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  • HELP with sql query involving two tables and a max date

    - by wes
    hello all....firstly any help is greatly appreciated! i have been searching for a solution to my problem for a while and haven't found exactly what i am looking for. i have two tables notifications and mailmessages. notifications has fields( notifytime, notifynumber, and accountnumber). mailmessages has fields(id, messagesubject, messagenumber, accountnumber) my goal is to create a single sql query to retrieve distinct rows from mailmessages WHERE the accountnumber is a specific number AND the notifynumber=messagenumber AND ONLY the most recent notifytime from the notifications table where the accountnumbers match in both tables. i am using sqlexpress2008 as a backend to an asp.net page....this query should return distinct messages for an account with only the most recent date from the notifications table..please help! i'll buy you a beer!!!

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  • Help with optimising SQL query

    - by user566013
    Hi i need some help with this problem. I am working web application and for database i am using sqlite. Can someone help me with one query from databse which must be optimized == fast =) I have table x: ID | ID_DISH | ID_INGREDIENT 1 | 1 | 2 2 | 1 | 3 3 | 1 | 8 4 | 1 | 12 5 | 2 | 13 6 | 2 | 5 7 | 2 | 3 8 | 3 | 5 9 | 3 | 8 10| 3 | 2 .... ID_DISH is id of different dishes, ID_INGREDIENT is ingredient which dish is made of: so in my case dish with id 1 is made with ingredients with ids 2,3 In this table a have more then 15000 rows and my question is: i need query which will fetch rows where i can find ids of dishes ordered by count of ingreedients ASC which i haven added to my algoritem. examle: foo(2,4) will rows in this order: ID_DISH | count(stillMissing) 10 | 2 1 | 3 Dish with id 10 has ingredients with id 2 and 4 and hasn't got 2 more, then is

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  • PHP image resize on the fly vs storing resized images

    - by Pablo
    I'm building a image sharing site and would like to know the pros and cons of resizing images on the fly with php and having the resized images stored. Which is faster? Which is more reliable? how big is the gap between the two methods in speed and performance? Please note that either way the images go through a PHP script for statistics like views or if hotlinking is allow etc... so is not like it will be a direct link for images if i opt to store the resize images. I'll appreciated your comments or any helpful links on the subject, Thanks.

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  • Average of a Sum in Mysql query

    - by chupeman
    I am having some problems creating a query that gives me the average of a sum. I read a few examples here in stackoverflow and couldn't do it. Can anyone help me to understand how to do this please? This is the data I have: Basically I need the average transaction value by cashier. I can't run a basic avg because it will take all rows but each transaction can have multiple rows. At the end I want to have: Cashier| Average| 131 | 44.31 |(Which comes from the sum divided by 3 transactions not 5 rows) 130 | 33.15 | etc. This is the query I have to SUM the transactions but don't know how or where to include the AVG function. SELECT `products`.`Transaction_x0020_Number`, Sum(`products`.`Sales_x0020_Value`) AS `SUM of Sales_x0020_Value`, `products`.`Cashier` FROM `products` GROUP BY `products`.`Transaction_x0020_Number`, `products`.`Date`, `products`.`Cashier` HAVING (`products`.`Date` ={d'2010-06-04'}) Any help is appreciated.

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  • Faking a Single Address Space

    - by dsimcha
    I have a large scientific computing task that parallelizes very well with SMP, but at too fine grained a level to be easily parallelized via explicit message passing. I'd like to parallelize it across address spaces and physical machines. Is it feasible to create a scheduler that would parallelize already multithreaded code across multiple physical computers under the following conditions: The code is already multithreaded and can scale pretty well on SMP configurations. The fact that not all of the threads are running in the same address space or on the same physical machine must be transparent to the program, even if this comes at a significant performance penalty in some use cases. You may assume that all of the physical machines involved are running operating systems and CPU architectures that are binary compatible. Things like locks and atomic operations may be slow (having network latency to deal with and all) but must "just work".

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  • Alternatives to FastDateFormat for efficient date parsing?

    - by Tom Tucker
    Well aware of performance and thread issues with SimpleDateFormat, I decided to go with FastDateFormat, until I realized that FastDateFormat is for formatting only, no parsing! Is there an alternative to FastDateFormat, that is ready to use out of the box and much faster than SimpleDateFormat? I believe FastDateFormat is one of the faster ones, so anything that is about as fast would do. Just curious , any idea why FastDateFormat does not support parsing? Doesn't it seriously limit its use? Thanks! EDIT Holy crap, I just left a comment and that literally REMOVED a good answer! This appears a serious bug on stackoverflow!

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  • MySQL update query, how to skip empty values?

    - by Pawel
    I've got such query: $sql = "UPDATE test_accs SET acc_owner = '$owner_id', acc_policy_version = '$version', acc_policy_last_update = '$approved', acc_policy_next_update = '$renewed' WHERE acc_id = '1'"; Now, all of these values on the web folmular are optional, one can set one of these values, two, or so. Now, after I submit the form, it goes in the query like that: UPDATE test_accs SET acc_owner = '2', acc_policy_version = '1.2', acc_policy_last_update = '2012-12-19', acc_policy_next_update = '2012-12-18' WHERE acc_id = '1' It works only when I submit all values from the form. Can you please show me how could it work even if not all the values has been sent, just for example one of them? When I set one value (f.ex. policy version), it looks like that: UPDATE test_accs SET acc_owner = '', acc_policy_version = '1.2', acc_policy_last_update = '', acc_policy_next_update = '' WHERE acc_id = '1' and it isn't working. It might be possible cause of the acc_owner table values? #1366 - Incorrect integer value: '' for column 'acc_owner' at row 1 Thanks in advice.

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  • MySQL Limiting a query to one consistent value

    - by Lucas Matos
    My current query returns a table like: +------------+ value1 | .... value1 | .... value2 | .... value3 | .... +------------+ I want: +------------+ value1 | .... value1 | .... +------------+ I want to only receive all rows with the first value. Normally I would do a WHERE clause if I knew that value, and I cannot use a LIMIT because each value has a different number of rows. Right now My query looks like "SELECT u.*, n.something, w.* FROM ... AS u, ... AS n, ... AS w WHERE u.id = n.id AND w.val = n.val AND u.desc LIKE '%GET REQUEST VARIABLE%';" This works great, except I get way too many rows and using PHP to do this ruins code portability and is superfluous. Thanks for reading

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  • Invisible JFrame/JTable how much faster ?

    - by chacko
    I have a swing app. with a jframe with lots of internal frames containing large JTable. Those jtables get updated continuously so there is lots of repainting going on. in some circumstances I can simply keep the JFrame invisible. (frame.setVisible(false)) I was wondering if anybody knows if I will gain something in terms of performance (something considerable or not) such as 50% gain or you would only get 2% gain... and maybe some sort of explaination on what to expect. thanks

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  • How can I write faster JavaScript?

    - by a paid nerd
    I'm writing an HTML5 canvas visualization. According to the Chrome Developer Tools profiler, 90% of the work is being done in (program), which I assume is the V8 interpreter at work calling functions and switching contexts and whatnot. Other than logic optimizations (e.g., only redrawing parts of the visualization that have changed), what can I do to optimize the CPU usage of my JavaScript? I'm willing to sacrifice some amount of readability and extensibility for performance. Is there a big list I'm missing because my Google skills suck? I have some ideas but I'm not sure if they're worth it: Limit function calls When possible, use arrays instead of objects and properties Use variables for math operation results as much as possible Cache common math operations such as Math.PI / 180 Use sin and cos approximation functions instead of Math.sin() and Math.cos() Reuse objects when passing around data instead of creating new ones Replace Math.abs() with ~~ Study jsperf.com until my eyes bleed Use a preprocessor on my JavaScript to do some of the above operations

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  • How to find which method makes my iPhone app slow ?

    - by Stewart Hou
    Currently I am working on a production app. One function acts like the settings.app on iPhone. When the user click a cell of a tableView, as shown below http://www.penguintech.net/images/stackoverflow/1.png It will push another view, which includes a textfield to let user input something. However, on both simulator and device, after the app just loaded, the delay between clicking and showing the second view takes around 2 seconds. Then if user get back to previous view and click again, it will be no delay at all. To detect which method makes the delay, I put a NSLog() in every involved methods, but when I was inspecting the console while running the app, all NSLog() message showed in 0.1 seconds, and then still a delay on the app. Is there any other way to trace the performance footage of a app? The Instruments shows only CPU usage in Mac OS not in iPhone.

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  • Access SQL query to SELECT from one table and INSERT into another

    - by typoknig
    Below is my query. Access does not like it, giving me the error Syntax error (missing operator) in query expression 'answer WHERE question = 1'. Hopefully you can see what I am trying to do. Please pay particular attention to 3rd, 4th, and 5th lines under the SELECT statement. INSERT INTO Table2 (respondent,1,2,3-1,3-2,3-3,4,5) SELECT respondent, answer WHERE question = 1, answer WHERE question = 2, answer WHERE answer = 'text 1' AND question = 3, answer WHERE answer = 'text 2' AND question = 3, answer WHERE answer = 'text 3' AND question = 3, answer WHERE question = 4, longanswer WHERE question 5 FROM Table1 GROUP BY respondent;

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  • Should i use TabContainer for multiple pages?

    - by Tim
    I'm considering if it is a good idea to use an ASP.Net TabContainer-Control in the way that every TabPanel contains content of a different page. For example: Next i want to implement in my application is the masterdata management. Normally i would create one aspx page for every masterdata-table (f.e. Customer - MD_Customer.aspx). Then i would add a link into my Menu to this page. Now i'm thinking of creating one aspx page for all(Masterdata.aspx) with a Tabcontainer and an UpdatePanel for every type of Masterdata. The link it the menu could have an additional MDType as URL-Parameter. My main concerns are related to performance(one "page" for every TabPanel currently means 7 "pages" in one) and maintainability because of increasing complexity. Is it a good approach or a bad idea? Thanks

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  • get js file query param from inside it

    - by vsync
    I load this file with some query param like this: src='somefile.js?userId=123' I wrote the below function in 'somefile.js' file that reads the 'userId' query param but I feel this is not the best approach. Frankly, its quite ugly. Is there a better way? function getId(){ var scripts = document.getElementsByTagName('script'), script; for(var i in scripts){ if( scripts.hasOwnProperty(i) && scripts[i].src.indexOf('somefile.js') != -1 ) var script = scripts[i]; } var s = (script.getAttribute.length !== undefined) ? script.getAttribute('src') : script.getAttribute('src', 2); return getQueryParams('userId',s); };

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  • mysql query to concat information from 3 tables - getting incorrect result count

    - by iPfaffy
    I have 3 tables in my database. ab_contacts id first_name last_name addressbook_id ab_addressbooks name id co_comments id link_id comment I'd like to create a query that will let me select all the contacts and comments related to them in a given addressbook. To select all the people in a given addressbook, I can use: select count(*) from ab_contacts where addressbook_id = '50'; This returns 8152 people. However, when I run my query: select ab_contacts.first_name, ab_contacts.last_name, ab_contacts.email, ab_addressbooks.name, co_comments.comments from ab_contacts JOIN ab_addressbooks ON (ab_contacts.addressbook_id = ab_addressbooks.id) JOIN co_comments ON (ab_contacts.id = co_comments.link_id) WHERE ab_contacts.addressbook_id = '50';` the format works, but I only get 1045 results. I'm sure there is something I am missing, but I cannot figure it out. Any help would be greatly appreciated.

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  • MySQL query with 2 COUNT() of other tables with where conditions

    - by Isern Palaus
    Hello, I've a table called sports that contains a list of list of sports, other called seasons that contains the seasons for a specific sport and competitions that have the competitions of a specific sport and season. I need one MySQL query to print the list of sports with how much seasons and competitions has each. My tables structure: sports +--------------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------------------+------------------+------+-----+---------+----------------+ | id | int(10) unsigned | NO | PRI | NULL | auto_increment | | name | varchar(32) | NO | | NULL | | | slug | varchar(45) | NO | | NULL | | | description | varchar(128) | NO | | NULL | | +--------------------+------------------+------+-----+---------+----------------+ seasons +--------------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------------------+------------------+------+-----+---------+----------------+ | id | int(10) unsigned | NO | PRI | NULL | auto_increment | | id_sport | int(10) unsigned | NO | MUL | NULL | | | name | varchar(32) | NO | | NULL | | | slug | varchar(32) | NO | | NULL | | +--------------------+------------------+------+-----+---------+----------------+ competitions +--------------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------------------+------------------+------+-----+---------+----------------+ | id | int(10) unsigned | NO | PRI | NULL | auto_increment | | id_season | int(10) unsigned | NO | MUL | NULL | | | name | varchar(32) | NO | | NULL | | | slug | varchar(64) | NO | | NULL | | | description | varchar(128) | YES | | NULL | | +--------------------+------------------+------+-----+---------+----------------+ The result of my query needs to contain: sports.*, total_seasons (SUM of seasons where seasons.id_sport=sports.id) and total_competitions (SUM of competitions where competitions.id_season=seasons.id AND seasons.id_sport=sports.id). Thank you in advance!

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  • Speed up this query joining to a table multiple times

    - by Mongus Pong
    Hi, I have this query that (stripped right down) goes something like this : SELECT [Person_PrimaryContact].[LegalName], [Person_Manager].[LegalName], [Person_Owner].[LegalName], [Person_ProspectOwner].[LegalName], [Person_ProspectBDM].[LegalName], [Person_ProspectFE].[LegalName], [Person_Signatory].[LegalName] FROM [Cache] LEFT JOIN [dbo].[Person] AS [Person_Owner] WITH (NOLOCK) ON [Person_Owner].[PersonID] = [Cache].[ClientOwnerID] LEFT JOIN [dbo].[Person] AS [Person_Manager] WITH (NOLOCK) ON [Person_Manager].[PersonID] = [Cache].[ClientManagerID] LEFT JOIN [dbo].[Person] AS [Person_Signatory] WITH (NOLOCK) ON [Person_Signatory].[PersonID] = [Cache].[ClientSignatoryID] LEFT JOIN [dbo].[Person] AS [Person_PrimaryContact] WITH (NOLOCK) ON [Person_PrimaryContact].[PersonID] = [Cache].[PrimaryContactID] LEFT JOIN [dbo].[Person] AS [Person_ProspectOwner] WITH (NOLOCK) ON [Person_ProspectOwner].[PersonID] = [Cache].[ProspectOwnerID] LEFT JOIN [dbo].[Person] AS [Person_ProspectBDM] WITH (NOLOCK) ON [Person_ProspectBDM].[PersonID] = [Cache].[ProspectBDMID] LEFT JOIN [dbo].[Person] AS [Person_ProspectFE] WITH (NOLOCK) ON [Person_ProspectFE].[PersonID] = [Cache].[ProspectFEID] Person is a huge table and each join to it has a pretty significant hit in the execution plan. Is there anyway I can adjust this query so that I am only linking to it once, or at least get SQL Server to scan through it only once?

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  • Does a servlet-based stack have significant overheads?

    - by John
    I don't know if it's simply because page-loads take a little time, or the way servlets have an abstraction framework above the 'bare metal' of HTTP, or just because of the "Enterprise" in Jave-EE, but in my head I have the notion that a servlet-based app is inherently adding overhead compared to a Java app which simply deals with sockets directly. Forget web-pages, imagine instead a Java server app where you send it a question over an HTTP request and it looks up an answer from memory and returns the answer in the response. You can easily write a Java socket-based app which does this, you can also do a servlet approach and get away from the "bare metal" of sockets. Is there any measurable performance impact to be expected implementing the same approach using Servlets rather than a custom socket-based HTTP listening app? And yes, I am hazy on the exact data sent in HTTP requests and I know it's a vague question. It's really about whether servlet implementations have lots of layers of indirection or anything else that would add up to a significant overhead per call, where by significant I mean maybe an additional 0.1s or more.

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  • Why is this javascript function so slow on Firefox?

    - by macrael
    This function was adapted from the website: http://eriwen.com/javascript/measure-ems-for-layout/ function getEmSize(el) { var tempDiv = document.createElement("div"); tempDiv.style.height = "1em"; el.appendChild(tempDiv); var emSize = tempDiv.offsetHeight; el.removeChild(tempDiv); return emSize; } I am running this function as part of another function on window.resize, and it is causing performance problems on Firefox 3.6 that do not exist on current Safari or Chrome. Firefox's profiler says I'm spending the most time in this function and I'm curious as to why that is. Is there a way to get the em size in javascript without doing all this work? I would like to recalculate the size on resize incase the user has changed it.

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  • get foreign key objects in a single query - Django

    - by John
    Hi I have 2 models in my django code: class ModelA(models.Model): name = models.CharField(max_length=255) description = models.CharField(max_length=255) created_by = models.ForeignKey(User) class ModelB(models.Model): category = models.CharField(max_length=255) modela_link = models.ForeignKey(ModelA, 'modelb_link') functions = models.CharField(max_length=255) created_by = models.ForeignKey(User) Say ModelA has 100 records, all of which may or may not have links to ModelB Now say I want to get a list of every ModelA record along with the data from ModelB I would do: list_a = ModelA.objects.all() Then to get the data for ModelB I would have to do for i in list_a: i.additional_data = i.modelb_link.all() However this runs a query on every instance of i. Thus making 101 queries to run. Is there any way of running this all in just 1 query. Or at least less than the 101 queries. I've tried putting in ModelA.objects.select_related().all() but this didn't seem to have any effect. Thanks

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  • [PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute query]

    - by doniyor
    i need help. i am trying to select from database thru sql statement in play framework, but it gives me error, i cannot figure out where the clue is. here is the code: @Transactional public static Users findByUsernameAndPassword(String username, String password){ String hash = DigestUtils.md5Hex(password); Query q = JPA.em().createNativeQuery("select * from USERS where" + "USERNAME=? and PASSWORD=?").setParameter(1, username).setParameter(2, password); List<Users> users = q.getResultList(); if(users.isEmpty()){ return null; } else{ return users.get(0); here is the eror message: [PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute query] can someone help me please! any help i would appreciate! thanks

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  • Making linq avoid using in memory filtering where possible

    - by linqmonkey
    Consider the these two LINQ2SQL data retrieval methods. The first creates a 'proper' SQL statement that filters the data, but requires passing the data context into the method. The second has a nicer syntax but loads the entire list of that accounts projects, then does in memory filtering. Is there any way to preserve the syntax of the second method but with the performance advantage of the first? public partial class Account { public IQueryable<Project> GetProjectsByYear(LinqDataContext context, int year) { return context.Projects.Where(p => p.AccountID==this.AccountID && p.Year==year).OrderBy(p => p.ProjectNo) } public IQueryable<Project> GetProjectsByYear(int year) { return this.Projects.Where(p => p.Year==year).OrderBy(p => p.ProjectNo).AsQueryable() } }

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  • help me with the following sql query

    - by rupeshmalviya
    could somebody correct my following query, i am novice to software development realm, i am to a string builder object in comma separated form to my query but it's not producing desired result qyery is as follows and string cmd = "SELECT * FROM [placed_student] WHERE passout_year=@passout AND company_id=@companyId AND course_id=@courseId AND branch_id IN('" + sb + "')"; StringBuilder sb = new StringBuilder(); foreach (ListItem li in branch.Items) { if (li.Selected == true) { sb.Append(Convert.ToInt32(li.Value) +", "); } } li is integer value of my check box list which are getting generated may be differne at different time ...please also suggest me some good source to learn sql..

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  • mysql PHP query question

    - by camran
    Ok, i have a problem here... I am sending values of drop down lists via ajax to this PHP file. Now I want to search a mysql database using these values, which I have managed to do, BUT, only if I set the values to something... Take a look: $query = "SELECT * FROM cars_db WHERE price BETWEEN '$cars_price_from' AND '$cars_price_to' AND year BETWEEN '$cars_year_from' AND '$cars_year_to' AND mileage BETWEEN '$cars_mileage_from' AND '$cars_mileage_to' AND gearbox = '$cars_gearbox' AND fuel = '$cars_fuel'"; now, what if the user doesnt select any "price_from" or "year_from"... The fields are only optional, so if the user doesnt enter any "price from" or "year from", then the user wants ALL cars to show... Do I have to write a query statement for each case or is there another way?

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