Search Results

Search found 34305 results on 1373 pages for 'self referencing table'.

Page 597/1373 | < Previous Page | 593 594 595 596 597 598 599 600 601 602 603 604  | Next Page >

  • Is there a C# equivalent of typeof for properties/methods/members?

    - by David
    A classes Type metadata can be obtained in several ways. Two of them are: var typeInfo = Type.GetType("MyClass") and var typeInfo = typeof(MyClass) The advantage of the second way is that typos will be caught by the compiler, and the IDE can understand what I'm talking about (allowing features like refactoring to work without silently breaking the code) Does there exist an equivalent way of strongly referencing members/properties/methods for metadata and reflection? Can I replace: var propertyInfo = typeof(MyClass).GetProperty("MyProperty") with something like: var propertyInfo = property(MyClass.MyProperty)

    Read the article

  • Could not load file or assembly ... or one of its dependencies. An attempt was made to load a progra

    - by Dan
    I am getting the following error message when compiling or attempting to run my application on Windows 7 64 bit. I've scoured the internet and many people have the same error message however none of the solutions address my problem or situation. Using VS 2010. Error 38 Could not load file or assembly 'file:///D:/Projects/Windows Projects/Weld/Components/FileAttachments/FileAttachments/FileAttachments/bin/x86/Debug/FileAttaching.dll' or one of its dependencies. An attempt was made to load a program with an incorrect format. Line 1212, position 5. D:\Projects\Windows Projects\Weld\Weld\Weld.UI\frmMain.resx 1212 5 Weld.UI Ok, so I have 2 projects a UI project and a FileAttachment project. UI project has a reference to FileAttachment project. When I compile UI project in "Any CPU" mode everything works fine and it runs. I assume 'Any CPU' will run in 64bit mode when I compile as that is the platform I am using. I want to run/compile as x86 so I try to do that, so I change configuration for all projects to x86 and verify that these configurations are compiling to x86. I compile and get the error as stated above. I find it odd that it compiles and works fine in 64bit but not 32bit. However when compiled and deployed to users as 'Any CPU', if these users have x86 it still works for them no problem. I just can't compile or run as x86 on my PC. Again, I can compile as Any CPU and deploy to a 32bit PC no problem. Neither project are referencing any 64bit only dlls. Both projects are verified to be targetting 32bit dll's and .NET Framework assemblies. I need to compile and run this locally under 32bit mode. I need JIT edit/continue among other things. Here is the line of code in the resx file that is causing the problem: </data> <data name="Appearance17.Image" type="System.Drawing.Bitmap, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64"> <value> The resx file is verified to be generated for .NET 2.0 amnd is only referencing .NET 2.0 assemblies and not .NET 4.0 versions. Any ideas here? I've searched the net and have found hundreds of people with the same error message but a different problem.

    Read the article

  • When to use a foreign key in MySQL

    - by Mel
    Is there official guidance or a threshold to indicate when it is best practice to use a foreign key in a MySQL database? Suppose you created a table for movies. One way to do it is to integrate the producer and director data into the same table. (movieID, movieName, directorName, producerName). However, suppose most directors and producers have worked on many movies. Would it be best to create two other tables for producers and directors, and use a foreign key in the movie table? When does it become best practice to do this? When many of the directors and producers are appearing several times in the column? Or is it best practice to employ a foreign key approach at the start? While it seems more efficient to use a foreign key, it also raises the complexity of the database. So when does the trade off between complexity and normalization become worth it? I'm not sure if there is a threshold or a certain number of cell repetitions that makes it more sensible to use a foreign key. I'm thinking about a database that will be used by hundreds of users, many concurrently. Many thanks!

    Read the article

  • sql queries slower than expected

    - by neubert
    Before I show the query here are the relevant table definitions: CREATE TABLE phpbb_posts ( topic_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, poster_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, KEY topic_id (topic_id), KEY poster_id (poster_id), ); CREATE TABLE phpbb_topics ( topic_id mediumint(8) UNSIGNED NOT NULL auto_increment ); Here's the query I'm trying to do: SELECT p.topic_id, p.poster_id FROM phpbb_topics AS t LEFT JOIN phpbb_posts AS p ON p.topic_id = t.topic_id AND p.poster_id <> ... WHERE p.poster_id IS NULL; Basically, the query is an attempt to find all topics where the number of times someone other than the target user has posted in is zero. In other words, the topics where the only person who has posted is the target user. Problem is that query is taking a super long time. My general assumption when it comes to SQL is that JOINs of any are super fast and can be done in no time at all assuming all relevant columns are primary or foreign keys (which in this case they are). I tried out a few other queries: SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id; That returns 353340 pretty quickly. I then do these: SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id AND p.poster_id <> 77198; SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id WHERE p.poster_id <> 77198; And both of those take quite a while (between 15-30 seconds). If I change the < to a = it takes no time at all. Am I making some incorrect assumptions? Maybe my DB is just foobar'd?

    Read the article

  • Java Persistence: Cast to something the result of Query.getResultList() ?

    - by GuiSim
    Hey everyone, I'm new to persistence / hibernate and I need your help. Here's the situation. I have a table that contains some stuff. Let's call them Persons. I'd like to get all the entries from the database that are in that table. I have a Person class that is a simple POJO with a property for each column in the table (name, age,..) Here's what I have : Query lQuery = myEntityManager.createQuery("from Person") List<Person> personList = lQuery.getResultList(); However, I get a warning saying that this is an unchecked conversion from List to List<Person> I thought that simply changing the code to Query lQuery = myEntityManager.createQuery("from Person") List<Person> personList = (List<Person>)lQuery.getResultList(); would work.. but it doesn't. Is there a way to do this ? Does persistence allow me to set the return type of the query ? (Through generics maybe ? )

    Read the article

  • multiple-to-one relationship mysql, submissions

    - by Yulia
    Hello, I have the following problem. Basically I have a form with an option to submit up to 3 images. Right now, after each submission it creates 3 records for album table and 3 records for images. I need it to be one record for album and 3 for images, plus to link images to the album. I hope it all makes sense... Here is my structure. TABLE `albums` ( `id` int(11) NOT NULL auto_increment, `title` varchar(50) NOT NULL, `fullname` varchar(40) NOT NULL, `email` varchar(100) NOT NULL, `created_at` datetime NOT NULL, `theme_id` int(11) NOT NULL, `description` int(11) NOT NULL, `vote_cache` int(11) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=20 ; TABLE `images` ( `id` int(11) NOT NULL auto_increment, `album_id` int(11) NOT NULL, `name` varchar(30) NOT NULL, and my code function create_album($params) { db_connect(); $query = sprintf("INSERT INTO albums set albums.title = '%s', albums.email = '%s', albums.discuss_url = '%s', albums.theme_id = '%s', albums.fullname = '%s', albums.description = '%s', created_at = NOW()", mysql_real_escape_string($params['title']), mysql_real_escape_string($params['email']), mysql_real_escape_string($params['theme_id']), mysql_real_escape_string($params['fullname']), mysql_real_escape_string($params['description']) ); $result = mysql_query($query); if(!$result) { return false; } $album_id = mysql_insert_id(); return $album_id; } if(!is_uploaded_file($_FILES['userfile']['tmp_name'][$i])) { $warning = 'No file uploaded'; } elseif is_valid_file_size($_FILES['userfile']['size'][$i])) { $_POST['album']['theme_id'] = $theme['id']; create_album($_POST['album']); mysql_query("INSERT INTO images(name) VALUES('$newName')"); copy($_FILES['userfile']['tmp_name'][$i], './photos/'.$original_dir.'/' .$newName.'.jpg');

    Read the article

  • OpenERP model tracking external resource, hooking into parent's copy() or copy_data()

    - by CB.
    I have added a new model (call it crm_lead_external) that is linked via a new one2many on crm_lead. Thus, my module has two models defined: an updated crm_lead (with _name=crm_lead) and a new crm_lead_external. This external model tracks a file and as such has a 'filename' field. I also created a unique SQL index on this filename field. This is part of my module: def copy(self, cr, uid, id, default=None, context=None): if not default: default = {} default.update({ 'state': 'new', 'filename': '', }) ret = super(crm_lead_external, self).copy(cr, uid, id, default, context=context) #do file copy return ret The intent here is to allow an external entity to be duplicated, but to retarget the file path. Now, if I click duplicate on the Lead, I get an IntegrityError on my unique constraint. Is there a particular reason why copy() isn't being called? Should I add this logic to copy_data()? Myst I really override copy() for the lead? Thanks in advance.

    Read the article

  • Why the input and the select do not get the same width?

    - by Bytecode Ninja
    I have a table with two rows. The first row contains an input and the second row contains a select. Even though I have set their widths to be 100%, the select box is a few pixels smaller than the input. Any ideas why is this so and how can I set their widths to be equal to each other and as big as possible (e.g. %100) in a way that works across all (A-grade) browsers? <table width="100%" style="margin-top: 5px;"> <tr> <td width="35"><label for="desc">Description</label></td> <td> <input type="text" style="width: 100%;" name="desc" id="desc" /> </td> </tr> <tr> <td width="35"><label for="group">Group</label></td> <td> <select id="group" name="group" style="width: 100%; line-height: 17px;"> <option value="val">name</option> </select> </td> </tr> </table>

    Read the article

  • Is there a way to ignore Cache errors in Django?

    - by Josh Smeaton
    I've just set our development Django site to use redis for a cache backend and it was all working fine. I brought down redis to see what would happen, and sure enough Django 404's due to cache backend behaviour. Either the Connection was refused, or various other errors. Is there any way to instruct Django to ignore Cache errors, and continue processing the normal way? It seems weird that caching is a performance optimization, but can bring down an entire site if it fails. I tried to write a wrapper around the backend like so: class CacheClass(redis_backend.CacheClass): """ Wraps the desired Cache, and falls back to global_settings default on init failure """ def __init__(self, server, params): try: super(CacheClass, self).__init__(server, params) except Exception: from django.core import cache as _ _.cache = _.get_cache('locmem://') But that won't work, since I'm trying to set the cache type in the call that sets the cache type. It's all a very big mess. So, is there any easy way to swallow cache errors? Or to set the default cache backend on failure?

    Read the article

  • MS-Access auto enter information based on date

    - by Desert Spider
    I have a query that calculates an employees anniversary date. I would like that query to generate an entry event for my Table based on the current date. Basically automatically generate an anniversary vacation accrual when their anniversary date comes. Here is an example of my table. Table name "SchedulingLog" LogID "PrimaryKey AutoNbr" UserID "Employee specific" LogDate EventDate Category "ex Vacation, Anniversary..." CatDetail "ex. Vacation Day Used, Anniversary..." Value "ex. -1, 1..." My query Query Name "qry_YOS" UserID "Employee Specific" DOH "Employee hire date" YearsOfService "calculated Field" Annual "calculated Field" Schedule "Employee Specific" Annual Vac Days "calculated field" Anniversary "calculated Field" Query associated SQL INSERT INTO schedulinglog (userid, [value], eventdate, logdate, category, catdetail) SELECT roster.userid, [annual] * [schedule] AS [Value], Month([wm doh]) & "/" & Day([wm doh]) & "/" & Year(DATE()) AS EventDate, DATE() AS LogDate, category.[category name] AS Category, catdetail.catdetail FROM roster, tblaccrual, category INNER JOIN catdetail ON category.categoryid = catdetail.categoryid WHERE (( ( [tblaccrual] ! [years] ) < Round(( DATE() - [wm doh] ) / 365, 2) )) GROUP BY roster.userid, roster.[wm doh], Round(( DATE() - [wm doh] ) / 365, 2), roster.schedule, Month([wm doh]) & "/" & Day([wm doh]) & "/" & Year(DATE()), DATE(), category.[category name], catdetail.catdetail HAVING ( ( ( category.[category name] ) LIKE "vacation*" ) AND ( ( catdetail.catdetail ) LIKE "anniversary*" ) ); I know it is possible I just dont know where to begin.

    Read the article

  • Minimum and maximum Date in date Picker in iphone

    - by Iphony
    I want to get minimum and maximum date from date picker but minimum date should be "- 18" of current date and maximum date should be "- 100" of current date. Suppose current year is 2018 then I want minimum date 2000 and maximum date 1918. what I have done so far is : NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; NSDateComponents *components = [gregorian components:NSYearCalendarUnit fromDate:[NSDate date]]; NSInteger year = [components year]; int mindt = year - 18; int maxdt = year -100; // NSDate * MinDate = [components year] - 18; // NSDate * MaxDate = [components year] - 100; // self.datePicker.minimumDate = MinDate; // self.datePicker.maximumDate = MaxDate; but I cant get this integer to my date formate.. pls suggest any way ...

    Read the article

  • Post JSON array to mvc controller

    - by Yustme
    I'm trying to post a JSON array to a mvc controller. But no matter what i try, everything is 0 or null. I have this table that contains textboxes. I need from all those textboxes it's ID and value as an object. This is my java code: $(document).ready(function () { $('#submitTest').click(function (e) { var $form = $('form'); var trans = new Array(); var parameters = { TransIDs: $("#TransID").val(), ItemIDs: $("#ItemID").val(), TypeIDs: $("#TypeID").val(), }; trans.push(parameters); if ($form.valid()) { $.ajax( { url: $form.attr('action'), type: $form.attr('method'), data: JSON.stringify(parameters), dataType: "json", contentType: "application/json; charset=utf-8", success: function (result) { $('#result').text(result.redirectTo) if (result.Success == true) { return fase; } else { $('#Error').html(result.Html); } }, error: function (request) { alert(request.statusText) } }); } e.preventDefault(); return false; }); }); This is my view code: <table> <tr> <th>trans</th> <th>Item</th> <th>Type</th> </tr> @foreach (var t in Model.Types.ToList()) { { <tr> <td> <input type="hidden" value="@t.TransID" id="TransID" /> <input type="hidden" value="@t.ItemID" id="ItemID" /> <input type="hidden" value="@t.TypeID" id="TypeID" /> </td> </tr> } } </table> This is the controller im trying to receive the data to: [HttpPost] public ActionResult Update(CustomTypeModel ctm) { return RedirectToAction("Index"); } What am i doing wrong?

    Read the article

  • super(type,subclass) in simple singleton implementation

    - by Tianchen Wu
    when I was implementing naive singleton in python, I came up with a problem with super key word. As usual the behavior of super is always tricky and buggy, hope someone can shed light on it. Thanks :) The problem is that: class Singleton(object): def __new__(cls,*args,**kw): if not hasattr(cls,'_instance'): #create a instance of type cls, origin=super(Singleton,Singleton).__new__(cls,*args,**kw) cls._instance=origin return cls._instance class B(Singleton): def __init__(self,b): self.b=b It actually works, but I am wondering Will it be better if I change line 5 to the below, like in most of the books? origin=super(Singleton,cls).__new__(cls,*args,**ks) what's the difference to make?

    Read the article

  • Question on SQL Grouping

    - by Lijo
    Hi Team, I am trying to achieve the following without using sub query. For a funding, I would like to select the latest Letter created date and the ‘earliest worklist created since letter created’ date for a funding. FundingId Leter (1, 1/1/2009 )(1, 5/5/2009) (1, 8/8/2009) (2, 3/3/2009) FundingId WorkList (1, 5/5/2009 ) (1, 9/9/2009) (1, 10/10/2009) (2, 2/2/2009) Expected Result - FundingId Leter WorkList (1, 8/8/2009, 9/9/2009) I wrote a query as follows. It has a bug. It will omit those FundingId for which the minimum WorkList date is less than latest Letter date (even though it has another worklist with greater than letter created date). CREATE TABLE #Funding( [Funding_ID] [int] IDENTITY(1,1) NOT NULL, [Funding_No] [int] NOT NULL, CONSTRAINT [PK_Center_Center_ID] PRIMARY KEY NONCLUSTERED ([Funding_ID] ASC) ) ON [PRIMARY] CREATE TABLE #Letter( [Letter_ID] [int] IDENTITY(1,1) NOT NULL, [Funding_ID] [int] NOT NULL, [CreatedDt] [SMALLDATETIME], CONSTRAINT [PK_Letter_Letter_ID] PRIMARY KEY NONCLUSTERED ([Letter_ID] ASC) ) ON [PRIMARY] CREATE TABLE #WorkList( [WorkList_ID] [int] IDENTITY(1,1) NOT NULL, [Funding_ID] [int] NOT NULL, [CreatedDt] [SMALLDATETIME], CONSTRAINT [PK_WorkList_WorkList_ID] PRIMARY KEY NONCLUSTERED ([WorkList_ID] ASC) ) ON [PRIMARY] SELECT F.Funding_ID, Funding_No, MAX (L.CreatedDt), MIN(W.CreatedDt) FROM #Funding F INNER JOIN #Letter L ON L.Funding_ID = F.Funding_ID LEFT OUTER JOIN #WorkList W ON W.Funding_ID = F.Funding_ID GROUP BY F.Funding_ID,Funding_No HAVING MIN(W.CreatedDt) MAX (L.CreatedDt) How can I write a correct query without using subquery? Please help Thanks Lijo

    Read the article

  • Setting new class variables inside a module

    - by Sean McCleary
    I have a plugin I have been working on that adds publishing to ActiveRecord classes. I extend my classes with my publisher like so: class Note < ActiveRecord::Base # ... publishable :related_attributes => [:taggings] end My publisher is structured like: module Publisher def self.included(base) base.send(:extend, ClassMethods) @@publishing_options = [] # does not seem to be available end module ClassMethods def publishable options={} include InstanceMethods @@publishing_options = options # does not work as class_variable_set is a private method # self.class_variable_set(:@@publishing_options, options) # results in: uninitialized class variable @@publishing_options in Publisher::ClassMethods puts "@@publishing_options: #{@@publishing_options.inspect}" # ... end # ... end module InstanceMethods # results in: uninitialized class variable @@publishing_options in Publisher::InstanceMethods def related_attributes @@publishing_options[:related_attributes] end # ... end end Any ideas on how to pass options to publishable and have them available as a class variable?

    Read the article

  • Problem with accessing classes from another class.

    - by srikanth rongali
    I have a classA, classB,classC. I have another class classABC; All are CCLayer inherited. I need to call all the classA, classB, classC from classABC. #import <Foundation/Foundation.h> #import "cocos2d.h" @interface classABC : CCLayer { classA *aClass; } @property(nonatomic, retain)classA *aClass; @end #import "classABC" #import "classA.h" #import "classB.h" #import "classC.h" @implementation classABC -(id)init { if( (self = [super init]) ) { ClassA *aClass = [[ClassA alloc]init]; CCScene *aClassS = [CCScene node]; CCLayer * aClassL = [aClass node]; [aClassS addChild: aClassL]; [[CCDirector sharedDirector] setAnimationInterval:60.0/60]; [[CCDirector sharedDirector] replaceScene: aClass]; } return self; } @end But I am not getting the classA displayed. How should I do it ? Thank You.

    Read the article

  • Adding a method to a function object at runtime

    - by Carson Myers
    I read a question earlier asking if there was a times method in Python, that would allow a function to be called n times in a row. Everyone suggested for _ in range(n): foo() but I wanted to try and code a different solution using a function decorator. Here's what I have: def times(self, n, *args, **kwargs): for _ in range(n): self.__call__(*args, **kwargs) import new def repeatable(func): func.times = new.instancemethod(times, func, func.__class__) @repeatable def threeArgs(one, two, three): print one, two, three threeArgs.times(7, "one", two="rawr", three="foo") When I run the program, I get the following exception: Traceback (most recent call last): File "", line 244, in run_nodebug File "C:\py\repeatable.py", line 24, in threeArgs.times(7, "one", two="rawr", three="foo") AttributeError: 'NoneType' object has no attribute 'times' So I suppose the decorator didn't work? How can I fix this?

    Read the article

  • Problem in creating another thread

    - by Avinash
    Hi, I am using NSThread to create different thread and displaying images in my application on a new thread instead of main thread. On main thread i am working with a table view which is displaying data from XML file, In the same view I am displaying images below. But, displaying images on new thread is not working properly. Did i made any mistake in creating Here below is my code. Please help me its urgent. Thanks in advance...................... - (void)viewDidLoad { [super viewDidLoad]; [NSThread detachNewThreadSelector:@selector(startTheBackgroundJob) toTarget:self withObject:nil]; } - (void)startTheBackgroundJob { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; currentLocationImageView = [[UIImageView alloc] init]; NSArray *images = [NSArray arrayWithObjects:img1, img2, nil]; [currentLocationImageView setAnimationImages:images]; [currentLocationImageView setAnimationRepeatCount:0]; [currentLocationImageView setAnimationDuration:5.0]; [self.view addSubview:currentLocationImageView]; [pool release]; }

    Read the article

  • MySQL Update query with left join and group by

    - by Rob
    I am trying to create an update query and making little progress in getting the right syntax. The following query is working: SELECT t.Index1, t.Index2, COUNT( m.EventType ) FROM Table t LEFT JOIN MEvents m ON (m.Index1 = t.Index1 AND m.Index2 = t.Index2 AND (m.EventType = 'A' OR m.EventType = 'B') ) WHERE (t.SpecialEventCount IS NULL) GROUP BY t.Index1, t.Index2 It creates a list of triplets Index1,Index2,EventCounts. It only does this for case where t.SpecialEventCount is NULL. The update query I am trying to write should set this SpecialEventCount to that count, i.e. COUNT(m.EventType) in the query above. This number could be 0 or any positive number (hence the left join). Index1 and Index2 together are unique in Table t and they are used to identify events in MEvent. How do I have to modify the select query to become an update query? I.e. something like UPDATE Table SET SpecialEventCount=COUNT(m.EventType)..... but I am confused what to put where and have failed with numerous different guesses.

    Read the article

  • How to store sorted records in csv file ?

    - by Harikrishna
    I sort the records of the datatable datewise with the column TradingDate which is type of datetime. TableWithOnlyFixedColumns.DefaultView.Sort = "TradingDate asc"; Now I want to display these sorted records into csv file but it does not display records sorted by date. TableWithOnlyFixedColumns.DefaultView.Sort = "TradingDate asc";TableWithOnlyFixedColumns.Columns["TradingDate"].ColumnName + "] asc"; DataTable newTable = TableWithOnlyFixedColumns.Clone(); newTable.DefaultView.Sort = TableWithOnlyFixedColumns.DefaultView.Sort; foreach (DataRow oldRow in TableWithOnlyFixedColumns.Rows) { newTable.ImportRow(oldRow); } // we'll use these to check for rows with nulls var columns = newTable.DefaultView.Table.Columns.Cast<DataColumn>(); using (var writer = new StreamWriter(@"C:\Documents and Settings\Administrator\Desktop\New Text Document (3).csv")) { for (int i = 0; i < newTable.DefaultView.Table.Rows.Count; i++) { DataRow row = newTable.DefaultView.Table.Rows[i]; // check for any null cells if (columns.Any(column => row.IsNull(column))) continue; string[] textCells = row.ItemArray .Select(cell => cell.ToString()) // may need to pick a text qualifier here .ToArray(); // check for non-null but EMPTY cells if (textCells.Any(text => string.IsNullOrEmpty(text))) continue; writer.WriteLine(string.Join(",", textCells)); } } So how to store sorted records in csv file ?

    Read the article

  • Codeigniter - Active record - sql - complex join

    - by Jack
    I have a function that retrieves all tags from a table: function global_popular_tags() { $this->db->select('tags.*, COUNT(tags.id) AS count'); $this->db->from('tags'); $this->db->join('tags_to_work', 'tags.id = tags_to_work.tag_id'); $this->db->group_by('tags.id'); $this->db->order_by('count', 'desc'); $query = $this->db->get()->result_array(); return $query; } I have another table called 'work'. The 'work' table has a 'draft' column with values of either 1 or 0. I want the COUNT(tags.id) to take into account whether the work with the specific tag is in draft mode (1) or not. Say there are 10 pieces of work tagged with, for example, 'design'. The COUNT will be 10. But 2 of these pieces of work are in draft mode, so the COUNT should really be 8. How do I manage this?

    Read the article

  • Rails create_table query

    - by Steve
    Hi, I am a beginner in Rails. In the following code,there is an id which is set as false. What's the meaning of it? class CreateCoursesStudents < ActiveRecord::Migration def self.up create_table :courses_students, :id => false do |t| t.integer :course_id, :null => false t.integer :student_id, :null => false end # Add index to speed up looking up the connection, and ensure # we only enrol a student into each course once add_index :courses_students, [:course_id, :student_id], :unique => true end def self.down remove_index :courses_students, :column => [:course_id, :student_id] drop_table :courses_students end end Thanks

    Read the article

  • MySql product\tag query optimisation - please help!

    - by Nige
    Hi There I have an sql query i am struggling to optimise. It basically is used to pull back products for a shopping cart. The products each have tags attached using a many to many table product_tag and also i pull back a store name from a separate store table. Im using group_concat to get a list of tags for the display (this is why i have the strange groupby orderby clauses at the bottom) and i need to order by dateadded, showing the latest scheduled product first. Here is the query.... SELECT products.*, stores.name, GROUP_CONCAT(tags.taglabel ORDER BY tags.id ASC SEPARATOR " ") taglist FROM (products) JOIN product_tag ON products.id=product_tag.productid JOIN tags ON tags.id=product_tag.tagid JOIN stores ON products.cid=stores.siteid WHERE dateadded < '2010-05-28 07:55:41' GROUP BY products.id ASC ORDER BY products.dateadded DESC LIMIT 2 Unfortunately even with a small set of data (3 tags and about 12 products) the query is taking 00.0034 seconds to run. Eventually i want to have about 2000 products and 50 tagsin this system (im guessing this will be very slooooow). Here is the ExplainSql... id|select_type|table|type|possible_keys|key|key_len|ref|rows|Extra 1|SIMPLE|tags|ALL|PRIMARY|NULL|NULL|NULL|4|Using temporary; Using filesort 1|SIMPLE|product_tag|ref|tagid,productid|tagid|4|cs_final.tags.id|2| 1|SIMPLE|products|eq_ref|PRIMARY,cid|PRIMARY|4|cs_final.product_tag.productid|1|Using where 1|SIMPLE|stores|ALL|siteid|NULL|NULL|NULL|7|Using where; Using join buffer Can anyone help?

    Read the article

  • UITableView issue (iOS)

    - by Oktay
    I wonder why cellForRowAtIndexPath function is called when scrolling the UITableView. Does it mean on every scrolling cell configuration code runs again? I have a slowness problem when scrolling the table. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"CountryCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } // Configure the cell... NSString *continent = [self tableView:tableView titleForHeaderInSection:indexPath.section]; NSString *country = [[self.countries valueForKey:continent] objectAtIndex:indexPath.row]; cell.textLabel.text = country; cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; return cell; }

    Read the article

< Previous Page | 593 594 595 596 597 598 599 600 601 602 603 604  | Next Page >