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  • Is it possible to write a SQL query to return specific rows, but then join some columns of those row

    - by Rob
    I'm having trouble wrapping my head around how to write this query. A hypothetical problem that is that same as the one I'm trying to solve: Say I have a table of apples. Each apple has numerous attributes, such as color_id, variety_id and the orchard_id they were picked from. The color_id, variety_id, and orchard_id all refer to their respective tables: colors, varieties, and orchards. Now, say I need to query for all apples that have color_id = '3', which refers to yellow in the colors table. I want to somehow obtain this yellow value from the query. Make sense? Here's what I was trying: SELECT * FROM apples, colors.id WHERE color_id = '3' LEFT JOIN colors ON apples.color_id = colors.id

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  • problems with Haskell's Number Types

    - by mindeavor.
    I have the following haskell code: fac n = product [1..n] taylor3s w0 f f' f'' t h = w1 : taylor3s w1 f f' f'' (t+h) h where hp i = h^i / fac i w1 = w0 + (hp 1) * f t w0 + (hp 2) * f' t w0 + (hp 3) * f'' t w0 taylor_results = take 4 $ taylor3s 1 f f' f'' 1 0.25 where f t x = t^4 - 4*x/t f' t x = 4*t^3 - 4*(f t x)/t + 4*x/t^2 f'' t x = 12*t^2 - 4*(f' t x)/t + 8*(f t x)/t^2 - 8*x/t^3 taylor_results is supposed to be a use case of taylor3s. However, there is something wrong with the number type inferencing. When I try to compile, this is the error I get: practice.hs:93:26: Ambiguous type variable `a' in the constraints: `Integral a' arising from a use of `taylor3s' at practice.hs:93:26-51 `Fractional a' arising from a use of `f' at practice.hs:93:37 Possible cause: the monomorphism restriction applied to the following: taylor_results :: [a] (bound at practice.hs:93:0) Probable fix: give these definition(s) an explicit type signature or use -XNoMonomorphismRestriction Can someone help me with understanding what the problem is?

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  • What is wrong with my SQL syntax for an UPDATE with a JOIN?

    - by Phil H
    I have two tables, related by a common key. So TableA has key AID and value Name and TableB has keys AID, BID and values Name, Value: AID Name 74 Alpha AID BID Name Value 74 4 Beta Brilliance I would like to update the TableB Value here from Brilliance to Barmy, using just the Name fields. I thought I could do it via an UPDATE containing a JOIN, but Access (I know...) is complaining with 'Syntax error (missing operator) in query expression ' and then everything from 'Barmy' here: UPDATE tB SET tB.BValue='Barmy' FROM TableB tB INNER JOIN TableA tA ON tB.AID=tA.AID WHERE tB.Name='Beta' AND tA.Name='Alpha'; What is my heinous crime? Or is it just Access not conforming?

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  • Reflection for Class of generic parameter in Java?

    - by hatboysam
    Imagine the following scenario: class MyClass extends OtherClass<String>{ String myName; //Whatever } class OtherClass<T> { T myfield; } And I am analyzing MyClass using reflection specifically (MyClass.class).getDeclaredFields(), in this case I will get the following fields (and Types, using getType() of the Field): myName --> String myField --> T I want to get the actual Type for T, which is known at runtime due to the explicit "String" in the extends notation, how do I go about getting the non-genetic type of myField?

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  • MVC4 not binding a list of basic types

    - by admanb
    I cannot, for the life of me, get this data to bind. Here's my JavaScript: var params = { 'InvItemIDs': ["188475", "188490"]}; $.post("api/Orders/OrderFromInventory?" + $.param(params)) and the Controller action: public HttpResponseMessage OrderFromInventory(IList<int> InvItemIDs) { return new HttpResponseMessage(); } I've built the query string so that it's sending: ?InvItemIDs=188475&InvItemIDs=188490 as well as ?InvItemIDs[]=188475&InvItemIDs[]=188490 and even ?InvItemIDs[0]=188475&InvItemIDs[1]=188490 and none of them are binding. InvItemIDs is always null. What am I doing wrong? EDIT: So it turns out all this is a bug (or something) in the new Web API controller code in MVC4. As soon as I moved the exact same code over to a standard controller it started working. I'm still interested if anyone has any insight as to why the Web API would break this binding.

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  • How to write function where argument is type but not typed value?

    - by ssp
    I want to convert a string representations of few dozen enum types to enum values. It's easy to convert string to concrete type: Enum.Parse(typeof<FontStyle>,"Bold") |> unbox<FontStyle> but for now i want to write function where type and string are parameters. The best one i can write is: > let s2e (_: 'a) s = Enum.Parse(typeof<'a>,s) |> unbox<'a>;; val s2e : 'a -> string -> 'a > s2e FontStyle.Regular "Bold";; val it : FontStyle = Bold Is there any option to write something like this but with type itself as first argument?

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  • SQL: Is it quicker to insert sorted data into a table?

    - by AngryWhenHungry
    A table in Sybase has a unique varchar(32) column, and a few other columns. It is indexed on this column too. At regular intervals, I need to truncate it, and repopulate it with fresh data from other tables. insert into MyTable select list_of_columns from OtherTable where some_simple_conditions order by MyUniqueId If we are dealing with a few thousand rows, would it help speed up the insert if we have the order by clause for the select? If so, would this gain in time compensate for the extra time needed to order the select query? I could try this out, but currently my data set is small and the results don't say much.

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  • How should I do this (business logic) in Sql Server? A constraint?

    - by Pure.Krome
    Hi folks, I wish to add some type of business logic constraint to a table, but not sure how / where. I have a table with the following fields. ID INTEGER IDENTITY HubId INTEGER CategoryId INTEGER IsFeatured BIT Foo NVARCHAR(200) etc. So what i wish is that you can only have one featured thingy, per articleId + hubId. eg. 1, 1, 1, 1, 'blah' -- Ok. 2, 1, 2, 1, 'more blah' -- Also Ok 3, 1, 1, 1, 'aaa' -- constraint error 4, 1, 1, 0, 'asdasdad' -- Ok. 5, 1, 1, 0, 'bbbb' -- Ok. etc. so the third row to be inserterd would fail because that hub AND category already have a featured thingy. Is this possible?

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  • Oracle SQL: Multiple Subqueries Unioned Without Running Original Query Multiple Times.

    - by Bob
    So I've got a very large database, and need to work on a subset ~1% of the data to dump into an excel spreadsheet to make a graph. Ideally, I could select out the subset of data and then run multiple select queries on that, which are then UNION'ed together. Is this even possible? I can't seem to find anyone else trying to do this and would improve the performance of my current query quite a bit. Right now I have something like this: SELECT ( SELECT ( SELECT( long list of requirements ) UNION SELECT( slightly different long list of requirements ) ) ) and it would be nice if i could group the commonalities of the two long requirements and have simple differences between the two select statements being unioned.

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  • Incompatible format types

    - by nebffa
    I'm playing around with strncpy in C and am having some trouble. The code is as follows: #include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { char src[] = "Benjamin Franklin"; char dest[5]; strncpy(src, dest, sizeof(dest) / sizeof(char)); dest[5] = '\0'; printf("%s\n", dest); return 0; } which compiles with no errors using: gcc -Wall -g -Werror test.c -o test and prints out gibberish like p4?? I cannot really understand what I'm doing wrong especially since I have played around with it a lot and been looking online for answers. Perhaps since I am using arrays I am passing the address to printf without realising it?

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  • Why did the following linq to sql query generate a subquery?

    - by Xaisoft
    I did the following query: var list = from book in books where book.price > 50 select book; list = list.Take(50); I would expect the above to generate something like: SELECT top 50 id, title, price, author FROM Books WHERE price > 50 but it generates: SELECT [Limit1].[C1] as [C1] [Limit1].[id] as [Id], [Limit1].[title] as [title], [Limit1].[price] as [price], [Limit1].[author] FROM (SELECT TOP (50) [Extent1].[id] as as [Id], [Extent1].[title] as [title], [Extent1].[price] as [price], [Extent1].[author] as [author] FROM Books as [Extent1] WHERE [Extent1].[price] > 50 ) AS [Limit1] Why does the above linq query generate a subquery and where does the C1 come from?

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  • Dilemma with two types and operator +

    - by user35443
    I have small problem with operators. I have this code: public class A { public string Name { get; set; } public A() { } public A(string Name) { this.Name = Name; } public static implicit operator B(A a) { return new B(a.Name); } public static A operator+(A a, A b) { return new A(a.Name + " " + b.Name); } } public class B { public string Name { get; set; } public B() { } public B(string Name) { this.Name = Name; } public static implicit operator A(B b) { return new A(b.Name); } public static B operator +(B b, B a) { return new B(b.Name + " " + a.Name); } } Now I want to know, which's conversion operator will be called and which's addition operator will be called in this operation: new A("a") + new B("b"); Will it be operator of A, or of B? (Or both?) Thanks....

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  • How to check if the sum of some records equals the difference between two other records in t-sql?

    - by Dan Appleyard
    I have a view that contains bank account activity. ACCOUNT BALANCE_ROW AMOUNT SORT_ORDER 111 1 0.00 1 111 0 10.00 2 111 0 -2.50 3 111 1 7.50 4 222 1 100.00 5 222 0 25.00 6 222 1 125.00 7 ACCOUNT = account number BALANCE_ROW = either starting or ending balance would be 1, otherwise 0 AMOUNT = the amount SORT_ORDER = simple order to return the records in the order of start balance, activity, and end balance I need to figure out a way to see if the sum of the non balance_row rows equal the difference between the ending balance and the starting balance. The result for each account (1 for yes, 0 for no) would be simply added to the resulting result set. Example: Account 111 had a starting balance of 0.00. There were two account activity records of 10.00 and -2.5. That resulted in the ending balance of 7.50. I've been playing around with temp tables, but I was not sure if there is a more efficient way of accomplishing this. Thanks for any input you may have!

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  • How can I get a list of modified records from a SQL Server database?

    - by Pixelfish
    I am currently in the process of revamping my company's management system to run a little more lean in terms of network traffic. Right now I'm trying to figure out an effective way to query only the records that have been modified (by any user) since the last time I asked. When the application starts it loads the job information and caches it locally like the following: SELECT * FROM jobs. I am writing out the date/time a record was modified ala UPDATE jobs SET Widgets=@Widgets, LastModified=GetDate() WHERE JobID=@JobID. When any user requests the list of jobs I query all records that have been modified since the last time I requested the list like the following: SELECT * FROM jobs WHERE LastModified>=@LastRequested and store the date/time of the request to pass in as @LastRequest when the user asks again. In theory this will return only the records that have been modified since the last request. The issue I'm running into is when the user's date/time is not quite in sync with the server's date/time and also of server load when querying an un-indexed date/time column. Is there a more effective system then querying date/time information?

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  • Forcing entry of certain character types in UITextField

    - by cannyboy
    If I have a UITextField which the user is inputing a registration number, which has the format: 11-11-1111 (that is 2 digits, a dash, 2 digits, a dash, four digits) How do I force the user to enter this kind of data only... so they can't enter anything except 0-9 in the first character, and only '-' for the third character etc.

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  • In SQL find the combination of rows whose sum add up to a specific amount (or amt in other table)

    - by SamH
    Table_1 D_ID Integer Deposit_amt integer Table_2 Total_ID Total_amt integer Is it possible to write a select statement to find all the rows in Table_1 whose Deposit_amt sum to the Total_amt in Table_2. There are multiple rows in both tables. Say the first row in Table_2 has a Total_amt=100. I would want to know that in Table_1 the rows with D_ID 2, 6, 12 summed = 100, the rows D_ID 2, 3, 42 summed = 100, etc. Help appreciated. Let me know if I need to clarify. I am asking this question as someone as part of their job has a list of transactions and a list of totals, she needs to find the possible list of transactions that could have created the total. I agree this sounds dangerous as finding a combination of transactions that sums to a total does not guarantee that they created the total. I wasn't aware it is an np-complete problem.

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  • SQL: Using a CASE Statement to update a 1000 rows at once, how??

    - by SoLoGHoST
    Ok, I would like to use a CASE STATEMENT for this, but I am lost with this. Basically, I need to update a ton of rows, but just on the "position" column. I need to update all "position" values from 0 - count(position) for each id_layout_position column per id_layout column. Here's what I got for a regular update, but I don't wanna throw this into a foreach loop, as it would take forever to do it. I'm using SMF (Simple Machines Forums), so it might look a little different, but the idea is the same, and CASE statements are supported... $smcFunc['db_query']('', ' UPDATE {db_prefix}dp_positions SET position = {int:position} WHERE id_layout_position = {int:id_layout_position} AND id_layout = {int:id_layout}', array( 'position' => $position++, 'id_layout_position' => (int) $id_layout_position, 'id_layout' => (int) $id_layout, ) ); Anyways, I need to apply some sort of CASE on this so that I can auto-increment by 1 all values that it finds and update to the next possible value. I know I'm doing this wrong, even in this QUERY. But I'm totally lost when it comes to CASES. Here's an example of a CASE being used within SMF, so you can see this and hopefully relate: $conditions = ''; foreach ($postgroups as $id => $min_posts) { $conditions .= ' WHEN posts >= ' . $min_posts . (!empty($lastMin) ? ' AND posts <= ' . $lastMin : '') . ' THEN ' . $id; $lastMin = $min_posts; } // A big fat CASE WHEN... END is faster than a zillion UPDATE's ;). $smcFunc['db_query']('', ' UPDATE {db_prefix}members SET id_post_group = CASE ' . $conditions . ' ELSE 0 END' . ($parameter1 != null ? ' WHERE ' . (is_array($parameter1) ? 'id_member IN ({array_int:members})' : 'id_member = {int:members}') : ''), array( 'members' => $parameter1, ) ); Before I do the update, I actually have a SELECT which throws everything I need into arrays like so: $disabled_sections = array(); $positions = array(); while ($row = $smcFunc['db_fetch_assoc']($request)) { if (!isset($disabled_sections[$row['id_group']][$row['id_layout']])) $disabled_sections[$row['id_group']][$row['id_layout']] = array( 'info' => $module_info[$name], 'id_layout_position' => $row['id_layout_position'] ); // Increment the positions... if (!is_null($row['position'])) { if (!isset($positions[$row['id_layout']][$row['id_layout_position']])) $positions[$row['id_layout']][$row['id_layout_position']] = 1; else $positions[$row['id_layout']][$row['id_layout_position']]++; } else $positions[$row['id_layout']][$row['id_layout_position']] = 0; } Thanks, I know if anyone can help me here it's definitely you guys and gals... Anyways, here is my question: How do I use a CASE statement in the first code example, so that I can update all of the rows in the position column from 0 - total # of rows found, that have that id_layout value and that id_layout_position value, and continue this for all different id_layout values in that table? Can I use the arrays above somehow? I'm sure I'll have to use the id_layout and id_layout_position values for this right? But how can I do this?

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  • Mapping integers to types using C++ template fails in a specific case

    - by Shailesh Kumar
    I am attempting to compile the following template based code in VC++ 2005. #include <iostream> using namespace std; /* * T is a template which maps an integer to a specific type. * The mapping happens through partial template specialization. * In the following T<1> is mapped to char, T<2> is mapped to long * and T<3> is mapped to float using partial template specializations */ template <int x> struct T { public: }; template<> struct T<1> { public: typedef char xType; }; template<> struct T<2> { public: typedef long xType; }; template<> struct T<3> { public: typedef float xType; }; // We can easily access the specific xType for a specific T<N> typedef T<3>::xType x3Type; /*! * In the following we are attempting to use T<N> inside another * template class T2<R> */ template<int r> struct T2 { //We can map T<r> to some other type T3 typedef T<r> T3; // The following line fails typedef T3::xType xType; }; int main() { T<1>::xType a1; cout << typeid(a1).name() << endl; T<2>::xType a2; cout << typeid(a2).name() << endl; T<3>::xType a3; cout << typeid(a3).name() << endl; return 0; } There is a particular line in the code which doesn't compile: typedef T3::xType xType; If I remove this line, compilation goes fine and the result is: char long float If I retain this line, compilation errors are observed. main.cpp(53) : warning C4346: 'T<x>::xType' : dependent name is not a type prefix with 'typename' to indicate a type main.cpp(54) : see reference to class template instantiation 'T2<r>' being compiled main.cpp(53) : error C2146: syntax error : missing ';' before identifier 'xType' main.cpp(53) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int I am not able to figure out how to make sure that T::xType can be treated as a type inside the T2 template. Any help is highly appreciated.

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  • Can you use the same Enum in multiple entities in Linq-to-SQL?

    - by Mark
    In my persistence layer, I've declared a load of Enums to represent tables containing reference data (i.e. data never changes). In Linq2SQL, I am able to set the type of an entity property to an enum type and all is well, but as soon as I set a second entity's property to use the same enum type, the Code Generator (MSLinqToSQLGenerator) start generating an empty code file. I assume that MSLinqToSQLGenerator is quietly crashing. The question is why, and are there any work-arounds? Anyone else experienced this problem?

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  • How do I create a create and execute an SQL command using OleDB directly?

    - by Pagis
    I want to use the OleDB interfaces directly to open a connection to a DB, create a command and executing it (for example using the ICommandText interface). The main thing I can't find is how to create the connection and the command object and how to connect the object that implements the ICommandText to the connection. In ADO I would just use the ActiveConnection property but I want to do this directly on the OleDB interfaces. Also, if anyone can recommend a tutorial to OleDB, ether online or a book, free or not that would be great (but a tutorial and not just a reference / API) I'm using C++ but any native code would be fine.

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