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  • How do I handle priority and propagation in an event system?

    - by Peeter
    Lets say I have a simple event system with the following syntax: object = new Object(); object.bind("my_trigger", function() { print "hello"; }); object.bind("my_trigger", function() { print "hello2"; }); object.trigger("my_trigger"); How could I make sure hello2 is printed out first (I do not want my code to depend on which order the events are binded). Ontop of that, how would I prevent my events from propagating (e.g. I want to stop every other event from being executed)

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  • Efficiency of checking for null varbinary(max) column ?

    - by Moe Sisko
    Using SQL Server 2008. Example table : CREATE table dbo.blobtest (id int primary key not null, name nvarchar(200) not null, data varbinary(max) null) Example query : select id, name, cast((case when data is null then 0 else 1 end) as bit) as DataExists from dbo.blobtest Now, the query needs to return a "DataExists" column, that returns 0 if the blob is null, else 1. This all works fine, but I'm wondering how efficient it is. i.e. does SQL server need to read in the whole blob to its memory, or is there some optimization so that it just does enough reads to figure out if the blob is null or not ? (FWIW, the sp_tableoption "large value types out of row" option is set to OFF for this example).

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  • mysql birthday reminder, leap year

    - by moodh
    Hi, I'm trying to sort out a result set that gives the 5 closest users sorted by upcoming birthday. This works perfectly until leap years comes into play. For example: May 15th - 96 days left May 15th - 97 days left The top result is a birth at 1987 and the lower is from 1988. u_birth is stored as yyyy-mm-dd. Is there a simple way to sort this problem without having to rewrite the entire query? SELECT u_birth, IF( DAYOFYEAR( u_birth ) >= DAYOFYEAR( NOW() ), DAYOFYEAR( u_birth ) - DAYOFYEAR( NOW() ), DAYOFYEAR( u_birth ) - DAYOFYEAR( NOW() ) + DAYOFYEAR( CONCAT( YEAR( NOW() ), '-12-31' ) ) ) AS distance FROM (blog_users) WHERE `s_agehide` = 0 ORDER BY distance ASC LIMIT 5 This query is taken and modified from the mysql manual: http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#c7489

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  • SQL: select random row from table where the ID of the row isn't in another table?

    - by johnrl
    I've been looking at fast ways to select a random row from a table and have found the following site: http://74.125.77.132/search?q=cache:http://jan.kneschke.de/projects/mysql/order-by-rand/&hl=en&strip=1 What I want to do is to select a random url from my table 'urls' that I DON'T have in my other table 'urlinfo'.The query I am using now selects a random url from 'urls' but I need it modified to only return a random url that is NOT in the 'urlinfo' table. Heres the query: SELECT url FROM urls JOIN (SELECT CEIL(RAND() * (SELECT MAX(urlid) FROM urls ) ) AS urlid ) AS r2 USING(urlid); And the two tables: CREATE TABLE urls ( urlid INT NOT NULL AUTO_INCREMENT PRIMARY KEY, url VARCHAR(255) NOT NULL, ) ENGINE=INNODB; CREATE TABLE urlinfo ( urlid INT NOT NULL PRIMARY KEY, urlinfo VARCHAR(10000), FOREIGN KEY (urlid) REFERENCES urls (urlid) ) ENGINE=INNODB;

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  • Detailed C++ book for a programmer already familiar with C and object-oriented programming?

    - by Anto
    I know (to some extent) a few languages, including C, Java and Python. I'm also (somewhat) familiar with Scala and Scheme, plus I can read (but not write) x86 Assembly. Say I want to learn C++, what is a good book which doesn't try to teach me what a class is, teach me inheritance, polymorphism or loosely coupled classes again, nor does try to teach me other basics, just the C++ language (as well as how to write idiomatic C++ code, not e.g. Java with C++ syntax) and its standard library? Note: "Detailed" as used in the title means that it doesn't try to cover C++ in 100 pages, I want to know the details of the language. Of course, mastery comes from practice, but I don't want to learn just a little bit of C++ from the book, but learn it quite thoroughly.

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  • should i concentrate on logical and puzzles part in programming, i want to be a web (flex)developer?

    - by abhilashm86
    I'm a student not good and can't easily crack at more puzzle, complex mathematics, hard logic problems? in college i studied c++, java, oops. I'm comfortable with all syntax and writing programs and using API's and doing mashups, i can do.......... but once a friend asked help on coding contest, i was in dilemma and frustration? It was simple and complex, i could not write code for those, so got scared? Is logical ability,complex mathematics, puzzles required for a developer point of view? please help and suggest methods to achieve things......

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  • iPhone OSStatus -25308 or errSecInteractionNotAllowed SFHFKeychainUtils

    - by George Octavio
    Hi again guys. I'm trying to access my iPhone's device keychain. I want to access in order to create a simple user-password value intended for a log in function. This is the code I'm using from SFHFKeychainUtils NSArray *keys = [[[NSArray alloc] initWithObjects: (NSString *) kSecClass, kSecAttrService, kSecAttrLabel, kSecAttrAccount, kSecValueData, nil] autorelease]; NSArray *objects = [[[NSArray alloc] initWithObjects: (NSString *) kSecClassGenericPassword, serviceName, serviceName, @"TestUser", @"TestPass", nil] autorelease]; NSDictionary *query = [[[NSDictionary alloc] initWithObjects: objects forKeys: keys] autorelease]; OSStatus status = SecItemAdd((CFDictionaryRef) query, NULL); } else if (status != noErr) { //Output to screen with error code goes here return NO; } return YES; } The error code I'm getting is OSStatus-25308 or errSecInteractionNotAllowed. I'm guessing this means I don't actually have access to my iPhone's keychain? Is there a way to allow access? Thanks for your time.

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  • SQL finding members who are not friends of another member

    - by thedirktastik
    I'm struggling to find a query which will return members who aren't friends of a certain member. Here is the layout of my tables: member_login: MemberID, email, password member_info: memberID, first_name, last_name member_friends: friendID, req_member, req_date, app_member, app_date, date_deactivated I tried to use NOT IN to run a query that would return the opposite of friends but nothing I try seems to be working. Here's what I thought would work: SELECT Mi.First_Name, Mi.Last_Name FROM Member_Info Mi WHERE Mi.Memberid NOT IN( SELECT Mi.Memberid, Mi.First_Name, Mi.Last_Name FROM Member_Info Mi, Member_Login Ml, Member_Friends Mf WHERE Mi.Memberid = Ml.Memberid AND (Mi.Memberid = Mf.Req_Member AND Mf.App_Member = 1 OR Mi.Memberid = Mf.App_Member AND Mf.Req_Member =1) AND Ml.Date_Deactivated <= 0 AND Mf.App_Date > 0 ); Any ideas?

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  • Does SQL Server Compact Edition (SqlCe) have a SNAPSHOT table like Oracle Lite?

    - by MusiGenesis
    In Oracle Lite, you can create a SNAPSHOT table which is like a normal table except that it tracks changes to itself. The syntax is CREATE SNAPSHOT TABLE tblWhatever ... and you can perform CRUD operations on it like a normal table. To get the change information, you query the table like this: SELECT * FROM tblWhatever + WHERE ... which returns all the rows in the table (including deleted ones) meeting the WHERE clause, and you can access each row's row_state column as a normal field (which is invisible to a normal SELECT * FROM tblWhatever WHERE ... query). Is there some way to do the same thing with Sql Compact Edition (3.5) - i.e. create a table that tracks changes without using RDA?

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  • Declarative JDOQL vs Single-String JDOQL : performance

    - by DrDro
    When querying with JDOQL is there a performance difference between using the declarative version and the Single-String version: Example from the JDOQL doc: //Declarative JDOQL : Query q = pm.newQuery(org.jpox.Person.class, "lastName == \"Jones\" && age < age_limit"); q.declareParameters("double age_limit"); List results = (List)q.execute(20.0); //Single-String JDOQL : Query q = pm.newQuery("SELECT FROM org.jpox.Person WHERE lastName == \"Jones\"" + " && age < :age_limit PARAMETERS double age_limit"); List results = (List)q.execute(20.0); Other then performance, are there any reasons for which one is better to use then the other or is it just about the one with which we feel more comfortable.

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  • Prevent SQL Injection in Dynamic column names

    - by Mr Shoubs
    I can't get away without writing some dynamic sql conditions in a part of my system (using Postgres). My question is how best to avoid SQL Injection with the method I am currently using. EDIT (Reasoning): There are many of columns in a number of tables (a number which grows (only) and is maintained elsewhere). I need a method of allowing the user to decide which (predefined) column they want to query (and if necessary apply string functions to). The query itself is far too complex for the user to write themselves, nor do they have access to the db. There are 1000's of users with varying requirements and I need to remain as flexible as possible - I shouldn't have to revisit the code unless the main query needs to change - Also, there is no way of knowing what conditions the user will need to use. I have objects (received via web service) that generates a condition (the generation method is below - it isn't perfect yet) for some large sql queries. The _FieldName is user editable (parameter name was, but it didn't need to be) and I am worried it could be an attack vector. I put double quotes (see quoted identifier) around the field name in an attempt to sanitize the string, this way it can never be a key word. I could also look up the field name against a list of fields, but it would be difficult to maintain on a timely basis. Unfortunately the user must enter the condition criteria, I am sure there must be more I can add to the sanatize method? and does quoting the column name make it safe? (my limited testing seems to think so). an example built condition would be "AND upper(brandloaded.make) like 'O%' and upper(brandloaded.make) not like 'OTHERBRAND'" ... Any help or suggestions are appreciated. Public Function GetCondition() As String Dim sb As New Text.StringBuilder 'put quote around the table name in an attempt to prevent some sql injection 'http://www.postgresql.org/docs/8.2/static/sql-syntax-lexical.html sb.AppendFormat(" {0} ""{1}"" ", _LogicOperator.ToString, _FieldName) Select Case _ConditionOperator Case ConditionOperatorOptions.Equals sb.Append(" = ") ... End Select sb.AppendFormat(" {0} ", Me.UniqueParameterName) 'for parameter Return Me.Sanitize(sb) End Function Private Function Sanitize(ByVal sb As Text.StringBuilder) As String 'compare against a similar blacklist mentioned here: http://forums.asp.net/t/1254125.aspx sb.Replace(";", "") sb.Replace("'", "") sb.Replace("\", "") sb.Replace(Chr(8), "") Return sb.ToString End Function Public ReadOnly Property UniqueParameterName() As String Get Return String.Concat(":" _UniqueIdentifier) End Get End Property

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  • SQL joins "going up" two tables

    - by blcArmadillo
    I'm trying to create a moderately complex query with joins: SELECT `history`.`id`, `parts`.`type_id`, `serialized_parts`.`serial`, `history_actions`.`action`, `history`.`date_added` FROM `history_actions`, `history` LEFT OUTER JOIN `parts` ON `parts`.`id` = `history`.`part_id` LEFT OUTER JOIN `serialized_parts` ON `serialized_parts`.`parts_id` = `history`.`part_id` WHERE `history_actions`.`id` = `history`.`action_id` AND `history`.`unit_id` = '1' ORDER BY `history`.`id` DESC I'd like to replace `parts`.`type_id` in the SELECT statement with `part_list`.`name` where the relationship I need to enforce between the two tables is `part_list`.`id` = `parts`.`type_id`. Also I have to use joins because in some cases `history`.`part_id` may be NULL which obviously isn't a valid part id. How would I modify the query to do this?

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  • SQL GROUP BY - also SELECT not-constant columns

    - by Michal Kosek
    can someone please help me with this query? I have 2 tables in my database: log_visitors: -------------------- id | host_id log_access: -------------------- visitor | document | timestamp "log_access.visitor" links to "log_visitors.id" Currently, I'm using this query: SELECT log_visitors.host_id , MIM(log_access.timestamp) AS min_timestamp FROM log_access INNER JOIN log_visitors ON (log_access.visitor = log_visitors.id) GROUP BY log_visitors.host_id; to get "MIN(timestamp)" for each "host_id" in the database. HERE'S MY QUESTION: I also need to get "document" for that access with that timestamp... I can't simply add "log_access.document" into SELECT list, since it's not constant and I am not grouping by document... Any ideas?

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  • Django DecimalField returns "None" instead of empty value

    - by Ed
    Is there a way to force django to display nothing instead of "None" for a Decimal Field that's been left blank? In my template, I show a list of all the values for a particular field. Each value is hyperlinked to a page that displays the results of a query filtered on that value. But because there are some entries with null value, my list includes actual DecimalField entries and "None" for all those that are empty. When a user clicks on None, django throws a validation error because you cannot query a DecimalField using a string. I could write if statements checking all instances of decimal fields for Nones and skipping them, but that is far from an elegant solution. Any advice? This is one part of the code, though there are other templates that derive the None value in slightly different manners: {% for item in choices %} <a href={% url app_views.field_choice item %}>{{ item }}</a><br> {% endfor %}

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  • hibernate order by association

    - by Gary Kephart
    I'm using Hibernate 3.2, and using criteria to build a query. I'd like to add and "order by" for a many-to-one association, but I don't see how that can be done. The Hibernate query would end up looking like this, I guess: select t1.a, t1.b, t1.c, t2.dd, t2.ee from t1 inner join t2 on t1.a = t2.aa order by t2.dd <-- need to add this I've tried criteria.addOrder("assnName.propertyName") but it doesn't work. I know it can be done for normal properties. Am I missing something?

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  • dilemma about mysql. using condition to limit load on a dbf

    - by ondrobaco
    hi, I have a table of about 800 000 records. Its basically a log which I query often. I gave condition to query only queries that were entered last month in attempt to reduce the load on a database. My thinking is a) if the database goes only through the first month and then returns entries, its good. b) if the database goes through the whole database + checking the condition against every single record, it's actually worse than no condition. What is your opinion? How would you go about reducing load on a dbf?

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  • SQL joining 3 tables when 1 table is emty

    - by AdRock
    I am trying to write a query that connects 3 tables. The first table is info about each festival The second table is the number of votes for each festival The third table is reviews for each festival I want to join all 3 tables so i get all the feilds from table1, join table1 with table2 on the festivalid but i also need to count the number of records in table 3 that applys to each festival. The first 2 tables give me a result becuase they both have data in them but table 3 is empty becuase there are no reviews yet so adding that to my query fives me no results SELECT f.*, v.total, v.votes, v.festivalid, r.reviewcount as count FROM festivals f INNER JOIN vote v ON f.festivalid = v.festivalid INNER JOIN (SELECT festivalid, count(*) as reviewcount FROM reviews) GROUP BY festivalid) as r on r.festivalid = v.festivalid

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  • An INSERT conditioned on COUNT

    - by Anders Feder
    How can I construct a MySQL INSERT query that only executes if the number of rows satisfying some condition already in the table is less than 20, and fails otherwise? That is, if the table has 18 rows satisfying the condition, then the INSERT should proceed. If the table has 23 rows satisfying the condition, then the INSERT should fail. For atomicity, I need to express this in a single query, so two requests can not INSERT at the same time, each in the 'belief' that only 19 rows satisfy the condition. Thank you.

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  • ORDER BY giving wrong order

    - by Cody Dull
    I have an SQL statement in my C# program that looks like: SELECT * FROM XXX.dbo.XXX WHERE Source = 'OH' AND partnum = '1231202085' ORDER BY partnum, Packaging, Quantity When running this query in SQL Server Management, the results are ordered as expected. My first 3 results have the same partnum and Packaging with Quantities of 32.0, 50.8, and 51.0. However, when I run the query from my program, the result set with quantity 50.8 is the first to be returned. The datatype of Quantity is decimal(18,9). I've tried cast, it doesn't appear to be a datatype problem. I cant figure out why its getting the middle quantity.

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  • Development on Terminal or IDE [on hold]

    - by Taylor Flores
    I've been using nano, make, gcc, and gdb for 6 months now and I've found it much easier than using VS or Codeblocks. But I'm wondering now: Is development on a terminal more/less efficient that using an IDE? In what situations is one preferred more sensible than the other? I'm not asking about opinions, I want to know if there's specific reasons to use one over the other. From what I can gather: terminals can be used on environments where a GUI is not available terminal projects can be created and configured more quickly IDEs contain better syntax highlighters (ie identity highlighters) This question is C biased, but I think it's relevant to other languages as well.

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  • Database solutions for storing/searching EXIF data

    - by webdestroya
    I have thousands of photos on my site (each with a numeric PhotoID) and I have EXIF data (photos can have different EXIF tags as well). I want to be able to store the data effectively and search it. Some photos have more EXIF data than others, some have the same, so on.. Basically, I want to be able to query say 'Select all photos that have a GPS location' or 'All photos with a specific camera' I can't use MySQL (tried it, it doesn't work). I thought about Cassandra, but I don't think it lets me query on fields. I looked at SimpleDB, but I would rather: not pay for the system, and I want to be able to run more advanced queries on the data. Also, I use PHP and Linux, so it would be awesome if it could interface nicely to PHP. Any ideas?

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  • Visual Studio error on valid SQL

    - by Sam
    I'm getting an annoying error in visual studio for SQL that executes fine. SELECT InvoiceLines.LineID, InvoiceLines.InvoiceID, InvoiceLines.Text, InvoiceLines.Rate, InvoiceLines.Count, InvoiceLines.Rate * InvoiceLines.Count AS LineTotal, ((InvoiceLines.Rate * InvoiceLines.Count) * (1 + Invoices.VatRate / 100)) * (1 - CAST(Invoices.Discount AS money) * InvoiceLines.ApplyDiscount / 100) AS LineTotalIncVat, InvoiceLines.ApplyDiscount FROM InvoiceLines LEFT JOIN Invoices ON Invoices.InvoiceID = InvoiceLines.InvoiceID What LineTotalIncVat is trying to do is compute the total for the invoice item while adding the vat and subtracting the discount, and yes, probably better to do this in code (would if I could) The error visual studio gives is: There was an error parsing the query [token line number =1, token line offset =14, token in error = InvoiceLines] Even though it will validate and execute without a problem in the query builder...

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  • Whats the thing the report bugs in php?

    - by Max Hazard
    Currently I am learning php. Php is understood by browser itself right from php sdk right? SDK include libraries right? So browser is like an interpreter of php codes. I want to know that whenever I type a wrong php syntax what is the thing report me the error? Obviously the browser is reporting the error. But what part of it? I mean I don't get it. Like writing a compiler we do lexical analysis and make the compiler which report any bug in source code. I assume here browser is analogous to compiler. I don't know exactly but compiler contains bug report functions or methods which is debugger. Debugger is part of compiler which report bugs. Does the browser contains such debuggers? Can there be any browser which doesn't understand php?

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  • Command line options style - POSIX or what?

    - by maaartinus
    Somewhere I saw a rant against java/javac allegedly using a mix of Windows and Unix style like java -classpath ... -ea ... Something IMHO, it is no mix, it's just like find works as well, isn't it? AFAIK, according to POSIX, the syntax should be like java --classpath ... --ea ... Something and -abcdef would mean specifying 6 short options at once. I wonder which version leads in general to less typing and less errors. I'm writing a small utility in Java and in no case I'm going to use Windows style /a /b since I'm interested primarily in Unix. What style should I choose?

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