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  • Linq to Entities and LEFT OUTER JOIN issue with MANY:1 relations

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer join instead of inner join? Because there's referential constraint on DB itself that ensures there's a record in the right table, so inner join should be used instead (and it would work much faster) If relation was many to 0..1 left outer join would be correct. Question Is it possible to write LINQ in a way so it will translate to inner join rather than left outer join. It would speed query execution a lot... I haven't used eSQL before, but would it be wise to use it in instead of LINQ? Edit I updated my tags to include technology I'm using in the background: Entity Framework V1 Devart dotConnect for Mysql MySql database If someone could test if the same is true on Microsoft SQL server it would also give me some insight if this is Devart's issue or it's a general L2EF functionality... But I suspect EF is the culprit here.

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  • MEF Error message

    - by cmaduro
    Can anybody explain this error message: The composition remains unchanged. The changes were rejected because of the following error(s): The composition produced a single composition error. The root cause is provided below. Review the CompositionException.Errors property for more detailed information. 1) No valid exports were found that match the constraint '((exportDefinition.ContractName == "Silverbits.ApplicationServices.ApplicationServicesManager") AndAlso (exportDefinition.Metadata.ContainsKey("ExportTypeIdentity") AndAlso "Silverbits.ApplicationServices.ApplicationServicesManager".Equals(exportDefinition.Metadata.get_Item("ExportTypeIdentity"))))', invalid exports may have been rejected. Resulting in: Cannot set import 'Silverbits.Applications.SilverbitsApplication.ApplicationServices (ContractName="Silverbits.ApplicationServices.ApplicationServicesManager")' on part 'Manpower4U.App'. Element: Silverbits.Applications.SilverbitsApplication.ApplicationServices (ContractName="Silverbits.ApplicationServices.ApplicationServicesManager") -- Manpower4U.App

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  • How can I encode four unsigned bytes (0-255) to a float and back again using HLSL?

    - by Statement
    Hello! I am facing a task where one of my hlsl shaders require multiple texture lookups per pixel. My 2d textures are fixed to 256*256, so two bytes should be sufficient to address any given texel given this constraint. My idea is then to put two xy-coordinates in each float, giving me eight xy-coordinates in pixel space when packed in a Vector4 format image. These eight coordinates are then used to sample another texture(s). The reason for doing this is to save graphics memory and an attempt to optimize processing time, since then I don't require multiple texture lookups. By the way: Does anyone know if encoding/decoding 16 bytes from/to 4 floats using 1 sampling is slower than 4 samplings with unencoded data?

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  • Override default operations order in LINQ

    - by Erick
    For one of our applications we do use LINQ to update a few reccords of the database. For business reasons we do require that only one item of a list to be primary. When we designed we decided to fire all of queries at the database at once. The problems occurs when we add one row and update the primary element to be the second item. See, the default behavior for order of operations with LINQ is to Insert, Update, Delete. If I Insert a first element I get a check constraint error with SQL Server. The best in my opinion would be to override and make sure to Update before Insert, this way we make sure that check constraints are kept. Tho there is not a lot of documentation on the mather. Any idea ?

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  • How do I create a foreign key in SQL Server?

    - by mmattax
    I have never "hand coded" creation code for SQL Server and foreign key deceleration is seemingly different from SQL Server and Postgres...here is my sql so far: drop table exams; drop table question_bank; drop table anwser_bank; create table exams ( exam_id uniqueidentifier primary key, exam_name varchar(50), ); create table question_bank ( question_id uniqueidentifier primary key, question_exam_id uniqueidentifier not null, question_text varchar(1024) not null, question_point_value decimal, constraint question_exam_id foreign key references exams(exam_id) ); create table anwser_bank ( anwser_id uniqueidentifier primary key, anwser_question_id uniqueidentifier, anwser_text varchar(1024), anwser_is_correct bit ); when I run the query I get this error: Msg 8139, Level 16, State 0, Line 9 Number of referencing columns in foreign key differs from number of referenced columns, table 'question_bank'. Can you spot the error? thanks.

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  • Calendar Table - Week number of month

    - by Saif Khan
    I have a calendar table with data from year 2000 to 2012 (2012 wasn't intentional!). I just realize that I don't have the week number of month (e.g In January 1,2,3,4 February 1,2,3,4) How do I go about calculating the week numbers in a month to fill this table? Here is the table schema CREATE TABLE [TCalendar] ( [TimeKey] [int] NOT NULL , [FullDateAlternateKey] [datetime] NOT NULL , [HolidayKey] [tinyint] NULL , [IsWeekDay] [tinyint] NULL , [DayNumberOfWeek] [tinyint] NULL , [EnglishDayNameOfWeek] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [SpanishDayNameOfWeek] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [FrenchDayNameOfWeek] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [DayNumberOfMonth] [tinyint] NULL , [DayNumberOfYear] [smallint] NULL , [WeekNumberOfYear] [tinyint] NULL , [EnglishMonthName] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [SpanishMonthName] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [FrenchMonthName] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [MonthNumberOfYear] [tinyint] NULL , [CalendarQuarter] [tinyint] NULL , [CalendarYear] [char] (4) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [CalendarSemester] [tinyint] NULL , [FiscalQuarter] [tinyint] NULL , [FiscalYear] [char] (4) COLLATE SQL_Latin1_General_CP1_CI_AS NULL , [FiscalSemester] [tinyint] NULL , [IsLastDayInMonth] [tinyint] NULL , CONSTRAINT [PK_TCalendar] PRIMARY KEY CLUSTERED ( [TimeKey] ) ON [PRIMARY] ) ON [PRIMARY] GO

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  • Can Hibernate automatically uppercase a column on read/insert via configuration?

    - by T Reddy
    We have some columns with data that must always be in uppercase to ensure uniqueness. I was wondering if hibernate can force all such columns to uppercase via some configuration file change? We actually use a custom UserType for encrypting/decrypting column data for some other table, but I figured that would be overkill just to uppercase everything... Alternatively, I was thinking about modifying the models such that all getters/setters will uppercase any string coming and going. The worst(?) case scenario is to modify the Oracle column constraint to ignore case while checking uniqueness. Any thoughts?

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  • What operating systems available for an 8-bit microprocessor?

    - by Benoit
    It does not need to be a full fledged OS, but at least have multitasking capabilities (i.e. a scheduler). Please mention what processor architecture it works on. This is a survey, so exact capabilities are not really important. Think of this as being a place to look at for possibilities when your next 8-bit embedded project comes up... I realize that most 8-bit micro do not require an OS, but just as a counter-example, Rabbit Semiconductor offers the RCM3710 processor module with 4 serial ports, a 10-BaseT ethernet port, 512K RAM and 512K Flash. All that for $39. All based around an 8-bit Z80 core. 8-bit does NOT necessarily mean extreme resource constraint.

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  • C# to Java: where T : new() Syntax

    - by Shiftbit
    I am porting some C# code over to Java. I am having trouble with the where Syntax, specifically new(). I understand that where is similar to Java's generic: T extends FOO. How I can replicate the new() argument in Java? "The new() Constraint lets the compiler know that any type argument supplied must have an accessible parameterless--or default-- constructor." - MSDN ie: public class BAR<T> : BAR where T : FOO, new() Right now I have: public class BAR<T extends FOO> extends ABSTRACTBAR { public HXIT(T t){ this.value = t; } .... }

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  • How can I make datagridview can only select the cells in the same column at a time?

    - by MemoryLeak
    I am using winforms to develop my application. And I set my datagridview control's selectionmode to "CellSelect", and this allow the user to select as many cells as he want which spread over several columns; but I want to constraint my user can only select cells in single column at a time, and there isn't any such kind of selectionmode for me. So If I want to implement this, how can I extend the datagridview class ? I also think that I can check in eventhandler whenever the selection cells are changed, through which I might make the user can not select cells spread over multiple columns, but this is not that good, I think. Can any other people help me to find out a better solution ?

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  • ASP.NET - How to add a label to a RadioButtonList ListItem?

    - by EWizard
    I have a RadioButtonList with two ListItems included: <asp:RadioButtonList runat="server" ID="optRollover" OnSelectedIndexChanged="RolloverOptionSelected" AutoPostBack="true"> <asp:ListItem Value="0">100% </asp:ListItem> <asp:ListItem Value="1">Less than 100%</asp:ListItem> </asp:RadioButtonList><br /> On the first ListItem I need to have a label that displays some text from the code behind of the page. Logically it seems to me like I would be able to do something like this: 100% Obviously this does not work because I am getting an error: The 'Text' property of 'asp:ListItem' does not allow child objects. Can anyone think of a way around this constraint?

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  • VC7.1 C1204 internal compiler error

    - by Nathan Ernst
    I'm working on modifying Firaxis' Civilization 4 core game DLL. The host application is built using VC7, hence the constraint (source not provided for the host EXE). I've been working on rewriting a large chunk of the code (focusing on low-hanging performance issues & memory leaks). I recently ran into an internal compiler error when trying to mod the code to use an array class instead of dynamically allocated 2-d arrays, I was going to use matrices from the boost lib (Civ4 is already using boost, so why not?). Basically, the issue comes down to: if I include "boost/numeric/ublas/matrix.hpp", I run into an internal compiler error C1204. MSDN has this to say: MSDN C1204 KB has this to say: KB 883655 So, I'm curious, is it possible to solve this error without a KB/SP being applied and dramatically reducing the complexity of the code? Additionally, as VC7 is no longer "supported", does anyone have a valid (supported) link for a VC7 service pack?

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  • SQLite Modify Column

    - by Nathan
    I need to modify a column in a SQLite database but I have to do it programatically due to the database already being in production. From my research I have found that in order to do this I must do the following. Create a new table with new schema Copy data from old table to new table Drop old table Rename new table to old tables name That seems like a ridiculous amount of work for something that should be relatively easy. Is there not an easier way? All I need to do is change a constraint on a existing column and give it a default value.

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  • Binary comparison operators on generic types

    - by Brian Triplett
    I have a generic class that takes a type T. Within this class I have a method were I need to compare a type T to another type T such as: public class MyClass<T> { public T MaxValue { // Implimentation for MaxValue } public T MyMethod(T argument) { if(argument > this.MaxValue) { // Then do something } } } The comparison operation inside of MyMethod fails with Compiler Error CS0019. Is it possible to add a constraint to T to make this work? I tried adding a where T: IComparable<T> to the class definition to no avail.

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  • Problems with contenttypes when loading a fixture in Django

    - by gerdemb
    I am having trouble loading Django fixtures into my MySQL database because of contenttypes conflicts. First I tried dumping the data from only my app like this: ./manage.py dumpdata escola > fixture.json but I kept getting missing foreign key problems, because my app "escola" uses tables from other applications. I kept adding additional apps until I got to this: ./manage.py dumpdata contenttypes auth escola > fixture.json Now the problem is the following constraint violation when I try to load the data as a test fixture: IntegrityError: (1062, "Duplicate entry 'escola-t23aluno' for key 2") It seems the problem is that Django is trying to dynamically recreate contenttypes with different primary key values that conflict with the primary key values from the fixture. This appears to be the same as bug documented here: http://code.djangoproject.com/ticket/7052 The problem is that the recommended workaround is to dump the contenttypes app which I'm already doing!? What gives? If it makes any difference I do have some custom model permissions as documented here: http://docs.djangoproject.com/en/dev/ref/models/options/#permissions

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  • Linq to sql Error "Data at the root level is invalid " for nullable xml column

    - by Mukesh
    I have Created a table like CREATE TABLE [dbo].[tab1]( [Id] [int] NOT NULL, [Name] [varchar](100) NOT NULL, [Meta] [xml] NULL, CONSTRAINT [PK_tab1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] When I am doing linq to sql query to fetch a data it throw an error "data at the root level is invalid linq". In further investigation I come to know that the meta column is null in that case. In real it is nullable Do I have to remove the nullable and set some blank root node as default or there is some another way to get rid of the error. My linq Query which throws error var obj1= (from obj in dbContext.tab1s where obj.id== 123 select obj).FirstOrDefault<Tab1>();

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  • How do I ignore the Perl shebang on Windows with Apache 2?

    - by nbolton
    I have set up a local Perl web environment on my Windows machine. The application I'm working on is originally from a Linux server, and so the shebang for source .pl files look like so: #!/usr/bin/perl This causes the following error on my Windows dev machine: (OS 2)The system cannot find the file specified. Is it possible to change my Apache 2 conf so that the shebang is ignored on my Windows machine? Of course I could set the shebang to #!c:\perl\bin\perl.exe, that much is obvious; but the problem comes to deploying the updated files. Clearly it would be very inconvenient to change this back on each deploy. I am using ActivePerl on Windows 7. Update: I should have mentioned that I need to keep the shebang so that the scripts will work on our shared hosting Linux production server. If I did not have this constraint and I didn't have to use the shebang, the obvious answer would be to just not use it.

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  • deploying gwt web application on jetty

    - by Azhar
    Hi I am deploying my web application created in Gwt on the jetty. I have used mongodb as my database.After starting the server it starts deploying the weapp.war and gives following error - 694 [main] INFO org.mortbay.log - Extract /usr/share/jetty/webapps/myapp.war to /tmp/Jetty_0_0_0_0_8090_myapp.war__myapp__n6yltk/webapp 3567 [main] WARN org.mortbay.log - failed Startup: java.lang.LinkageError: loader constraint violation: loader (instance of org/mortbay/jetty/webapp/WebAppClassLoader) previously initiated loading for a different type with name "javax/management/MBeanServer" at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:634) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) at java.net.URLClassLoader.access$000(URLClassLoader.java:73) at java.net.URLClassLoader$1.run(URLClassLoader.java:212) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:392) at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:363) at com.mongodb.DBPortPool$Holder.get(DBPortPool.java:58) at com.mongodb.DBTCPConnector._set(DBTCPConnector.java:458) at com.mongodb.DBTCPConnector.<init>(DBTCPConnector.java:46) at com.mongodb.Mongo.<init>(Mongo.java:137) at com.mongodb.Mongo.<init>(Mongo.java:123)

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  • Concurency problem with Isolation - read-committed

    - by Ratn Deo--Dev
    I have to write a simple demo for amount withdrawl from a joint Bank amount .Andy and Jen holds a joint bank account with number 123 . Suppose they have 100$ in their account .Jen and Andy are operating their account at the same time and both are trying to withdraw 90$ at the time being .My transaction Isolation is set to read-committed and both are able to withdraw money leaving the balance to -(minus)80$ although I have constraint that balance should never be less than 0. I am using hibernate .Is versioning only way to solve this problem or I should go for another Isolation level ?

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  • using check contraint in MySQL for controlling string length not working

    - by ptrn
    Dear stackoverflow, I'm tumbled with a problem! I've set up my first check constraint using MySQL, but unfortunately I'm having a problem. When inserting a row that should fail the test, the row is inserted anyway. The structure: CREATE TABLE user ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, uname VARCHAR(10) NOT NULL, fname VARCHAR(50) NOT NULL, lname VARCHAR(50) NOT NULL, mail VARCHAR(50) NOT NULL, PRIMARY KEY (id), CHECK (LENGTH(fname) > 3) ); The insert statement: INSERT INTO user VALUES (null, 'user', 'Fname', 'Lname', '[email protected]'); I'm pretty sure I'm missing something basic here.

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  • python- scipy optimization

    - by pear
    In scipy fmin_slsqp (Sequential Least Squares Quadratic Programming), I tried reading the code 'slsqp.py' provided with the scipy package, to find what are the criteria to get the exit_modes 0? I cannot find which statements in the code produce this exit mode? Please help me 'slsqp.py' code as follows, exit_modes = { -1 : "Gradient evaluation required (g & a)", 0 : "Optimization terminated successfully.", 1 : "Function evaluation required (f & c)", 2 : "More equality constraints than independent variables", 3 : "More than 3*n iterations in LSQ subproblem", 4 : "Inequality constraints incompatible", 5 : "Singular matrix E in LSQ subproblem", 6 : "Singular matrix C in LSQ subproblem", 7 : "Rank-deficient equality constraint subproblem HFTI", 8 : "Positive directional derivative for linesearch", 9 : "Iteration limit exceeded" } def fmin_slsqp( func, x0 , eqcons=[], f_eqcons=None, ieqcons=[], f_ieqcons=None, bounds = [], fprime = None, fprime_eqcons=None, fprime_ieqcons=None, args = (), iter = 100, acc = 1.0E-6, iprint = 1, full_output = 0, epsilon = _epsilon ): # Now do a lot of function wrapping # Wrap func feval, func = wrap_function(func, args) # Wrap fprime, if provided, or approx_fprime if not if fprime: geval, fprime = wrap_function(fprime,args) else: geval, fprime = wrap_function(approx_fprime,(func,epsilon)) if f_eqcons: # Equality constraints provided via f_eqcons ceval, f_eqcons = wrap_function(f_eqcons,args) if fprime_eqcons: # Wrap fprime_eqcons geval, fprime_eqcons = wrap_function(fprime_eqcons,args) else: # Wrap approx_jacobian geval, fprime_eqcons = wrap_function(approx_jacobian, (f_eqcons,epsilon)) else: # Equality constraints provided via eqcons[] eqcons_prime = [] for i in range(len(eqcons)): eqcons_prime.append(None) if eqcons[i]: # Wrap eqcons and eqcons_prime ceval, eqcons[i] = wrap_function(eqcons[i],args) geval, eqcons_prime[i] = wrap_function(approx_fprime, (eqcons[i],epsilon)) if f_ieqcons: # Inequality constraints provided via f_ieqcons ceval, f_ieqcons = wrap_function(f_ieqcons,args) if fprime_ieqcons: # Wrap fprime_ieqcons geval, fprime_ieqcons = wrap_function(fprime_ieqcons,args) else: # Wrap approx_jacobian geval, fprime_ieqcons = wrap_function(approx_jacobian, (f_ieqcons,epsilon)) else: # Inequality constraints provided via ieqcons[] ieqcons_prime = [] for i in range(len(ieqcons)): ieqcons_prime.append(None) if ieqcons[i]: # Wrap ieqcons and ieqcons_prime ceval, ieqcons[i] = wrap_function(ieqcons[i],args) geval, ieqcons_prime[i] = wrap_function(approx_fprime, (ieqcons[i],epsilon)) # Transform x0 into an array. x = asfarray(x0).flatten() # Set the parameters that SLSQP will need # meq = The number of equality constraints if f_eqcons: meq = len(f_eqcons(x)) else: meq = len(eqcons) if f_ieqcons: mieq = len(f_ieqcons(x)) else: mieq = len(ieqcons) # m = The total number of constraints m = meq + mieq # la = The number of constraints, or 1 if there are no constraints la = array([1,m]).max() # n = The number of independent variables n = len(x) # Define the workspaces for SLSQP n1 = n+1 mineq = m - meq + n1 + n1 len_w = (3*n1+m)*(n1+1)+(n1-meq+1)*(mineq+2) + 2*mineq+(n1+mineq)*(n1-meq) \ + 2*meq + n1 +(n+1)*n/2 + 2*m + 3*n + 3*n1 + 1 len_jw = mineq w = zeros(len_w) jw = zeros(len_jw) # Decompose bounds into xl and xu if len(bounds) == 0: bounds = [(-1.0E12, 1.0E12) for i in range(n)] elif len(bounds) != n: raise IndexError, \ 'SLSQP Error: If bounds is specified, len(bounds) == len(x0)' else: for i in range(len(bounds)): if bounds[i][0] > bounds[i][1]: raise ValueError, \ 'SLSQP Error: lb > ub in bounds[' + str(i) +'] ' + str(bounds[4]) xl = array( [ b[0] for b in bounds ] ) xu = array( [ b[1] for b in bounds ] ) # Initialize the iteration counter and the mode value mode = array(0,int) acc = array(acc,float) majiter = array(iter,int) majiter_prev = 0 # Print the header if iprint >= 2 if iprint >= 2: print "%5s %5s %16s %16s" % ("NIT","FC","OBJFUN","GNORM") while 1: if mode == 0 or mode == 1: # objective and constraint evaluation requird # Compute objective function fx = func(x) # Compute the constraints if f_eqcons: c_eq = f_eqcons(x) else: c_eq = array([ eqcons[i](x) for i in range(meq) ]) if f_ieqcons: c_ieq = f_ieqcons(x) else: c_ieq = array([ ieqcons[i](x) for i in range(len(ieqcons)) ]) # Now combine c_eq and c_ieq into a single matrix if m == 0: # no constraints c = zeros([la]) else: # constraints exist if meq > 0 and mieq == 0: # only equality constraints c = c_eq if meq == 0 and mieq > 0: # only inequality constraints c = c_ieq if meq > 0 and mieq > 0: # both equality and inequality constraints exist c = append(c_eq, c_ieq) if mode == 0 or mode == -1: # gradient evaluation required # Compute the derivatives of the objective function # For some reason SLSQP wants g dimensioned to n+1 g = append(fprime(x),0.0) # Compute the normals of the constraints if fprime_eqcons: a_eq = fprime_eqcons(x) else: a_eq = zeros([meq,n]) for i in range(meq): a_eq[i] = eqcons_prime[i](x) if fprime_ieqcons: a_ieq = fprime_ieqcons(x) else: a_ieq = zeros([mieq,n]) for i in range(mieq): a_ieq[i] = ieqcons_prime[i](x) # Now combine a_eq and a_ieq into a single a matrix if m == 0: # no constraints a = zeros([la,n]) elif meq > 0 and mieq == 0: # only equality constraints a = a_eq elif meq == 0 and mieq > 0: # only inequality constraints a = a_ieq elif meq > 0 and mieq > 0: # both equality and inequality constraints exist a = vstack((a_eq,a_ieq)) a = concatenate((a,zeros([la,1])),1) # Call SLSQP slsqp(m, meq, x, xl, xu, fx, c, g, a, acc, majiter, mode, w, jw) # Print the status of the current iterate if iprint > 2 and the # major iteration has incremented if iprint >= 2 and majiter > majiter_prev: print "%5i %5i % 16.6E % 16.6E" % (majiter,feval[0], fx,linalg.norm(g)) # If exit mode is not -1 or 1, slsqp has completed if abs(mode) != 1: break majiter_prev = int(majiter) # Optimization loop complete. Print status if requested if iprint >= 1: print exit_modes[int(mode)] + " (Exit mode " + str(mode) + ')' print " Current function value:", fx print " Iterations:", majiter print " Function evaluations:", feval[0] print " Gradient evaluations:", geval[0] if not full_output: return x else: return [list(x), float(fx), int(majiter), int(mode), exit_modes[int(mode)] ]

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  • Generate 10-digit number using a phone keypad

    - by srikfreak
    Given a phone keypad as shown below: 1 2 3 4 5 6 7 8 9 0 How many different 10-digit numbers can be formed starting from 1? The constraint is that the movement from 1 digit to the next is similar to the movement of the Knight in a chess game. For eg. if we are at 1 then the next digit can be either 6 or 8 if we are at 6 then the next digit can be 1, 7 or 0. Repetition of digits are allowed - 1616161616 is a valid number. Is there a polynomial time algorithm which solves this problem? The problem requires us to just give the count of 10-digit numbers and not necessarily list the numbers.

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  • SQL for selecting only the last item from a versioned table

    - by Jeremy
    I have a table with the following structure: CREATE TABLE items ( id serial not null, title character varying(255), version_id integer DEFAULT 1, parent_id integer, CONSTRAINT items_pkey PRIMARY KEY (id) ) So the table contains rows that looks as so: id: 1, title: "Version 1", version_id: 1, parent_id: 1 id: 2, title: "Version 2", version_id: 2, parent_id: 1 id: 3, title: "Completely different record", version_id: 1, parent_id: 3 This is the SQL code I've got for selecting out all of the records with the most recent version ids: select * from items inner join ( select parent_id, max(version_id) as version_id from items group by parent_id) as vi on items.version_id = vi.version_id and items.parent_id = vi.parent_id Is there a way to write that SQL statement so that it doesn't use a subselect?

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  • Please help me to create a insert query (error of foreign key constrant)

    - by Rajesh Rolen- DotNet Developer
    I want to move data from one database's table to another database's table its giving me foreign key error. please tell me how can i insert all those data which is valid except those rows who have error of foreign key. i am using sql server 2005 My query is : SET IDENTITY_INSERT City ON INSERT INTO City ([cityid],[city],[country],[state],[cityinfo] ,[enabled],[countryid],[citycode],[stateid],[latitude],[longitude]) SELECT [cityid],[city],[country],[state],[cityinfo] ,[enabled],[countryid],[citycode],[stateid],[latitude],[longitude] FROM TD.DBo.City getting this error: The INSERT statement conflicted with the FOREIGN KEY constraint "FK__city__countryid__3E52440B". The conflict occurred in database "schoolHigher", table "dbo.country", column 'countryId'. please tell how can i move those data whose foreign key is valid.

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  • I am not able to create foreign key in mysql Error 150. Please help

    - by Shantanu Gupta
    i am trying to create a foreign key in my table. But when i executes my query it shows me error 150 Error Code : 1005 Can't create table '.\vts#sql-6ec_1.frm' (errno: 150) (0 ms taken) My Queries are Query to create a foreign Key alter table `vts`.`tblguardian` add constraint `FK_tblguardian` FOREIGN KEY (`GuardianPickPointId`) REFERENCES `tblpickpoint` (`PickPointId`) Primary Key table CREATE TABLE `tblpickpoint` ( `PickPointId` int(4) NOT NULL auto_increment, `PickPointName` varchar(500) default NULL, `PickPointLabel` varchar(500) default NULL, `PickPointLatLong` varchar(100) NOT NULL, PRIMARY KEY (`PickPointId`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 CHECKSUM=1 DELAY_KEY_WRITE=1 ROW_FORMAT=DYNAMIC Foreign Key Table CREATE TABLE `tblguardian` ( `GuardianId` int(4) NOT NULL auto_increment, `GuardianName` varchar(500) default NULL, `GuardianAddress` varchar(500) default NULL, `GuardianMobilePrimary` varchar(15) NOT NULL, `GuardianMobileSecondary` varchar(15) default NULL, `GuardianPickPointId` varchar(100) default NULL, PRIMARY KEY (`GuardianId`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1

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