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  • learn the programming language for computing functions about integers

    - by asd
    Hi I know something about Pascal, Mathematica and Matlab, but I dont have any idea about C,C++,C# languages. I want to learn one of the languages that they they are fast and exact to compute some arithmetic functions for large numbers(for example larger than $10^3000$). I asked somebody and he said he used C++ and he said I computed this sequence in less than 10 min. I want to know C, C++, C# and visual kind of theses programs and know which is better for my goal. Let $f$ be an arithmetic function and A={k1,k2,...,kn} are integers in increasing order. Now I want to start with k1 and compare f(ki) with f(k1). If f(ki)f(k1), put ki as k1. Now start with ki, and compare f(kj) with f(ki), for ji. If f(kj)f(ki), put kj as ki, and repeat this procedure. At the end we will have a sub sequence B={L1,...,Lm} of A by this property: f(L(i+1))f(L(i)), for any 1<=i<=m-1 I have written a code for this program with Mathematica, and it take some hours to compute f of ki's or the set B for large numbers. For example, let f is the divisor function of integers. Do you know how to write the code for my purpose in Mathematica or Matlab. Mathematica is preferable.

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  • MySQL – Introduction to CONCAT and CONCAT_WS functions

    - by Pinal Dave
    MySQL supports two types of concatenation functions. They are CONCAT and CONCAT_WS CONCAT function just concats all the argument values as such SELECT CONCAT('Television','Mobile','Furniture'); The above code returns the following TelevisionMobileFurniture If you want to concatenate them with a comma, either you need to specify the comma at the end of each value, or pass comma as an argument along with the values SELECT CONCAT('Television,','Mobile,','Furniture'); SELECT CONCAT('Television',',','Mobile',',','Furniture'); Both the above return the following Television,Mobile,Furniture However you can omit the extra work by using CONCAT_WS function. It stands for Concatenate with separator. This is very similar to CONCAT function, but accepts separator as the first argument. SELECT CONCAT_WS(',','Television','Mobile','Furniture'); The result is Television,Mobile,Furniture If you want pipeline as a separator, you can use SELECT CONCAT_WS('|','Television','Mobile','Furniture'); The result is Television|Mobile|Furniture So CONCAT_WS is very flexible in concatenating values along with separate. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Tips and Tricks, T SQL

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  • TDD with SQL and data manipulation functions

    - by Xophmeister
    While I'm a professional programmer, I've never been formally trained in software engineering. As I'm frequently visiting here and SO, I've noticed a trend for writing unit tests whenever possible and, as my software gets more complex and sophisticated, I see automated testing as a good idea in aiding debugging. However, most of my work involves writing complex SQL and then processing the output in some way. How would you write a test to ensure your SQL was returning the correct data, for example? Then, say if the data wasn't under your control (e.g., that of a 3rd party system), how can you efficiently test your processing routines without having to hand write reams of dummy data? The best solution I can think of is making views of the data that, together, cover most cases. I can then join those views with my SQL to see if it's returning the correct records and manually process the views to see if my functions, etc. are doing what they're supposed to. Still, it seems excessive and flakey; particularly finding data to test against...

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  • Problem with missing JSON functions on PHP 5.2.6 / Plesk 8.4

    - by Drachenviech
    I have a vserver running openSuse 10.3, Apache 2 and Plesk 8.4. I can update/upgrade neither, as it is apparently not recommended to upgrade openSuse 10.3 (and an update to the EOL 10.4 does not seem to make much sense) and Plesk fails to update no matter what version I try (even fails to upgrade to 8.4.1). Still I can live with that somehow, primarily because I don’t have the time to do a fresh remote install on the vserver. What really is a problem is, that though the installed PHP is 5.2.6 it has no zip library and no json functions. The first is probably because PHP was not compiled with --enable-zip. The second is a big mystery though. As I understand it, it always comes with PHP unless its compiled with the --disable-json configure option. This is however not the case. And the json extension module is just not there. I even tried to enable it with extension=json.so with no luck either. the configure options of my PHP are (as shipped with Plesk 8.4) '../configure' '--prefix=/usr' '--datadir=/usr/share/php5' '--mandir=/usr/share/man' '--bindir=/usr/bin' '--with-libdir=lib' '--includedir=/usr/include' '--sysconfdir=/etc/php5/apache2' '--with-config-file-path=/etc/php5/apache2' '--with-config-file-scan-dir=/etc/php5/conf.d' '--enable-libxml' '--enable-session' '--with-mm' '--with-pcre-regex=/usr' '--enable-xml' '--enable-simplexml' '--enable-spl' '--enable-filter' '--disable-debug' '--enable-inline-optimization' '--disable-rpath' '--disable-static' '--enable-shared' '--program-suffix=5' '--with-pic' '--with-gnu-ld' '--with-system-tzdata=/usr/share/zoneinfo' '--with-apxs2=/usr/sbin/apxs2' '--disable-all' '--disable-cli' As I understand it, PECL is not an option with 5.2.6. Or am I mistaken? Even if I was not, the openSuse repository only goes as far as PHP 5.2.4. The openSuse install even came without zypper, which I had to manually install. So is there a way to get ziplib and json running in PHP 5.2.6 without having to recompile the binary?

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  • how to fully unit test functions and their internal validation

    - by Patrick
    I am just now getting into formal unit testing and have come across an issue in testing separate internal parts of functions. I have created a base class of data manipulation (i.e.- moving files, chmodding file, etc) and in moveFile() I have multiple levels of validation to pinpoint when a moveFile() fails (i.e.- source file not readable, destination not writeable). I can't seem to figure out how to force a couple particular validations to fail while not tripping the previous validations. Example: I want the copying of a file to fail, but by the time I've gotten to the actual copying, I've checked for everything that can go wrong before copying. Code Snippit: (Bad code on the fifth line...) // if the change permissions is set, change the file permissions if($chmod !== null) { $mod_result = chmod($destination_directory.DIRECTORY_SEPARATOR.$new_filename, $chmod); if($mod_result === false || $source_directory.DIRECTORY_SEPARATOR.$source_filename == '/home/k...../file_chmod_failed.qif') { DataMan::logRawMessage('File permissions update failed on moveFile [ERR0009] - ['.$destination_directory.DIRECTORY_SEPARATOR.$new_filename.' - '.$chmod.']', sfLogger::ALERT); return array('success' => false, 'type' => 'Internal Server Error [ERR0009]'); } } So how do I simulate the copy failing. My stop-gap measure was to perform a validation on the filename being copied and if it's absolute path matched my testing file, force the failure. I know this is very bad to put testing code into the actual code that will be used to run on the production server but I'm not sure how else to do it. Note: I am on PHP 5.2, symfony, using lime_test(). EDIT I am testing the chmodding and ensuring that the array('success' = false, 'type' = ..) is returned

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  • How to get the Entire Function from a file

    - by SoLoGHoST
    Ok, I'm reading through a file now, line by line. I know each functions name in the file, since it is defined elsewhere in an XML document. That is what should be this: function function_name Where function_name is the name of the function. I get all of the function definitions from an XML document that I already have put into an array of function names, and I need to grab just those functions from the php file. And rebuild that php file so that it only has those functions in it. That is to say, if a php file has more functions than what is defined in the XML tag, than I need to strip out those functions, and rewrite the .php file with only the functions that the user specified in the XML file. So, the dilemma I face is how to determine the END of a function reading line by line, and I'm aware that functions can have function within them. So I don't want to remove the functions within them. Just functions that are standalone and aren't defined within the accompanying XML file. Any ideas on how to do this?? Thanks :)

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  • SQL SERVER – Introduction to PERCENTILE_DISC() – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    SQL Server 2012 introduces new analytical function PERCENTILE_DISC(). The book online gives following definition of this function: Computes a specific percentile for sorted values in an entire rowset or within distinct partitions of a rowset in Microsoft SQL Server 2012 Release Candidate 0 (RC 0). For a given percentile value P, PERCENTILE_DISC sorts the values of the expression in the ORDER BY clause and returns the value with the smallest CUME_DIST value (with respect to the same sort specification) that is greater than or equal to P. If you are clear with understanding of the function – no need to read further. If you got lost here is the same in simple words – find value of the column which is equal or more than CUME_DIST. Before you continue reading this blog I strongly suggest you read about CUME_DIST function over here Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012. Now let’s have fun following query: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, CUME_DIST() OVER(PARTITION BY SalesOrderID ORDER BY ProductID ) AS CDist, PERCENTILE_DISC(0.5) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS PercentileDisc FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO The above query will give us the following result: You can see that I have used PERCENTILE_DISC(0.5) in query, which is similar to finding median but not exactly. PERCENTILE_DISC() function takes a percentile as a passing parameters. It returns the value as answer which value is equal or great to the percentile value which is passed into the example. For example in above example we are passing 0.5 into the PERCENTILE_DISC() function. It will go through the resultset and identify which rows has values which are equal to or great than 0.5. In first example it found two rows which are equal to 0.5 and the value of ProductID of that row is the answer of PERCENTILE_DISC(). In some third windowed resultset there is only single row with the CUME_DIST() value as 1 and that is for sure higher than 0.5 making it as a answer. To make sure that we are clear with this example properly. Here is one more example where I am passing 0.6 as a percentile. Now let’s have fun following query: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, CUME_DIST() OVER(PARTITION BY SalesOrderID ORDER BY ProductID ) AS CDist, PERCENTILE_DISC(0.6) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS PercentileDisc FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO The above query will give us the following result: The result of the PERCENTILE_DISC(0.6) is ProductID of which CUME_DIST() is more than 0.6. This means for SalesOrderID 43670 has row with CUME_DIST() 0.75 is the qualified row, resulting answer 773 for ProductID. I hope this explanation makes it further clear. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    This blog post is written in response to the T-SQL Tuesday post of Prox ‘n’ Funx. This is a very interesting subject. By the way Brad Schulz is my favorite guy when it is about blogging. I respect him as well learn a lot from him. Everybody is writing something new his subject, I decided to start SQL Server 2012 analytic functions series. SQL Server 2012 introduces new analytical function CUME_DIST(). This function provides cumulative distribution value. It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT SalesOrderID, OrderQty, CUME_DIST() OVER(ORDER BY SalesOrderID) AS CDist FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY CDist DESC GO Above query will give us following result. Now let us understand what is the formula behind CUME_DIST and why the values in SalesOrderID = 43670 are 1. Let us take more example and be clear about why the values in SalesOrderID = 43667 are 0.5. Now let us enhence the same example and use PARTITION BY into the OVER clause and see the results. Run following query in SQL Server 2012. USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, CUME_DIST() OVER(PARTITION BY SalesOrderID ORDER BY ProductID ) AS CDist FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID DESC, CDist DESC GO Now let us see the result of this query. We are have changed the ORDER BY clause as well partitioning by SalesOrderID. You can see that CUME_DIST() function provides us different results. Additionally now we see value 1 multiple times. As we are using partitioning for each group of SalesOrderID we get the CUME_DIST() value. CUME_DIST() was long awaited Analytical function and I am glad to see it in SQL Server 2012. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Extending Currying: Partial Functions in Javascript

    - by kerry
    Last week I posted about function currying in javascript.  This week I am taking it a step further by adding the ability to call partial functions. Suppose we have a graphing application that will pull data via Ajax and perform some calculation to update a graph.  Using a method with the signature ‘updateGraph(id,value)’. To do this, we have do something like this: 1: for(var i=0;i<objects.length;i++) { 2: Ajax.request('/some/data',{id:objects[i].id},function(json) { 3: updateGraph(json.id, json.value); 4: } 5: } This works fine.  But, using this method we need to return the id in the json response from the server.  This works fine, but is not that elegant and increase network traffic. Using partial function currying we can bind the id parameter and add the second parameter later (when returning from the asynchronous call).  To do this, we will need the updated curry method.  I have added support for sending additional parameters at runtime for curried methods. 1: Function.prototype.curry = function(scope) { 2: scope = scope || window 3: var args = []; 4: for (var i=1, len = arguments.length; i < len; ++i) { 5: args.push(arguments[i]); 6: } 7: var m = this; 8: return function() { 9: for (var i=0, len = arguments.length; i < len; ++i) { 10: args.push(arguments[i]); 11: } 12: return m.apply(scope, args); 13: }; 14: } To partially curry this method we will call the curry method with the id parameter, then the request will callback on it with just the value.  Any additional parameters are appended to the method call. 1: for(var i=0;i<objects.length;i++) { 2: var id=objects[i].id; 3: Ajax.request('/some/data',{id: id}, updateGraph.curry(id)); 4: } As you can see, partial currying gives is a very useful tool and this simple method should be a part of every developer’s toolbox.

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  • Calling functions from different classes

    - by A Ron Hubbard Clevenger
    I'm writing a program and I'm supposed to check and see if a certain object is in the list before I call it. I set up the contains() method which is supposed to use the equals() method of the Comparable interface I implemented on my Golfer class but it doesn't seem to call it (I put print statements in to check). I can't seem to figure out whats wrong with the code, the ArrayUnsortedList class I'm using to go through the list even uses the correct toString() method I defined in my Golfer class but for some reason it won't use the equals() method I implemented. //From "GolfApp.java" public class GolfApp{ ListInterface <Golfer>golfers = new ArraySortedList<Golfer> (20); Golfer golfer; //..*snip*.. if(this.golfers.contains(new Golfer(name,score))) System.out.println("The list already contains this golfer"); else{ this.golfers.add(this.golfer = new Golfer(name,score)); System.out.println("This golfer is already on the list"); } //From "ArrayUnsortedList.java" protected void find(T target){ location = 0; found = false; while (location < numElements){ if (list[location].equals(target)) //Where I think the problem is { found = true; return; } else location++; } } public boolean contains(T element){ find(element); return found; } //From "Golfer.java" public class Golfer implements Comparable<Golfer>{ //..irrelavant code sniped..// public boolean equals(Golfer golfer) { String thisString = score + ":" + name; String otherString = golfer.getScore() + ":" + golfer.getName() ; System.out.println("Golfer.equals() has bee called"); return thisString.equalsIgnoreCase(otherString); } public String toString() { return (score + ":" + name); } My main problem seems to be getting the find function of the ArrayUnsortedList to call my equals function in the find() part of the List but I'm not exactly sure why, like I said when I have it printed out it works with the toString() method I implemented perfectly. I'm almost positive the problem has to do with the find() function in the ArraySortedList not calling my equals() method. I tried using some other functions that relied on the find() method and got the same results.

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  • Retrieve input and output parameters for SQL stored procs and functions?

    - by Darth Continent
    For a given SQL stored proc or function, I'm trying to obtain its input and output parameters, where applicable, in a Winforms app I'm creating to browse objects and display their parameters and other attributes. So far I've discovered the SQL system function object_definition, which takes a given sysobjects.id and returns the text of that object; also discovered via search this post which describes extracting the parameters in the context of a app using the ADO.NET method DeriveParameters in conjunction with some caching for better performance; and for good measure found some helpful system stored procs from this earlier post on Hidden Features of SQL Server. I'm leaning towards implementing the DeriveParameters method in my C# app, since parsing the output of object_definition seems messy, and I haven't found a hidden feature in that post so far that would do the trick. Is DeriveParameters applicable to both functions and stored procs for purposes of retreiving their parameters, and if so, could someone please provide an example?

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  • Is a base class with shared fields and functions good design

    - by eych
    I've got a BaseDataClass with shared fields and functions Protected Shared dbase as SqlDatabase Protected Shared dbCommand as DBCommand ... //also have a sync object used by the derived classes for Synclock'ing Protected Shared ReadOnly syncObj As Object = New Object() Protected Shared Sub Init() //initializes fields, sets connections Protected Shared Sub CleanAll() //closes connections, disposes, etc. I have several classes that derive from this base class. The derived classes have all Shared functions that can be called directly from the BLL with no instantiation. The functions in these derived classes call the base Init(), call their specific stored procs, call the base CleanAll() and then return the results. So if I have 5 derived classes with 10 functions each, totaling 50 possible function calls, since they are all Shared, the CLR only calls one at a time, right? All calls are queued to wait until each Shared function completes. Is there a better design with having Shared functions in your DAL and still have base class functions? Or since I have a base class, is it better to move towards instance methods within the DAL?

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  • python function that returns a function from list of functions

    - by thkang
    I want to make following function: 1)input is a number. 2)functions are indexed, return a function whose index matches given number here's what I came up with: def foo_selector(whatfoo): def foo1(): return def foo2(): return def foo3(): return ... def foo999(): return #something like return foo[whatfoo] the problem is, how can I index the functions (foo#)? I can see functions foo1 to foo999 by dir(). however, dir() returns name of such functions, not the functions themselves. In the example, those foo-functions aren't doing anything. However in my program they perform different tasks and I can't automatically generate them. I write them myself, and have to return them by their name.

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  • How do I make lambda functions generic in Scala?

    - by Electric Coffee
    As most of you probably know you can define functions in 2 ways in scala, there's the 'def' method and the lambda method... making the 'def' kind generic is fairly straight forward def someFunc[T](a: T) { // insert body here what I'm having trouble with here is how to make the following generic: val someFunc = (a: Int) => // insert body here of course right now a is an integer, but what would I need to do to make it generic? val someFunc[T] = (a: T) => doesn't work, neither does val someFunc = [T](a: T) => Is it even possible to make them generic, or should I just stick to the 'def' variant?

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  • Origin of common list-processing function names

    - by Heatsink
    Some higher-order functions for operating on lists or arrays have been repeatedly adopted or reinvented. The functions map, fold[l|r], and filter are found together in several programming languages, such as Scheme, ML, and Python, that don't seem to have a common ancestor. I'm going with these three names to keep the question focused. To show that the names are not universal, here is a sampling of names for equivalent functionality in other languages. C++ has transform instead of map and remove_if instead of filter (reversing the meaning of the predicate). Lisp has mapcar instead of map, remove-if-not instead of filter, and reduce instead of fold (Some modern Lisp variants have map but this appears to be a derived form.) C# uses Select instead of map and Where instead of filter. C#'s names came from SQL via LINQ, and despite the name changes, their functionality was influenced by Haskell, which was itself influenced by ML. The names map, fold, and filter are widespread, but not universal. This suggests that they were borrowed from an influential source into other contemporary languages. Where did these function names come from?

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  • The idea of functionN in Scala / Functionaljava

    - by Luke Murphy
    From brain driven development It turns out, that every Function you’ll ever define in Scala, will become an instance of an Implementation which will feature a certain Function Trait. There is a whole bunch of that Function Traits, ranging from Function1 up to Function22. Since Functions are Objects in Scala and Scala is a statically typed language, it has to provide an appropriate type for every Function which comes with a different number of arguments. If you define a Function with two arguments, the compiler picks Function2 as the underlying type. Also, from Michael Froh's blog You need to make FunctionN classes for each number of parameters that you want? Yes, but you define the classes once and then you use them forever, or ideally they're already defined in a library (e.g. Functional Java defines classes F, F2, ..., F8, and the Scala standard library defines classes Function1, ..., Function22) So we have a list of function traits (Scala), and a list of interfaces (Functional-java) to enable us to have first class funtions. I am trying to understand exactly why this is the case. I know, in Java for example, when I write a method say, public int add(int a, int b){ return a + b; } That I cannot go ahead and write add(3,4,5); ( error would be something like : method add cannot be applied to give types ) We simply have to define an interface/trait for functions with different parameters, because of static typing?

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  • SQL Server Date Comparison Functions

    - by HighAltitudeCoder
    A few months ago, I found myself working with a repetitive cursor that looped until the data had been manipulated enough times that it was finally correct.  The cursor was heavily dependent upon dates, every time requiring the earlier of two (or several) dates in one stored procedure, while requiring the later of two dates in another stored procedure. In short what I needed was a function that would allow me to perform the following evaluation: WHERE MAX(Date1, Date2) < @SomeDate The problem is, the MAX() function in SQL Server does not perform this functionality.  So, I set out to put these functions together.  They are titled: EarlierOf() and LaterOf(). /**********************************************************                               EarlierOf.sql   **********************************************************/ /**********************************************************   Return the later of two DATETIME variables.   Parameter 1: DATETIME1 Parameter 2: DATETIME2   Works for a variety of DATETIME or NULL values. Even though comparisons with NULL are actually indeterminate, we know conceptually that NULL is not earlier or later than any other date provided.   SYNTAX: SELECT dbo.EarlierOf('1/1/2000','12/1/2009') SELECT dbo.EarlierOf('2009-12-01 00:00:00.000','2009-12-01 00:00:00.521') SELECT dbo.EarlierOf('11/15/2000',NULL) SELECT dbo.EarlierOf(NULL,'1/15/2004') SELECT dbo.EarlierOf(NULL,NULL)   **********************************************************/ USE AdventureWorks GO   IF EXISTS       (SELECT *       FROM sysobjects       WHERE name = 'EarlierOf'       AND xtype = 'FN'       ) BEGIN             DROP FUNCTION EarlierOf END GO   CREATE FUNCTION EarlierOf (       @Date1                              DATETIME,       @Date2                              DATETIME )   RETURNS DATETIME   AS BEGIN       DECLARE @ReturnDate     DATETIME         IF (@Date1 IS NULL AND @Date2 IS NULL)       BEGIN             SET @ReturnDate = NULL             GOTO EndOfFunction       END         ELSE IF (@Date1 IS NULL AND @Date2 IS NOT NULL)       BEGIN             SET @ReturnDate = @Date2             GOTO EndOfFunction       END         ELSE IF (@Date1 IS NOT NULL AND @Date2 IS NULL)       BEGIN             SET @ReturnDate = @Date1             GOTO EndOfFunction       END         ELSE       BEGIN             SET @ReturnDate = @Date1             IF @Date2 < @Date1                   SET @ReturnDate = @Date2             GOTO EndOfFunction       END         EndOfFunction:       RETURN @ReturnDate   END -- End Function GO   ---- Set Permissions --GRANT SELECT ON EarlierOf TO UserRole1 --GRANT SELECT ON EarlierOf TO UserRole2 --GO                                                                                             The inverse of this function is only slightly different. /**********************************************************                               LaterOf.sql   **********************************************************/ /**********************************************************   Return the later of two DATETIME variables.   Parameter 1: DATETIME1 Parameter 2: DATETIME2   Works for a variety of DATETIME or NULL values. Even though comparisons with NULL are actually indeterminate, we know conceptually that NULL is not earlier or later than any other date provided.   SYNTAX: SELECT dbo.LaterOf('1/1/2000','12/1/2009') SELECT dbo.LaterOf('2009-12-01 00:00:00.000','2009-12-01 00:00:00.521') SELECT dbo.LaterOf('11/15/2000',NULL) SELECT dbo.LaterOf(NULL,'1/15/2004') SELECT dbo.LaterOf(NULL,NULL)   **********************************************************/ USE AdventureWorks GO   IF EXISTS       (SELECT *       FROM sysobjects       WHERE name = 'LaterOf'       AND xtype = 'FN'       ) BEGIN             DROP FUNCTION LaterOf END GO   CREATE FUNCTION LaterOf (       @Date1                              DATETIME,       @Date2                              DATETIME )   RETURNS DATETIME   AS BEGIN       DECLARE @ReturnDate     DATETIME         IF (@Date1 IS NULL AND @Date2 IS NULL)       BEGIN             SET @ReturnDate = NULL             GOTO EndOfFunction       END         ELSE IF (@Date1 IS NULL AND @Date2 IS NOT NULL)       BEGIN             SET @ReturnDate = @Date2             GOTO EndOfFunction       END         ELSE IF (@Date1 IS NOT NULL AND @Date2 IS NULL)       BEGIN             SET @ReturnDate = @Date1             GOTO EndOfFunction       END         ELSE       BEGIN             SET @ReturnDate = @Date1             IF @Date2 > @Date1                   SET @ReturnDate = @Date2             GOTO EndOfFunction       END         EndOfFunction:       RETURN @ReturnDate   END -- End Function GO   ---- Set Permissions --GRANT SELECT ON LaterOf TO UserRole1 --GRANT SELECT ON LaterOf TO UserRole2 --GO                                                                                             The interesting thing about this function is its simplicity and the built-in NULL handling functionality.  Its interesting, because it seems like something should already exist in SQL Server that does this.  From a different vantage point, if you create this functionality and it is easy to use (ideally, intuitively self-explanatory), you have made a successful contribution. Interesting is good.  Self-explanatory, or intuitive is FAR better.  Happy coding! Graeme

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  • SQL SERVER – Number-Crunching with SQL Server – Exceed the Functionality of Excel

    - by Pinal Dave
    Imagine this. Your users have developed an Excel spreadsheet that extracts data from your SQL Server database, manipulates that data through the use of Excel formulas and, possibly, some VBA code which is then used to calculate P&L, hedging requirements or even risk numbers. Management comes to you and tells you that they need to get rid of the spreadsheet and that the results of the spreadsheet calculations need to be persisted on the database. SQL Server has a very small set of functions for analyzing data. Excel has hundreds of functions for analyzing data, with many of them focused on specific financial and statistical calculations. Is it even remotely possible that you can use SQL Server to replace the complex calculations being done in a spreadsheet? Westclintech has developed a library of functions that match or exceed the functionality of Excel’s functions and contains many functions that are not available in EXCEL. Their XLeratorDB library of functions contains over 700 functions that can be incorporated into T-SQL statements. XLeratorDB takes advantage of the SQL CLR architecture introduced in SQL Server 2005. SQL CLR permits managed code to be compiled into the database and run alongside built-in SQL Server functions like COUNT or SUM. The Westclintech developers have taken advantage of this architecture to bring robust analytical functions to the database. In our hypothetical spreadsheet, let’s assume that our users are using the YIELD function and that the data are extracted from a table in our database called BONDS. Here’s what the spreadsheet might look like. We go to column G and see that it contains the following formula. Obviously, SQL Server does not offer a native YIELD function. However, with XLeratorDB we can replicate this calculation in SQL Server with the following statement: SELECT *, wct.YIELD(CAST(GETDATE() AS date),Maturity,Rate,Price,100,Frequency,Basis) AS YIELD FROM BONDS This produces the following result. This illustrates one of the best features about XLeratorDB; it is so easy to use. Since I knew that the spreadsheet was using the YIELD function I could use the same function with the same calling structure to do the calculation in SQL Server. I didn’t need to know anything at all about the mechanics of calculating the yield on a bond. It was pretty close to cut and paste. In fact, that’s one way to construct the SQL. Just copy the function call from the cell in the spreadsheet and paste it into SMS and change the cell references to column names. I built the SQL for this query by starting with this. SELECT * ,YIELD(TODAY(),B2,C2,D2,100,E2,F2) FROM BONDS I then changed the cell references to column names. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) ,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Finally, I replicated the TODAY() function using GETDATE() and added the schema name to the function name. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) --,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) ,wct.YIELD(GETDATE(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Then I am able to execute the statement returning the results seen above. The XLeratorDB libraries are heavy on financial, statistical, and mathematical functions. Where there is an analog to an Excel function, the XLeratorDB function uses the same naming conventions and calling structure as the Excel function, but there are also hundreds of additional functions for SQL Server that are not found in Excel. You can find the functions by opening Object Explorer in SQL Server Management Studio (SSMS) and expanding the Programmability folder under the database where the functions have been installed. The  Functions folder expands to show 3 sub-folders: Table-valued Functions; Scalar-valued functions, Aggregate Functions, and System Functions. You can expand any of the first three folders to see the XLeratorDB functions. Since the wct.YIELD function is a scalar function, we will open the Scalar-valued Functions folder, scroll down to the wct.YIELD function and and click the plus sign (+) to display the input parameters. The functions are also Intellisense-enabled, with the input parameters displayed directly in the query tab. The Westclintech website contains documentation for all the functions including examples that can be copied directly into a query window and executed. There are also more one hundred articles on the site which go into more detail about how some of the functions work and demonstrate some of the extensive business processes that can be done in SQL Server using XLeratorDB functions and some T-SQL. XLeratorDB is organized into libraries: finance, statistics; math; strings; engineering; and financial options. There is also a windowing library for SQL Server 2005, 2008, and 2012 which provides functions for calculating things like running and moving averages (which were introduced in SQL Server 2012), FIFO inventory calculations, financial ratios and more, without having to use triangular joins. To get started you can download the XLeratorDB 15-day free trial from the Westclintech web site. It is a fully-functioning, unrestricted version of the software. If you need more than 15 days to evaluate the software, you can simply download another 15-day free trial. XLeratorDB is an easy and cost-effective way to start adding sophisticated data analysis to your SQL Server database without having to know anything more than T-SQL. Get XLeratorDB Today and Now! Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Excel

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  • Does query plan optimizer works well with joined/filtered table-valued functions?

    - by smoothdeveloper
    In SQLSERVER 2005, I'm using table-valued function as a convenient way to perform arbitrary aggregation on subset data from large table (passing date range or such parameters). I'm using theses inside larger queries as joined computations and I'm wondering if the query plan optimizer work well with them in every condition or if I'm better to unnest such computation in my larger queries. Does query plan optimizer unnest table-valued functions if it make sense? If it doesn't, what do you recommend to avoid code duplication that would occur by manually unnesting them? If it does, how do you identify that from the execution plan? code sample: create table dbo.customers ( [key] uniqueidentifier , constraint pk_dbo_customers primary key ([key]) ) go /* assume large amount of data */ create table dbo.point_of_sales ( [key] uniqueidentifier , customer_key uniqueidentifier , constraint pk_dbo_point_of_sales primary key ([key]) ) go create table dbo.product_ranges ( [key] uniqueidentifier , constraint pk_dbo_product_ranges primary key ([key]) ) go create table dbo.products ( [key] uniqueidentifier , product_range_key uniqueidentifier , release_date datetime , constraint pk_dbo_products primary key ([key]) , constraint fk_dbo_products_product_range_key foreign key (product_range_key) references dbo.product_ranges ([key]) ) go . /* assume large amount of data */ create table dbo.sales_history ( [key] uniqueidentifier , product_key uniqueidentifier , point_of_sale_key uniqueidentifier , accounting_date datetime , amount money , quantity int , constraint pk_dbo_sales_history primary key ([key]) , constraint fk_dbo_sales_history_product_key foreign key (product_key) references dbo.products ([key]) , constraint fk_dbo_sales_history_point_of_sale_key foreign key (point_of_sale_key) references dbo.point_of_sales ([key]) ) go create function dbo.f_sales_history_..snip.._date_range ( @accountingdatelowerbound datetime, @accountingdateupperbound datetime ) returns table as return ( select pos.customer_key , sh.product_key , sum(sh.amount) amount , sum(sh.quantity) quantity from dbo.point_of_sales pos inner join dbo.sales_history sh on sh.point_of_sale_key = pos.[key] where sh.accounting_date between @accountingdatelowerbound and @accountingdateupperbound group by pos.customer_key , sh.product_key ) go -- TODO: insert some data -- this is a table containing a selection of product ranges declare @selectedproductranges table([key] uniqueidentifier) -- this is a table containing a selection of customers declare @selectedcustomers table([key] uniqueidentifier) declare @low datetime , @up datetime -- TODO: set top query parameters . select saleshistory.customer_key , saleshistory.product_key , saleshistory.amount , saleshistory.quantity from dbo.products p inner join @selectedproductranges productrangeselection on p.product_range_key = productrangeselection.[key] inner join @selectedcustomers customerselection on 1 = 1 inner join dbo.f_sales_history_..snip.._date_range(@low, @up) saleshistory on saleshistory.product_key = p.[key] and saleshistory.customer_key = customerselection.[key] I hope the sample makes sense. Much thanks for your help!

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  • Implement two functions with the same name but different, non-covariant return types due to multiple abstract base classes

    - by user1508167
    If I have two abstract classes defining a pure virtual function with the same name, but different, non-covariant return types, how can I derive from these and define an implementation for both their functions? #include <iostream> class ITestA { public: virtual ~ITestA() {}; virtual float test() =0; }; class ITestB { public: virtual ~ITestB() {}; virtual bool test() =0; }; class C : public ITestA, public ITestB { public: /* Somehow implement ITestA::test and ITestB::test */ }; int main() { ITestA *a = new C(); std::cout << a->test() << std::endl; // should print a float, like "3.14" ITestB *b = dynamic_cast<ITestB *>(a); if (b) { std::cout << b->test() << std::endl; // should print "1" or "0" } delete(a); return 0; } As long as I don't call C::test() directly there's nothing ambiguous, so I think that it should work somehow and I guess I just didn't find the right notation yet. Or is this impossible, if so: Why?

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  • What triggered the popularity of lambda functions in modern mainstream programming languages?

    - by Giorgio
    In the last few years anonymous functions (AKA lambda functions) have become a very popular language construct and almost every major / mainstream programming language has introduced them or is planned to introduce them in an upcoming revision of the standard. Yet, anonymous functions are a very old and very well-known concept in Mathematics and Computer Science (invented by the mathematician Alonzo Church around 1936, and used by the Lisp programming language since 1958, see e.g. here). So why didn't today's mainstream programming languages (many of which originated 15 to 20 years ago) support lambda functions from the very beginning and only introduced them later? And what triggered the massive adoption of anonymous functions in the last few years? Is there some specific event, new requirement or programming technique that started this phenomenon? IMPORTANT NOTE The focus of this question is the introduction of anonymous functions in modern, main-stream (and therefore, maybe with a few exceptions, non functional) languages. Also, note that anonymous functions (blocks) are present in Smalltalk, which is not a functional language, and that normal named functions have been present even in procedural languages like C and Pascal for a long time. Please do not overgeneralize your answers by speaking about "the adoption of the functional paradigm and its benefits", because this is not the topic of the question.

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  • F#: Advantages of converting top-level functions to member methods?

    - by J Cooper
    Earlier I requested some feedback on my first F# project. Before closing the question because the scope was too large, someone was kind enough to look it over and leave some feedback. One of the things they mentioned was pointing out that I had a number of regular functions that could be converted to be methods on my datatypes. Dutifully I went through changing things like let getDecisions hand = let (/=/) card1 card2 = matchValue card1 = matchValue card2 let canSplit() = let isPair() = match hand.Cards with | card1 :: card2 :: [] when card1 /=/ card2 -> true | _ -> false not (hasState Splitting hand) && isPair() let decisions = [Hit; Stand] let split = if canSplit() then [Split] else [] let doubleDown = if hasState Initial hand then [DoubleDown] else [] decisions @ split @ doubleDown to this: type Hand // ...stuff... member hand.GetDecisions = let (/=/) (c1 : Card) (c2 : Card) = c1.MatchValue = c2.MatchValue let canSplit() = let isPair() = match hand.Cards with | card1 :: card2 :: [] when card1 /=/ card2 -> true | _ -> false not (hand.HasState Splitting) && isPair() let decisions = [Hit; Stand] let split = if canSplit() then [Split] else [] let doubleDown = if hand.HasState Initial then [DoubleDown] else [] decisions @ split @ doubleDown Now, I don't doubt I'm an idiot, but other than (I'm guessing) making C# interop easier, what did that gain me? Specifically, I found a couple *dis*advantages, not counting the extra work of conversion (which I won't count, since I could have done it this way in the first place, I suppose, although that would have made using F# Interactive more of a pain). For one thing, I'm now no longer able to work with function "pipelining" easily. I had to go and change some |> chained |> calls to (some |> chained).Calls etc. Also, it seemed to make my type system dumber--whereas with my original version, my program needed no type annotations, after converting largely to member methods, I got a bunch of errors about lookups being indeterminate at that point, and I had to go and add type annotations (an example of this is in the (/=/) above). I hope I haven't come off too dubious, as I appreciate the advice I received, and writing idiomatic code is important to me. I'm just curious why the idiom is the way it is :) Thanks!

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  • How can arguments to variadic functions be passed by reference in PHP?

    - by outis
    Assuming it's possible, how would one pass arguments by reference to a variadic function without generating a warning in PHP? We can no longer use the '&' operator in a function call, otherwise I'd accept that (even though it would be error prone, should a coder forget it). What inspired this is are old MySQLi wrapper classes that I unearthed (these days, I'd just use PDO). The only difference between the wrappers and the MySQLi classes is the wrappers throw exceptions rather than returning FALSE. class DBException extends RuntimeException {} ... class MySQLi_throwing extends mysqli { ... function prepare($query) { $stmt = parent::prepare($query); if (!$stmt) { throw new DBException($this->error, $this->errno); } return new MySQLi_stmt_throwing($this, $query, $stmt); } } // I don't remember why I switched from extension to composition, but // it shouldn't matter for this question. class MySQLi_stmt_throwing /* extends MySQLi_stmt */ { protected $_link, $_query, $_delegate; public function __construct($link, $query, $prepared) { //parent::__construct($link, $query); $this->_link = $link; $this->_query = $query; $this->_delegate = $prepared; } function bind_param($name, &$var) { return $this->_delegate->bind_param($name, $var); } function __call($name, $args) { //$rslt = call_user_func_array(array($this, 'parent::' . $name), $args); $rslt = call_user_func_array(array($this->_delegate, $name), $args); if (False === $rslt) { throw new DBException($this->_link->error, $this->errno); } return $rslt; } } The difficulty lies in calling methods such as bind_result on the wrapper. Constant-arity functions (e.g. bind_param) can be explicitly defined, allowing for pass-by-reference. bind_result, however, needs all arguments to be pass-by-reference. If you call bind_result on an instance of MySQLi_stmt_throwing as-is, the arguments are passed by value and the binding won't take. try { $id = Null; $stmt = $db->prepare('SELECT id FROM tbl WHERE ...'); $stmt->execute() $stmt->bind_result($id); // $id is still null at this point ... } catch (DBException $exc) { ... } Since the above classes are no longer in use, this question is merely a matter of curiosity. Alternate approaches to the wrapper classes are not relevant. Defining a method with a bunch of arguments taking Null default values is not correct (what if you define 20 arguments, but the function is called with 21?). Answers don't even need to be written in terms of MySQL_stmt_throwing; it exists simply to provide a concrete example.

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  • Is it possible to view the "source" for a ksh function?

    - by stevec
    Our ksh environment defines several functions, which can be listed using then "functions" ksh function. Is it possible to see the definition (ie source code) for these functions? This seems like an obvious question, but I've tried all manner of parameters to the "functions" and "function" functions with no luck. Thanks, Steve

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  • T-SQL Tuesday #24 : Dude, where's the rest of my procedure?

    - by AaronBertrand
    This month's T-SQL Tuesday is being hosted by Brad Schulz ( blog ) and the topic is one that should attract a lot of submissions: Procedures and Functions. Last week, I talked about the case against INFORMATION_SCHEMA views - I provided several examples where I feel the INFORMATION_SCHEMA views fall short of the catalog views, and expressed my belief that you are better off programming consistently against the catalog views all the time, instead of only when the INFORMATION_SCHEMA views fail. Having...(read more)

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