Search Results

Search found 40744 results on 1630 pages for 'sql interview questions a'.

Page 440/1630 | < Previous Page | 436 437 438 439 440 441 442 443 444 445 446 447  | Next Page >

  • Java dynamic proxy questions.

    - by Tony
    1.Does dynamic proxy instance subclass the target class? The java doc says the proxy instance implements "a list of interfaces", says nothing about subclassing, but through debugging, I saw that the proxy instance did inherit the target class properites.What does the "a list of interfaces " mean? Can I exclude those interfaces implemented by target class ? 2.Can I invoke target class specific methods on a proxy instance? 3. I think dynamic proxy is an interface methods invocation proxy but rather than a target class proxy, is that right (I am deeply infected by hibernate proxy object concept)?

    Read the article

  • SUM of metric for normalized logical hierarchy

    - by Alex254
    Suppose there's a following table Table1, describing parent-child relationship and metric: Parent | Child | Metric (of a child) ------------------------------------ name0 | name1 | a name0 | name2 | b name1 | name3 | c name2 | name4 | d name2 | name5 | e name3 | name6 | f Characteristics: 1) Child always has 1 and only 1 parent; 2) Parent can have multiple children (name2 has name4 and name5 as children); 3) Number of levels in this "hierarchy" and number of children for any given parent are arbitrary and do not depend on each other; I need SQL request that will return result set with each name and a sum of metric of all its descendants down to the bottom level plus itself, so for this example table the result would be (look carefully at name1): Name | Metric ------------------ name1 | a + c + f name2 | b + d + e name3 | c + f name4 | d name5 | e name6 | f (name0 is irrelevant and can be excluded). It should be ANSI or Teradata SQL. I got as far as a recursive query that can return a SUM (metric) of all descendants of a given name: WITH RECURSIVE temp_table (Child, metric) AS ( SELECT root.Child, root.metric FROM table1 root WHERE root.Child = 'name1' UNION ALL SELECT indirect.Child, indirect.metric FROM temp_table direct, table1 indirect WHERE direct.Child = indirect.Parent) SELECT SUM(metric) FROM temp_table; Is there a way to turn this query into a function that takes name as an argument and returns this sum, so it can be called like this? SELECT Sum_Of_Descendants (Child) FROM Table1; Any suggestions about how to approach this from a different angle would be appreciated as well, because even if the above way is implementable, it will be of poor performance - there would be a lot of iterations of reading metrics (value f would be read 3 times in this example). Ideally, the query should read a metric of each name only once.

    Read the article

  • SQL Server 2008 R2: StreamInsight - User-defined aggregates

    - by Greg Low
    I'd briefly played around with user-defined aggregates in StreamInsight with CTP3 but when I started working with the new Count Windows, I found I had to have one working. I learned a few things along the way that I hope will help someone. The first thing you have to do is define a class: public class IntegerAverage : CepAggregate < int , int > { public override int GenerateOutput( IEnumerable < int > eventData) { if (eventData.Count() == 0) { return 0; } else { return eventData.Sum()...(read more)

    Read the article

  • Some questions about setting up Amazon S3 with Ruby on Rails

    - by ben
    I'm trying to setup Amazon S3 hosting with my Ruby on Rails 3 app, which is hosted on Heroku. After reading these instructions in the Heroku docs, I'm trying to use the aws-s3 gem. The instructions say to put the S3 account details in config/amazon_s3.yml, but the aws-s3 Github page says you create a connection like this: AWS::S3::Base.establish_connection!( :access_key_id => 'abc', :secret_access_key => '123' ) Why is the connection created by providing the details if they're already provided in the config file? Is that not the correct way to establish a connection? Do I have to establish a connection for each user everytime an upload is about to occur, or is a connection established for the application as a whole? Thanks for reading.

    Read the article

  • C# Vector maths questions

    - by Mark
    Im working in a screen coordinate space that is different to that of the classical X/Y coordinate space, where my Y direction goes down in the positive instead of up. Im also trying to figure out how to make a Circle on my screen always face away from the center point of the screen. If the center point of my screen is at x(200) y(300) and the point of my circle's center is at x(150) and y(380) then I would like to calculate the angle that the circle should be facing. At the moment I have this: Point centerPoint = new Point(200, 300); Point middleBottom = new Point(200, 400); Vector middleVector = new Vector(centerPoint.X - middleBottom.X, centerPoint.Y - middleBottom.Y); Vector vectorOfCircle = new Vector(centerPoint.X - 150, centerPoint.Y - 400); middleVector.Normalize(); vectorOfCircle.Normalize(); var angle = Math.Acos(Vector.CrossProduct(vectorOfCircle, middleVector)); Console.WriteLine("Angle: {0}", angle * (180/Math.PI)); Im not getting what I would expect. I would say that when I enter in x(150) and y(300) of my circle, I would expect to see the rotation of 90 deg, but Im not getting that... Im getting 180!! Any help here would be greatly appreciated. Cheers, Mark

    Read the article

  • Regular expression for finding non-breaking string names in code and then breaking them up for SQL q

    - by Rob Segal
    I am trying to devlop a regex for finding camel case strings in several code files I am working with so I can break them up into separate words for use in a SQL query. I have strings of the form... EmailAddress FirstName MyNameIs And I want them like this... Email Address First Name My Name Is An example SQL query which I currently have is... select FirstName, MyNameIs from MyTables I need the queries in the form... select FirstName as 'First Name', MyNameIs as 'My Name Is' from MyTables Any time a new capital letter appears that should be a new grouping which I can pick out of the matched string. I currently have the following regex... ([A-Z][a-z]+)+ Which does match the cases I have shown above but when I want to perform a replace I need to define groups. Currently I have tried... (([A-Z])([a-z]+))+ Which sort of works. It will pick out "Address" as the first grouping from "EmailAddress" as opposed to "Email" which is what I was expecting. No doubt there is something I'm misunderstanding here so any help is greatly appreciated.

    Read the article

  • How to represent and insert into an ordered list in SQL?

    - by Travis
    I want to represent the list "hi", "hello", "goodbye", "good day", "howdy" (with that order), in a SQL table: pk | i | val ------------ 1 | 0 | hi 0 | 2 | hello 2 | 3 | goodbye 3 | 4 | good day 5 | 6 | howdy 'pk' is the primary key column. Disregard its values. 'i' is the "index" that defines that order of the values in the 'val' column. It is only used to establish the order and the values are otherwise unimportant. The problem I'm having is with inserting values into the list while maintaining the order. For example, if I want to insert "hey" and I want it to appear between "hello" and "goodbye", then I have to shift the 'i' values of "goodbye" and "good day" (but preferably not "howdy") to make room for the new entry. So, is there a standard SQL pattern to do the shift operation, but only shift the elements that are necessary? (Note that a simple "UPDATE table SET i=i+1 WHERE i=3" doesn't work, because it violates the uniqueness constraint on 'i', and also it updates the "howdy" row unnecessarily.) Or, is there a better way to represent the ordered list? I suppose you could make 'i' a floating point value and choose values between, but then you have to have a separate rebalancing operation when no such value exists. Or, is there some standard algorithm for generating string values between arbitrary other strings, if I were to make 'i' a varchar? Or should I just represent it as a linked list? I was avoiding that because I'd like to also be able to do a SELECT .. ORDER BY to get all the elements in order.

    Read the article

  • What is the performance penalty of XML data type in SQL Server when compared to NVARCHAR(MAX)?

    - by Piotr Owsiak
    I have a DB that is going to keep log entries. One of the columns in the log table contains serialized (to XML) objects and a guy on my team proposed to go with XML data type rather than NVARCHAR(MAX). This table will have logs kept "forever" (archiving some very old entries may be considered in the future). I'm a little worried about the CPU overhead, but I'm even more worried that DB can grow faster (FoxyBOA from the referenced question got 70% bigger DB when using XML). I have read this question http://stackoverflow.com/questions/514827/microsoft-sql-server-2005-2008-xml-vs-text-varchar-data-type and it gave me some ideas but I am particulairly interrested in clarification on whether the DB size increases or decreases. Can you please share your insight/experiences in that matter. BTW. I don't currently have any need to depend on XML features within SQL Server (there's nearly zero advantage to me in the specific case). Ocasionally log entries will be extracted, but I prefer to handle the XML using .NET (either by writing a small client or using a function defined in a .NET assembly).

    Read the article

  • [C#][WebBrowser] Two Questions

    - by Rudi
    How can I get an HtmlElement if the source code doesn't have the "id=''", but only has the "name=''". Document.GetElementById() doesn't work, and Document.All[""] doesn't work (obviously, because there is no ID. How can I simulate a form post? Question 1 is more important because I found it harder to search. Question 2 I think i can get with more searching.

    Read the article

  • Questions about .NET CollectionEditor

    - by smwikipedia
    Who can tell me the internal working mechanism of a CollectionEditor in plain English? I have implemented every virtual function and step into each of them. Still got no clue of its intended algorithm. I searched the web and found tons of compaints about the CollectionEditor type, and even bugs. I am kind of thinking of the CollectionEditor as a total mess.

    Read the article

  • SQL Is it possible to setup a column that will contain a value dependent on another column?

    - by Wesley
    I have a table (A) that lists all bundles created off a machine in a day. It lists the date created and the weight of the bundle. I have an ID column, a date column, and a weight column. I also have a table (B) that holds the details related to that machine for the day. In that table (B), I want a column that lists a sum of weights from the other table (A) that the dates match on. So if the machine runs 30 bundles in a day, I'll have 30 rows in table (A) all dated the same day. In table (B) I'll have 1 row detailing other information about the machine for the day plus the column that holds the total bundle weight created for the day. Is there a way to make the total column in table (B) automatically adjust itself whenever a row is added to table (A)? Is this possible to do in the table schema itself rather than in an SQL statement each time a bundle is added? If it's not, what sort of SQL statement do I need? Wes

    Read the article

  • GTK Menu Questions

    - by Lothar
    My application has some special requirements and i need to know if i can draw my own accelerator key description. Also is it possible to get a signal when the main menu is activated and one when it is left (either by selecting a menu option or clicking somewhere to close it).

    Read the article

  • How can I map stored procedure result into a custom class with linq-to-sql?

    - by Remnant
    I have a stored procedure that returns a result set (4 columns x n Rows). The data is based on multiple tables within my database and provides a summary for each department within a corporate. Here is sample: usp_GetDepartmentSummary DeptName EmployeeCount Male Female HR 12 5 7 etc... I am using linq-to-sql to retrieve data from my database (nb - have to use sproc as it is something I have inherited). I would like to call the above sproc and map into a department class: public class Department { public string DeptName {get; set;} public int EmployeeCount {get; set;} public int MaleCount {get; set;} public int FemaleCount {get; set;} } In VS2008, I can drag and drop my sproc onto the methods pane of the linq-to-sql designer. When I examine the designer.cs the return type for this sproc is defined as: ISingleResult<usp_GetDepartmentSummaryResult> What I would like to do is amend this somehow so that it returns a Department type so that I can pass the results of the sproc as a strongly typed view: <% foreach (var dept in Model) { %> <ul> <li class="deptname"><%= dept.DeptName %></li> <li class="deptname"><%= dept.EmployeeCount %></li> etc... Any ideas how to achieve this? NB - I have tried amending the designer.cs and dbml xml file directly but with limited success. I admit to being a little out of my depth when it comes to updating those files directly and I am not sure it is best practice? Would be good to get some diretion. Thanks much

    Read the article

  • Some questions regarding Flex

    - by Rachel
    For what real time scenarios/use cases one should go to Flex Technology ? What real time problems you have solved using Flex Technology ? What real time problems have you faced because of using Flex Technology and what was your work around for that use case ?

    Read the article

  • Two questions on ensuring EndInvoke() gets called on a list of IAsyncResult objects

    - by RobV
    So this question is regarding the .Net IAsyncResult design pattern and the necessity of calling EndInvoke as covered in this question Background I have some code where I'm firing off potentially many asynchronous calls to a particular function and then waiting for all these calls to finish before using EndInvoke() to get back all the results. Question 1 I don't know whether any of the calls has encountered an exception until I call EndInvoke() and in the event that an exception occurs in one of the calls the entire method should fail and the exception gets wrapped into an API specific exception and thrown upwards. So my first question is what's the best way then to ensure that the remainder of the async calls get properly terminated? Is a finally block which calls EndInvoke() on the remainder of the unterminated calls (and ignores any further exceptions) the best way to do this? Question 2 Secondly when I first fire off all my asyc calls I then call WaitHandle.WaitAll() on the array of WaitHandle instances that I've got from my IAsyncResult instances. The method which is firing all these async calls has a timeout to adhere to so I provide this to the WaitAll() method. Then I test whether all the calls have completed, if not then the timeout must have been reached so the method should also fail and throw another API specific exception. So my second question is what should I do in this case? I need to call EndInvoke() to terminate all these async calls before I throw the error but at the same time I don't want the code to get stuck since EndInvoke() is blocking. In theory at least if the WaitAll() call times out then all the async calls should themselves have timed out and thrown exceptions (thus completing the call) since they are also governed by a timeout but this timeout is potentially different from the main timeout

    Read the article

  • Approaching events #mstc11 #ppws #sqlbits

    - by Marco Russo (SQLBI)
    The spring season is always full of events and I’m just preparing for a number of them. First of all, we are getting very good interest for the PowerPivot Workshop in Copenhagen on 21-22 March 2011. Tomorrow (Friday March 4) will be the last day to take advantage of the Early Bird rate for this date. We will also participate to an evening meeting of local user groups on March 21 in Copenhagen, more news about this in the next few days. Other scheduled dates are in Dublin (28-29 March 2011) and in...(read more)

    Read the article

  • SQL Deprecation event uses depracted feature

    - by simonsabin
    Something mildly amusing for a monday morning. The Deprecation Event Class uses the ntext data type which is a deprecated feature. To have a look yourself go to http://msdn.microsoft.com/en-us/library/ms178053.aspx Yeh I know its profiler that is using ntext, still made me smile.

    Read the article

  • Bleeding Edge 2012 – session material

    - by Hugo Kornelis
    As promised, here are the slide deck and demo code I used for my presentation at the Bleeding Edge 2012 conference in Laško, Slovenia. Okay, I promised to have them up by Tuesday or Wednesday at worst, and it is now Saturday – my apologies for the delay. Thanks again to all the attendees of my session. I hope you enjoyed it, and if you have any question then please don’t hesitate to get in touch with me. I had a great time in Slovenia, both during the event and in the after hours. Even if everything...(read more)

    Read the article

  • Python virtualenv questions

    - by orokusaki
    I'm using VirtualEnv on Windows XP. I'm wondering if I have my brain wrapped around it correctly. I ran virtualenv ENV and it created C:\WINDOWS\system32\ENV. I then changed my PATH variable to include C:\WINDOWS\system32\ENV\Scripts instead of C:\Python27\Scripts. Then, I checked out Django into C:\WINDOWS\system32\ENV\Lib\site-packages\django-trunk, updated my PYTHON_PATH variable to point the new Django directory, and continued to easy_install other things (which of course go into my new C:\WINDOWS\system32\ENV\Lib\site-packages directory). I understand why I should use VirtualEnv so I can run multiple versions of Django, and other libraries on the same machine, but does this mean that to switch between environments I have to basically change my PATH and PYTHON_PATH variable? So, I go from developing one Django project which uses Django 1.2 in an environment called ENV and then change my PATH and such so that I can use an environment called ENV2 which has the dev version of Django? Is that basically it, or is there some better way to automatically do all this (I could update my path in Python code, but that would require me to write machine-specific code in my application)? Also, how does this process compare to using VirtualEnv on Linux (I'm quite the beginner at Linux).

    Read the article

  • SQL Server Database Settings

    - by rbishop
    For those using Data Relationship Management on Oracle DB this does not apply, but for those using Microsoft SQL Server it is highly recommended that you run with Snapshot Isolation Mode. The Data Governance module will not function correctly without this mode enabled. All new Data Relationship Management repositories are created with this mode enabled by default. This mode makes SQL Server (2005+) behave more like Oracle DB where readers simply see older versions of rows while a write is in progress, instead of readers being blocked by locks while a write takes place. Many common sources of deadlocks are eliminated. For example, if one user starts a 5 minute transaction updating half the rows in a table, without snapshot isolation everyone else reading the table will be blocked waiting. With snapshot isolation, they will see the rows as they were before the write transaction started. Conversely, if the readers had started first, the writer won't be stuck waiting for them to finish reading... the writes can begin immediately without affecting the current transactions. To make this change, make sure no one is using the target database (eg: put it into single-user mode), then run these commands: ALTER DATABASE [DB] SET ALLOW_SNAPSHOT_ISOLATION ONALTER DATABASE [DB] SET READ_COMMITTED_SNAPSHOT ON Please make sure you coordinate with your DBA team to ensure tempdb is appropriately setup to support snapshot isolation mode, as the extra row versions are stored in tempdb until the transactions are committed. Let me take this opportunity to extremely strongly highly recommend that you use solid state storage for your databases with appropriate iSCSI, FiberChannel, or SAN bandwidth. The performance gains are significant and there is no excuse for not using 100% solid state storage in 2013. Actually unless you need to store petabytes of archival data, there is no excuse for using hard drives in any systems, whether laptops, desktops, application servers, or database servers. The productivity benefits alone are tremendous, not to mention power consumption, heat, etc.

    Read the article

  • emacs -- keybind questions

    - by user565739
    I have successfully used Ctrl+Shift+Up ' Ctrl+Shift+down ' Ctrl+Shift+left' Ctrl+Shift+Right to different commands. But when I tried to use Ctrl+s to the command save-buffer and Ctrl+Shift+s, which is equivalent to Ctrl+S, to another command, it has some problem. save-buffer works fine, but when I type Ctrl+Shift+s, it excute the command save-buffer. I used Ctrl+q to find the control sequences of Ctrl+s and Ctrl+Shift+S, I get the same result, which is ^S. I expect that I will get ^s for Ctrl+s, but it doesn't. Anyone knows the reason? Another queston is: I use Ctrl+c for the command killing-ring-save. In this case, all commands (which are of large number) begin with Ctrl+c don't work now. Is there a way to replace the prefix Ctrl+c by another customized prefix? I may pose my question in the wrong direction. I use ctrl+c as killing-ring-save. It works fine in emacs (no mode). But if I open a .c file (C-mode), then when I type Ctrl+c, it waits me to type another key. I think in this case, ctrl+c is regarded as a prefix. In this case, I need the following modifications: Using a custom defined prefix, say Ctrl+a, as Ctrl+c ; Remove the prefix Ctrl+c ; Using Ctrl+c as killing-ring-save. I add the following to my ~/.emacs : (defun my-c-initialization-hook () (define-key c-mode-base-map (kbd "C-a") mode-specific-map) (define-key c-mode-base-map (kbd "C-c") 'kill-ring-save)) (add-hook 'c-initialization-hook 'my-c-initialization-hook) But this doesn't work. Ctrl+c is still regarded as a prefix, so I can't use it as kill-ring-save. Furthermore, if I type Ctrl+a Ctrl+c, it said it's not defined. (I thought it will have the same result as I type Ctrl+c Ctrl+c)

    Read the article

  • How In-Memory Database Objects Affect Database Design: Hybrid Code

    - by drsql
    In my first attempts at building my code, I strictly went with either native or on-disk code. I specifically wrote the on-disk code to only use features that worked in-memory. This lead to one majorly silly bit of code, used to create system assigned key values. How would I create a customer number that was unique. We can’t use the Max(value) + 1 approach because it will be very hideous with MVCC isolation levels, since 100 connections might see the same value, leading to lots of duplication. You...(read more)

    Read the article

  • Move SQL Server transaction log to another disk

    - by Jim Lahman
    When restoring a database backup, by default, SQL Server places the database files in the master database file directory.  In this example, that location is in L:\MSSQL10.CHTL\MSSQL\DATA as shown by the issuance of sp_helpfile   Hence, the restored files for the database CHTL_L2_DB are in the same directory     Per SQL Server best practices, the log file should be on its own disk drive so that the database and log file can operate in a sequential manner and perform optimally. The steps to move the log file is as follows: Record the location of the database files and the transaction log files Note the future destination of the transaction log file Get exclusive access to the database Detach from the database Move the log file to the new location Attach to the database Verify new location of transaction log Record the location of the database file To view the current location of the database files, use the system stored procedure, sp_helpfile 1: use chtl_l2_db 2: go 3:   4: sp_helpfile 5: go   Note the future destination of the transaction log file The future destination of the transaction log file will be located in K:\MSSQLLog   Get exclusive access to the database To get exclusive access to the database, alter the database access to single_user.  If users are still connected to the database, remove them by using with rollback immediate option.  Note:  If you had a pane connected to the database when the it is placed into single_user mode, then you will be presented with a reconnection dialog box. 1: alter database chtl_l2_db 2: set single_user with rollback immediate 3: go Detach from the database   Now detach from the database so that we can use windows explorer to move the transaction log file 1: use master 2: go 3:   4: sp_detach_db 'chtl_l2_db' 5: go   After copying the transaction log file re-attach to the database 1: use master 2: go 3:   4: sp_attach_db 'chtl_l2_db', 5: 'L:\MSSQL10.CHTL\MSSQL\DATA\CHTL_L2_DB.MDF', 6: 'K:\MSSQLLog\CHTL_L2_DB_4.LDF', 7: 'L:\MSSQL10.CHTL\MSSQL\DATA\CHTL_L2_DB_1.NDF', 8: 'L:\MSSQL10.CHTL\MSSQL\DATA\CHTL_L2_DB_2.NDF', 9: 'L:\MSSQL10.CHTL\MSSQL\DATA\CHTL_L2_DB_3.NDF' 10: GO

    Read the article

  • Interesting questions related to lighttpd on Amazon EC2

    - by terence410
    This problem appeared today and I have no idea what is going on. Please share you ideas. I have 1 EC2 DB server (MYSQL + NFS File Sharing + Memcached). And I have 3 EC2 Web servers (lighttpd) where it will mounted the NFS folders on the DB server. Everything going smoothly for months but suddenly there is an interesting phenomenon. In every 8 minutes to 10 minutes, PHP file will be unreachable. This will last about 1 minute and then back to normal. Normal files like .html file are unaffected. All servers have the same problem exactly at the same time. I have spent one whole day to analysis the reason. Finally, I find out when the problem appear, the file descriptor of lighttpd suddenly increased a lot. I used ls /proc/1234/fd | wc -l to check the number of fd. The # of fd is around 250 in normal time. However, when the problem appeared, it will be raised to 1500 and then back to normal. It sounds funny, right? Do you have any idea what's going on? ======================== The CPU graph of one of the web server.

    Read the article

< Previous Page | 436 437 438 439 440 441 442 443 444 445 446 447  | Next Page >