' NULL 2 'Penauts R Us' 3 20 180000 '2010-08-01' NULL 3 'Springfield Cattle Fair' 4 15 150000 '2010-05-01' '2010-10-31' Now I want to add some fees that relate to one specific item. Since there are very little subtypes, it's feasible to do this: fee === fee_id INT fee_description VARCHAR item_magazine_id INT -> Foreign key to item_magazine.item_magazine_id item_web_site_id INT -> Foreign key to item_web_site.item_web_site_id net_price DECIMAL E.g.: 1 'Front cover' 2 NULL 1999.99 2 'Half page' 2 NULL 500.00 3 'Square banner' NULL 3 790.50 4 'Animation' NULL 3 2000.00 I have tight foreign keys to handle cascaded editions and I presume I can add a constraint so only one of the IDs is NOT NULL. However, my intuition suggests that it would be cleaner to get rid of the item_WHATEVER_id columns and keep a separate table: fee_to_item =========== fee_id INT -> Foreign key to fee.fee_id product_id INT -> Foreign key to product.product_id item_id INT -> ??? But I can't figure out how to create foreign keys on item_id since the source table varies depending on product_id. Should I stick to my original idea?

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  • How to use an IN clause in iBATIS?

    - by furtelwart
    I'm using iBATIS to create select statements. Now I would like to implement the following SQL statement with iBATIS: SELECT * FROM table WHERE col1 IN ('value1', 'value2'); With the following approach, the statement is not prepared correctly and no result returns: SELECT * FROM table WHERE col1 IN #listOfValues#; iBATIS seems to restructure this list and tries to interpret it as a string. How can I use the IN clause correctly?

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  • Tree View in c# with recursive

    - by user188886
    hi there i have table in DB with 3 column = ParentId , Id , Text i wanna make Tree in C# by the Records that we have saved in this table i dont know how should i write my recursive method in c# please help me thanks

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  • Ruby on Rails DataTable now working.

    - by Nimroo
    [Ruby on Rails DataTable guide][1]https://github.com/phronos/rails_datatables/blob/master/README.md I"m following the above and have installed the git plugin as well. All i'm getting is the <%= datatable() % returning " <script type="text/javascript"> $(function() { $('#expenses').dataTable({ "oLanguage": { "sSearch": "Search", "sProcessing": 'Processing' }, "sPaginationType": "full_numbers", "iDisplayLength": 25, "bProcessing": true, "bServerSide": false, "bLengthChange": false, "bStateSave": true, "bFilter": true, "bAutoWidth": true, 'aaSorting': [[0, 'desc']], "aoColumns": [ { 'sType': 'html', 'bSortable':true, 'bSearchable':true ,'sClass':'first' },{ 'sType': 'html', 'bSortable':true, 'bSearchable':true },{ 'sType': 'html', 'bSortable':true, 'bSearchable':true },{ 'sType': 'string', 'bSortable':true, 'bSearchable':true ,'sClass':'last' } ], "fnServerData": function ( sSource, aoData, fnCallback ) { aoData.push( ); $.getJSON( sSource, aoData, function (json) { fnCallback(json); } ); } }); }); </script>". My .html.erb looks like this: <% @page_title="User Page"%> <link rel="stylesheet" href="http://code.jquery.com/ui/1.9.2/themes/base/jquery-ui.css" /> <script src="http://code.jquery.com/jquery-1.8.3.js"></script> <script src="http://code.jquery.com/ui/1.9.2/jquery-ui.js"></script> <%=javascript_include_tag "jquery.dataTables" %> <%=stylesheet_link_tag "jquery-ui-1.9.2.custom" %> <script> $(function() { $( "#tabs" ).tabs(); }); </script> <% if current_user %> <div id="tabs"> <ul> <li><a href="#tabs-1">Expenses</a></li> <li><a href="#tabs-2">Accountant</a></li> <li><a href="#tabs-3">Requests (<%[email protected]%>)</a></li> </ul> <div id="tabs-3"> <p> <% if @requests.count != 0 %> <h2> Accountant Requests </h2> <table > <tr> <thead> <th>First Name</th> <th>Last Name</th> <th>Email Address</th> <th>Accept</th> <th>Reject</th> </thead> </tr> <% @requests.each do |request| %> <tr> <td><%= request.accountant.first_name %></td> <td><%= request.accountant.last_name %></td> <td><%= request.accountant.email %></td> <td><%= link_to 'accept', confirm_accountant_path(:accountant_id => request.accountant_id) %></td> <td><%= link_to 'Edit', edit_expense_path(request) %></td> </tr> <% end %> </tbody> </table> <% else %> <h4> You have no pending requests <h4> <% end %> </p> </div> <div id="tabs-2"> <p> <% if @accountants.count != 0 %> <h2> Accountant Info </h2> <table> <tr> <th>First Name</th> <th>Last Name</th> <th>Email Address</th> </tr> <% @accountants.each do |accountant| %> <tr> <td><%= accountant.first_name %></td> <td><%= accountant.last_name %></td> <td><%= accountant.email %></td> </tr> <% end %> </table> <% else %> <h4> Add Accountant <h4> <p> You don't have an accountant yet, perhaps consider adding one by e-mail </p> <%= render 'add_accountant_form' %> <% end %> <% end %> </p> </div> <div id="tabs-1"> <p><% if current_user %> <h4> Submit new expense </h4> <%= render 'expenses/form' %> <% columns = [{:type => 'html', :class => "first"}, {:type => 'html'}, {:type => 'html'}, {:type => nil, :class => "last"}] %> <%= datatable(columns, {:sort_by => "[0, 'desc']", table_dom_id:"expenses" }) %> <table id="expenses" class="datatable"> <thead> <tr> <th>Entry Date</th> <th>Last Update</th> <th>Amount</th> <th>User</th> <th>Receipt</th> <th></th> <th></th> </tr> </thead> <% @expenses.each do |user_expense| %> <tbody> <tr> <td><%= user_expense.created_at %></td> <td><%= user_expense.updated_at %></td> <td><%= user_expense.amount %></td> <td><%= user_expense.user.username %></td> <% if !user_expense.receipt_img.nil? %> <td><%= image_tag user_expense.receipt_img.url(:thumb) %></td> <% else %> <td>Future Button Here</td> <% end %> <td><%= link_to 'Show', user_expense %></td> <td><%= link_to 'Edit', edit_expense_path(user_expense) %></td> </tr> </tbody> <% end %> </table> <% end %></p> </div> </div>

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  • Select where and where not

    - by Simon
    I have a table containing lessons that I called "cours" (french) and I have several cours inside and I have linked them to students with a table between them to see if they go to the lessons or not. I would like to return data with the SELECT and the data that are NOT select. So, If one student follow 3 courses of 5, I would like to return the 3 courses that he follow and the 2 courses that he doesn't follow. Is there a way to do it ?

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  • B-trees, databases, sequential inputs, and speed.

    - by IanC
    I know from experience that b-trees have awful performance when data is added to them sequentially (regardless of the direction). However, when data is added randomly, best performance is obtained. This is easy to demonstrate with the likes of an RB-Tree. Sequential writes cause a maximum number of tree balances to be performed. I know very few databases use binary trees, but rather used n-order balanced trees. I logically assume they suffer a similar fate to binary trees when it comes to sequential inputs. This sparked my curiosity. If this is so, then one could deduce that writing sequential IDs (such as in IDENTITY(1,1)) would cause multiple re-balances of the tree to occur. I have seen many posts argue against GUIDs as "these will cause random writes". I never use GUIDs, but it struck me that this "bad" point was in fact a good point. So I decided to test it. Here is my code: SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[T1]( [ID] [int] NOT NULL CONSTRAINT [T1_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO CREATE TABLE [dbo].[T2]( [ID] [uniqueidentifier] NOT NULL CONSTRAINT [T2_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO declare @i int, @t1 datetime, @t2 datetime, @t3 datetime, @c char(300) set @t1 = GETDATE() set @i = 1 while @i < 2000 begin insert into T2 values (NEWID(), @c) set @i = @i + 1 end set @t2 = GETDATE() WAITFOR delay '0:0:10' set @t3 = GETDATE() set @i = 1 while @i < 2000 begin insert into T1 values (@i, @c) set @i = @i + 1 end select DATEDIFF(ms, @t1, @t2) AS [Int], DATEDIFF(ms, @t3, getdate()) AS [GUID] drop table T1 drop table T2 Note that I am not subtracting any time for the creation of the GUID nor for the considerably extra size of the row. The results on my machine were as follows: Int: 17,340 ms GUID: 6,746 ms This means that in this test, random inserts of 16 bytes was almost 3 times faster than sequential inserts of 4 bytes. Would anyone like to comment on this? Ps. I get that this isn't a question. It's an invite to discussion, and that is relevant to learning optimum programming.

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  • Sql Server: all object dependencies

    - by Gjorgji
    Hi, Is there any place where I can find all possible object dependencies in Sql Server? What I mean by "object dependency" is a list of object that one object can depend on. For example, TABLE can depend on SCHEMA, TYPE, TABLE, FUNCTION, etc.

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  • help with t-sql self join

    - by stackoverflowuser
    Based on the following table ID Date State ----------------------------- 1 06/10/2010 Complete 1 06/04/2010 Pending 2 06/06/2010 Active 2 06/05/2010 Pending I want the following ouptut ID Date State --------------------------- 1 06/04/2010 Complete 2 06/05/2010 Active So date is the earliest one and State is the latest one. I am failing to apply self join on the table to get the output. Thanks

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  • SQL Server Multiple Running Totals

    - by Nai
    I have a table like this UserID Score Date 5 6 2010-1-1 7 8 2010-1-2 5 4 2010-1-3 6 3 2010-1-4 7 4 2010-1-5 6 1 2010-1-6 I would like to get a table like this UserID Score RunningTotal Date 5 6 6 2010-1-1 5 4 10 2010-1-3 6 3 3 2010-1-4 6 1 4 2010-1-6 7 8 8 2010-1-2 7 4 12 2010-1-5 Thanks!

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  • Emacs : problem with tags file ?

    - by KaluSingh Gabbar
    I am using ctags to create tags for my Emacs to read symbols from, using cygwin. Emacs says "visit-tags-table-buffer: File /home/superman/tags is not a valid tags table" here are my options to find files and generate tags. $>find . -type f -regex '.*\.[hc]\|.*\.cpp' -print0 | xargs -0 ctags -e --extra=+q --fields=+fksaiS --c++-kinds=+px --append -f ~/tags

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  • Oracle query to select rows with unique code

    - by Jasim
    I have a table like this C1 C2 C3 Code 1 2 3 33 1 2 3 34 2 4 1 14 1 2 3 14 i want to select only those record whose code is appearing only in single row. ie, in this case rows with code 33 and 34.. as they appear only once in this table. How can i write a query for that

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  • CoreData NSFetchedResultsController Empty Section Display

    - by user280390
    Hello I would like to show a fixed number of sections in a table view with a Fetched Results Controller as the data source. If you image the contacts app where sections organised by the alphabet, it will not have a header for B if there are no contacts in that section, so the section headers you see are A then C. I would like to display a section header in my table (for B), but without any rows. an empty section in effect. Can NSFetchedResultsController do this for me?

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  • make field a dropdown in access 2007

    - by Crash893
    I'm creating a HR database in access 2007 I have a main table of employee info and several tables that relate to that table ( education for example) that list the acceptable elements that can populate that cell in that row When i create a form it was created as just a plain text field which is constrained but I wanted to create a dropdown that had just the data that they are allowed to enter to avoid confusion.

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  • How can one prevent page breaks between Tables in SQL Reporting Services 2005?

    - by James
    I've been developing an SSRS 2005 report (a form letter) that contains two tables. The first "table" uses DataSet "A" to populate address fields on letterhead. The second table uses DataSet "B" to display a basic list of records that pertain to the addressed party. Even though the two tables are within the same page and all PageBreak* properties are set to "False", SSRS renders the report as two pages. How can I force both tables to render in series, without any forced page breaks?

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  • mysqli_stmt_bind_param SQL Injection

    - by profitphp
    Is there still an injection risk when using prepared statements and mysqli_stmt_bind_param? For example: $malicious_input = 'bob"; drop table users'; mysqli_stmt_bind_param($stmt, 's', $malicious_input); Behind the scenes does mysqli_stmt_bind_param pass this query string to mysql: SET @username = "bob"; drop table users"; Or does it perform the SET command through the API, or use some type of protection to keep this from happening?

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  • Postgresql 9.1: ERROR: type "citext" does not exist

    - by gotuskar
    I am trying to execute following query through PgAdmin utility. CREATE TABLE svcr."EventLogs" ("eventId" BIGINT NOT NULL, "eventTime" TIMESTAMP WITH TIME ZONE NOT NULL, "userid" CITEXT, "realmid" CITEXT NOT NULL, "onUserid" CITEXT, "description" TEXT, CONSTRAINT eventlogs_pkey PRIMARY KEY ("eventId")); And I get following error - ERROR: type "citext" does not exist SQL state: 42704 Character: 120 However, following query runs fine - CREATE TABLE svcr."CategoryMap" ("category" INT NOT NULL, "userData" INT NOT NULL); What is wrong with the first query?

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  • Is it bad practice to use an enum that maps to some seed data in a Database?

    - by skb
    I have a table in my database called "OrderItemType" which has about 5 records for the different OrderItemTypes in my system. Each OrderItem contains an OrderItemType, and this gives me referential integrity. In my middletier code, I also have an enum which matches the values in this table so that I can have business logic for the different types. My dev manager says he hates it when people do this, and I am not exactly sure why. Is there a better practice I should be following?

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