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• Paramaterising SQL in SSIS

  - by Anonymouslemming

  Hi all, I'm trying to paramaterize some queries in SSIS. After some reading, it sounds like my best option is to create one variable that contains my base sql, another that contains my criteria and a final variable that is evaluated as an expression that includes both of these. I want to end up with an SQL query that is effectively UPDATE mytable set something='bar' where something_else='foo' So my first two variables have the scope of my package and are as follows: Name: BaseSQL Data Type: String Value: UPDATE mytable set something = 'bar' where something_else = Name: MyVariable Data Type: String Value: foo My third variable has a scope of the data flow task where I want to use this SQL and is as follows: Name: SQLQuery Data Type: String Value: @[User::BaseSQL] + "'" + @[User::MyVariable] + "'" EvaluateAsExpression: True In the OLE DB Source, I then choose my connection and 'SQL command from variable' and select User::SQLQuery from the dropdown box. The Variable Value window then displays the following: @[User::BaseSQL] + "'" + @[User::MyVariable] + "'" This is as desired, and would provide the output I want from my DB. The variable name dropdown also contains User::BaseSQL and User::MyVariable so I believe that my namespaces are correct. However, when I then click preview, I get the following error when configuring an OLE DB Source (using SQL command from variable): TITLE: Microsoft Visual Studio Error at Set runtime in DB [Set runtime in myDb DB [1]]: SSIS Error Code DTS_E_OLEDBERROR. An OLE DB error has occurred. Error code: 0x80040E14. An OLE DB record is available. Source: "Microsoft SQL Server Native Client 10.0" Hresult: 0x80040E14 Description: "Statement(s) could not be prepared.". An OLE DB record is available. Source: "Microsoft SQL Server Native Client 10.0" Hresult: 0x80040E14 Description: "Must declare the scalar variable "@".". (Microsoft Visual Studio) Can anyone advise what I'm missing or how I can resolve this please ? Thanks in advance!

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• Finding height in Binary Search Tree

  - by mike

  Hey I was wondering if anybody could help me rework this method to find the height of a binary search tree. So far my code looks like this however the answer im getting is larger than the actual height by 1, but when I remove the +1 from my return statements its less than the actual height by 1? I'm still trying to wrap my head around recursion with these BST any help would be much appreciated. public int findHeight(){ if(this.isEmpty()){ return 0; } else{ TreeNode<T> node = root; return findHeight(node); } } private int findHeight(TreeNode<T> aNode){ int heightLeft = 0; int heightRight = 0; if(aNode.left!=null) heightLeft = findHeight(aNode.left); if(aNode.right!=null) heightRight = findHeight(aNode.right); if(heightLeft > heightRight){ return heightLeft+1; } else{ return heightRight+1; } }

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• Is it possible to create ICriteria/ICriterion from LINQ or HQL?

  - by adrin

  I am creating a method that can create filter understood by NHibernate (by filter i mean a set of ICriteria object for example) from my abstract filter object. public static IEnumerable<ICriterion> ToNhCriteria(this MyCriteria criteria) { // T4 generated function // lots of result.Add(Expression.Or(Expression.Eq(),Expression.Eq)) expression trees - hard to generate // Is there a way to generate HQL/Linq query here istead? } then i want to do something like session.CreateCriteria<Entity>().Add(myCriteria.ToNhCriteria()) to filter entities. The problem is that using Expression. methods (Expression.Or etc) is quite tedious (the method is generated and i have multiple or statements that have to be joined into an expression somehow). Is there a way to avoid using Expression.Or() and create ICrietrion / ICriteria using LINQ or HQL?

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• Can MySQL / SQL's short hand of "Using" be used without saying "Inner Join" ?

  - by Jian Lin

  The following 2 statements are to join using gifts.giftID = sentgifts.giftID: mysql> select * from gifts, sentgifts using (giftID); ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'using (giftID)' at line 1 and the second one: mysql> select * from gifts INNER JOIN sentgifts using (giftID); +--------+------------+----------------+---------------------+--------+------------+--------+------+---------------------+ | giftID | name | filename | effectiveTime | sentID | whenSent | fromID | toID | trytryWhen | +--------+------------+----------------+---------------------+--------+------------+--------+------+---------------------+ | 2 | teddy bear | bear.jpg | 2010-04-24 04:36:03 | 4 | 2010-04-24 | NULL | 111 | 2010-04-24 03:10:42 | | 6 | beer | beer_glass.png | 2010-04-24 05:18:12 | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | | 6 | beer | beer_glass.png | 2010-04-24 05:18:12 | 6 | 2010-04-24 | 11 | 222 | 2010-04-24 03:54:49 | | 6 | beer | beer_glass.png | 2010-04-24 05:18:12 | 7 | 2010-04-24 | 1 | 2 | 2010-04-24 03:58:45 | +--------+------------+----------------+---------------------+--------+------------+--------+------+---------------------+ 4 rows in set (0.00 sec) Can the first statement also use the "using" shorthand? It seems that when it is used then the word "Inner Join" must be specified... but the first statement is actually an inner join?

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• Logging from multiple apps/processes to a single log file

  - by Andrew

  Our app servers (weblogic) all use log4j to log to the same file on a network share. On top of this we have all web apps in a managed server logging errors to a common error.log. I can't imagine this is a good idea but wanted to hear from some pros. I know that each web app has its own classloader, so any thread synchronization only occurs within the app. So what happens when multiple processes start converging on a single log file? Can we expect interspersed log statements? Performance problems? What about multiple web apps logging to a common log file? The environment is Solaris.

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• Multiple many-to-many JOINs in a single mysql query without Cartesian Product

  - by VWD

  At the moment I can get the results I need with two seperate SELECT statements SELECT COUNT(rl.refBiblioID) FROM biblioList bl LEFT JOIN refList rl ON bl.biblioID = rl.biblioID GROUP BY bl.biblioID SELECT GROUP_CONCAT( CONCAT_WS( ':', al.lastName, al.firstName ) ORDER BY al.authorID ) FROM biblioList bl LEFT JOIN biblio_author ba ON ba.biblioID = bl.biblioID JOIN authorList al ON al.authorID = ba.authorID GROUP BY bl.biblioID Combining them like this however SELECT GROUP_CONCAT( CONCAT_WS( ':', al.lastName, al.firstName ) ORDER BY al.authorID ), COUNT(rl.refBiblioID) FROM biblioList bl LEFT JOIN biblio_author ba ON ba.biblioID = bl.biblioID JOIN authorList al ON al.authorID = ba.authorID LEFT JOIN refList rl ON bl.biblioID = rl.biblioID GROUP BY bl.biblioID causes the author result column to have duplicate names. How can I get the desired results from one SELECT statement without using DISTINCT? With subqueries?

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• Python - Things I shouldn't be doing?

  - by cornjuliox

  I've got a few questions about best practices in Python. Not too long ago I would do something like this with my code: ... junk_block = "".join(open("foo.txt","rb").read().split()) ... I don't do this anymore because I can see that it makes code harder to read, but would the code run slower if I split the statements up like so: f_obj = open("foo.txt", "rb") f_data = f_obj.read() f_data_list = f_data.split() junk_block = "".join(f_data_list) I also noticed that there's nothing keeping you from doing an 'import' within a function block, is there any reason why I should do that?

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• Expression Tree : C#

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally when our LINQ to SQL query compiler translates it to parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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• Clustered index dilemma - ID or sort?

  - by richardtallent

  I have a table with two very important fields: id INT identity(1,1) PRIMARY KEY identifiersortcode VARCHAR(900) My app always sorts and pages search results in the UI based on identifiersortcode, but all table joins (and they are legion) are on the id field. (Aside: yes, the sort code really is that long. There's a strong BL reason.) Also, due to O/RM use, most SELECT statements are going to pull almost every column. Currently, the clustered index is on id, but I'm wondering if the TOP / ORDER BY portion of most queries would make identifiersortcode a more attractive option as the clustered key, even considering all of the table joins going on. Inserts on the table and changes to the identifiersortcode are limited enough that changing my clustered index would be a problem for insert/update operations. Trying to make the sort code's non-clustered index a covering index (using INCLUDE) is not a good option. There are a number of large columns, and some of them have a lot of update activity.

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• Haskell: What is the difference between $ (dollar) and $! (dollar exclamation point)

  - by Jelle Fresen

  Can anybody explain the difference in Haskell between the operators ($) and ($!) (dollar sign vs dollar sign exclamation point)? I haven't seen the use of $! anywhere so far, but while browsing through the Haskell reference on www.zvon.org, I noticed its existence and that it has the exact same definition as $. When trying some simple statements in a Haskell interpreter (ghci), I couldn't find any difference, nor could I find any reference to the operator in the top listed tutorials when googling for haskell tutorial. So, just out of curiosity, what is the difference, if at all?

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• Making an SVG DOM JavaScript class

  - by CryptoQuick

  I'm unsatisfied with other JavaScript libraries and frameworks like jQuery, MooTools, and Raphael, because of their inability to support SVG grouping. You'd think it'd be a very simple thing for them to implement. Anyway, I'm trying to make a JavaScript class (using John Resig's class.js script) like this: var El = Class.extend({ el: null, svgNS: "http://www.w3.org/2000/svg", init: function (type) { this.el = document.createElementNS(this.svgNS, type); }, set: function (name, attr) { this.el.setAttributeNS(null, name, attr); }, get: function (el, name) { var attr = this.el.getAttributeNS(null, name); return attr; }, add: function (targEl) { targEl.el.appendChild(this.el); }, remove: function (targEl) { targEl.el.removeChild(this.el); }, setEl: function (docId) { this.el = document.getElementById(docId); } }); I can add elements to the DOM using these statements outside of the class, but storing the element inside the class becomes problematic. Anyone have any creative ideas?

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• Is using Natural Join or Implicit column names not a good practice when writing SQL in a programming

  - by Jian Lin

  When we use Natural Join, we are joining the tables when both table have the same column names. But what if we write it in PHP and then the DBA add some more fields to both tables, then the Natural Join can break? The same goes for Insert, if we do a insert into gifts values (NULL, "chocolate", "choco.jpg", now()); then it will break the code as well as contaminating the table when the DBA adds some fields to the table (example as column 2 or 3). So it is always best to spell out the column names when the SQL statements are written inside a programming language and stored in a file in a big project.

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• Performance concern when using LINQ "everywhere"?

  - by stiank81

  After upgrading to ReSharper5 it gives me even more useful tips on code improvements. One I see everywhere now is a tip to replace foreach-statements with LINQ queries. Take this example: private Ninja FindNinjaById(int ninjaId) { foreach (var ninja in Ninjas) { if (ninja.Id == ninjaId) return ninja; } return null; } This is suggested replaced with the following using LINQ: private Ninja FindNinjaById(int ninjaId) { return Ninjas.FirstOrDefault(ninja => ninja.Id == ninjaId); } This looks all fine, and I'm sure it's no problem regarding performance to replace this one foreach. But is it something I should do in general? Or might I run into performance problems with all these LINQ queries everywhere?

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• Add custom Model Binders for derived objects and their base

  - by mare

  My class diagram: BaseContentClass Page inherits BaseContentClass Tab inherits BaseContentClass ... If I do this ModelBinders.Binders.Add(typeof(BaseContentObject), new BaseContentObjectCommonPropertiesBinder()); then when in controller action parameter of type Tab appears, custom model binder is not fired. It gets fired if I do this: ModelBinders.Binders.Add(typeof(Tab), new BaseContentObjectCommonPropertiesBinder()); But I don't want to go writing "n" number of Add statements in my global.asax.cs to associate all the derived classes with my custom model binder, do I? I don't know if I have any other option.

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• How do you retrieve the array adapter currently set for a spinner? Android OS, Droid

  - by Sean

  Looking to create a menu toggle that switches between two possible arrays for a spinner. For example, if the spinner is set to show array A, then when I press this menu button, I want the spinner to be set to array B. If I press it again, I want it to be set back to array A. I can handle the if/then statements and all, but how do I call the spinner's array adapter? I know how to call its value using getSelectedItemPosition(); but is there a similar method for retrieving WHICH array it is currently set to?

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• How does polymorphism work in Python?

  - by froadie

  I'm new to Python... and coming from a mostly Java background, if that accounts for anything. I'm trying to understand polymorphism in Python. Maybe the problem is that I'm expecting the concepts I already know to project into Python. But I put together the following test code: class animal(object): "empty animal class" class dog(animal): "empty dog class" myDog = dog() print myDog.__class__ is animal print myDog.__class__ is dog From the polymorphism I'm used to (e.g. java's instanceof), I would expect both of these statements to print true, as an instance of dog is an animal and also is a dog. But my output is: False True What am I missing?

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• How to Prove that using subselect queries in SQL is killing performance of server

  - by adopilot

  One of my jobs it to maintain our database, usually we have troubles with lack of performance while getting reports and working whit that base. When I start looking at queries which our ERP sending to database I see a lot of totally needlessly subselect queries inside main queries. As I am not member of developers which is creator of program we using, they do not like much when I criticize they code and job. Let say they do not taking my review as serious statements. So I asking you few questions about subselect in SQL Does subselect is taking a lot of more time then left outer joins? Does exists any blog, article or anything where I subselect is recommended not to use ? How I can prove that if we avoid subselesct in query that query is going to be faster ? Our database server is MSSQL2005

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• Can/Should you throw exceptions in a c# switch statement?

  - by Kettenbach

  Hi All, I have an insert query that returns an int. Based on that int I may wish to throw an exception. Is this appropriate to do within a switch statement? switch (result) { case D_USER_NOT_FOUND: throw new ClientException(string.Format("D User Name: {0} , was not found.", dTbx.Text)); case C_USER_NOT_FOUND: throw new ClientException(string.Format("C User Name: {0} , was not found.", cTbx.Text)); case D_USER_ALREADY_MAPPED: throw new ClientException(string.Format("D User Name: {0} , is already mapped.", dTbx.Text)); case C_USER_ALREADY_MAPPED: throw new ClientException(string.Format("C User Name: {0} , is already mapped.", cTbx.Text)); default: break; } I normally add break statements to switches but they will not be hit. Is this a bad design? Please share any opinions/suggestions with me. Thanks, ~ck in San Diego

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• Is this code well-defined?

  - by Nawaz

  This code is taken from a discussion going on here. someInstance.Fun(++k).Gun(10).Sun(k).Tun(); Is this code well-defined? Is ++k Fun() evaluated before k in Sun()? What if k is user-defined type, not built-in type? And in what ways the above function calls order is different from this: eat(++k);drink(10);sleep(k); As far as I can say, in both situations, there exists a sequence point after each function call. If so, then why can't the first case is also well-defined like the second one? Section 1.9.17 of the C++ ISO standard says this about sequence points and function evaluation: When calling a function (whether or not the function is inline), there is a sequence point after the evaluation of all function arguments (if any) which takes place before execution of any expressions or statements in the function body. There is also a sequence point after the copying of a returned value and before the execution of any expressions outside the function.

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• Ruby switch like idiom

  - by Eef

  Hey, I have recently started a project in Ruby on Rails. I used to do all my projects before in Python but decided to give Ruby a shot. In the projects I wrote in Python I used a nice little technique explained by the correct answer in this post: http://stackoverflow.com/questions/277965/dictionary-or-if-statements-jython I use this technique due to Python not having a native switch function and it also get rid of big if else blocks I have been trying to do recreate the above method in Ruby but can't seem to quite get it. Could anyone help me out? Thanks Eef

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• tipfy for Google App Engine: Is it stable? Can auth/session components of tipfy be used with webapp?

  - by cv12

  I am building a web application on Google App Engine that requires users to register with the application and subsequently authenticate with it and maintain sessions. I don't want to force users to have Google accounts. Also, the target audience for the application is the average non-geek, so I'm not very keen on using OpenID or OAuth. I need something simple like: User registers with an e-mail and password, and then can log back in with those credentials. I understand that this approach does not provide the security benefits of Google or OpenID authentication, but I am prepared to trade foolproof security for end-user convenience and hassle-free experience. I explored Django, but decided that consecutive deprecations from appengine-helper to app-engine-patch to django-nonrel may signal that path may be a bit risky in the long-term. I'd like to use a code base that is likely to be maintained consistently. I also explored standalone session/auth packages like gaeutilities and suas. GAEUtilities looked a bit immature (e.g., the code wasn't pythonic in places, in my opinion) and SUAS did not give me a lot of comfort with the cookie-only sessions. I could be wrong with my assessment of these two, so I would appreciate input on those (or others that may serve my objective). Finally, I recently came across tipfy. It appears to be based on Werkzeug and Alex Martelli spoke highly of it here on stackoverflow. I have two primary questions related to tipfy: As a framework, is it as mature as webapp? Is it stable and likely to be maintained for some time? Since my primary interest is the auth/session components, can those components of the tipfy framework be used with webapp, independent of the broader tipfy framework? If yes, I would appreciate a few pointers to how I could go about doing that.

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• Equivalence Classes

  - by orcik

  I need to write a program for equivalence classes and get this outputs... (equiv '((a b) (a c) (d e) (e f) (c g) (g h))) => ((a b c g h) (d e f)) (equiv '((a b) (c d) (e f) (f g) (a e))) => ((a b e f g) (c d)) Basically, A set is a list in which the order doesn't matter, but elements don't appear more than once. The function should accept a list of pairs (elements which are related according to some equivalence relation), and return a set of equivalence classes without using iteration or assignment statements (e.g. do, set!, etc.). However, set utilities such as set-intersection, set-union and a function which eliminates duplicates in a list and built-in functions union, intersection, and remove-duplicates are allowed. Thanks a lot! By the way, It's not a homework question. A friend of mine need this piece of code to solve smilar questions.

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• Which design pattern should I be using?

  - by Gabriel

  Here's briefly what I'm trying to do. The user supplies me with a link to a photo from one of several photo-sharing websites (such as Flickr, Zooomr, et. al). I then do some processing on the photo using their respective APIs. Right now, I'm only implementing one service, but I will most likely add more in the near future. I don't want to have a bunch of if/else or switch statements to define the logic for the different websites (but maybe that's necessary?) I'd rather just call GetImage(url) and have it get me the image from whatever service the url's domain is from. I'm confused how the GetImage function and classes should be designed. Maybe I need the strategy pattern? I'm still reading and trying to understand the various design patterns and how I could make one fit in this case. I'm doing this in C#, but this question is language-agnostic.

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• Problem using pantheios file stock back end

  - by Tanuj

  I am trying to use pantheios file stock back end to log from my dll in c++. The file gets created but nothing gets written to the file. Here is a snippet of my code if (pantheios::pantheios_init() < 0) { MessageBox(NULL, "Init Failed", "fvm", MB_OK); }else { MessageBox(NULL, "Init Passed", "fvm", MB_OK); pantheios::log_INFORMATIONAL("Logger enabled!"); } DWORD pid = GetCurrentProcessId(); sprintf_s(moduleName, sizeof(moduleName), "C:\\%d.log", pid); pantheios_be_file_setFilePath(moduleName, PANTHEIOS_BE_FILE_F_TRUNCATE,PANTHEIOS_BE_FILE_F_TRUNCATE, PANTHEIOS_BEID_LOCAL); pantheios::log(pantheios::debug, "Entering main"); I get the Init Passed message box but no log statements are dumped in the file.

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• ODBC Linked server in sql 2005 doesn’t work from remote box

  - by mhj96813

  I have a dev workstation with sql 2005 installed and in it I created a linked server to a odbc connection to a clarion database. I can run select statements against it inside sql Mgt studio. When I take a second workstation and connect to the sql on the first box using sql mgt studio, then try the exact same query I get OLE DB provider "MSDASQL" for linked server "liveclarion" returned message "[SoftVelocity Inc.][TopSpeed ODBC Driver][ISAM]ISAM Table Not Found". Any thoughts? It appears to have the same functionality on a second sql server. No remote sql mgt studio connect success in queries against my linked ODBC clarion DB. All done with windows authentication and the same AD user.

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