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  • What non-programming books should a programmer read (that helps developing programming skills/thinking)?

    - by FeatureCreep
    There are a lot of questions about what programming books should be on the programmer's bookshelf. How about non-programming related books that can help you become a better programmer or developer? It would also be interesting to know why they would help. My first choice would be Sun Tzu's "Art of War" (however cliché), because it made it obvious that the success of any project depends on the strength of its weakest link (and warfare is a big project).

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  • MySQL unique clustered constraint not constraining as expected

    - by igor
    I'm creating a table with: CREATE TABLE movies ( id INT AUTO_INCREMENT PRIMARY KEY, name CHAR(255) NOT NULL, year INT NOT NULL, inyear CHAR(10), CONSTRAINT UNIQUE CLUSTERED (name, year, inyear) ); (this is jdbc SQL) Which creates a MySQL table with a clustered index, "index kind" is "unique", and spans the three clustered columns: full size However, once I dump my data (without exceptions thrown), I see that the uniqueness constraint has failed: SELECT * FROM movies WHERE name = 'Flawless' AND year = 2007 AND inyear IS NULL; gives: id, name, year, inyear 162169, 'Flawless', 2007, NULL 162170, 'Flawless', 2007, NULL Does anyone know what I'm doing wrong here?

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  • How do I create a check constraint?

    - by Zack Peterson
    Please imagine this small database... Diagram Tables Volunteer Event Shift EventVolunteer ========= ===== ===== ============== Id Id Id EventId Name Name EventId VolunteerId Email Location VolunteerId Phone Day Description Comment Description Start End Associations Volunteers may sign up for multiple events. Events may be staffed by multiple volunteers. An event may have multiple shifts. A shift belongs to only a single event. A shift may be staffed by only a single volunteer. A volunteer may staff multiple shifts. Check Constraints Can I create a check constraint to enforce that no shift is staffed by a volunteer that's not signed up for that shift's event? Can I create a check constraint to enforce that two overlapping shifts are never staffed by the same volunteer?

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  • MYSQL: Error: Cannot add or update a child row: a foreign key constraint fails

    - by DalivDali
    Hi all, Using MySQL on Windows OS, and am getting an error upon attempting to create a foreign key between two tables: CREATE TABLE tf_traffic_stats ( domain_name char(100) NOT NULL, session_count int(11) NULL, search_count int(11) NULL, click_count int(11) NULL, revenue float NULL, rpm float NULL, cpc float NULL, traffic_date date NOT NULL DEFAULT '0000-00-00', PRIMARY KEY(domain_name,traffic_date)) and CREATE TABLE td_domain_name ( domain_id int(10) UNSIGNED AUTO_INCREMENT NOT NULL, domain_name char(100) NOT NULL, update_date date NOT NULL, PRIMARY KEY(domain_id)) The following statement gives me the error present in the subject line (cannot add or update a child row: a foreign key constraint fails): ALTER TABLE td_domain_name ADD CONSTRAINT FK_domain_name FOREIGN KEY(domain_name) REFERENCES tf_traffic_stats(domain_name) ON DELETE RESTRICT ON UPDATE RESTRICT Can someone point me in the right direction of what may be causing the error. I also have a foreign key referencing td_domain_name.domain_id, but I don't think this should be interfering... Appreciate it!

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  • Implement a vpn

    - by jackson
    I want to build an application client(client.exe) - server to do the following: when the clients run it they are thrown in a VPN and they can communicate each other within 1 applicataion. For example : clients run client.exe and they can see each other in LAN ONLY in Starcraft. From what i have read the right type of vpn for this situation is Secured Socket Tunneling Protocol: "Secure socket tunneling protocol, also referred to as SSTP, is by definition an application-layer protocol. It is designed to employ a synchronous communication in a back and forth motion between two programs. It allows many application endpoints over one network connection, between peer nodes, thereby enabling efficient usage of the communication resources that are available to that network. " Question: I don't have experience with networking programming so my question for the ones who have, is this the right approach? PS1: i don't want something done like OpenVpn, i do this as learning exercise. PS2: the application is targeting Windows and i plan to use .NET Thanks for reading the whole story, i am waiting for your replies.

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  • Identifying which value of a multi-row inserts fails foreign key constraint

    - by Jonathan
    I have a multi-row insert that looks something like: insert into table VALUES (1, 2, 3), (4, 5, 6), (7, 8, 9); Assume the first attribute (1, 4, 7) is a foreign key to another table and assume that this referenced table does not have the value '4'. A MySQLExeption is thrown with error code 1452. EXCEPTION: Cannot add or update a child row: a foreign key constraint fails (dbName/tableName, CONSTRAINT id FOREIGN KEY (customer_id) REFERENCES referencedTable (customer_id)) Is there a way to identify which value caused the error? I would love to give my user an error message that said something like: Error: '4' does not exist in the referenced table. I am using the .NET mysql connector to execute the insert. Thanks- Jonathan

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  • SQL CHECK constraint issues

    - by blahblah
    I'm using SQL Server 2008 and I have a table with three columns: Length, StartTime and EndTime. I want to make a CHECK constraint on this table which says that: if Length == NULL then StartTime <> NULL and EndTime <> NULL else StartTime == NULL and EndTime == NULL I've begun to try things like this: Length == NULL AND StartTime <> NULL AND EndTime <> NULL Obviously this is not enough, but even this simple expression will not validate. I get the error: "Error validating 'CK_Test_Length_Or_Time'. Do you want to edit the constraint?" Any ideas on how to go about doing this?

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  • After Trigger execute before constraint check in oracle

    - by satakare
    Hi, I have After Insert/Update trigger on Table T1 which get the referential data for Col1 from T2 and does some work and insert it into another table. The col1 is FK to Table T2. When user insert the incorrect or non existing value into the Col1 and if trigger is disabled I am getting constraint error that is fine. But when trigger is enabled and user insert the wrong value in Col1 trigger is getting fired and shows the 'no data found' error message. Actually I am expecting the table to throw constraint error, but trigger is throwing it. Please let me know your comments about this trigger behaviour.

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  • unique constraint (w/o Trigger) on "one-to-many" relation

    - by elgcom
    To illustrate the problem, I make an example: A tag_bundle consists of one or more than one tags. A unique tag combination can map to a unique tag_bundle, vice versa. tag_bundle tag tag_bundle_relation +---------------+ +--------+ +---------------+--------+ | tag_bundle_id | | tag_id | | tag_bundle_id | tag_id | +---------------+ +--------+ +---------------+--------+ | 1 | | 100 | | 1 | 100 | +---------------+ +--------+ +---------------+--------+ | 101 | | 1 | 101 | +--------+ +---------------+--------+ There can't be another tag_bundle having the combination from tag 100 and tag 101. How can I ensure such unique constraint when executing SQL "concurrently"!! that is, to prevent concurrently adding two bundles with the same tag combination Adding a simple unique constraint on any table does not work, Is there any solution other than Trigger or explicit lock. I come to only this simple way: make tag combination into string, and let it be unique. tag_bundle (unique on tags) tag tag_bundle_relation +---------------+--------+ +--------+ +---------------+--------+ | tag_bundle_id | tags | | tag_id | | tag_bundle_id | tag_id | +---------------+--------+ +--------+ +---------------+--------+ | 1 | 100,101| | 100 | | 1 | 100 | +---------------+--------+ +--------+ +---------------+--------+ | 101 | | 1 | 101 | +--------+ +---------------+--------+ but it seems not a good way :(

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  • Cannot add or update a child row: a foreign key constraint fails

    - by myaccount
    // Getting the id of the restaurant to which we are uploading the pictures $restaurant_id = intval($_GET['restaurant-id']); if(isset($_POST['submit'])) { $tmp_files = $_FILES['rest_pics']['tmp_name']; $target_files = $_FILES['rest_pics']['name']; $tmp_target = array_combine($tmp_files, $target_files); $upload_dir = $rest_pics_path; foreach($tmp_target as $tmp_file => $target_file) { if(move_uploaded_file($tmp_file, $upload_dir."/".$target_file)) { $sql = sprintf(" INSERT INTO rest_pics (branch_id, pic_name) VALUES ('%s', '%s')" , mysql_real_escape_string($restaurant_id) , mysql_real_escape_string(basename($target_file))); $result = mysql_query($sql) or die(mysql_error()); } I get the next error: Cannot add or update a child row: a foreign key constraint fails (rest_v2.rest_pics, CONSTRAINT rest_pics_ibfk_1 FOREIGN KEY (branch_id) REFERENCES rest_branches (branch_id) ON DELETE CASCADE ON UPDATE CASCADE However, this error totally disappears and everything goes well when I put directly the restaurant id (14 for example) instead of $restaurant_id variable in the sql query. The URL am getting the id from is: http://localhost/rest_v2/public_html/admin/add-delete-pics.php?restaurant-id=2 Any help please?

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  • Error 1005 when adding a foreign key constraint on mysql table

    - by luc
    Hello, I have a problem when upgrading a django and mysql app with south. I've tried to make a sql-based upgrade with the code generated by the django sqlall command and I have a similar problem. Here is the sql code: CREATE TABLE `programmations_basissupport` ( `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY, `value` numeric(6, 0) NOT NULL ) ALTER TABLE `programmations_concert` ADD `basis_support_id` integer AFTER program_status_id; ALTER TABLE `programmations_concert` ADD CONSTRAINT `basis_support_id_refs_id_1e4ed8d7` FOREIGN KEY (`basis_support_id`) REFERENCES `programmations_basissupport` (`id`); An error is raised when adding the FK constraint: ERROR 1005 (HY000): Can't create table 'apidev_mnl.#sql-106e_632b00a' (errno: 150) Does anybody have an idea? Update: DEFAULT values where missing but even if I add the default='' in the django model, the creation of foreign keys fails. Thanks for your help

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  • SQL Check Constraint cannot reference other column

    - by user1777711
    I trying to add this sql check in ALTER TABLE School add Role check_role CHECK (check_role IN ('Teaching Assistant', 'Lecturer', 'Professor')); I get the error below ERROR at line 3: ORA-02438: Column check constraint cannot reference other columns SQL> desc School; Name Null? Type ----------------------------------------- -------- ---------------------------- STAFFNUM NOT NULL VARCHAR2(12) NAME NOT NULL VARCHAR2(50) ADDRESS NOT NULL VARCHAR2(300) DOB DATE I am trying add a column call Role, with the check constraint check_role I am using Oracle SQL. Thanks for all help!

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  • Is this too much to ask for a game programming and developing enthusiast? Am I doing this wrong?

    - by I_Question_Things_Deeply
    I have been a computer-fanatic for almost a decade now. I've always loved and wondered how computers work, even from the purest, lowest hardware level to the very smallest pixel on the screen, and all the software around that. That seems to be my problem though ... as I try to write code (I'm pretty fluent at C++) I always sit there enormous amounts of time in front of a text-editor wondering how every line, statement, datum, function, etc. will correspond to every Assembly and machine instruction performed to do absolutely everything necessary for the kernel to allocate memory to run my compiled program, and all of the other hardware being used as well. For example ... I would write cout << "Before memory changed" << endl; and run the debugger to get the Assembly for this, and then try and reverse disassemble the Assembly to machine code based on my ISA, and then research every .dll, library file, linked library, linking process, linker source code of the program, the make file, the kernel I'm using's steps of processing this compilation, the hardware's part aside from the processor (e.g. video card, sound card, chipset, cache latency, byte-sized registers, calling convention use, DDR3 RAM and disk drive, filesystem functioning and so many other things). Am I going about programming wrong? I mean I feel I should know everything that goes on underneath English syntax on a computer program. But the problem is that the more I research every little thing the less I actually accomplish at all. I can never finish anything because of this mentality, yet I feel compelled to know everything... what should I do?

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  • C# 4.0: Dynamic Programming

    - by Paulo Morgado
    The major feature of C# 4.0 is dynamic programming. Not just dynamic typing, but dynamic in broader sense, which means talking to anything that is not statically typed to be a .NET object. Dynamic Language Runtime The Dynamic Language Runtime (DLR) is piece of technology that unifies dynamic programming on the .NET platform, the same way the Common Language Runtime (CLR) has been a common platform for statically typed languages. The CLR always had dynamic capabilities. You could always use reflection, but its main goal was never to be a dynamic programming environment and there were some features missing. The DLR is built on top of the CLR and adds those missing features to the .NET platform. The Dynamic Language Runtime is the core infrastructure that consists of: Expression Trees The same expression trees used in LINQ, now improved to support statements. Dynamic Dispatch Dispatches invocations to the appropriate binder. Call Site Caching For improved efficiency. Dynamic languages and languages with dynamic capabilities are built on top of the DLR. IronPython and IronRuby were already built on top of the DLR, and now, the support for using the DLR is being added to C# and Visual Basic. Other languages built on top of the CLR are expected to also use the DLR in the future. Underneath the DLR there are binders that talk to a variety of different technologies: .NET Binder Allows to talk to .NET objects. JavaScript Binder Allows to talk to JavaScript in SilverLight. IronPython Binder Allows to talk to IronPython. IronRuby Binder Allows to talk to IronRuby. COM Binder Allows to talk to COM. Whit all these binders it is possible to have a single programming experience to talk to all these environments that are not statically typed .NET objects. The dynamic Static Type Let’s take this traditional statically typed code: Calculator calculator = GetCalculator(); int sum = calculator.Sum(10, 20); Because the variable that receives the return value of the GetCalulator method is statically typed to be of type Calculator and, because the Calculator type has an Add method that receives two integers and returns an integer, it is possible to call that Sum method and assign its return value to a variable statically typed as integer. Now lets suppose the calculator was not a statically typed .NET class, but, instead, a COM object or some .NET code we don’t know he type of. All of the sudden it gets very painful to call the Add method: object calculator = GetCalculator(); Type calculatorType = calculator.GetType(); object res = calculatorType.InvokeMember("Add", BindingFlags.InvokeMethod, null, calculator, new object[] { 10, 20 }); int sum = Convert.ToInt32(res); And what if the calculator was a JavaScript object? ScriptObject calculator = GetCalculator(); object res = calculator.Invoke("Add", 10, 20); int sum = Convert.ToInt32(res); For each dynamic domain we have a different programming experience and that makes it very hard to unify the code. With C# 4.0 it becomes possible to write code this way: dynamic calculator = GetCalculator(); int sum = calculator.Add(10, 20); You simply declare a variable who’s static type is dynamic. dynamic is a pseudo-keyword (like var) that indicates to the compiler that operations on the calculator object will be done dynamically. The way you should look at dynamic is that it’s just like object (System.Object) with dynamic semantics associated. Anything can be assigned to a dynamic. dynamic x = 1; dynamic y = "Hello"; dynamic z = new List<int> { 1, 2, 3 }; At run-time, all object will have a type. In the above example x is of type System.Int32. When one or more operands in an operation are typed dynamic, member selection is deferred to run-time instead of compile-time. Then the run-time type is substituted in all variables and normal overload resolution is done, just like it would happen at compile-time. The result of any dynamic operation is always dynamic and, when a dynamic object is assigned to something else, a dynamic conversion will occur. Code Resolution Method double x = 1.75; double y = Math.Abs(x); compile-time double Abs(double x) dynamic x = 1.75; dynamic y = Math.Abs(x); run-time double Abs(double x) dynamic x = 2; dynamic y = Math.Abs(x); run-time int Abs(int x) The above code will always be strongly typed. The difference is that, in the first case the method resolution is done at compile-time, and the others it’s done ate run-time. IDynamicMetaObjectObject The DLR is pre-wired to know .NET objects, COM objects and so forth but any dynamic language can implement their own objects or you can implement your own objects in C# through the implementation of the IDynamicMetaObjectProvider interface. When an object implements IDynamicMetaObjectProvider, it can participate in the resolution of how method calls and property access is done. The .NET Framework already provides two implementations of IDynamicMetaObjectProvider: DynamicObject : IDynamicMetaObjectProvider The DynamicObject class enables you to define which operations can be performed on dynamic objects and how to perform those operations. For example, you can define what happens when you try to get or set an object property, call a method, or perform standard mathematical operations such as addition and multiplication. ExpandoObject : IDynamicMetaObjectProvider The ExpandoObject class enables you to add and delete members of its instances at run time and also to set and get values of these members. This class supports dynamic binding, which enables you to use standard syntax like sampleObject.sampleMember, instead of more complex syntax like sampleObject.GetAttribute("sampleMember").

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  • Oracle pl\sql question for my homework in oracle 11G class [migrated]

    - by Bjolds
    I am new to oracle 11G programming and i have run into a tough situation with pl\sql funtions and automation. I ame unsure how to create the function for the automation of Registration system for a College registration system. Here is what i want to do. I want to automate the registrations system so that it automaticly registers students. Then I want a procedure to automate the grading system. I have included the code that i am written to make most of this assignment work which it does but unsure how to incorporate Pl\SQL automated fuctions for the registrations system, and the grading system. So Any help or Ideas I would greatly appreciate please. set Linesize 250 set pagesize 150 drop table student; drop table faculty; drop table Course; drop table Section; drop table location; DROP TABLE courseInstructor; DROP TABLE Registration; DROP TABLE grade; create table student( studentid number(10), Lastname varchar2(20), Firstname Varchar2(20), MI Char(1), address Varchar2(20), city Varchar2(20), state Char(2), zip Varchar2(10), HomePhone Varchar2(10), Workphone Varchar2(10), DOB Date, Pin VARCHAR2(10), Status Char(1)); ALTER TABLE Student Add Constraint Student_StudentID_pk Primary Key (studentID); Insert into student values (1,'xxxxxxxx','xxxxxxxxxx','x','xxxxxxxxxxxxxxx','Columbus','oh','44159','xxx-xxx-xxxx','xxx-xxx-xxxx','06-Mar-1957','1211','c'); create table faculty( FacultyID Number(10), FirstName Varchar2(20), Lastname Varchar2(20), MI Char(1), workphone Varchar2(10), CellPhone Varchar2(10), Rank Varchar2(20), Experience Varchar2(10), Status Char(1)); ALTER TABLE Faculty ADD Constraint Faculty_facultyId_PK PRIMARY KEY (FacultyID); insert into faculty values (1,'xxx','xxxxxxxxxxxx',xxx-xxx-xxxx','xxx-xxx-xxxx','professor','20','f'); create table Course( CourseId number(10), CourseNumber Varchar2(20), CourseName Varchar(20), Description Varchar(20), CreditHours Number(4), Status Char(1)); ALTER TABLE Course ADD Constraint Course_CourseID_pk PRIMARY KEY(CourseID); insert into course values (1,'cit 100','computer concepts','introduction to PCs','3.0','o'); insert into course values (2,'cit 101','Database Program','Database Programming','4.0','o'); insert into course values (3,'Math 101','Algebra I','Algebra I Concepts','5.0','o'); insert into course values (4,'cit 102a','Pc applications','Aplications 1','3.0','o'); insert into course values (5,'cit 102b','pc applications','applications 2','3.0','o'); insert into course values (6,'cit 102c','pc applications','applications 3','3.0','o'); insert into course values (7,'cit 103','computer concepts','introduction systems','3.0','c'); insert into course values (8,'cit 110','Unified language','UML design','3.0','o'); insert into course values (9,'cit 165','cobol','cobol programming','3.0','o'); insert into course values (10,'cit 167','C++ Programming 1','c++ programming','4.0','o'); insert into course values (11,'cit 231','Expert Excel','spreadsheet apps','3.0','o'); insert into course values (12,'cit 233','expert Access','database devel.','3.0','o'); insert into course values (13,'cit 169','Java Programming I','Java Programming I','3.0','o'); insert into course values (14,'cit 263','Visual Basic','Visual Basic Prog','3.0','o'); insert into course values (15,'cit 275','system analysis 2','System Analysis 2','3.0','o'); create table Section( SectionID Number(10), CourseId Number(10), SectionNumber VarChar2(10), Days Varchar2(10), StartTime Date, EndTime Date, LocationID Number(10), SeatAvailable Number(3), Status Char(1)); ALTER TABLE Section ADD Constraint Section_SectionID_PK PRIMARY KEY(SectionID); insert into section values (1,1,'18977','r','21-Sep-2011','10-Dec-2011','1','89','o'); create table Location( LocationId Number(10), Building Varchar2(20), Room Varchar2(5), Capacity Number(5), Satus Char(1)); ALTER TABLE Location ADD Constraint Location_LocationID_pk PRIMARY KEY (LocationID); insert into Location values (1,'Clevleand Hall','cl209','35','o'); insert into Location values (2,'Toledo Circle','tc211','45','o'); insert into Location values (3,'Akron Square','as154','65','o'); insert into Location values (4,'Cincy Hall','ch100','45','o'); insert into Location values (5,'Springfield Dome','SD','35','o'); insert into Location values (6,'Dayton Dorm','dd225','25','o'); insert into Location values (7,'Columbus Hall','CB354','15','o'); insert into Location values (8,'Cleveland Hall','cl204','85','o'); insert into Location values (9,'Toledo Circle','tc103','75','o'); insert into Location values (10,'Akron Square','as201','46','o'); insert into Location values (11,'Cincy Hall','ch301','73','o'); insert into Location values (12,'Dayton Dorm','dd245','57','o'); insert into Location values (13,'Springfield Dome','SD','65','o'); insert into Location values (14,'Cleveland Hall','cl241','10','o'); insert into Location values (15,'Toledo Circle','tc211','27','o'); insert into Location values (16,'Akron Square','as311','28','o'); insert into Location values (17,'Cincy Hall','ch415','73','o'); insert into Location values (18,'Toledo Circle','tc111','67','o'); insert into Location values (19,'Springfield Dome','SD','69','o'); insert into Location values (20,'Dayton Dorm','dd211','45','o'); Alter Table Student Add Constraint student_Zip_CK Check(Rtrim (Zip,'1234567890-') is null); Alter Table Student ADD Constraint Student_Status_CK Check(Status In('c','t')); Alter Table Student ADD Constraint Student_MI_CK2 Check(RTRIM(MI,'abcdefghijklmnopqrstuvwxyz')is Null); Alter Table Student Modify pin not Null; Alter table Faculty Add Constraint Faculty_Status_CK Check(Status In('f','a','i')); Alter table Faculty ADD Constraint Faculty_Rank_CK Check(Rank In ('professor','doctor','instructor','assistant','tenure')); Alter table Faculty ADD Constraint Faculty_MI_CK2 Check(RTRIM(MI,'abcdefghijklmnopqrstuvwxyz')is Null); Update Section Set Starttime = To_date('09-21-2011 6:00 PM', 'mm-dd-yyyy hh:mi pm'); Update Section Set Endtime = To_date('12-10-2011 9:50 PM', 'mm-dd-yyyy hh:mi pm'); alter table Section Add Constraint StartTime_Status_CK Check (starttime < Endtime); Alter Table Section Add Constraint Section_StartTime_ck check (StartTime < EndTime); Alter Table Section ADD Constraint Section_CourseId_FK FOREIGN KEY (CourseID) References Course(CourseId); Alter Table Section ADD Constraint Section_LocationID_FK FOREIGN KEY (LocationID) References Location (LocationId); Alter Table Section ADD Constraint Section_Days_CK Check(RTRIM(Days,'mtwrfsu')IS Null); update section set seatavailable = '99'; Alter Table Section ADD Constraint Section_SeatsAvailable_CK Check (SeatAvailable < 100); Alter Table Course Add Constraint Course_CreditHours_ck check(CreditHours < = 6.0); update location set capacity = '99'; Alter Table Location Add Constraint Location_Capacity_CK Check(Capacity < 100); Create Table Registration ( StudentID Number(10), SectionID Number(10), Constraint Registration_pk Primary key (studentId, Sectionid)); Insert into registration values (1, 2); Insert into Registration values (2, 3); Insert into registration values (3, 4); Insert into registration values (4, 5); Insert into registration values (5, 6); Insert into registration values (6, 7); Insert into registration values (7, 8); Insert into registration values (8, 9); insert into registration values (9, 10); insert into registration values (10, 11); insert into registration values (9, 12); insert into registration values (8, 13); insert into registration values (7, 14); insert into registration values (6, 15); insert into registration values (5, 17); insert into registration values (4, 18); insert into registration values (3, 19); insert into registration values (2, 20); insert into registration values (1, 21); insert into registration values (2, 22); insert into registration values (3, 23); insert into registration values (4, 24); insert into registration values (5, 25); Insert into registration values (6, 24); insert into registration values (7, 23); insert into registration values (8, 22); insert into registration values (9, 21); insert into registration values (10, 20); insert into registration values (9, 19); insert into registration values (8, 17); Create Table courseInstructor( FacultyID Number(10), SectionID Number(10), Constraint CourseInstructor_pk Primary key (FacultyId, SectionID)); insert into courseInstructor values (1, 1); insert into courseInstructor values (2, 2); insert into courseInstructor values (3, 3); insert into courseInstructor values (4, 4); insert into courseInstructor values (5, 5); insert into courseInstructor values (5, 6); insert into courseInstructor values (4, 7); insert into courseInstructor values (3, 8); insert into courseInstructor values (2, 9); insert into courseInstructor values (1, 10); insert into courseInstructor values (5, 11); insert into courseInstructor values (4, 12); insert into courseInstructor values (3, 13); insert into courseInstructor values (2, 14); insert into courseInstructor values (1, 15); Create table grade( StudentID Number(10), SectionID Number(10), Grade Varchar2(1), Constraint grade_pk Primary key (StudentID, SectionID)); CREATE OR REPLACE TRIGGER TR_CreateGrade AFTER INSERT ON Registration FOR EACH ROW BEGIN INSERT INTO grade (SectionID,StudentID,Grade) VALUES(:New.SectionID,:New.StudentID,NULL); END TR_createGrade; / CREATE OR REPLACE FORCE VIEW V_reg_student_course AS SELECT Registration.StudentID, student.LastName, student.FirstName, course.CourseName, Registration.SectionID, course.CreditHours, section.Days, TO_CHAR(StartTime, 'MM/DD/YYYY') AS StartDate, TO_CHAR(StartTime, 'HH:MI PM') AS StartTime, TO_CHAR(EndTime, 'MM/DD/YYYY') AS EndDate, TO_CHAR(EndTime, 'HH:MI PM') AS EndTime, location.Building, location.Room FROM registration, student, section, course, location WHERE registration.StudentID = student.StudentID AND registration.SectionID = section.SectionID AND section.LocationID = location.LocationID AND section.CourseID = course.CourseID; CREATE OR REPLACE FORCE VIEW V_teacher_to_course AS SELECT courseInstructor.FacultyID, faculty.FirstName, faculty.LastName, courseInstructor.SectionID, section.Days, TO_CHAR(StartTime, 'MM/DD/YYYY') AS StartDate, TO_CHAR(StartTime, 'HH:MI PM') AS StartTime, TO_CHAR(EndTime, 'MM/DD/YYYY') AS EndDate, TO_CHAR(EndTime, 'HH:MI PM') AS EndTime, location.Building, location.Room FROM courseInstructor, faculty, section, course, location WHERE courseInstructor.FacultyID = faculty.FacultyID AND courseInstructor.SectionID = section.SectionID AND section.LocationID = location.LocationID AND section.CourseID = course.CourseID; SELECT * FROM V_reg_student_course; SELECT * FROM V_teacher_to_course;

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  • Creating packages in code - Workflow

    This is just a quick one prompted by a question on the SSIS Forum, how to programmatically add a precedence constraint (aka workflow) between two tasks. To keep the code simple I’ve actually used two Sequence containers which are often used as anchor points for a constraint. Very often this is when you have task that you wish to conditionally execute based on an expression. If it the first or only task in the package you need somewhere to anchor the constraint too, so you can then set the expression on it and control the flow of execution. Anyway, back to my code sample, here’s a quick screenshot of the finished article: Now for the code, which is actually pretty simple and hopefully the comments should explain exactly what is going on. Package package = new Package(); package.Name = "SequenceWorkflow"; // Add the two sequence containers to provide anchor points for the constraint // If you use tasks, it follows exactly the same pattern, they all derive from Executable Sequence sequence1 = package.Executables.Add("STOCK:Sequence") as Sequence; sequence1.Name = "SEQ Start"; Sequence sequence2 = package.Executables.Add("STOCK:Sequence") as Sequence; sequence2.Name = "SEQ End"; // Add the precedence constraint, here we use the package's constraint collection // as it hosts the two objects we want to constrain (link) // The default constraint is a basic On Success constraint just like in the designer PrecedenceConstraint constraint = package.PrecedenceConstraints.Add(sequence1, sequence2); // Change the settings to use a (dummy) expression only constraint.EvalOp = DTSPrecedenceEvalOp.Expression; constraint.Expression = "1 == 1";   The complete code file is available to download below. SequenceWorkflow.cs

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  • How to manipulate *huge* amounts of data

    - by Alejandro
    Hi there! I'm having the following problem. I need to store huge amounts of information (~32 GB) and be able to manipulate it as fast as possible. I'm wondering what's the best way to do it (combinations of programming language + OS + whatever you think its important). The structure of the information I'm using is a 4D array (NxNxNxN) of double-precission floats (8 bytes). Right now my solution is to slice the 4D array into 2D arrays and store them in separate files in the HDD of my computer. This is really slow and the manipulation of the data is unbearable, so this is no solution at all! I'm thinking on moving into a Supercomputing facility in my country and store all the information in the RAM, but I'm not sure how to implement an application to take advantage of it (I'm not a professional programmer, so any book/reference will help me a lot). An alternative solution I'm thinking on is to buy a dedicated server with lots of RAM, but I don't know for sure if that will solve the problem. So right now my ignorance doesn't let me choose the best way to proceed. What would you do if you were in this situation? I'm open to any idea. Thanks in advance!

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  • XSD: how to use 'unique' & 'key'/'keyref' with element values?

    - by Koohoolinn
    I trying to use and / with element values but I just can't get it to work. If I do it with attrubute values it works like a charm. Test.xml <test:config xmlns:test="http://www.example.org/Test" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.org/Test Test.xsd "> <test:location id="id1" path="/path2"> <test:roles> <test:role>role1</test:role> <test:role>role2</test:role> <test:role>role2</test:role> <!-- DUPLICATE: FAIL VALIDATION --> </test:roles> <test:action name="action1"> <test:roles> <test:role>role1</test:role> <test:role>role1</test:role> <!-- DUPLICATE: FAIL VALIDATION --> <test:role>role3</test:role> <!-- NOT DEFINED: FAIL VALIDATION --> </test:roles> </test:action> </test:location> </test:config> I want ensure that roles are only defined once and that the roles defined under the action element are only those defined at the upper level. Test.xsd <xs:element name="config"> <xs:complexType> <xs:sequence> <xs:element ref="test:location" maxOccurs="unbounded" /> </xs:sequence> </xs:complexType> </xs:element> <xs:element name="location" type="test:LocationType"> <xs:key name="keyRole"> <xs:selector xpath="test:roles" /> <xs:field xpath="test:role" /> </xs:key> <xs:keyref name="keyrefRole" refer="test:keyRole"> <xs:selector xpath="test:action/test:roles" /> <xs:field xpath="test:role" /> </xs:keyref> </xs:element> <xs:complexType name="LocationType"> <xs:sequence> <xs:element ref="test:roles" minOccurs="0" /> <xs:element name="action" type="test:ActionType" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> <xs:attribute name="id" type="xs:string" use="required"/> <xs:attribute name="path" type="xs:string" use="required"/> </xs:complexType> <xs:element name="roles" type="test:RolesType"> <xs:unique name="uniqueRole"> <xs:selector xpath="." /> <xs:field xpath="test:role" /> </xs:unique> </xs:element> <xs:complexType name="RolesType"> <xs:sequence> <xs:element name="role" type="xs:string" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> <xs:complexType name="ActionType"> <xs:sequence> <xs:element ref="test:roles" /> </xs:sequence> <xs:attribute name="name" type="xs:string" use="required" /> </xs:complexType> The validation fails with these messages: Description Resource Path Location Type cvc-identity-constraint.3: Field "./test:role" of identity constraint "keyrefRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 15 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "keyrefRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 16 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "keyRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 9 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "keyRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 10 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "uniqueRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 9 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "uniqueRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 10 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "uniqueRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 15 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "uniqueRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 16 XML Problem cvc-identity-constraint.4.1: Duplicate unique value [role1] declared for identity constraint "uniqueRole" of element "roles". Test.xml /filebrowser-ejb/src/test/resources line 9 XML Problem cvc-identity-constraint.4.1: Duplicate unique value [role1] declared for identity constraint "uniqueRole" of element "roles". Test.xml /filebrowser-ejb/src/test/resources line 15 XML Problem cvc-identity-constraint.4.2.2: Duplicate key value [role1] declared for identity constraint "keyRole" of element "location". Test.xml /filebrowser-ejb/src/test/resources line 9 XML Problem cvc-identity-constraint.4.3: Key 'keyrefRole' with value 'role3' not found for identity constraint of element 'location'. Test.xml /filebrowser-ejb/src/test/resources line 19 XML Problem If I comment out the lines that should fail, validation still fails now with these messages: Description Resource Path Location Type cvc-identity-constraint.3: Field "./test:role" of identity constraint "keyRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 10 XML Problem cvc-identity-constraint.3: Field "./test:role" of identity constraint "uniqueRole" matches more than one value within the scope of its selector; fields must match unique values. Test.xml /filebrowser-ejb/src/test/resources line 10 XML Problem What am I doing wrong?

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  • Most useful parallel programming algorithm?

    - by Zubair
    I recenty asked a question about parallel programming algorithms which was closed quite fast due to my bad ability to communicate my intent: http://stackoverflow.com/questions/2407631/what-is-the-most-useful-parallel-programming-algorithm-closed I had also recently asked another question, specifically: http://stackoverflow.com/questions/2407493/is-mapreduce-such-a-generalisation-of-another-programming-principle/2407570#2407570 The other question was specifically about map reduce and to see if mapreduce was a more specific version of some other concept in parallel programming. This question (about a useful parallel programming algorithm) is more about the whole series of algorithms for parallel programming. You will have to excuse me though as I am quite new to parallel programming, so maybe MapReduce or something that is a more general form of mapreduce is the "only" parallel programming construct which is available, in which case I apologise for my ignorance

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  • AJI Report #19 | Scott K Davis and his son Tommy on Gamification and Programming for Kids

    - by Jeff Julian
    We are very excited about this show. John and Jeff sat down with Scott Davis and his son Tommy to talk about Gamification and Programming for Kids. Tommy is nine years old and the Iowa Code Camp was his second time presenting. Scott and Tommy introduce a package called Scratch that was developed by MIT to teach kids about logic and interacting with programming using sprites. Tommy's favorite experience with programming right now is Lego Mindstorms because of the interaction with the Legos and the development. Most adults when they get started with development also got started with interacting more with the physical machines. The next generation is given amazing tools, but the tools tend to be sealed and the physical interaction is not there. With some of these alternative hobby platforms like Legos, Arduino, and .NET Micro Framework, kids can write some amazing application and see their code work with physical movement and interaction with devices and sensors. In the second half of this podcast, Scott talks about how companies can us Gamification to prompt employees to interact with software and processes in the organization. We see gamification throughout the consumer space and you need to do is open up the majority of the apps on our phones or tablets and there is some interaction point to give the user a reward for using the tool. Scott gets into his product Qonqr which is described as the board game Risk and Foursquare together. Scott gets into the different mindsets of gamers (Bartle Index) and how you can use these mindsets to get the most out of your team through gamification techniques. Listen to the Show Site: http://scottkdavis.com/ Twitter: @ScottKDavis LinkedIn: ScottKDavis Scratch: http://scratch.mit.edu/ Lego Mindstorms: http://mindstorms.lego.com/ Bartle Test: Wikipedia Gamification: Wikipedia

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  • Programming concepts taken from the arts and humanities

    - by Joey Adams
    After reading Paul Graham's essay Hackers and Painters and Joel Spolsky's Advice for Computer Science College Students, I think I've finally gotten it through my thick skull that I should not be loath to work hard in academic courses that aren't "programming" or "computer science" courses. To quote the former: I've found that the best sources of ideas are not the other fields that have the word "computer" in their names, but the other fields inhabited by makers. Painting has been a much richer source of ideas than the theory of computation. — Paul Graham, "Hackers and Painters" There are certainly other, much stronger reasons to work hard in the "boring" classes. However, it'd also be neat to know that these classes may someday inspire me in programming. My question is: what are some specific examples where ideas from literature, art, humanities, philosophy, and other fields made their way into programming? In particular, ideas that weren't obviously applied the way they were meant to (like most math and domain-specific knowledge), but instead gave utterance or inspiration to a program's design and choice of names. Good examples: The term endian comes from Gulliver's Travels by Tom Swift (see here), where it refers to the trivial matter of which side people crack open their eggs. The terms journal and transaction refer to nearly identical concepts in both filesystem design and double-entry bookkeeping (financial accounting). mkfs.ext2 even says: Writing superblocks and filesystem accounting information: done Off-topic: Learning to write English well is important, as it enables a programmer to document and evangelize his/her software, as well as appear competent to other programmers online. Trigonometry is used in 2D and 3D games to implement rotation and direction aspects. Knowing finance will come in handy if you want to write an accounting package. Knowing XYZ will come in handy if you want to write an XYZ package. Arguably on-topic: The Monad class in Haskell is based on a concept by the same name from category theory. Actually, Monads in Haskell are monads in the category of Haskell types and functions. Whatever that means...

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  • What are Web runtime environments and programming languages

    - by Bradly Spicer
    I've been looking into the details behind these two different categories: Web runtime environments Web application programming languages I believe I have the correct information and have phrased it correctly but I am unsure. I have been searching for a while but only find snippets of information or what I can see as useless information (I could be wrong). Here are my descriptions so far: Web runtime environments - A Run-time environment implements part of the core behaviour of any computer language and allows it to be modified via an API or embedded domain-specific language. A web runtime environment is similar except it uses web based languages such as Java-script which utilises the core behaviour a computer language. Another example of a Run-time environment web language is JsLibs which is a standable JavaScript development runtime environment for using JavaScript as a general all round scripting language. JavaScript is often used to create responsive interfaces which improve the user experience and provide dynamic functionality without having to wait for the server to react and direct to another page. Web application programming languages - A web application program language is something that mimics a traditional desktop application within a web page. For example, using PHP you can create forms and tables which use a database similar to that of Microsoft Excel. Some of the other languages for web application programming are: Ajax Perl Ruby Here are some of the resources used: http://en.wikipedia.org/wiki/Web_application_development http://code.google.com/p/jslibs/ I would like some confirmation that the descriptions I have created are correct as I am still slightly unsure as to whether I have hit the nail on the head.

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  • Empirical evidence for choice of programming paradigm to address a problem

    - by Graham Lee
    The C2 wiki has a discussion of Empirical Evidence for Object-Oriented Programming that basically concludes there is none beyond appeal to authority. This was last edited in 2008. Discussion here seems to bear this out: questions on whether OO is outdated, when functional programming is a bad choice and the advantages and disadvantages of AOP are all answered with contributors' opinions without reliance on evidence. Of course, opinions of established and reputed practitioners are welcome and valuable things to have, but they're more plausible when they're consistent with experimental data. Does this evidence exist? Is evidence-based software engineering a thing? Specifically, if I have a particular problem P that I want to solve by writing software, does there exist a body of knowledge, studies and research that would let me see how the outcome of solving problems like P has depended on the choice of programming paradigm? I know that which paradigm comes out as "the right answer" can depend on what metrics a particular study pays attention to, on what conditions the study holds constant or varies, and doubtless on other factors too. That doesn't affect my desire to find this information and critically appraise it. It becomes clear that some people think I'm looking for a "turn the crank" solution - some sausage machine into which I put information about my problem and out of which comes a word like "functional" or "structured". This is not my intention. What I'm looking for is research into how - with a lot of caveats and assumptions that I'm not going into here but good literature on the matter would - certain properties of software vary depending on the problem and the choice of paradigm. In other words: some people say "OO gives better flexibility" or "functional programs have fewer bugs" - (part of) what I'm asking for is the evidence of this. The rest is asking for evidence against this, or the assumptions under which these statements are true, or evidence showing that these considerations aren't important. There are plenty of opinions on why one paradigm is better than another; is there anything objective behind any of these?

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  • Can I assume interface oriented programming as a good object oriented programming?

    - by david
    I have been programming for decades but I have not been used to object oriented programming. But for recenet years, I had a great opportunity to learn OOP, its principles, and a lot of patterns that are great. Since I've learned OOP, I tried to apply them to a couple of projects and found those projects successful. Unfortunately I didn't follow extreme programming that suggests writing test first, mainly because their time frame were tight. What I did for those projects were Identify all necessary classes and create them with proper properties and methods whenever there is dependency between classes, write interface between them see if there is any patterns for certain relationships between classes to replace By successful, I meant that it was quick development effort, the classes can be reused better, and flexible enough so that another programmer does not have to change something else to fix another part. But I wonder if this is a good practice. Of course, I know I need to put writing unit tests first in my work process. But other than that, is there any problem with this approach - creating lots of interfaces - in long term?

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