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  • T-SQL - how to get around the order by restriction in CTEs

    - by David
    Hi all I have the following CTE. Its purpose is to provide unique Month/Year pairs. Later code will use the CTE to produce a concatenated string list of the Month/Year pairs. ;WITH tblStoredWillsInPeriod AS ( SELECT DISTINCT Kctc.GetMonthAndYearString(DateWillReceived) Month FROM Kctc.StoredWills WHERE DateWillReceived BETWEEN '2010/01/01' AND '2010/03/31' ORDER BY DateWillReceived ) I have omitted the implmementation of the GetMonthAndYearString function as it is trivial. Sadly, it seems T-SQL is always one step ahead. When I run this code, it tells me I'm not allowed to use ORDER BY in a CTE unless I also use TOP (or FOR XML, whatever that is.) If I use TOP, it tells me I can't use it with DISTINCT. Yup, T-SQL has all the answers. Can anyone think of a solution to this problem which is quicker than simply slashing my wrists? I understand that death from blood loss can be surprisingly lingering, and I have deadlines to meet. Thanks for your help. David

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  • SQL Server Multi-statement UDF - way to store data temporarily required

    - by Kharlos Dominguez
    Hello, I have a relatively complex query, with several self joins, which works on a rather large table. For that query to perform faster, I thus need to only work with a subset of the data. Said subset of data can range between 12 000 and 120 000 rows depending on the parameters passed. More details can be found here: http://stackoverflow.com/questions/3054843/sql-server-cte-referred-in-self-joins-slow As you can see, I was using a CTE to return the data subset before, which caused some performance problems as SQL Server was re-running the Select statement in the CTE for every join instead of simply being run once and reusing its data set. The alternative, using temporary tables worked much faster (while testing the query in a separate window outside the UDF body). However, when I tried to implement this in a multi-statement UDF, I was harshly reminded by SQL Server that multi-statement UDFs do not support temporary tables for some reason... UDFs do allow table variables however, so I tried that, but the performance is absolutely horrible as it takes 1m40 for my query to complete whereas the the CTE version only took 40minutes. I believe the table variables is slow for reasons listed in this thread: http://stackoverflow.com/questions/1643687/table-variable-poor-performance-on-insert-in-sql-server-stored-procedure Temporary table version takes around 1 seconds, but I can't make it into a function due to the SQL Server restrictions, and I have to return a table back to the caller. Considering that CTE and table variables are both too slow, and that temporary tables are rejected in UDFs, What are my options in order for my UDF to perform quickly? Thanks a lot in advance.

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  • What are the pros and cons of using an in memory DB rather than a ThreadLocal

    - by Pangea
    We have been using ThreadLocal so far to carry some data so as to not clutter the API. However below are some of issues of using thread local that which I don't like: 1) Over the years the data items being carried in thread local has increased 2) Since we started using threads (for some light weight processing), we have also migrating these data to the threads in the pool and copying them back again I am thinking of using an in memory DB for these (we doesn't want to add this to the API). I wondering if this approach is good. What are the pros and cons? thx in advance.

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  • git doesn't show where code was removed.

    - by Andrew Myers
    So I was tasked at replacing some dummy code that our project requires for historical compatibility reasons but has mysteriously dropped out sometime since the last release. Since disappearing code makes me nervous about what else might have gone missing but un-noticed I've been digging through the logs trying to find in what commit this handful of lines was removed. I've tried a number of things including "git log -S'add-visit-resource-pcf'", git blame, and even git bisect with a script that simply checks for the existence of the line but have been unable to pinpoint exactly where these lines were removed. I find this very perplexing, particularly since the last log entry (obtained by the above command) before my re-introduction of this code was someone else adding the code as well. commit 0b0556fa87ff80d0ffcc2b451cca1581289bbc3c Author: Andrew Date: Thu May 13 10:55:32 2010 -0400 Re-introduced add-visit-resource-pcf, see PR-65034. diff --git a/spike/hst/scheduler/defpackage.lisp b/spike/hst/scheduler/defpackage.lisp index f8e692d..a6f8d38 100644 --- a/spike/hst/scheduler/defpackage.lisp +++ b/spike/hst/scheduler/defpackage.lisp @@ -115,6 +115,7 @@ #:add-to-current-resource-pcf #:add-user-package-nickname #:add-value-criteria + #:add-visit-resource-pcf #:add-window-to-gs-params #:adjust-derived-resources #:adjust-links-candidate-criteria-types commit 9fb10e25572c537076284a248be1fbf757c1a6e1 Author: Bob Date: Sun Jan 17 18:35:16 2010 -0500 update-defpackage for Spike 33.1 Delivery diff --git a/spike/hst/scheduler/defpackage.lisp b/spike/hst/scheduler/defpackage.lisp index 983666d..47f1a9a 100644 --- a/spike/hst/scheduler/defpackage.lisp +++ b/spike/hst/scheduler/defpackage.lisp @@ -118,6 +118,7 @@ #:add-user-package-nickname #:add-value-criteria #:add-vars-from-proposal + #:add-visit-resource-pcf #:add-window-to-gs-params #:adjust-derived-resources #:adjust-links-candidate-criteria-types This is for one of our package definition files, but the relevant source file reflects something similar. Does anyone know what could be going on here and how I could find the information I want? It's not really that important but this kind of things makes me a bit nervous.

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  • IoC from start to finish

    - by Dave
    I'm quite sure that IoC is the way to go for my application. There are a ton of articles and even questions here on SO that discuss the different containers. I've read several blogs today with partial examples. I am personally leaning towards starting with the CommonServiceLocator and Unity as two way to solve the same problem -- I just need a bunch of assemblies to get data from a database, which I assume is what needs to be injected everywhere. I've yet to find any sites that really take a problem from beginning to end, with concrete code examples. For example, I've yet to find one that discusses an IServiceLocator and how to actually register it (or do whatever is required to make it known). What are your favorite posts / articles / SO questions that can take a noob from start to finish with the implementation?

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  • How can I SETF an element in a tree by an accessor?

    - by Willi Ballenthin
    We've been using Lisp in my AI course. The assignments I've received have involved searching and generating tree-like structures. For each assignment, I've ended up writing something like: (defun initial-state () (list 0 ; score nil ; children 0 ; value 0)) ; something else and building my functions around these "states", which are really just nested lists with some loosely defined structure. To make the structure more rigid, I've tried to write accessors, such as: (defun state-score ( state ) (nth 2 state)) This works for reading the value (which should be all I need to do in a nicely functional world. However, as time crunches, and I start to madly hack, sometimes I want a mutable structure). I don't seem to be able to SETF the returned ...thing (place? value? pointer?). I get an error with something like: (setf (state-score *state*) 10) Sometimes I seem to have a little more luck writing the accessor/mutator as a macro: (defmacro state-score ( state ) `(nth 2 ,state)) However I don't know why this should be a macro, so I certainly shouldn't write it as a macro (except that sometimes it works. Programming by coincidence is bad). What is an appropriate strategy to build up such structures? More importantly, where can I learn about whats going on here (what operations affect the memory in what way)?

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  • Using COALESCE to avoid dynamic SQL ?

    - by krul
    I would like to use following sql to avoid constructing sql dynamically: SELECT CommentID, Comment, FROM Comments --if Author id is not null then filter upon author id otherwise get all comments (ignore author id) WHERE AuthorID LIKE COALESCE(@AuthorId, '%') --if comment type is present filter upon it, otherwise get all comments (ignore comment type condition) AND CommentType LIKE COALESCE(@CommentType, '%') I want to know is that safe way to approach this problem? EDIT: Here is final code that satisfy my need to ignore search parameter if is null and applied it if is present: SELECT CommentID, Comment, FROM Comments --if @AuthorId is not null then filter upon @AuthorId otherwise get all comments (ignore author id) WHERE AuthorID = COALESCE(@AuthorId, AuthorID) --if @CommentType is present filter upon it, otherwise get all comments (ignore comment type condition) AND CommentType = COALESCE(@CommentType, CommentType)

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  • How do you do merges using Git, Eclipse and Egit

    - by PaulHurleyuk
    I, like many others, love Eclipse as my ide of choice, and because of the way I work (moving about, different places, different projects) want to use Git for CVS. There is a plugin for Git in Eclipse, Egit, which is now an official Eclipse project, and currently at version 0.7.1. As I've just started using it I'm interested in how others are using it, and what work arounds they are using. Currently Egit doesn't have support for merges, so these have to be done outside of Eclipse and then the workspace refreshed. So, How do you do this task ? (and any other tasks that Egit doesn't do right now)

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  • single line vs multi-line CSS formatting

    - by pixeltocode
    hi...though it's debatable, i've heard majority of CSS developers prefer multi-line because of the ease at which a property can be found within the CSS file. But doesn't this make the CSS file bigger and less readable on the whole? I think single-line lets you scan the CSS file much faster. Any thoughts?

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  • What are some programming questions (or mistakes) you get wrong only as you get better?

    - by BlueRaja
    In programming, as many professions, there are mistakes you'll make now that you may not have made as a beginner. For instance, consider pointers: In C++, is there any difference between arrays and pointers? The beginner will say yes, they are two completely different concepts, and treat them as such. The intermediate programmer (having learned that arrays are pointers internally) will tell you no, they are the same thing, and may miss some crucial bugs by interchanging them all willy-nilly. The expert, however, will again say they are different things (ex. see here or here). What other questions/mistakes are like this?

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  • Remove first and last characters from a string in Lisp

    - by powerj1984
    I am passing in command line arguments to my Lisp program and they are formatted like this when they hit my main function: ("1 1 1" "dot" "2 2 2") I have a dot function and would like to call it directly from the argument, but first I must strip the " characters. I tried variations of this function: (defun remove-quotes (s) (setf (aref s 0) '"")) to no avail, Lisp complains that "" is not a member of base-char. Thanks!

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  • Python - Things one MUST avoid

    - by Anurag Uniyal
    Today I was bitten again by "Mutable default arguments" after many years. I usually don't use mutable default arguments unless needed but I think with time I forgot about that, and today in the application I added tocElements=[] in a pdf generation function's argument list and now 'Table of Content' gets longer and longer after each invocation of "generate pdf" :) My question is what other things should I add to my list of things to MUST avoid? 1 Mutable default arguments 2 import modules always same way e.g. 'from y import x' and 'import x' are totally different things actually they are treated as different modules see http://stackoverflow.com/questions/1459236/module-reimported-if-imported-from-different-path 3 Do not use range in place of lists because range() will become an iterator anyway, so things like this will fail, so wrap it by list myIndexList = [0,1,3] isListSorted = myIndexList == range(3) # will fail in 3.0 isListSorted = myIndexList == list(range(3)) # will not same thing can be mistakenly done with xrange e.g myIndexList == xrange(3). 4 Catching multiple exceptions try: raise KeyError("hmm bug") except KeyError,TypeError: print TypeError It prints "hmm bug", though it is not a bug, it looks like we are catching exceptions of type KeyError,TypeError but instead we are catching KeyError only as variable TypeError, instead use try: raise KeyError("hmm bug") except (KeyError,TypeError): print TypeError

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  • SQL Server CTE referred in self joins slow

    - by Kharlos Dominguez
    Hello, I have written a table-valued UDF that starts by a CTE to return a subset of the rows from a large table. There are several joins in the CTE. A couple of inner and one left join to other tables, which don't contain a lot of rows. The CTE has a where clause that returns the rows within a date range, in order to return only the rows needed. I'm then referencing this CTE in 4 self left joins, in order to build subtotals using different criterias. The query is quite complex but here is a simplified pseudo-version of it WITH DataCTE as ( SELECT [columns] FROM table INNER JOIN table2 ON [...] INNER JOIN table3 ON [...] LEFT JOIN table3 ON [...] ) SELECT [aggregates_columns of each subset] FROM DataCTE Main LEFT JOIN DataCTE BananasSubset ON [...] AND Product = 'Bananas' AND Quality = 100 LEFT JOIN DataCTE DamagedBananasSubset ON [...] AND Product = 'Bananas' AND Quality < 20 LEFT JOIN DataCTE MangosSubset ON [...] GROUP BY [ I have the feeling that SQL Server gets confused and calls the CTE for each self join, which seems confirmed by looking at the execution plan, although I confess not being an expert at reading those. I would have assumed SQL Server to be smart enough to only perform the data retrieval from the CTE only once, rather than do it several times. I have tried the same approach but rather than using a CTE to get the subset of the data, I used the same select query as in the CTE, but made it output to a temp table instead. The version referring the CTE version takes 40 seconds. The version referring the temp table takes between 1 and 2 seconds. Why isn't SQL Server smart enough to keep the CTE results in memory? I like CTEs, especially in this case as my UDF is a table-valued one, so it allowed me to keep everything in a single statement. To use a temp table, I would need to write a multi-statement table valued UDF, which I find a slightly less elegant solution. Did some of you had this kind of performance issues with CTE, and if so, how did you get them sorted? Thanks, Kharlos

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  • How do implement a breadth first traversal?

    - by not looking for answer
    //This is what I have. I thought pre-order was the same and mixed it up with depth first! import java.util.LinkedList; import java.util.Queue; public class Exercise25_1 { public static void main(String[] args) { BinaryTree tree = new BinaryTree(new Integer[] {10, 5, 15, 12, 4, 8 }); System.out.print("\nInorder: "); tree.inorder(); System.out.print("\nPreorder: "); tree.preorder(); System.out.print("\nPostorder: "); tree.postorder(); //call the breadth method to test it System.out.print("\nBreadthFirst:"); tree.breadth(); } } class BinaryTree { private TreeNode root; /** Create a default binary tree */ public BinaryTree() { } /** Create a binary tree from an array of objects */ public BinaryTree(Object[] objects) { for (int i = 0; i < objects.length; i++) { insert(objects[i]); } } /** Search element o in this binary tree */ public boolean search(Object o) { return search(o, root); } public boolean search(Object o, TreeNode root) { if (root == null) { return false; } if (root.element.equals(o)) { return true; } else { return search(o, root.left) || search(o, root.right); } } /** Return the number of nodes in this binary tree */ public int size() { return size(root); } public int size(TreeNode root) { if (root == null) { return 0; } else { return 1 + size(root.left) + size(root.right); } } /** Return the depth of this binary tree. Depth is the * number of the nodes in the longest path of the tree */ public int depth() { return depth(root); } public int depth(TreeNode root) { if (root == null) { return 0; } else { return 1 + Math.max(depth(root.left), depth(root.right)); } } /** Insert element o into the binary tree * Return true if the element is inserted successfully */ public boolean insert(Object o) { if (root == null) { root = new TreeNode(o); // Create a new root } else { // Locate the parent node TreeNode parent = null; TreeNode current = root; while (current != null) { if (((Comparable)o).compareTo(current.element) < 0) { parent = current; current = current.left; } else if (((Comparable)o).compareTo(current.element) > 0) { parent = current; current = current.right; } else { return false; // Duplicate node not inserted } } // Create the new node and attach it to the parent node if (((Comparable)o).compareTo(parent.element) < 0) { parent.left = new TreeNode(o); } else { parent.right = new TreeNode(o); } } return true; // Element inserted } public void breadth() { breadth(root); } // Implement this method to produce a breadth first // search traversal public void breadth(TreeNode root){ if (root == null) return; System.out.print(root.element + " "); breadth(root.left); breadth(root.right); } /** Inorder traversal */ public void inorder() { inorder(root); } /** Inorder traversal from a subtree */ private void inorder(TreeNode root) { if (root == null) { return; } inorder(root.left); System.out.print(root.element + " "); inorder(root.right); } /** Postorder traversal */ public void postorder() { postorder(root); } /** Postorder traversal from a subtree */ private void postorder(TreeNode root) { if (root == null) { return; } postorder(root.left); postorder(root.right); System.out.print(root.element + " "); } /** Preorder traversal */ public void preorder() { preorder(root); } /** Preorder traversal from a subtree */ private void preorder(TreeNode root) { if (root == null) { return; } System.out.print(root.element + " "); preorder(root.left); preorder(root.right); } /** Inner class tree node */ private class TreeNode { Object element; TreeNode left; TreeNode right; public TreeNode(Object o) { element = o; } } }

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  • How to write (simple) macro?

    - by krzysz00
    I need to write a macro (with-hooks (monster method who what) &body body) for a game I'm writing. Monster is a CLOS object, method and who are strings and what is a function (#' notation). The macroexpansion would be something to the effect of (add-hook monster method who what) ,@body (remove-hook monster method who) I have absolutely no idea how to write such a macro, and I would appreciate some help.

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  • Does CLOS have an eql specialization dispatch on strings?

    - by mhb
    Examples of what you can do. (defmethod some-fn ((num real)) (print "an integer")) (defmethod some-fn ((num real)) (print "a real")) (defmethod some-fn ((num (eql 0))) (print "zero")) (some-fn 19323923198319) "an integer" (some-fn 19323923198319.3) "a real" (some-fn 0) "zero" It also works with a general 'string type. (defmethod some-fn ((num string)) (print "a string")) (some-fn "asrt") "a string" Not with a specific string, however (defmethod some-fn ((num (eql "A")) (print "a specifict string"))) => doesn't compile I imagine it doesn't work because eql does not work on strings in the way that would be necessary for it to work. (eql "a" "a") => nil Is there a way to do it?

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  • Macro and array crossing

    - by Thomas
    I am having a problem with a lisp macro. I would like to create a macro which generate a switch case according to an array. Here is the code to generate the switch-case: (defun split-elem(val) `(,(car val) ',(cdr val))) (defmacro generate-switch-case (var opts) `(case ,var ,(mapcar #'split-elem opts))) I can use it with a code like this: (generate-switch-case onevar ((a . A) (b . B))) But when I try to do something like this: (defparameter *operators* '((+ . OPERATOR-PLUS) (- . OPERATOR-MINUS) (/ . OPERATOR-DIVIDE) (= . OPERATOR-EQUAL) (* . OPERATOR-MULT))) (defmacro tokenize (data ops) (let ((sym (string->list data))) (mapcan (lambda (x) (generate-switch-case x ops)) sym))) (tokenize data *operators*) I got this error: *** - MAPCAR: A proper list must not end with OPS. But I don't understand why. When I print the type of ops I get SYMBOL I was expecting CONS, is it related? Also, for my function tokenize how many times the lambda is evaluated (or the macro expanded)?

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  • How does an interpreter switch scope?

    - by Dox
    I'm asking this because I'm relatively new to interpreter development and I wanted to know some basic concepts before reinventing the wheel. I thought of the values of all variables stored in an array which makes the current scope, upon entering a function the array is swapped and the original array put on some sort of stack. When leaving the function the top element of the "scope stack" is popped of and used again. Is this basically right? Isn't swapping arrays (which means moving around a lot of data) not very slow and therefore not used by modern interpreters?

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  • Help using Lisp debugger

    - by Joel
    I'm trying understand how to interpret the output of, and use, the Lisp debugger. I've got a pretty simple Backtrace for the evaluation of my function, but I cann't seem to work out how to use it to find out in which Lisp 'form' in my function the exception occurred. I'd appreciate any clues as to what I should be doing, to find the source of the error. I've attached a screen shot (if it's too small to read I can re-post it in parts), with the debug output, the function and the repl (please ignore my very wrong function, I'm just interested in learning how to use the debugger properly). In addition, I hit 'v' on the first frame to go to the source, but this resulted in the error at the bottom of the screen.

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  • When should we use private variables and when should we use properties.

    - by Shantanu Gupta
    In most of the cases we usually creates a private variable and its corresponding public properties and uses them for performing our functionalities. Everyone has different approach like some ppl uses properties every where and some uses private variables within a same class as they are private and opens it to be used by external environment by using properties. Suppose I takes a scenario say insertion in a database. I creates some parameters that need to be initialized. I creates 10 private variables and their corresp public properties which are given as private string name; public string Name { get{return name;} set{name=value;} } and so on. In these cases what should be used internally variables or properties. And in those cases like public string Name { get{return name;} set{name=value>5?5:0;} //or any action can be done. this is just an eg. } In such cases what should be done.

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  • Consolidating values in a junction table

    - by senloe
    I have the following schema: Parcels Segments SegmentsParcels ========= ========== ================= ParcelID SegmentID ParcelID ... Name SegmentID ... id A user of the data wants to consolidate Segments.Names and gave me a list of current Segment.Names mapped to new Segment.Names (all of which currently exist). So now I have this list in a temporary table with the currentID and newID to map to. What I want to do is update the SegmentID in SegmentsParcels based on this map. I could use the statement: update SegmentParcels set segmentID = [newID] from newsegments where segmentID = currentid but this will create some duplicates I have a unique constraint on ParcelID and SegmentID in SegmentParcels. What is the best way to go about this? I considered removing the constraint and then dealing with removing the duplicates (which I did at one point and could probably do again) but I was hoping there was a simpler way.

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  • Starting a code library.

    - by Rob Stevenson-Leggett
    Hi, I've been meaning to start a library of reusable code snippets for a while and never seem to get round to it. I think my main problems are: Where to start. What structure should my library take? Should it be a compiled library (where appropriate or just classes I can drop into any project? Or a library project that can be included? In my experience, a built library will quickly become out of date and the source will get lost. So I'm leaning towards source libraries that I can export from SVN and include in any project. Intellectual property. I am employeed, so a lot of the code I write is not my IP. How can I ensure that I don't give my own IP away using it on projects in work and at home? I'm thinking the best way would be to licence my library with an open source licence and make sure I only add to it in my own time using my own equipment and therefore making sure that if I use it in a work project the same rules apply as if I was using a third party library. I write in many different languages and often would require two or more parts of this library. Should I look at implementing a few template projects and a core project for each of my chosen reusable components and languages? Has anyone else got this sort of library and how do you organise and update it?

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  • How to change aif to be able to access 'it' within the macrocall without making 'it' public in the package

    - by Sim
    If you put the aif code presented in onlisp in a package and try to use it in another you run in the problem that packagename:it is not external. (in-package :packagename) (defmacro aif (test-form then-form &optional else-form) ‘(let ((it ,test-form)) (if it ,then-form ,else-form))) wanted call syntax (in-package :otherpackage) (aif (do-stuff) (FORMAT t "~a~%" it) (FORMAT t "just got nil~%")) How can I fix this behavior in code, without making the variable it external in the package declaration and beeing able to access it just by it instead of packagename:it?

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