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  • Sequential searching with sorted linked lists

    - by John Graveston
    struct Record_node* Sequential_search(struct Record_node *List, int target) { struct Record_node *cur; cur = List->head ; if(cur == NULL || cur->key >= target) { return NULL; } while(cur->next != NULL) { if(cur->next->key >= target) { return cur; } cur = cur->next; } return cur; } I cannot interpret this pseudocode. Can anybody explain to me how this program works and flows? Given this pseudocode that searches for a value in a linked list and a list that is in an ascending order, what would this program return? a. The largest value in the list that is smaller than target b. The largest value in the list that is smaller than or same as target c. The smallest value in the list that is larger than or same as target d. Target e. The smallest value in the list that is larger than target And say that List is [1, 2, 4, 5, 9, 20, 20, 24, 44, 69, 70, 71, 74, 77, 92] and target 15, how many comparisons are occurred? (here, comparison means comparing the value of target)

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  • Is it possible to cache all the data in a SQL Server CE database using LinqToSql?

    - by DanM
    I'm using LinqToSql to query a small, simple SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of what makes LinqToSql so appealing. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance besides resorting to doing all the joins manually? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view. Update Here are the table definitions for the example I used in my question: create table Order ( Id int identity(1, 1) primary key, ProductName ntext null ) create table Customer ( Id int identity(1, 1) primary key, OrderId int null references Order (Id) )

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  • MySQLDB query not returning all rows

    - by RBK
    I am trying to do a simple fetch using MySQLDB in Python. I have 2 tables(Accounts & Products). I have to look up Accounts table, get acc_id from it & query the Products table using it. The Products tables has more than 10 rows. But when I run this code it randomly returns between 0 & 6 rows each time I run it. Here's the code snippet: # Set up connection con = mdb.connect('db.xxxxx.com', 'user', 'password', 'mydb') # Create cursor cur = con.cursor() # Execute query cur.execute("SELECT acc_id FROM Accounts WHERE ext_acc = '%s'" % account_num ) # account_num is alpha-numberic and is got from preceding part of the program # A tuple is returned, so get the 0th item from it acc_id = cur.fetchone()[0] print "account_id = ", acc_id # Close the cursor - I was not sure if I can reuse it cur.close() # Reopen the cursor cur = con.cursor() # Second query cur.execute("SELECT * FROM Products WHERE account_id = %d" % acc_id) keys = cur.fetchall() print cur.rowcount # This prints incorrect row count for key in keys: # Does not print all rows. Tried to directly print keys instead of iterating - same result :( print key # Closing the cursor & connection cur.close() con.close() The weird part is, I tried to step through the code using a debugger(PyDev on Eclipse) and it correctly gets all rows(both the value stored in the variable 'keys' as well as console output are correct). I am sure my DB has correct data since I ran the same SQL on MySQL console & got the correct result. Just to be sure I was not improperly closing the connection, I tried using with con instead of manually closing the connection and it's the same result. I did RTFM but I couldn't find much in it to help me with this issue. Where am I going wrong? Thank you. EDIT: I noticed another weird thing now. In the line cur.execute("SELECT * FROM Products WHERE account_id = %d" % acc_id), I hard-coded the acc_id value, i.e made it cur.execute("SELECT * FROM Products WHERE account_id = %d" % 322) and it returns all rows

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  • Why trigger query fails in the sqlite with Qt?

    - by dexterous_stranger
    I am a beginner in the SQL. I am using SQLite, Qt - on embedded systems. I want to put a trigger here. The trigger is that whenever the primary key Id is greater than 32145, then channelNum=101 should be set. I want to set the attrib name - text also, but I got the compilation issue. I believe that the setting of trigger is the part of DDL - Data definition language. Please let me know that if I am wrong here. Here is my create db code. I get the sql query error. Also please do suggest how to set the text attrib = "COmedy". /** associate db with query **/ QSqlQuery query ( m_demo_db ); /** Foreign keys are disabled by default in sqlite **/ /** Here is the pragma to turn them on first **/ query.exec("PRAGMA foreign_keys = ON;"); if ( false == query.exec()) { qDebug()<<"Pragma failed"; } /** Create Table for storing user preference LCN for DTT **/ qDebug()<<"Create Table postcode.db"; query.prepare(" CREATE TABLE dttServiceList (Id INTEGER PRIMARY KEY, attrib varchar(20), channelNum integer )" ); if ( false == query.exec()) { qDebug()<<"Create dttServiceList table failed"; } /** Try placing trigger here **/ triggerQuery = "CREATE TRIGGER upd_check BEFORE INSERT ON dttServiceList \ FOR EACH ROW \ BEGIN \ IF Id > 32145 THEN SET channelNum=101; \ END IF; \ END; "; query.prepare(triggerQuery); if ( false == query.exec()) { qDebug()<<"Trigger failed !!"; qDebug() << query.lastError(); } Also, how to set the text name in the trigger - I want to SET attrib = "Comedy".

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  • 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?

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  • Extract information from a Func<bool, T> or alike lambda

    - by Syska
    I''m trying to build a generic cache layer. ICacheRepository Say I have the following: public class Person { public int PersonId { get; set; } public string Firstname { get; set; } public string Lastname { get; set; } public DateTime Added { get; set; } } And I have something like this: list.Where(x => x.Firstname == "Syska"); Here I want to extract the above information, to see if the query supplied the "PersonId" which it did not, so I dont want to cache it. But lets say I run a query like this: list.Where(x => x.PersonId == 10); Since PersonId is my key ... I want to cache it. with the key like "Person_10" and I later can fetch it from the cache. I know its possible to extract the information with Expression<Func<>> but there seems to be a big overhead of doing this (when running compile and extract the Constant values etc. and a bunch of cache to be sure to parse right) Are there a framework for this? Or some smart/golden way of doing this ?

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  • How to retrive user input data entered tab bar View Controller when application start in iphone app

    - by TechFusion
    Hello, I have created window based application. Tab bar controller as root controller and it has three tabs. One Tab has Labels and TextFiled inputs like Name, Username and Password. I am looking to store this text filed inputs when user enters and able retrieve in other tabs. Previously I have set key for different text fields and setobject:withkey task and able to retrive text filed values in same view Controller [[NSUserDefaults standardUserDefaults] stringForKey:key] task. Now I am looking to create database which has different objects and each objects has data values of different Text Field inputs that I can access in whole application. like DatabaseName - Object1 - Name, Username & Password - Object2 - Name, Username & Password Something like structure in Normal C so it would be easy to retrieve data. I am looking NSUserDefaults Class and User Defaults Programming Topics in Cocoa(http://developer.apple.com/iPhone/library/documentation/Cocoa/Conceptual/UserDefaults/UserDefaults.html#//apple_ref/doc/uid/10000059-BCIDJFHD). Also Referring Archives and Serialization Programming guide(http://developer.apple.com/iphone/library/documentation/Cocoa/Conceptual/Archiving/Archiving.html#//apple_ref/doc/uid/10000047i). Which method i need to use to create such type of database ? Thanks,

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  • Error while converting function from oracle to mssql

    - by sss
    Hi, I am migrating a function from oracle to mssql 2008.This function raises Select statements included within a function cannot return data to a client as error.How can i solve this problem? Original PLSQL Code CREATE OR REPLACE function f_birim_cevrim_katsayi (p_ID_MAMUL in number, p_ID_BIRIMDEN in number, p_ID_BIRIME in number) return number is v_katsayi number; begin v_katsayi:=0; if p_ID_BIRIMDEN!=p_ID_BIRIME then for c in ( select * from CR_BIRIM_CEVRIM where ID_MAMUL = p_ID_MAMUL and ( (ID_BIRIM = p_ID_BIRIMDEN and ID_BIRIM2 = p_ID_BIRIME) OR ( ID_BIRIM2 = p_ID_BIRIMDEN and ID_BIRIM = p_ID_BIRIME) ) and VALID = 1) loop if c.ID_BIRIM=p_ID_BIRIMDEN then v_katsayi:=c.MT_ORAN; else v_katsayi:=1/c.MT_ORAN; end if; end loop; else v_katsayi:=1; end if; return round(v_katsayi,10); exception when others then return 0; end; TSQL CODE If Exists ( SELECT name FROM sysobjects WHERE name = 'f_birim_cevrim_katsayi' AND type = 'FN') DROP FUNCTION f_birim_cevrim_katsayi GO CREATE FUNCTION f_birim_cevrim_katsayi ( @p_ID_MAMUL FLOAT , @p_ID_BIRIMDEN FLOAT , @p_ID_BIRIME FLOAT ) RETURNS float AS BEGIN DECLARE @adv_error INT DECLARE @v_katsayi FLOAT SELECT @v_katsayi = 0 IF @p_ID_BIRIMDEN != @p_ID_BIRIME BEGIN DECLARE cursor_for_inline_select1 CURSOR LOCAL FOR SELECT * FROM CR_BIRIM_CEVRIM WHERE ID_MAMUL = @p_ID_MAMUL AND ((ID_BIRIM = @p_ID_BIRIMDEN AND ID_BIRIM2 = @p_ID_BIRIME) OR (ID_BIRIM2 = @p_ID_BIRIMDEN AND ID_BIRIM = @p_ID_BIRIME)) AND VALID = 1 OPEN cursor_for_inline_select1 FETCH NEXT FROM cursor_for_inline_select1 WHILE (@@FETCH_STATUS <> -1) BEGIN IF c.ID_BIRIM = @p_ID_BIRIMDEN BEGIN SELECT @v_katsayi = c.MT_ORAN END ELSE BEGIN SELECT @v_katsayi = 1/c.MT_ORAN END END CLOSE cursor_for_inline_select1 DEALLOCATE cursor_for_inline_select1 END ELSE BEGIN SELECT @v_katsayi = 1 END DEALLOCATE cursor_for_inline_select1 return ROUND(@v_katsayi, 10) GOTO ExitLabel1 Exception1: BEGIN DEALLOCATE cursor_for_inline_select1 return 0 END ExitLabel1: return ROUND(@v_katsayi, 10) END GO

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  • object references an unsaved transient instance

    - by developer
    Hi, I have 2 tables, user and userprofile, both with almost identical fields. user table references userprofile table by primary key ID. My requirement is that on click of a button I need to dump user table record to userprofile table. Now for a particular user table, if there is a corresponding userprofile entry, I am successfully able to dump the data, but if there is no record in userprofile table then I need to create a new record by dumping all the data. My problem is that I am able to update the data when the record is present in userprofile table, but in the case wherein I have to create a new record I get the below error "object references an unsaved transient instance - save the transient instance before flushing". `<class name="User"> <id name="ID" type="Int32"> <generator class="native" /> </id> <many-to-one name="Pid" class="UserProfile" /> </class>` UserProfile is another table and Pid above references the Primary key ID of UserProfile table.

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  • How to break out from nested doseqs

    - by fizbin
    Hi, I have a question regarding nested doseq loops. In the start function, once I find an answer I set the atom to true, so that the outer loop validation with :while fails. However it seems that it doesn't break it, and the loops keep on going. What's wrong with it? I am also quite confused with the usage of atoms, refs, agents (Why do they have different names for the update functions when then the mechanism is almost the same?) etc. Is it okay to use an atom in this situation as a flag? Obviously I need a a variable like object to store a state. (def pentagonal-list (map (fn [a] (/ (* a (dec (* 3 a))) 2)) (iterate inc 1))) (def found (atom false)) (defn pentagonal? [a] (let [y (/ (inc (Math/sqrt (inc (* 24 a)))) 6) x (mod (* 10 y) 10)] (if (zero? x) true false))) (defn both-pent? [a b] (let [sum (+ b a) diff (- a b)] (if (and (pentagonal? sum) (pentagonal? diff)) true false))) (defn start [] (doseq [x pentagonal-list :while (false? @found)] (doseq [y pentagonal-list :while (<= y x)] (if (both-pent? x y) (do (reset! found true) (println (- x y)))))))

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  • Easier way to populate form data and validation data in Code Igniter?

    - by John
    I'm new to code igniter. I'm following the form validation tutorial found at: http://www.codeignitor.com/user_guide/libraries/validation.html I find I am typing too much in the view to get the form to re-populate. For example, here's what one of my INPUT fields look like: <input type="text" name="email" value="<?=$this->validation->email ? $this->validation->email : $array_db_values['email'] ?>" /> Basically, when the form first loads, it should show a value from the database. If the user alters the value and it fails validation, then the form should post the erroneously submitted value. Does code igniter have a "cleaner" way of rendering this kind of output? Otherwise, I'm going to do something like this in my controller: $array_db_values = getdbresults(); if($_POST['submit']) foreach($_POST as $key=>$val) $array_db_values[$key] = $val; That way, if postback data exists, it will always override database values. Then input fields in my view can simply be: <input type="text" name="email" value="<?=$array_db_values['email'] ?>" /> Is there a better/native CI way to handle this scenario?

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  • Jquery (non-gem) plugin won't work in my rails 3.2 app

    - by jfdimark
    I'm trying to equalize columns in my rails 3.2 app, and while there may be a better way to do it then my current attempt, after hours of trying to make it work I'd like to see if anyone can point out specifically why this jQuery plugin (which isn't a gem) is not working. I'm not getting any errors in the developer console, so it's hard to pin point. Here's the relevant code: The index view, where I've followed the plugin's instructions: div id="column-group"> <div class="equalize span5 offset1 UserProfile"> <% if user_signed_in? %> <h3>Hello <%= current_user.name %>!</h3> </div> <div class="equalize span5 MemberDisplay"> My application.js file, where I've also included the specific js code, so it would definitely be picked up by the application: //= require jquery //= require jquery_ujs //= require bootstrap //= require equalize_column_heights //= require_tree . $(document).ready(function() { $("#column-group").equalize_column_heights("equalize"); }); The jQuery plugin code, which is saved in my vendor/assets/javascripts folder: (function ($) { $.fn.equalize_column_heights = function (equalize_class) { var tallest_column=0; parent_id = "column-group" + $(this).attr("id") + " ." + equalize_class; $(parent_id).each(function(index, value) { if (tallest_column < $(this).height()){ tallest_column = $(this).height(); } }); $(parent_id).each(function(index, value) { $(this).css({'min-height': tallest_column}); }); } }(jQuery)); I've read all the rails guides documentation on the asset pipeline and all the relevant jQuery-rails3 questions on SO, but after several hours, I just can't seem to figure this one out. If anyone can point to other tutorials on how to get non-gem jQuery plugins to work in a Rails 3.2 app then I'd be glad to take a look!

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  • SQL: find entries in 1:n relation that don't comply with condition spanning multiple rows

    - by milianw
    I'm trying to optimize SQL queries in Akonadi and came across the following problem that is apparently not easy to solve with SQL, at least for me: Assume the following table structure (should work in SQLite, PostgreSQL, MySQL): CREATE TABLE a ( a_id INT PRIMARY KEY ); INSERT INTO a (a_id) VALUES (1), (2), (3), (4); CREATE TABLE b ( b_id INT PRIMARY KEY, a_id INT, name VARCHAR(255) NOT NULL ); INSERT INTO b (b_id, a_id, name) VALUES (1, 1, 'foo'), (2, 1, 'bar'), (3, 1, 'asdf'), (4, 2, 'foo'), (5, 2, 'bar'), (6, 3, 'foo'); Now my problem is to find entries in a that are missing name entries in table b. E.g. I need to make sure each entry in a has at least the name entries "foo" and "bar" in table b. Hence the query should return something similar to: a_id = 3 is missing name "bar" a_id = 4 is missing name "foo" and "bar" Since both tables are potentially huge in Akonadi, performance is of utmost importance. One solution in MySQL would be: SELECT a.a_id, CONCAT('|', GROUP_CONCAT(name ORDER BY NAME ASC SEPARATOR '|'), '|') as names FROM a LEFT JOIN b USING( a_id ) GROUP BY a.a_id HAVING names IS NULL OR names NOT LIKE '%|bar|foo|%'; I have yet to measure the performance tomorrow, but severly doubt it's any fast for tens of thousand of entries in a and thrice as many in b. Furthermore we want to support SQLite and PostgreSQL where to my knowledge the GROUP_CONCAT function is not available. Thanks, good night.

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  • when to use Hibernate vs. Simple ResultSets for small application

    - by luke
    I just started working on upgrading a small component in a distributed java application. The main application is a rather complicated applet/servlet combo running on JBoss and it extensively uses Hibernate for its DataAccess. The component i am working on however is very a very straightforward data importing service. Basically the workflow is Listen for a network event Parse the data packet, extract a set of identifiers Map the identifier set to a primary key in our database Parse the rest of the packet and insert items in a related table using the foreign key found in step 3 Repeat in the previous version of this component it used a hibernate based DAL, that is no longer usable for a variety of reasons (in particular it is EOL), so I am in charge of replacing the Data Access layer for this component. So on the one hand I think i should use Hibernate because that's what the rest of the application does, but on the other i think i should just use regular java.sql.* classes because my requirements are really straightforward and aren't expected to change any time soon. So my question is (and i understand it is subjective) at what point do you think that the added complexity of using an ORM tool (in terms of configuration, dependencies...) is worth it? UPDATE due to the way the DataAccesLayer for the main application was written (weird dependencies) i cannot easily use it, i would have to implement it myself.

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  • How can I make this jQuery plugin chainable after all image load events have completed?

    - by BumbleB2na
    [UPDATE] Solution I decided on: Decided that passing in a callback to the plugin will take care of firing an event once all images have completed loading. Chaining is also still possible. Updated Fiddle I am building a chainable jQuery plugin that can load images dynamically. (View the following code as a JSFiddle) Html: <img data-img-src="http://www.lubasf.com/blog/wp-content/uploads/2009/03/gnome.jpg" style="display: none" /> <img data-img-src="http://buffered.io/uploads/2008/10/gnome.jpg" style="display: none" /> Instead of adding in a src attribute, I give these images a data-img-src attribute. My plugin uses the value of that to fill the src. Also, these images are hidden to begin with. jQuery plugin: (function(jQuery) { jQuery.fn.loadImages = function() { var numToLoad = jQuery(this).length; var numLoaded = 0; jQuery(this).each(function() { if(jQuery(this).attr('src') == undefined) { return jQuery(this).load(function() { numLoaded++; if(numToLoad == numLoaded) return this; // attempt at making this plugin // chainable, after all .load() // events have completed. }).attr('src', jQuery(this).attr('data-img-src')); } else { numLoaded++; if(numToLoad == numLoaded) return this; // attempt at making this plugin // chainable, after all .load() // events have completed. } }); // this works if uncommented, but returns before all .load() events have completed //return this; }; })(jQuery); // I want to chain a .fadeIn() after all images have completed loading $('img[data-img-src]').loadImages().fadeIn(); Is there a way to make this plugin chainable, and have my fadeIn() happen after all images have loaded?

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  • jquery .blur for entire block of HTML

    - by Stacey
    I have an HTML item for a 'drop down menu', structured like this... <li class="ui-dropdown-list" > <a href="#">Right Drop Down Menu</a> <ul> <li><a href="#">Item</a></li> <li><a href="#">Item</a></li> <li><a href="#">Item</a></li> </ul> </li> Using jQuery to make this a dropdown list, with the following code. jQuery.fn.dropdown = function () { var defaults = { button: null, menu: null, visible: false }; var options = $.extend(defaults, options); return this.each(function () { options.button = $(this); options.menu = $(this).find("ul"); // when the parent is clicked, determine whether dropdown needs to occur options.button.click(function () { options.visible ? lift(options.menu) : drop(options.menu); options.visible = !options.visible; }); // drop the menu down so that it can be seen. function drop(e) { options.button.addClass("open"); options.menu.show(); } // lift the menu up, hiding it from view. function lift(e) { options.menu.hide(); options.button.removeClass('open'); } }); }; I am trying to wire it up so that if the user clicks anywhere outside of the menu, it will collapse it. This is proving much more difficult than I anticipated; even trying to use page level events. Any suggestions? The menu itself never really 'receives' focus, so using .blur doesn't seem to be suiting the purpose.

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  • Getting Values from fetched Core Data

    - by user571905
    Hi there, Thanks to the wonderful people on this forum, I have overcome most of my Core Data woes. However one persists, and I'm certain it is a simple fix. I have a recipe app that parses an XML doc on load and puts the data in Core Data. Then I search that Core Data for particular recipes, ingredients, etc. Everything is working with one exception... I cannot do anything with the data I retrieve. For example, I search the core data for "eggplant" and get this at the end of the process: "<RecipeData: 0x6112a40> (entity: RecipeData; id: 0x6113880 <x-coredata:///RecipeData/tCDE9A0EE-DA3F-4BD0-AEF8-3C038586991D4> ; data: {\n ingredients = \"Eggplant|Cheese|Tomatoes|\";\n name = \"Eggplant Parm\";\n time = 40;\n})" How do I get the info out of there? I tried looping through, but that causes the app to crash: for (NSString* key in selectedRecipe) { id value = [selectedRecipe objectForKey:key]; NSLog(@"IN LOOP: %@", value); } Any suggestions? Thank you for your time.

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  • CakePHP 2.0: how to access properties of the parent object?

    - by PaulJ
    I just started learning CakePHP 2.0 a few days ago, and there's one thing that is leaving me stumped: say I have an User model and a Posts model: class User extends AppModel { public $name = "User"; public $hasMany=array( 'Post' => array( 'className' => 'Post', 'foreignKey' => 'author_id' ) ); } class Post extends AppModel { public $name = 'Post'; public $belongsTo = array( 'className' = 'User', 'foreignKey' = 'author_id', ); } (Where "author_id" is the foreign key in the posts table that references the Users table's primary key). And now, in the PostsController, I want to access the properties of the user that owns the current post (to show his display name, for example). What would be the proper syntax? I tried: $this->Post->User->find('first', array('conditions' => array('User.id' => "$usuario"))) But it didn't work (I guess it's because the User is the parent of the Post object, not its child). Or should CakePHP load everything automatically, once you've declared the $hasMany and $belongsTo relationships?

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  • How to combine two rows and calculate the time difference between two timestamp values in MySQL?

    - by Nadar
    I have a situation that I'm sure is quite common and it's really bothering me that I can't figure out how to do it or what to search for to find a relevant example/solution. I'm relatively new to MySQL (have been using MSSQL and PostgreSQL earlier) and every approach I can think of is blocked by some feature lacking in MySQL. I have a "log" table that simply lists many different events with their timestamp (stored as datetime type). There's lots of data and columns in the table not relevant to this problem, so lets say we have a simple table like this: CREATE TABLE log ( id INT NOT NULL AUTO_INCREMENT, name VARCHAR(16), ts DATETIME NOT NULL, eventtype VARCHAR(25), PRIMARY KEY (id) ) Let's say that some rows have an eventtype = 'start' and others have an eventtype = 'stop'. What I want to do is to somehow couple each "startrow" with each "stoprow" and find the time difference between the two (and then sum the durations per each name, but that's not where the problem lies). Each "start" event should have a corresponding "stop" event occuring at some stage later then the "start" event, but because of problems/bugs/crashed with the data collector it could be that some are missing. In that case I would like to disregard the event without a "partner". That means that given the data: foo, 2010-06-10 19:45, start foo, 2010-06-10 19:47, start foo, 2010-06-10 20:13, stop ..I would like to just disregard the 19:45 start event and not just get two result rows both using the 20:13 stop event as the stop time. I've tried to join the table with itself in different ways, but the key problems for me seems to be to find a way to correctly identify the corresponding "stop" event to the "start" event for the given "name". The problem is exactly the same as you would have if you had table with employees stamping in and out of work and wanted to find out how much they actually were at work. I'm sure there must be well known solutions to this, but I can't seem to find them...

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  • LINQ To SQL Dynamic Select

    - by mcass20
    Can someone show me how to indicate which columns I would like returned at run-time from a LINQ To SQL statement? I am allowing the user to select items in a checkboxlist representing the columns they would like displayed in a gridview that is bound to the results of a L2S query. I am able to dynamically generate the WHERE clause but am unable to do the same with the SELECT piece. Here is a sample: var query = from log in context.Logs select log; query = query.Where(Log => Log.Timestamp > CustomReport.ReportDateStart); query = query.Where(Log => Log.Timestamp < CustomReport.ReportDateEnd); query = query.Where(Log => Log.ProcessName == CustomReport.ProcessName); foreach (Pair filter in CustomReport.ExtColsToFilter) { sExtFilters = "<key>" + filter.First + "</key><value>" + filter.Second + "</value>"; query = query.Where(Log => Log.FormattedMessage.Contains(sExtFilters)); }

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  • Does this code depend on string interning to work?

    - by Nick Gotch
    I'm creating a key for a dictionary which is a structure of two strings. When I test this method in a console app, it works, but I'm not sure if the only reason it works is because the strings are being interned and therefore have the same references. Foo foo1 = new Foo(); Foo foo2 = new Foo(); foo1.Key1 = "abc"; foo2.Key1 = "abc"; foo1.Key2 = "def"; foo2.Key2 = "def"; Dictionary<Foo, string> bar = new Dictionary<Foo, string>(); bar.Add(foo1, "found"); if(bar.ContainsKey(foo2)) System.Console.WriteLine("This works."); else System.Console.WriteLine("Does not work"); The struct is simply: public struct Foo { public string Key1; public string Key2; } Are there any cases which would cause this to fail or am I good to rely on this as a unique key?

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  • Meaning of NEXT in Linked List creation in perl

    - by seleniumnewbie
    So I am trying to learn Linked Lists using Perl. I am reading "Mastering Algorithms with Perl" by Job Orwant. In the book he explains how to create a linked list I understand most of it, but I just simply fail to understand the command/index/key NEXT in the second last line of the code snippet. $list=undef; $tail=\$list; foreach (1..5){ my $node = [undef, $_ * $_]; $$tail = $node; $tail = \${$node->[NEXT]}; # The NEXT on this line? } What is he trying to do there? Isn $node a scalar, which stores the address of the unnamed array. Also even if we are de-referencing $node, should we not refer to the individual elements by an index number example (0,1). If we do use "NEXT" as a key, is $node a reference to a hash? I am very confused. Something in plain English will be highly appreciated.

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  • help to reiterate through my jquery snippet

    - by s2xi
    Code in question: $("#alpha").click(function(event) { event.preventDefault(); $("#show").slideToggle(); }); I have a list of files and its being outputted with PHP in alphabetical. I use this method in PHP: foreach(range('A','Z') as $i) { if (array_key_exists ("$i", $alpha)) { echo '<div id="alpha"><a href="#" name="'.$i.'"><h2>'.$i.'</h2></a></div><div id="show">'; foreach ($$i as $key=>$value) echo '<p>'.$value.' '.$key.'</p>'; } echo '</div>'; } What I want to do is when the user clicks on the #alpha to toggle the div #show that has the names that belong to a letter up. I can do this with the first listing, but every listing after that isn't affected. how can i tell jquery that foreach letter apply the js code so it can toggle up/down the #show. I don't want to this 26 times (one time for each letter in the alphabet), I tried to use class instead of id but that causes all the #show to toggleup heh.

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  • printing out dictionnaires

    - by kyril
    I have a rather specific question: I want to print out characters at a specific place using the \033[ syntax. This is what the code below should do: (the dict cells has the same keys as coords but with either '*' or '-' as value.) coords = {'x'+str(x)+'y'+str(y) : (x,y) for x,y, in itertools.product(range(60), range(20))} for key, value in coords.items(): char = cells[key] x,y = value HORIZ=str(x) VERT=str(y) char = str(char) print('\033['+VERT+';'+HORIZ+'f'+char) However, I noticed that if I put this into a infinite while loop, it does not always prints the same characters at the same position. There are only slight changes, but it deletes some and puts them back in after some loops. I already tried it with lists, and there it seems to behave just fine, so I tend to think it has something todo with the dict, but I can not figure out what it could be. You can see the Problem in a console here: SharedConsole.I am happy for every tip on this matter. On a related topic: After the printing, some changes should be made at the values of the cells dict, but for reason unknown to me, the only the first two rules are executed and the rest is ignored. The rules should test how many neighbours (which is in population) are around the cell and apply the according rule. In my implemention of this I have some kind of weird tumor growth (which should not happen, as if there more than three around they should the cell should die) (see FreakingTumor): if cells_copy [coord] == '-': if population == 3: cells [coord] = '*' if cells_copy [coord] == '*': if population > 3: cells [coord] = '-' elif population <= 1: cells [coord] = '-' elif population == 2 or 3: cells [coord] = '*' I checked the population variable several times, so I am quite sure that is not the matter. I am sorry for the slow consoles. Thanks in advance! Kyril

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  • Query with UDF works in Access but gives Undefined function in expression (Err 3085) in Excel

    - by ronwest
    I have an Access table with a date/time field. I wanted to make a composite Key field out of the date/time field and 3 other text fields in the same format as the matching Key field in another database. So I concatenated the 3 text fields and wrote a User-Defined-Function in a Module to output the date field as a string in the format "YYYYMMDD". Public Function YYYYMMDD(dteDate As Date) As String YYYYMMDD = Format(dteDate, "YYYYMMDD") End Function I can then successfully run my queries in Access and it all works fine. But when I set up some DAO code in Excel and try to run the query that works fine within Access... db.Execute "qryMake_tblValsDailyAccount" ...Excel gives me the "Undefined function in expression. (Error 3085)" error. To me this is a bug in Excel and/or Access, because the (Excel) client shouldn't need to know anything about the internal calculations that normally take place perfectly in the (Access) server when in isolation. Excel should send the querydef (name with no parameters) to the server, let the server do its work then receive the answers. Why does it need to get involved with a function internal to the server? Does anyone know a way around this?

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