Search Results

Search found 7321 results on 293 pages for 'john smith optional'.

Page 235/293 | < Previous Page | 231 232 233 234 235 236 237 238 239 240 241 242  | Next Page >

  • Where is the iPhone's Date & Time getting it's time zone list

    - by johnbdh
    I can get a list of time zones with [NSTimeZone knownTimeZoneNames], but that only gives the time zone IDs which include one or 2 cities in each time zone. The Date & Time settings has a great list of cities and I have seen a few other apps that have the same if not similar lookup lists. Where do these lists come from?? I do need to relate a picked city to it's time zone like Date & Time does. Thanks, John

    Read the article

  • 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 ?

    Read the article

  • AssertionFailure: "null identifier" - FluentNH + SQLServerCE

    - by Stefan
    The code fails at session.Save(employee); with AssertionFailure "null identifier". What am I doing wrong? using FluentNHibernate.Cfg; using FluentNHibernate.Cfg.Db; using FluentNHibernate.Mapping; using NHibernate; using NHibernate.Cfg; using NHibernate.Tool.hbm2ddl; namespace FNHTest { public class Employee { public virtual int Id { get; private set; } public virtual string Name { get; set; } public virtual string Surname { get; set; } } public class EmployeeMap : ClassMap { public EmployeeMap() { Id(e = e.Id); Map(e = e.Name); Map(e = e.Surname); } } public class DB { private static ISessionFactory mySessionFactory = null; private static ISessionFactory SessionFactory { get { if (mySessionFactory == null) { mySessionFactory = Fluently.Configure() .Database(MsSqlCeConfiguration.Standard .ConnectionString("Data Source=MyDB.sdf")) .Mappings(m = m.FluentMappings.AddFromAssemblyOf()) .ExposeConfiguration(BuildSchema) .BuildSessionFactory(); } return mySessionFactory; } } private static void BuildSchema(Configuration configuration) { SchemaExport schemaExport = new SchemaExport(configuration); schemaExport.Execute(false, true, false); } public static ISession OpenSession() { return SessionFactory.OpenSession(); } } public class Program { public static void Main(string[] args) { var employee = new Employee { Name = "John", Surname = "Smith" }; using (ISession session = DB.OpenSession()) { session.Save(employee); } } } }

    Read the article

  • How do I convert this XML to KML?

    - by TruMan1
    I am a little new to this, but I need to convert the below XML to KML format so I can feed it into Google maps. Can anyone help with this? <messageList> <totalCount>1</totalCount> - <message> <esn>0-7396996</esn> <esnName>JOHN</esnName> <messageType>TEST</messageType> <messageDetail> ALL IS WELL AT CURRENT LOCATION.</messageDetail> <timestamp>2010-05-24T00:39:12.000Z</timestamp> <timeInGMTSecond>1274661552</timeInGMTSecond> <latitude>25.19483</latitude> <longitude>65.7162</longitude> </message> </messageList>

    Read the article

  • How to compare the output of serializeArray using qunit

    - by dorelal
    I am using qunit and jquery. Latest version of both. In my code when I submit the form I have the event as e. I call e.serializeArray() Here is my test. equals(args.data, [ { "name": "user_name", "value": "john" } ], 'input data'); And this is the error message from qunit. expected: [ { "name": "user_name", "value": "david" } ] result: [ { "name": "user_name", "value": "david" } ] As you can see to the naked eye the expected and result value is same but qunit is not liking it. I guess I am missing something.

    Read the article

  • How to parse this xml document?

    - by dfjhdfjhdf
    Get such a XML document with the help of ajax (var data = request.responseXML;), how do I parse the contacts?: <?xml version="1.0" encoding="UTF-8"?> <Alladresses xmlns="http://somedomain.org/doc/2007-08-02/"> <Owner> <ID>gut74hfowesdfj49fjsifhryh8e8rta3uyhw4</ID> <Name>Mr.Bin</Name> </Owner> <Contacts> <Person> <Name>Greg</Name> <Phone>3254566756</Phone> </Person> <Person> <Name>Smith</Name> <Phone>342446446</Phone> </Person> <Person> <Name>Yuliya</Name> <Phone>675445566867</Phone> </Person> </Contacts> </Alladresses>

    Read the article

  • Multi-Threading in .NET

    - by AIC
    Hi all.. I wrote this program, that is supposed to read about 5000 email address and send an pre-defined html mail. I am using the background worker component. The problem is this: I have wired up the method who is supposed to send the mail. But I am calling another method that is supposed to append the body html to the salutation, like public string GiveMeFullHtml(string personname) ... "Dear Mr. John Doe" + HTML ... It seems that when it hits this method call, operation completes. IUt only sends the first mail and completes. I think because the HTML string method is on another thread or sth like that. Can you give me a little insight. Do I have to get everything done in the very same method when using multi-threading? Thanks in advance

    Read the article

  • Alternate widgets and logic for ManyToManyField with Django forms

    - by Jaearess
    In my Django project, I have a simple ticket system. When creating a ticket, certain users have the ability to assign the ticket to other users, and to email the ticket to other users as well (this is used as an FYI for those users, so they're aware of the ticket, even though it's not assigned to them.) At the moment, the form for adding a ticket is simply the default Django form, with the "assigned_to" and "email_to" fields being ManyToManyFields, and therefore displayed as MultipleSelect widgets, each with a list of all users. Due to the relatively large number of users, and general awkwardness of the MultipleSelect widget, and alternate layout is now required. The desired layout is a pair of simple Select widgets side-by-side. The first has the option of "Assign to" or "Email to" and the second is a list of the users. Essentially, like this: [Assign to] [John Doe] [Email to] [Jane Roe] [Jack Smith], etc. Of course, since an arbitrary number of users can be assigned or emailed a ticket, there's a simple button that runs some Javascript to add another set of widgets, to allow the user to assign and email as many people as they need to. So far all of that is fairly simple and straight forward. However, the problem I have is using this widget setup/logic setup with Django forms. Instead of lists of users to assign to and email, instead we're getting back pairs of information, one a user and the other which list that user should be placed in. What I'm looking for, but have yet to find, is a way to offload the translation between how the user uses the form, and how Django understands the model to the form itself, so I don't have to manually do the processing of the data before passing it to the form in each place this form is used. Additionally, there's a review screen with the option to go back and change the form before submitting it, so a way to have the form translate both to and from this format would be extremely helpful.

    Read the article

  • How to Look Up Email by Full Name in Active Directory?

    - by Danny
    I want to search for a user's email by using Active Directory. Available is the user's full name (ex. "John Doe" for the email with an email "[email protected]"). From what I've searched, this comes close to what I'm looking to do -- except that the Filter is set to "SAMAccountName", which is not what I have. Unless I'm misunderstanding, I just need to pick the right attribute and toss in the full name name in the same way. Unfortunately, I don't know what this attribute is, apparently no one has had to ask about searching for information in this manner, and that is a pretty big list (msdn * microsoft * com/en-us/library/ms675090(v=VS.85) * aspx, stackoverflow didn't let me link 2 hyperlinks because I don't have 10 rep) of attributes. Does anyone know how to obtain the user's email address through an Active Directory lookup by using the user's full name?

    Read the article

  • c++ passing unknown type to a function and any Class type definition

    - by user259789
    I am trying to create a generic class to write and read Objects to/from file. Called it ActiveRecord class only has one method, which saves the class itself: void ActiveRecord::saveRecord(){ string fileName = "data.dat"; ofstream stream(fileName.c_str(), ios::out); if (!stream) { cerr << "Error opening file: " << fileName << endl; exit(1); } stream.write(reinterpret_cast<const char *> (this), sizeof(ActiveRecord)); stream.close(); } now I'm extending this class with User class: class User : public ActiveRecord { public: User(void); ~User(void); string name; string lastName; }; to create and save the user I would like to do something like: User user = User(); user.name = "John"; user.lastName = "Smith" user.save(); how can I get this ActiveRecord::saveRecord() method to take any object, and class definition so it writes whatever i send it: to look like: void ActiveRecord::saveRecord(foo_instance, FooClass){ string fileName = "data.dat"; ofstream stream(fileName.c_str(), ios::out); if (!stream) { cerr << "Error opening file: " << fileName << endl; exit(1); } stream.write(reinterpret_cast<const char *> (foo_instance), sizeof(FooClass)); stream.close(); } and while we're at it, what is the default Object type in c++. eg. in objective-c it's id in java it's Object in AS3 it's Object what is it in C++??

    Read the article

  • Does Ivy's url resolver support transitive retrieval?

    - by Sean
    For some reason I can't seem to resolve the dependencies of my dependencies when using a url resolver to specify a repository's location. However, when using the ibiblio resolver, I am able to retrieve them. For example: <!-- Ivy File --> <ivy-module version="1.0"> <info organisation="org.apache" module="chained-resolvers"/> <dependencies> <dependency org="commons-lang" name="commons-lang" rev="2.0" conf="default"/> <dependency org="checkstyle" name="checkstyle" rev="5.0"/> </dependencies> </ivy-module> <!-- ivysettings file --> <ivysettings> <settings defaultResolver="chained"/> <resolvers> <chain name="chained"> <url name="custom-repo"> <ivy pattern="http://my.internal.domain.name/ivy/[organisation]/[module]/[revision]/ivy-[revision].xml"/> <artifact pattern="http://my.internal.domain.name/ivy/[organisation]/[module]/[revision]/[artifact]-[revision].[ext]"/> </url> <url name="ibiblio-mirror" m2compatible="true"> <artifact pattern="http://mirrors.ibiblio.org/pub/mirrors/maven2/[organisation]/[module]/[revision]/[artifact]-[revision].[ext]" /> </url> <ibiblio name="ibiblio" m2compatible="true"/> </chain> </resolvers> </ivysettings> <!-- checkstyle ivy.xml file generated from pom via ivy:install task --> <?xml version="1.0" encoding="UTF-8"?> <ivy-module version="1.0" xmlns:m="http://ant.apache.org/ivy/maven"> <info organisation="checkstyle" module="checkstyle" revision="5.0" status="release" publication="20090509202448" namespace="maven2" > <license name="GNU Lesser General Public License" url="http://www.gnu.org/licenses/lgpl.txt" /> <description homepage="http://checkstyle.sourceforge.net/"> Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard </description> </info> <configurations> <conf name="default" visibility="public" description="runtime dependencies and master artifact can be used with this conf" extends="runtime,master"/> <conf name="master" visibility="public" description="contains only the artifact published by this module itself, with no transitive dependencies"/> <conf name="compile" visibility="public" description="this is the default scope, used if none is specified. Compile dependencies are available in all classpaths."/> <conf name="provided" visibility="public" description="this is much like compile, but indicates you expect the JDK or a container to provide it. It is only available on the compilation classpath, and is not transitive."/> <conf name="runtime" visibility="public" description="this scope indicates that the dependency is not required for compilation, but is for execution. It is in the runtime and test classpaths, but not the compile classpath." extends="compile"/> <conf name="test" visibility="private" description="this scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases." extends="runtime"/> <conf name="system" visibility="public" description="this scope is similar to provided except that you have to provide the JAR which contains it explicitly. The artifact is always available and is not looked up in a repository."/> <conf name="sources" visibility="public" description="this configuration contains the source artifact of this module, if any."/> <conf name="javadoc" visibility="public" description="this configuration contains the javadoc artifact of this module, if any."/> <conf name="optional" visibility="public" description="contains all optional dependencies"/> </configurations> <publications> <artifact name="checkstyle" type="jar" ext="jar" conf="master"/> </publications> <dependencies> <dependency org="antlr" name="antlr" rev="2.7.6" force="true" conf="compile->compile(*),master(*);runtime->runtime(*)"/> <dependency org="apache" name="commons-beanutils-core" rev="1.7.0" force="true" conf="compile->compile(*),master(*);runtime->runtime(*)"/> <dependency org="apache" name="commons-cli" rev="1.0" force="true" conf="compile->compile(*),master(*);runtime->runtime(*)"/> <dependency org="apache" name="commons-logging" rev="1.0.3" force="true" conf="compile->compile(*),master(*);runtime->runtime(*)"/> <dependency org="com.google.collections" name="google-collections" rev="0.9" force="true" conf="compile->compile(*),master(*);runtime->runtime(*)"/> </dependencies> </ivy-module> Using the "ibiblio" resolver I have no problem resolving my project's two dependencies (commons-lang 2.0 and checkstyle 5.0) and checkstyle's dependencies. However, when attempting to exclusively use the "custom-repo" or "ibiblio-mirror" resolvers, I am able to resolve my project's two explicitly defined dependencies, but not checkstyle's dependencies. Is this possible? Any help would be greatly appreciated.

    Read the article

  • Overriding events of excel sheet using VBA

    - by Rashmi Pandit
    Hi, I need to programmatically override the following events of a worksheet: BeforeDoubleClick SelectionChange BeforeRightClick I have been able to override the OnActivate event using the following code: sheet.OnSheetActivate = "MyOwn_Activate" Private Sub MyOwn_Activate() myForm.Show End Sub I have implemented BeforeDoubleClick on similar lines: sheet.OnDoubleClick = "My_BeforeDoubleClick" Private Sub My_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean) ... End Sub However, an 'argument not optional' error is thrown at run-time when user double clicks a cell on the sheet. Can someone please suggest how should I pass the paramters? In addition, I am not able to find event names for SelectionChange & BeforeRightClick. I tried: sheet.BeforeRightClick = "My_BeforeRightClick" sheet.SelectionChange = "My_SelectionChange" But, both the above lines do not work. Any help/ suggestion is greatly appreciated. Thanks :)

    Read the article

  • Effects of the `extern` keyword on C functions

    - by Elazar Leibovich
    In C I did not notice any effect of the extern keyword used before function declaration. At first I thougth that when defining extern int f(); in a single file forces you to implement it outside of the files scope, however I found out that both extern int f(); int f() {return 0;} And extern int f() {return 0;} Compiles just fine, with no warnings from gcc. I used gcc -Wall -ansi, he wouldn't even accept // comments. Are there any effects for using extern before function definitions? Or is it just an optional keyword with no side effects for functions. In the latter case I don't understand why did the standard designers chose to litter the grammar with superfluous keywords. EDIT: to clarify, I know there's usage for extern in variables, but I'm only asking about extern in functions.

    Read the article

  • Perl - Read XML

    - by chinna_82
    XML <?xml version='1.0'?> <employee> <name>Smith</name> <age>43</age> <sex>M</sex> <department role='manager'>Operations</department> </employee> Perl use XML::Simple; use Data::Dumper; $xml = new XML::Simple; foreach my $data1 ($data = $xml->XMLin("test.xml")) { print Dumper($data1); } Above code managed to all the xml value like this. Output $VAR1 = { 'department' => { 'content' => 'Operations', 'role' => 'manager' }, 'name' => 'John Doe', 'sex' => 'M', 'age' => '43' }; How do I do, if I only want to get the role value. For this example I need to get Role = manager. Any advice or reference link is highly appreciated.

    Read the article

  • Click Once doesn't create StartMenu entry and Shortcut on Windows 7 x64

    - by MadBoy
    I've application that I deploy to share with ClickOnce so other users can install it and use it on their own machines. It worked fine till i noticed that when i install this app on my own machine (Windows 7 x 64) it doesn't add StartMenu (even thou it installs correctly and I have it in Control Panel / Programs). I didn't had that problem when my development machine was Windows XP. Application also deploys fine on other Windows XP computers. Also during installation (when i rerun setup) even thou I already have Net Framework 3.5 it always wants to install one (it starts that and terminates few seconds later - probably installer sees that it's already there). I can run application straigit from share just a bit of pain to do it. Are there some special settings I should do? Or some patches? I have Visual Studio 2008 and system with all optional updates installed. Application is written in C# and uses NET 3.5.

    Read the article

  • Logic for controll concurrent in block or funciton

    - by Hlex
    1)My environment is web application, I accept large request from selvets. A) In some block/method i want to control concurrent to not greater than 5 B) if there are 5 request in that block , the new coming must wait up to 60 second then throws error C) if there are sleep/waiting request most then 30,throws error How I do this? 2)(Optional Question) from above I have to distribute control logic to all clustered host. I plan to use hazelcast to share the control logic (e.g. current counter) I see they provide BlockingQueue & ExectorService but I have no idea how to use in my case. Please recommend if you have idea.

    Read the article

  • How do I stop ValueConverters from firing when swapping the content of a ContentControl

    - by DanM
    I thought what I was doing was right out of the Josh Smith MVVM handbook, but I seem to be having a lot of problems with value converters firing when no data in the view-model has changed. So, I have a ContentControl defined in XAML like this: <ContentControl Grid.Row="0" Content="{Binding CurrentViewModel}" /> The Window containing this ContentControl references a resource dictionary that looks something like this: <ResourceDictionary ...> <DataTemplate DataType="{x:Type lib_vm:SetupPanelViewModel}"> <lib_v:SetupPanel /> </DataTemplate> <DataTemplate DataType="{x:Type lib_vm:InstructionsPanelViewModel}"> <lib_v:InstructionsPanel /> </DataTemplate> </ResourceDictionary> So, basically, the two data templates specify which view to show with which view-model. This switches the views as expected whenever the CurrentViewModel property on my window's view-model changes, but it also seems to cause value converters on the views to fire even when no data has changed. It's a particular problem with IMultiValueConverter classes, because the values in the value array get set to DependencyProperty.UnsetValue, which causes exceptions unless I specifically check for that. But I'm getting other weird side effects too. This has me wondering if I shouldn't just do everything manually, like this: Instantiate each view. Set the DataContext of each view to the appropriate view-model. Give the ContentControl a name and make it public. Handle the PropertyChanged event for the window. In the event handler, manually set the Content property of the ContentControl to the appropriate view, based the CurrentViewModel (using if statements). This seems to work, but it also seems very inelegant. I'm hoping there's a better way. Could you please advise me the best way to handle view switching so that value converters don't fire unnecessarily?

    Read the article

  • 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?

    Read the article

  • Compare values for audit trail

    - by kagaku
    I'm attempting to develop an audit trail/tracking solution for an existing database written in PLSQL/PHP - however I'm still unsure as of yet on an easy (to implement and maintain) solution for tracking changes to fields/values. For instance, the project tracking portion of the DB APP tracks over 200 fields and ideally I'd like a nice way to show a history of changes, such as: 5/10/2010 - Project 435232 updated by John Doe Changed Project Name (Old: Test Project; New: Super Test Project) Changed Submission Date (Old: 5/10/2010; New: 5/11/2010) Changed Description (Old: This is an example!; New: This is a test example) Essentially for each field (db column) it would output a new line to show the old/new values. So far my current idea is saving the current version of the data to a temporary table, updating the primary table with the new data then loading each row into an array and doing an array compare to determine the differences. This seems a bit convoluted, and if there is an easier method I'd love to know it. Any ideas or suggestions are much appreciated!

    Read the article

  • MVC MapPageRoute and ActionLink

    - by Dismissile
    I have created a page route so I can integrate my MVC application with a few WebForms pages that exist in my project: public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); // register the report routes routes.MapPageRoute("ReportTest", "reports/test", "~/WebForms/Test.aspx" ); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); } This has created a problem whenever I use Html.ActionLink in my Views: <%: Html.ActionLink("Home", "Index", "Home") %> When I load the page in the browser the link appears like: http://localhost:12345/reports/test?action=Index&controller=Home Has anyone run into this before? How can I fix this?

    Read the article

  • Custom tool error: Command.proto:11:18: "Message2" is not defined.

    - by cornerback84
    I am using the latest version of protobuf-net with VS2008 integration. I have created 2 messages (Message1 and Message2), 1 message in 1 proto file. When I try to reference Message2 in Message1 the code generator tool gives me error "Message2" is not defined and won't generate the code file. The package for both messages is same. It look like that because of the integration of the tool with VS2008 it expects all the messages in same .proto file to compile. Currently I have to paste an empty message with same name in Message1.proto file, like this: message Message1 { optional Message2 message2 = 1; } message Message2 { } And then later on remove the declaration of class Message2 from Message1.cs. Are there any settings that I need to do so to avoid this error, or is providing an empty declaration the only way?

    Read the article

  • How can I concatinate a subquery result field into the parent query?

    - by Pure.Krome
    Hi folks, DB: Sql Server 2008. I have a really (fake) groovy query like this:- SELECT CarId, NumberPlate (SELECT Owner FROM Owners b WHERE b.CarId = a.CarId) AS Owners FROM Cars a ORDER BY NumberPlate And this is what I'm trying to get... => 1 ABC123 John, Jill, Jane => 2 XYZ123 Fred => 3 SOHOT Jon Skeet, ScottGu So, i tried using AS [Text()] ... FOR XML PATH('') but that was inlcuding weird encoded characters (eg. carriage return). ... so i'm not 100% happy with that. I also tried to see if there's a COALESCE solution, but all my attempts failed. So - any suggestions?

    Read the article

  • Fabfiles With Command Line Arguments

    - by phasetwenty
    Is there a clean way to have your fabfile take command line arguments? I'm writing an installation script for a tool that I want to be able to specify an optional target directory via the command line. I wrote some code to test what would happen if I passed in some command line arguments: # fabfile.py import sys def install(): _get_options() def _get_options(): print repr(sys.argv[1:]) A couple of runs: $ fab install ['install'] Done. $ fab install --electric-boogaloo Usage: fab [options] <command>[:arg1,arg2=val2,host=foo,hosts='h1;h2',...] ... fab: error: no such option: --electric-boogaloo

    Read the article

  • How can I populate highchart jQuery plugin dynamically from MVC action?

    - by Anders Svensson
    I'm trying out the Highcharts jQuery plugin for creating charts of data in an MVC application. But I need to get the data for the function dynamically from an Action Method. How can I do that? Taking the example from the Highcharts site (http://highcharts.com/documentation/how-to-use): var chart1; // globally available $(document).ready(function() { chart1 = new Highcharts.Chart({ chart: { renderTo: 'chart-container-1', defaultSeriesType: 'bar' }, title: { text: 'Fruit Consumption' }, xAxis: { categories: ['Apples', 'Bananas', 'Oranges'] }, yAxis: { title: { text: 'Fruit eaten' } }, series: [{ name: 'Jane', data: [1, 0, 4] }, { name: 'John', data: [5, 7, 3] }] }); }); How can I get the data in there dynamically from the action method? Someone suggested I might use JSon, but couldn't specify how. If this is the case, I would really appreciate a simple and specific example, because I don't know much about JSon. Any help appreciated!

    Read the article

  • Using Constraints on Hierarchical Data in a Self-Referential Table

    - by pbarney
    Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to update on cascades and prevent deletion of fruit if they have "children." So I used the following: CREATE TABLE `idtlp_main`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`iddoc_main`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

    Read the article

< Previous Page | 231 232 233 234 235 236 237 238 239 240 241 242  | Next Page >