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  • Merging exists and not exists into one query - oracle magic

    - by stic
    Hi, In a WHERE part of query we have SELECT * FROM SomeTable st WHERE NOT EXISTS (SELECT 1 FROM Tab t1 WHERE t1.A = st.A OR t1.B = st.A) OR EXISTS (SELECT 1 FROM Tab t2 WHERE (t2.A = st.A OR t2.B = st.A) AND t2.C IS NULL) Seems like a good candidate for merging... But I'm staring on that for an hour without any idea. Would you have some thoughts? Thanks,

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  • LINQ - Contains with anonymous type

    - by Marlos
    When using this code (simplified for asking): var rows1 = (from t1 in db.TABLE1 where (t1.COLUMN_A == 1) select new { t1.COLUMN_B, t1.COLUMN_C }); var rows2 = (from t2 in db.TABLE2 where (rows1.Contains(t2.COLUMN_A)) select t2; I got the following error: The type arguments for method 'System.Linq.Enumerable.Contains(System.Collections.Generic.IEnumerable, TSource)' cannot be inferred from the usage. Try specifying the type arguments explicitly. I need to filter the first result by COLUMN_B, but I don't know how. Is there a way to filter it?

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  • sampling integers uniformly efficiently in python using numpy/scipy

    - by user248237
    I have a problem where depending on the result of a random coin flip, I have to sample a random starting position from a string. If the sampling of this random position is uniform over the string, I thought of two approaches to do it: one using multinomial from numpy.random, the other using the simple randint function of Python standard lib. I tested this as follows: from numpy import * from numpy.random import multinomial from random import randint import time def use_multinomial(length, num_points): probs = ones(length)/float(length) for n in range(num_points): result = multinomial(1, probs) def use_rand(length, num_points): for n in range(num_points): rand(1, length) def main(): length = 1700 num_points = 50000 t1 = time.time() use_multinomial(length, num_points) t2 = time.time() print "Multinomial took: %s seconds" %(t2 - t1) t1 = time.time() use_rand(length, num_points) t2 = time.time() print "Rand took: %s seconds" %(t2 - t1) if __name__ == '__main__': main() The output is: Multinomial took: 6.58072400093 seconds Rand took: 2.35189199448 seconds it seems like randint is faster, but it still seems very slow to me. Is there a vectorized way to get this to be much faster, using numpy or scipy? thanks.

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  • Can shared memory be read and validated without mutexes?

    - by Bribles
    On Linux I'm using shmget and shmat to setup a shared memory segment that one process will write to and one or more processes will read from. The data that is being shared is a few megabytes in size and when updated is completely rewritten; it's never partially updated. I have my shared memory segment laid out as follows: ------------------------- | t0 | actual data | t1 | ------------------------- where t0 and t1 are copies of the time when the writer began its update (with enough precision such that successive updates are guaranteed to have differing times). The writer first writes to t1, then copies in the data, then writes to t0. The reader on the other hand reads t0, then the data, then t1. If the reader gets the same value for t0 and t1 then it considers the data consistent and valid, if not, it tries again. Does this procedure ensure that if the reader thinks the data is valid then it actually is? Do I need to worry about out-of-order execution (OOE)? If so, would the reader using memcpy to get the entire shared memory segment overcome the OOE issues on the reader side? (This assumes that memcpy performs it's copy linearly and ascending through the address space. Is that assumption valid?)

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  • Factorial in Prolog and C++

    - by Joshua Green
    I would like to work out a number's factorial. My factorial rule is in a Prolog file and I am connecting it to a C++ code. Can someone tell me what is wrong with my C++ interface please? % factorial.pl factorial( 1, 1 ):- !. factorial( X, Fac ):- X > 1, Y is X - 1, factorial( Y, New_Fac ), Fac is X * New_Fac. // factorial.cpp # headerfiles term_t t1; term_t t2; term_t goal_term; functor_t goal_functor; int main( int argc, char** argv ) { argc = 4; argv[0] = "libpl.dll"; argv[1] = "-G32m"; argv[2] = "-L32m"; argv[3] = "-T32m"; PL_initialise(argc, argv); if ( !PL_initialise(argc, argv) ) PL_halt(1); PlCall( "consult(swi('plwin.rc'))" ); PlCall( "consult('factorial.pl')" ); cout << "Enter your factorial number: "; long n; cin >> n; PL_put_integer( t1, n ); t1 = PL_new_term_ref(); t2 = PL_new_term_ref(); goal_term = PL_new_term_ref(); goal_functor = PL_new_functor( PL_new_atom("factorial"), 2 ); PL_put_atom( t1, t2 ); PL_cons_functor( goal_term, goal_functor, t1, t2 ); PL_halt( PL_toplevel() ? 0 : 1 ); }

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  • C2664 when casting child class to templated parent class

    - by DC
    I have a parent class which is templated, and a child class which implements it. template< typename T1, typename T2> class ParentClass{ . . . }; class ChildClass : public ParentClass<MyT1, MyT2> { . . . }; And I want to have a pointer which I can use polymorphically: ParentClass<T1, T2>* ptr; ptr = static_cast<ParentClass<MyT1, MyT2>* >(new ChildClass() ); No matter how I cast it, I always get a C2664 which has the same expression: error C2664: cannot convert parameter 1 from 'ParentClass< T1,T2 *' to 'ParentClass< T1,T2 *' Is it not possible to cast pointer types between inherited types if the parent is templated, even if the types specified in the templates are the same?

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  • print hierarchy data(adjacency list model) in a list(ul/ol/li)

    - by adi
    I have adjacency list model like on the page http://dev.mysql.com/tech-resources/articles/hierarchical-data.html i have make a full table containing all data ordered by level using this SELECT t1.name AS lev1, t2.name as lev2, t3.name as lev3, t4.name as lev4 FROM category AS t1 LEFT JOIN category AS t2 ON t2.parent = t1.category_id LEFT JOIN category AS t3 ON t3.parent = t2.category_id LEFT JOIN category AS t4 ON t4.parent = t3.category_id WHERE t1.name = 'ELECTRONICS'; ORDER by ..... I want to make an unordered list using php from the table Anyone can help me...

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  • LINQ thinks I need an extra INNER JOIN, but why?

    - by Saurabh Kumar
    I have a LINQ query, which for some reason is generating an extra/duplicatre INNER JOIN. This is causing the query to not return the expected output. If I manually comment that extra JOIN from the generated SQL, then I get seemingly correct output. Can you detect what I might have done i nthis LINQ to have cuased this extra JOIN? Thanks. Here is my approx LINQ var ids = context.Code.Where(predicate); var rs = from r in ids group r by new { r.phonenumbers.person.PersonID} into g let matchcount=g.Select(p => p.phonenumbers.PhoneNum).Distinct().Count() where matchcount ==2 select new { personid = g.Key }; and here is the generated SQL (the duplicate join is [t7]) Declare @p1 VarChar(10)='Home' Declare @p2 VarChar(10)='111' Declare @p3 VarChar(10)='Office' Declare @p4 VarChar(10)='222' Declare @p5 int=2 SELECT [t9].[PersonID] AS [pid] FROM ( SELECT [t3].[PersonID], ( SELECT COUNT(*) FROM ( SELECT DISTINCT [t7].[PhoneValue] FROM [dbo].[Person] AS [t4] INNER JOIN [dbo].[PersonPhoneNumber] AS [t5] ON [t5].[PersonID] = [t4].[PersonID] INNER JOIN [dbo].[CodeMaster] AS [t6] ON [t6].[Code] = [t5].[PhoneType] INNER JOIN [dbo].[PersonPhoneNumber] AS [t7] ON [t7].[PersonID] = [t4].[PersonID] WHERE ([t3].[PersonID] = [t4].[PersonID]) AND ([t6].[Enumeration] = @p0) AND ((([t6].[CodeDescription] = @p1) AND ([t5].[PhoneValue] = @p2)) OR (([t6].[CodeDescription] = @p3) AND ([t5].[PhoneValue] = @p4))) ) AS [t8] ) AS [value] FROM ( SELECT [t0].[PersonID] FROM [dbo].[Person] AS [t0] INNER JOIN [dbo].[PersonPhoneNumber] AS [t1] ON [t1].[PersonID] = [t0].[PersonID] INNER JOIN [dbo].[CodeMaster] AS [t2] ON [t2].[Code] = [t1].[PhoneType] WHERE ([t2].[Enumeration] = @p0) AND ((([t2].[CodeDescription] = @p1) AND ([t1].[PhoneValue] = @p2)) OR (([t2].[CodeDescription] = @p3) AND ([t1].[PhoneValue] = @p4))) GROUP BY [t0].[PersonID] ) AS [t3] ) AS [t9] WHERE [t9].[value] = @p5

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  • Differentiate generic methods by type parameters only using reflection?

    - by Brian Vallelunga
    I'm trying to use reflection to get a specific MethodInfo of a class, but am unsure how to differentiate between the two following methods: public class Test { public IBar<T1> Foo<T1>(); public IBar<T1, T2> Foo<T1, T2>(); } How can I get a reference to the different Foo methods, assuming I know the number of type parameters? Just calling typeof(Test).GetMethod("Foo") will throw an exception that the method name is ambiguous and there aren't a differing number of parameters to check.

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  • How to structure (normalize?) a database of physical parameters?

    - by Arrieta
    Hello: I have a collection of physical parameters associated with different items. For example: Item, p1, p2, p3 a, 1, 2, 3 b, 4, 5, 6 [...] where px stands for parameter x. I could go ahead and store the database exactly as presented; the schema would be CREATE TABLE t1 (item TEXT PRIMARY KEY, p1 FLOAT, p2 FLOAT, p3 FLOAT); I could retrieve the parameter p1 for all the items with the statement: SELECT p1 FROM t1; A second alternative is to have an schema like: CREATE TABLE t1 (id INT PRIMARY KEY, item TEXT, par TEXT, val FLOAT) This seems much simpler if you have many parameters (as I do). However, the parameter retrieval seems very awkward: SELECT val FROM t1 WHERE par == 'p1' What do you advice? Should go for the "pivoted" (first) version or the id, par, val (second) version? Many thanks.

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  • Prolog for beginners about logic and syntax

    - by lnotik
    Hello everybody. I have this question : I need to create a paradict "rightGuesses" which will get 3 arguments , each one of them is a list of letters : 1) The list of guessed letters 2) The word i have to guess 3) The letters that where guessed so far . for example : rightGuesses([n,o,p,q], [p,r,o,l,o,g], Ans). will give us Ans = [p, -, o, -, o, -]. i made: rightGuesses([],T2,[ANS]) rightGuesses([A|T1],T2,[ANS]):- (member(A,T2))=\=true , rightGuesses(T1,T2,[ _ |'-']). rightGuesses([A|T1],T2,[ANS]):- member(A,T2), rightGuesses(T1,T2,[ _ |A]). but i get : ERROR: c:/users/leonid/desktop/file3.pl:5:0: Syntax error: Operator expected Warning: c:/users/leonid/desktop/file3.pl:6: when i trying to compile it what is my problem , and is there is a better way to do it ? thanks in advance.

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  • c++ templates: problem with member specialization

    - by ChAoS
    I am attempting to create a template "AutoClass" that create an arbitrary class with an arbitrary set of members, such as: AutoClass<int,int,double,double> a; a.set(1,1); a.set(0,2); a.set(3,99.7); std::cout << "Hello world! " << a.get(0) << " " << a.get(1) << " " << a.get(3) << std::endl; By now I have an AutoClass with a working "set" member: class nothing {}; template < typename T1 = nothing, typename T2 = nothing, typename T3 = nothing, typename T4 = nothing, typename T5 = nothing, typename T6 = nothing> class AutoClass; template <> class AutoClass<nothing, nothing, nothing, nothing, nothing, nothing> { public: template <typename U> void set(int n,U v){} }; template < typename T1, typename T2, typename T3, typename T4, typename T5, typename T6> class AutoClass: AutoClass<T2,T3,T4,T5,T6> { public: T1 V; template <typename U> void set(int n,U v) { if (n <= 0) V = v; else AutoClass<T2,T3,T4,T5,T6>::set(n-1,v); } }; and I started to have problems implementing the corresponding "get". This approach doesn't compile: template < typename T1, typename T2, typename T3, typename T4, typename T5, typename T6> class AutoClass: AutoClass<T2,T3,T4,T5,T6> { public: T1 V; template <typename U> void set(int n,U v) { if (n <= 0) V = v; else AutoClass<T2,T3,T4,T5,T6>::set(n-1,v); } template <typename W> W get(int n) { if (n <= 0) return V; else return AutoClass<T2,T3,T4,T5,T6>::get(n-1); } template <> T1 get(int n) { if (n <= 0) return V; else return AutoClass<T2,T3,T4,T5,T6>::get(n-1); } }; Besides, it seems I need to implement get for the <nothing, nothing, nothing, nothing, nothing, nothing> specialization. Any Idea on how to solve this?

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  • MySQL: INNER JOIN

    - by ABC
    I have a table which contains UserId & his Friends Id like: ---------------------------------------------- UserFriendsId | UserId | FriendId ---------------------------------------------- 1 1 2 ---------------------------------------------- 2 1 3 ---------------------------------------------- 3 2 1 ---------------------------------------------- 4 2 3 ---------------------------------------------- This table data shows that User-1 & User-2 are friend & they also have frndship with User-3. Now I want to find common friend(s) among UserId 1 & UserId 2 for eg: In sentance my query is: User 1 & User 2 have 1 common Friend FriendId 3. For this I used SQL query for INNER JOIN: SELECT t1.* FROM userfriends t1 INNER JOIN userfriends t2 ON t1.FriendId = t2.FriendId WHERE t1.UserId = 2 But not return required result..

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  • B-trees, databases, sequential inputs, and speed.

    - by IanC
    I know from experience that b-trees have awful performance when data is added to them sequentially (regardless of the direction). However, when data is added randomly, best performance is obtained. This is easy to demonstrate with the likes of an RB-Tree. Sequential writes cause a maximum number of tree balances to be performed. I know very few databases use binary trees, but rather used n-order balanced trees. I logically assume they suffer a similar fate to binary trees when it comes to sequential inputs. This sparked my curiosity. If this is so, then one could deduce that writing sequential IDs (such as in IDENTITY(1,1)) would cause multiple re-balances of the tree to occur. I have seen many posts argue against GUIDs as "these will cause random writes". I never use GUIDs, but it struck me that this "bad" point was in fact a good point. So I decided to test it. Here is my code: SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[T1]( [ID] [int] NOT NULL CONSTRAINT [T1_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO CREATE TABLE [dbo].[T2]( [ID] [uniqueidentifier] NOT NULL CONSTRAINT [T2_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO declare @i int, @t1 datetime, @t2 datetime, @t3 datetime, @c char(300) set @t1 = GETDATE() set @i = 1 while @i < 2000 begin insert into T2 values (NEWID(), @c) set @i = @i + 1 end set @t2 = GETDATE() WAITFOR delay '0:0:10' set @t3 = GETDATE() set @i = 1 while @i < 2000 begin insert into T1 values (@i, @c) set @i = @i + 1 end select DATEDIFF(ms, @t1, @t2) AS [Int], DATEDIFF(ms, @t3, getdate()) AS [GUID] drop table T1 drop table T2 Note that I am not subtracting any time for the creation of the GUID nor for the considerably extra size of the row. The results on my machine were as follows: Int: 17,340 ms GUID: 6,746 ms This means that in this test, random inserts of 16 bytes was almost 3 times faster than sequential inserts of 4 bytes. Would anyone like to comment on this? Ps. I get that this isn't a question. It's an invite to discussion, and that is relevant to learning optimum programming.

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  • Translate to MIPS

    - by user2334400
    HELP Translate A[i] = B[i-1] + B[i] + B[i+1] to MIPS the address of array A is $s1 the address of array B is $s2 the value of i is $s3 lb $s1,0($s3) # $s1=A[i] lb $s2,0($s3) # $s2=B[i] sb $s2,0($s3) # store s2 add $t0, $zero, $s2 #t0=B[i] addi $s3,$s3,-1 #i=i-1 lb $s2 0($s3) #$s2=B[i-1] add $t1,$zero,$s2 #t1=B[i-1] add $s1,$t0,$t1 #A[i]=B[i-1]+B[i] addi $s3,$s3,2 #i+1 lb $s2,0($s3) #s2=B[i+1] add $t2,$zero,$s2 #t2=B[i+1] add $s1,$s1,$t2 #A[i] = t1 + B[i+1] sb $s1 I know this is kind of mess, but it's the best i can write

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  • odp.net SQL query retrieve set of rows from two input arrays.

    - by Karl Trumstedt
    I have a table with a primary key consisting of two columns. I want to retrieve a set of rows based on two input arrays, each corresponding to one primary key column. select pkt1.id, pkt1.id2, ... from PrimaryKeyTable pkt1, table(:1) t1, table(:2) t2 where pkt1.id = t1.column_value and pkt1.id2 = t2.column_value I then bind the values with two int[] in odp.net. This returns all different combinations of my resulting rows. So if I am expecting 13 rows I receive 169 rows (13*13). The problem is that each value in t1 and t2 should be linked. Value t1[4] should be used with t2[4] and not all the different values in t2. Using distinct solves my problem, but I'm wondering if my approach is wrong. Anyone have any pointers on how to solve this the best way? One way might be to use a for-loop accessing each index in t1 and t2 sequentially, but I wonder what will be more efficient. Edit: actually distinct won't solve my problem, it just did it based on my input-values (all values in t2 = 0)

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  • How to update a table using a select group by in a second one and itself as the data source in MySQL

    - by Jader Dias
    I can do this: SELECT t2.value + sum(t3.value) FROM tableA t2, tableB t3 WHERE t2.somekey = t3.somekey GROUP BY t3.somekey But how to do this? UPDATE tableA t1 SET speed = ( SELECT t2.value + sum(t3.value) FROM tableA t2, tableB t3 WHERE t2.somekey = t3.somekey AND t1.somekey = t3.somekey GROUP BY t3.somekey ) ; MySQL says it's illegal since you can't specify target table t1 for update in FROM clause.

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  • Mysql syntax help

    - by Karthick
    Query: select t1.col1 from table1 t1 inner join with (nolock) table2 t2 on t1.col2 = t2.col1 Am trying to use nolock option for optimized query in mySQL db, but for some reason the above query does not work and the error i receive is You have an error in your SQL syntax; Any thoughts?

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  • What value should .net SqlCommand.ExecuteNonQuery() return if no rows are affected?

    - by peacedog
    I have the following code: int result = -1; StringBuilder sb = new StringBuilder(); SqlCommand cmd = MyConnection. sb.AppendLine("delete from Table1 where ID in"); sb.AppendLine("(select id from Table1 t1 where not exists(select * from Table2 t2 where t2.Table1ID = t1.ID))"); cmd.CommandText = sb.ToString(); result = cmd.ExecuteNonQuery(); _log.Info("StoredXMLDocument Records Deleted: " + result.ToString()); That SQL, in a more readable format, is: delete from Table1 where ID in (select id from Table1 t1 where not exists(select * from Table2 t2 where t2.Table1ID = t1.ID)) I know that the SQL, when executed directly in the database, deletes no rows. When this code runs, however, result gets a value of 1. I was expecting it to be 0. Am I missing something? Why is it 1?

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  • How to SUM columns on multiple conditions in a GROUP BY

    - by David Liddle
    I am trying to return a list of Accounts with their Balances, Outcome and Income Account Transaction ------- ----------- AccountID TransactionID BankName AccountID Locale Amount Status Here is what I currently have. Could someone explain where I am going wrong? select a.ACCOUNT_ID, a.BANK_NAME, a.LOCALE, a.STATUS, sum(t1.AMOUNT) as BALANCE, sum(t2.AMOUNT) as OUTCOME, sum(t3.AMOUNT) as INCOME from ACCOUNT a left join TRANSACTION t1 on t1.ACCOUNT_ID = a.ACCOUNT_ID left join TRANSACTION t2 on t1.ACCOUNT_ID = a.ACCOUNT_ID and t2.AMOUNT < 0 left join TRANSACTION t3 on t3.ACCOUNT_ID = a.ACCOUNT_ID and t3.AMOUNT > 0 group by a.ACCOUNT_ID, a.BANK_NAME, a.LOCALE, a.[STATUS]

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  • compiling java program

    - by Hulk
    If the java program is compiled as javac t1.java a //error contents redirecedt to a,file a.But a doesnt have the error contents The contents of t1.java is as: class t1{ public static void main(String[] args) { System.out.printn("Hello World!"); // Display the string. } } So now there is a error i.e, println is written as print n ,how to capture this error in file a The command is executed from linux command prompt Thanks....

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  • Haskell: How to compose `not` with a function of arbitrary arity?

    - by Hynek -Pichi- Vychodil
    When I have some function of type like f :: (Ord a) => a -> a -> Bool f a b = a > b I should like make function which wrap this function with not. e.g. make function like this g :: (Ord a) => a -> a -> Bool g a b = not $ f a b I can make combinator like n f = (\a -> \b -> not $ f a b) But I don't know how. *Main> let n f = (\a -> \b -> not $ f a b) n :: (t -> t1 -> Bool) -> t -> t1 -> Bool Main> :t n f n f :: (Ord t) => t -> t -> Bool *Main> let g = n f g :: () -> () -> Bool What am I doing wrong? And bonus question how I can do this for function with more and lest parameters e.g. t -> Bool t -> t1 -> Bool t -> t1 -> t2 -> Bool t -> t1 -> t2 -> t3 -> Bool

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  • JPA @version - can it be used to calcualate version of a table entry

    - by OpenSource
    Hi, Please consider the following table (created using a corresponding entity) request ------- id requestor type version items 1 a t1 1 5 2 a t1 2 3 3 b t1 1 2 4 a t2 1 4 5 a t1 3 9 The above is what I want to achieve. The version field is a calculated field others are user provided. Basically the request's version needs to be calculated based on the combination of requestor and the type. The first occurance with a given combination will have a version 1 then version 2 and so on. I tried various things using @version on a different entity with just the three columns and joining the two entities using ManytoOne etc but I'm not able to get to the desired outcome. I dont want to confuse you with the things I tried. Since the objective is simple there should be an easier way I suppose? Can you please help? - any help greatly appreciated! thanks in advance

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  • How to exclude result from 2 different table and show the result?

    - by Lucy Amalia Lusiana
    I have 2 tables: T1 (Total User) T2 (User_id_that_have_done_something_for_today) the mysql_query result from T1 are (Total User) ----- ID ----- | 1 | | 2 | | 3 | | 4 | | 5 | | 6 | | 7 | | 8 | the mysql_query from T2 are (logged) ----- user_id_log ----- | 1 | | 3 | | 4 | | 7 | How to compare T1 and T2 And only show the user that not approved? The end result that i wanted is (result) ----- ID ----- | 2 | | 5 | | 6 | | 8 | I spent 2 days to make this work but i cannot do it I have try LEFT JOIN and NOT IT but the result is not what i wanted Please help me, thank you

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  • Index View Index Creation Failing

    - by aBetterGamer
    I'm trying to create an index on a view and it keeps failing, I'm pretty sure its b/c I'm using an alias for the column. Not sure how or if I can do it this way. Below is a simplified scenario. CREATE VIEW v_contracts WITH SCHEMABINDING AS SELECT t1.contractid as 'Contract.ContractID' t2.name as 'Customer.Name' FROM contract t1 JOIN customer t2 ON t1.contractid = t2.contractid GO CREATE UNIQUE CLUSTERED INDEX v_contracts_idx ON v_contracts(t1.contractid) GO --------------------------- Incorrect syntax near '.'. CREATE UNIQUE CLUSTERED INDEX v_contracts_idx ON v_contracts(contractid) GO --------------------------- Column name 'contractid' does not exist in the target table or view. CREATE UNIQUE CLUSTERED INDEX v_contracts_idx ON v_contracts(Contract.ContractID) GO --------------------------- Incorrect syntax near '.'. Anyone know how to create an indexed view using aliased columns please let me know.

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