Search Results

Search found 13723 results on 549 pages for 'constraint programming'.

Page 229/549 | < Previous Page | 225 226 227 228 229 230 231 232 233 234 235 236  | Next Page >

• General many-to-many relationship problem ( Postgresql )

  - by David

  Hi, i have two tables: CREATE TABLE "public"."auctions" ( "id" VARCHAR(255) NOT NULL, "auction_value_key" VARCHAR(255) NOT NULL, "ctime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, "mtime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, CONSTRAINT "pk_XXXX2" PRIMARY KEY("id"), ); and CREATE TABLE "public"."auction_values" ( "id" NUMERIC DEFAULT nextval('default_seq'::regclass) NOT NULL, "fk_auction_value_key" VARCHAR(255) NOT NULL, "key" VARCHAR(255) NOT NULL, "value" TEXT, "ctime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, "mtime" TIMESTAMP WITHOUT TIME ZONE NOT NULL, CONSTRAINT "pk_XXXX1" PRIMARY KEY("id"), ); if i want to create a many-to-many relationship on the auction_value_key like this: ALTER TABLE "public"."auction_values" ADD CONSTRAINT "auction_values_fk" FOREIGN KEY ("fk_auction_value_key") REFERENCES "public"."auctions"("auction_value_key") ON DELETE NO ACTION ON UPDATE NO ACTION NOT DEFERRABLE; i get this SQL error: ERROR: there is no unique constraint matching given keys for referenced table "auctions" Question: As you might see, i want "auction_values" to be be "reused" by different auctions without duplicating them for every auction... So i don't want a key relation on the "id" field in the auctions table... Am i thinking wrong here or what is the deal? ;) Thanks

  Read the article

• Using Constraints on Hierarchical Data in a Self-Referential Table

  - by pbarney

  Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to update on cascades and prevent deletion of fruit if they have "children." So I used the following: CREATE TABLE `idtlp_main`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`iddoc_main`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

  Read the article

• symfony doctrine build-sql error

  - by user313571

  I have some big problems with symfony and doctrine at the beginning of a new project. I have created database diagram with mysql workbench, inserted the sql into phpmyadmin and then I've tried symfony doctrine:build-schema to generate the YAML schema. It generates a wrong schema (relations don't have on delete/on update) and after this I've tried symfony doctrine:build --sql and symfony doctrine:insert-sql The insert-sql statement generates error (can't create table ... failing query alter table add constraint ....), so I've decided to take a look over the generated sql and I've found out some differences between the sql generated from mysql workbench (which works perfect, including relations) and the sql generated by doctrine. I'll be short from now: I have to tables, EVENT and FORM and a 1 to n relation (each event may have multiple forms) so the correct constraint (generated with workbench) is ALTER TABLE `form` ADD CONSTRAINT `fk_form_event1` FOREIGN KEY (`event_id`) REFERENCES `event` (`id`) ON DELETE CASCADE ON UPDATE CASCADE; doctrine generated statement is: ALTER TABLE event ADD CONSTRAINT event_id_form_event_id FOREIGN KEY (id) REFERENCES form(event_id); It's totally reversed and I am sure here is the error. What should I do? It's also correct like this?

  Read the article

• How to embed XBase expressions in an Xtext DSL

  - by Marcus Mathioudakis

  I am writing a simple little DSL for specifying constraints on messages, and Have been trying without success for a while to embed XBase expressions into the language. The Grammar looks like this: grammar org.xtext.businessrules.BusinessRules with org.eclipse.xtext.xbase.Xbase //import "http://www.eclipse.org/xtext/xbase/Xbase" as xbase import "http://www.eclipse.org/xtext/common/JavaVMTypes" as jvmTypes generate businessRules "http://www.xtext.org/businessrules/BusinessRules" Start: rules+=Constraint*; Constraint: {Constraint} 'FOR' 'PAYLOAD' payload=PAYLOAD 'ELEMENT' element=ID 'CONSTRAINED BY' constraint=XExpression; PAYLOAD: "SimulationSessionEvents" |"stacons" |"any" ; Range: 'above' min=INT ('below' max=INT)? |'below' max=INT ('above' min=INT)? ; When trying to parse a file such as: FOR PAYLOAD SimulationSessionEvents ELEMENT matrix CONSTRAINED BY ... I can't get it to work for ... = any kind of Arithmetic expression, although it works for ...= loop or if expression, or even just a number. As soon as I do something like '-5' or '4-5' it says Couldn't resolve reference to JvmIdentifiableElement '-', even though the Xbase.xtext Grammar looks like it allows these expressions. I don't think I'm missing any Jars, as it doesn't complain when I run the mwe workflow, but only when trying to parse the input file. Any help would be much appreciated.

  Read the article

• Which Stroustrup book should I use?

  - by Chris Simmons

  I'm a C# programmer that is looking to branch out. I'm bored of writing business software and want to start getting into graphics programming and games/simulators. So I figured, although writing that stuff isn't impossible in managed code, the "right" way to do that would be to look to C++, of course focussing on the language first, then getting into OpenGL or DirectX (or whatever). Way way back ('98? '99?) I had tried and failed to really grasp Stroustrup's The C++ Programming Language. I know that this book is often not recommended for the beginner. Anyway, I picked it back up (in a much more recent printing) and I'm actually getting it and enjoying it. I also have a copy of his textbook, Programming: Principles and Practice Using C++, which, as I understand it, is really geared toward teaching programming, not necessarily C++. I'm certainly not arrogant enough to claim I don't have anything more to learn about programming, data structures, algoriths, etc., however I'm not a novice there either. So my question is, with the goal of gaining the broader and more real-world-useful understanding of C++ and given my background, on which should I focus? The denser (as I perceive it) TCPPPL or the gentler Programming? EDIT: I thank everyone for the responses. However, I've got a personal choice here to make between these two books. Granted there are other very good books out there, but I'm already a good length into both of the books I mention and I'd like to finish one. So, can anyone respond on which would be the better and why? Time is not an issue; I'm not looking (at this point) at an "accelerated" read.

  Read the article

• Dealing with SQLException with spring,hibernate & Postgres

  - by mad

  Hi im working on a project using HibernateDaoSUpport from my Daos from Spring & spring-ws & hibernate & postgres who will be used in a national application (means a lot of users) Actually, every exception from hibernate is automatically transformed into some specific Spring dataAccesException. I have a table with a keyword on the dabatase & a unique constraint on the keywords : no duplicate keywords is allowed. I have found twows ways to deal with with that in the Insert Dao: 1- Check for the duplicate manually (with a select) prior to doing your insert. I means that the spring transaction will have a SERIALIZABLE isolation level. The obvious drawback is that we have now 2 queries for a simple insert.Advantage: independent of the database 2-let the insert gone & catch the SqlException & convert it to a userfriendly message & errorcode to the final consumer of our webservices. Solution 2: Spring has developped a way to translate specific exeptions into customized exceptions. see http://www.oracle.com/technology/pub/articles/marx_spring.html In my case i would have a ConstraintViolationException. Ideally i would like to write a custom SQLExceptionTranslator to map the duplicate word constraint in the database with a DuplicateWordException. But i can have many unique constraints on the same table. So i have to get the message of the SQLEXceptions in order to find the name of the constraint declared in the create table "uq_duplicate-constraint" for example. Now i have a strong dependency with the database. Thanks in advance for your answers & excuse me for my poor english (it is not my mother tongue)

  Read the article

• Is it Possible to Use Constraints on Hierarchical Data in a Self-Referential Table?

  - by pbarney

  Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to cascade on update and prevent deletion of a record if it has any "children." So I used the following: CREATE TABLE `test`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

  Read the article

• Loop to check all 14 days in the pay period

  - by Rachel Ann Arndt

  Name: Calc_Anniversary Input: Pay_Date, Hire_Date, Termination_Date Output: "Y" if is the anniversary of the employee's Hire_Date, "N" if it is not, and "T" if he has been terminated before his anniversary. Description: Create local variables to hold the month and day of the employee's Date_of_Hire, Termination_Date, and of the processing date using the TO_CHAR function. First check to see if he was terminated before his anniversary. The anniversary could be on any day during the pay period, so there will be a loop to check all 14 days in the pay period to see if one was his anniversary. CREATE OR replace FUNCTION Calc_anniversary( incoming_anniversary_date IN VARCHAR2) RETURN BOOLEAN IS hiredate VARCHAR2(20); terminationdate VARCHAR(20); employeeid VARCHAR2(38); paydate NUMBER := 0; BEGIN SELECT Count(arndt_raw_time_sheet_data.pay_date) INTO paydate FROM arndt_raw_time_sheet_data WHERE paydate = incoming_anniversary_date; WHILE paydate <= 14 LOOP SELECT To_char(employee_id, '999'), To_char(hire_date, 'DD-MON'), To_char(termination_date, 'DD-MON') INTO employeeid, hiredate, terminationdate FROM employees, time_sheet WHERE employees.employee_id = time_sheet.employee_id AND paydate = pay_date; IF terminationdate > hiredate THEN RETURN 'T'; ELSE IF To_char(SYSDATE, 'DD-MON') = To_char(hiredate, 'DD-MON')THEN RETURN 'Y'; ELSE RETURN 'N'; END IF; END IF; paydate := paydate + 1; END LOOP; END; Tables I am using CREATE TABLE Employees ( EMPLOYEE_ID INTEGER, FIRST_NAME VARCHAR2(15), LAST_NAME VARCHAR2(25), ADDRESS_LINE_ONE VARCHAR2(35), ADDRESS_LINE_TWO VARCHAR2(35), CITY VARCHAR2(28), STATE CHAR(2), ZIP_CODE CHAR(10), COUNTY VARCHAR2(10), EMAIL VARCHAR2(16), PHONE_NUMBER VARCHAR2(12), SOCIAL_SECURITY_NUMBER VARCHAR2(11), HIRE_DATE DATE, TERMINATION_DATE DATE, DATE_OF_BIRTH DATE, SPOUSE_ID INTEGER, MARITAL_STATUS CHAR(1), ALLOWANCES INTEGER, PERSONAL_TIME_OFF FLOAT, CONSTRAINT pk_employee_id PRIMARY KEY (EMPLOYEE_ID), CONSTRAINT fk_spouse_id FOREIGN KEY (SPOUSE_ID) REFERENCES EMPLOYEES (EMPLOYEE_ID)) / CREATE TABLE Arndt_Raw_Time_Sheet_data ( EMPLOYEE_ID INTEGER, PAY_DATE DATE, HOURS_WORKED FLOAT, SALES_AMOUNT FLOAT, CONSTRAINT pk_employee_id_pay_date_time PRIMARY KEY (EMPLOYEE_ID, PAY_DATE), CONSTRAINT fk_employee_id_time FOREIGN KEY (EMPLOYEE_ID) REFERENCES EMPLOYEES (EMployee_ID)); error FUNCTION Calc_Anniversary compiled Warning: execution completed with warning

  Read the article

• in haskell, why do I need to specify type constraints, why can't the compiler figure them out?

  - by Steve

  Consider the function, add a b = a + b This works: *Main> add 1 2 3 However, if I add a type signature specifying that I want to add things of the same type: add :: a -> a -> a add a b = a + b I get an error: test.hs:3:10: Could not deduce (Num a) from the context () arising from a use of `+' at test.hs:3:10-14 Possible fix: add (Num a) to the context of the type signature for `add' In the expression: a + b In the definition of `add': add a b = a + b So GHC clearly can deduce that I need the Num type constraint, since it just told me: add :: Num a => a -> a -> a add a b = a + b Works. Why does GHC require me to add the type constraint? If I'm doing generic programming, why can't it just work for anything that knows how to use the + operator? In C++ template programming, you can do this easily: #include <string> #include <cstdio> using namespace std; template<typename T> T add(T a, T b) { return a + b; } int main() { printf("%d, %f, %s\n", add(1, 2), add(1.0, 3.4), add(string("foo"), string("bar")).c_str()); return 0; } The compiler figures out the types of the arguments to add and generates a version of the function for that type. There seems to be a fundamental difference in Haskell's approach, can you describe it, and discuss the trade-offs? It seems to me like it would be resolved if GHC simply filled in the type constraint for me, since it obviously decided it was needed. Still, why the type constraint at all? Why not just compile successfully as long as the function is only used in a valid context where the arguments are in Num? Thank you.

  Read the article

• List all foreign key constraints that refer to a particular column in a specific table

  - by Sid

  I would like to see a list of all the tables and columns that refer (either directly or indirectly) a specific column in the 'main' table via a foreign key constraint that has the ON DELETE=CASCADE setting missing. The tricky part is that there would be an indirect relationships buried across up to 5 levels deep. (example: ... great-grandchild- FK3 = grandchild = FK2 = child = FK1 = main table). We need to dig up the leaf tables-columns, not just the very 1st level. The 'good' part about this is that execution speed isn't of concern, it'll be run on a backup copy of the production db to fix any relational issues for the future. I did SELECT * FROM sys.foreign_keys but that gives me the name of the constraint - not the names of the child-parent tables and the columns in the relationship (the juicy bits). Plus the previous designer used short, non-descriptive/random names for the FK constraints, unlike our practice below The way we're adding constraints into SQL Server: ALTER TABLE [dbo].[UserEmailPrefs] WITH CHECK ADD CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] FOREIGN KEY([UserId]) REFERENCES [dbo].[UserMasterTable] ([UserId]) ON DELETE CASCADE GO ALTER TABLE [dbo].[UserEmailPrefs] CHECK CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] GO The comments in this SO question inpire this question.

  Read the article

• Is it possible to modify the value of a record's primary key in Oracle when child records exist?

  - by Chris Farmer

  I have some Oracle tables that represent a parent-child relationship. They look something like this: create table Parent ( parent_id varchar2(20) not null primary key ); create table Child ( child_id number not null primary key, parent_id varchar2(20) not null, constraint fk_parent_id foreign key (parent_id) references Parent (parent_id) ); This is a live database and its schema was designed long ago under the assumption that the parent_id field would be static and unchanging for a given record. Now the rules have changed and we really would like to change the value of parent_id for some records. For example, I have these records: Parent: parent_id --------- ABC123 Child: child_id parent_id -------- --------- 1 ABC123 2 ABC123 And I want to modify ABC123 in these records in both tables to something else. It's my understanding that one cannot write an Oracle update statement that will update both parent and child tables simultaneously, and given the FK constraint, I'm not sure how best to update my database. I am currently disabling the fk_parent_id constraint, updating each table independently, and then enabling the constraint. Is there a better, single-step way to update this content?

  Read the article

• How to set up WebLogic 10.3.3. security for JAX_WS web services?

  - by Roman Kagan

  I have quite simple task to accomplish - I have to set up the security for web services ( basic authentication with hardcoded in WLES user id and password). I set the web.xml (see code fragment below) but I have tough time configuring WebLogic. I added IdentityAssertionAuthenticator Authentication Provider, set it as Required, modified DefaultAuthenticator as Optional and I went to deployed application's security and set the role to "thisIsUser" and at some point it worked, but not anymore (I redeployed war file and set web service security the same way but no avail.) I'd greatly appreciate for all your help. <security-constraint> <display-name>SecurityConstraint</display-name> <web-resource-collection> <web-resource-name>ABC</web-resource-name> <url-pattern>/ABC</url-pattern> </web-resource-collection> <auth-constraint> <role-name>thisIsUser</role-name> </auth-constraint> </security-constraint>

  Read the article

• How do I get the earlist DateTime of a set, where there is a few conditions

  - by radbyx

  Create script for Product SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[Product]( [ProductID] [int] IDENTITY(1,1) NOT NULL, [ProductName] [varchar](50) NOT NULL, CONSTRAINT [PK_Products] PRIMARY KEY CLUSTERED ( [ProductID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET ANSI_PADDING OFF GO Create script for StateLog SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[StateLog]( [StateLogID] [int] IDENTITY(1,1) NOT NULL, [ProductID] [int] NOT NULL, [Status] [bit] NOT NULL, [TimeStamp] [datetime] NOT NULL, CONSTRAINT [PK_Uptime] PRIMARY KEY CLUSTERED ( [StateLogID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[StateLog] WITH CHECK ADD CONSTRAINT [FK_Uptime_Products] FOREIGN KEY([ProductID]) REFERENCES [dbo].[Product] ([ProductID]) GO ALTER TABLE [dbo].[StateLog] CHECK CONSTRAINT [FK_Uptime_Products] GO I have this and it's not enough: select top 5 [ProductName], [TimeStamp] from [Product] inner join StateLog on [Product].ProductID = [StateLog].ProductID where [Status] = 0 order by TimeStamp desc; (My query givess the 5 lastest TimeStamp's where Status is 0(false).) But I need a thing more: Where there is a set of lastest TimeStamps for a product where Status is 0, i only want the earlist of them (not the lastet). Example: Let's say for Product X i have: TimeStamp1(status = 0) TimeStamp2(status = 1) TimeStamp3(status = 0) TimeStamp4(status = 0) TimeStamp5(status = 1) TimeStamp6(status = 0) TimeStamp7(status = 0) TimeStamp8(status = 0) Correct answer would then be:: TimeStamp6, because it's the first of the lastest timestamps.

  Read the article

• Mono for Android Book has been Released!!!!!

  - by Wallym

  If I understand things correctly, and I make no guarantees that I do, our Mono for Android book has been RELEASED!  I'm not quite sure what this means, but my guess is that that it has been printed and is being shipped to various book sellers.So, if you have pre-ordered a copy, its now up to Amazon to send it to you.  Its fully out of my control, Wrox, Wiley, as well as everyone but Amazon.If you haven't bought a copy already, why?  Seriously, go order 8-10 copies for the ones you love.  They'll make great romantic gifts for the ones you love.  Just think at the look on the other person's face when you give them a copy of our book. Here's a little about the book:The wait is over! For the millions of .NET/C# developers who have been eagerly awaiting the book that will guide them through the white-hot field of Android application programming, this is the book. As the first guide to focus on Mono for Android, this must-have resource dives into writing applications against Mono with C# and compiling executables that run on the Android family of devices.Putting the proven Wrox Professional format into practice, the authors provide you with the knowledge you need to become a successful Android application developer without having to learn another programming language. You'll explore screen controls, UI development, tables and layouts, and MonoDevelop as you become adept at developing Android applications with Mono for Android.Develop Android apps using tools you already know—C# and .NETAimed at providing readers with a thorough, reliable resource that guides them through the field of Android application programming, this must-have book shows how to write applications using Mono with C# that run on the Android family of devices. A team of authors provides you with the knowledge you need to become a successful Android application developer without having to learn another programming language. You'll explore screen controls, UI development, tables and layouts, and MonoDevelop as you become adept at planning, building, and developing Android applications with Mono for Android.Professional Android Programming with Mono for Android and .NET/C#:Shows you how to use your existing C# and .NET skills to build Android appsDetails optimal ways to work with data and bind data to controlsExplains how to program with Android device hardwareDives into working with the file system and application preferencesDiscusses how to share code between Mono for Android, MonoTouch, and Windows® Phone 7Reveals tips for globalizing your apps with internationalization and localization supportCovers development of tablet apps with Android 4Wrox Professional guides are planned and written by working programmers to meet the real-world needs of programmers, developers, and IT professionals. Focused and relevant, they address the issues technology professionals face every day. They provide examples, practical solutions, and expert education in new technologies, all designed to help programmers do a better job.Now, go buy a bunch of copies!!!!!If you are interested in iPhone and Android and would like to get a little more knowledgeable in the area of development, you can purchase the 3 pack of books from Wrox on Mobile Development with Mono.  This will cover MonoTouch, Mono for Android, and cross platform methods for using both tools.  A great package in and of itself.  The name of that package is: Wrox Cross Platform Android and iOS Mobile Development Three-Pack 

  Read the article

• Interesting Topics in Comp. Sci. for New Students?

  - by SoulBeaver

  I hope this is the right forum to ask this question. Last friday I was in a discussion with my professors about the students' lack of motivation and interest in the field of Computer Science. All of the students are enrolled, but through questionnaires and other questions that my professor posed it was revealed that over 90% of all enrolled students are just in it for the reward of getting a job sometime in the future (since it's a growing field with high job potential) I asked my professor for the permission to take over the first couple of lectures and try and motivate, interest and inspire students for the field of Computer Science and programming in particular (this is the Intro to Programming course). This request was granted and I now have a week to come up with a lecture topic for my professor's five groups. My main goal isn't to teach, I just want to get students to be as interested in the field as I am. I want to show them what's possible, what awesome magical things have been done in the field, the future we are heading towards using programming and Comp. Sci. Therefore, I would like to pose this question: I have a few topics, materials and sample projects that I would like to talk about: -- Grace Hopper (It is my hope to interest the female programmers in the class. There are never more than two or three per group and they, more than males, are prone to jumping ship and abandoning Comp. Sci.) -- The Singularity Institute -- Alan Turing -- Robotics -- Programming not as a chore or a must, but the idea that we are, at our core, the nexus to which anything anybody does in the digital world is connected to. We are the problem solvers; we assemble all the parts together and we are the ones that, essentially, make the vision a reality. -- Give them an idea for a programming project which, through the help of the professor, could be significant to every student (I want students to not only feel interested in the topic, but they should feel important, that what they do here makes a difference) Do you have interesting topics worthy of discussion, something I can tell the students which they can get interested about? How would you approach the lecture? If you had 90 minutes worth of time to try and get students interested in the project, what would you do?

  Read the article

• How to interview a natural scientist for a dev position?

  - by Silas

  I already did some interviews for my company, mostly computer scientists for dev positions but also some testers and project managers. Now I have to fill a vacancy in our research group within the R&D department (side note: “research” means that we try to solve problems in our professional domain/market niche using software in research projects together with universities, other companies, research centres and end user organisations. It’s not computer science research; we’re not going to solve the P=NP problem). Now we invited a guy holding an MSc in chemistry (with a lot of physics in his CV, too), who never had any computer science lesson. I already talked with him about half an hour at a local university’s career days and there’s no doubt the guy is smart. Also his marks are excellent and he graduated with distinction. For his BSc he needed to teach himself programming in Mathematica and told me believably that he liked programming a lot. Also he solved some physical chemistry problem that I probably don’t understand using his own software, implemented in Mathematica, for his MSc thesis. It includes a GUI and a notable size of 8,000 LoC. He seems to be very attracted by what we’re doing in our research group and to be honest it’s quite difficult for an SME like us to get good people. I also am very interested in hiring him since he could assist me in writing project proposals, reports, doing presentations and so on. He would probably fit to our team, too. The only question left is: How can I check if he will get the programming skills he needs to do software implementation in our projects since this will be a significant part of the job? Of course I will ask him what it is, that is fascinating him about programming. I’ll also ask how he proceeded to write his natural science software and how he structured it. I’ll ask about how he managed to obtain the skills and information about software development he needed. But is there something more I could ask? Something more concrete perhaps? Should I ask him to explain his Mathematica solution? To be clear: I’m not looking for knowledge in a particular language or technology stack. We’re a .NET shop in product development but I want to have a free choice for our research projects. So I’m interested in the meta-competence being able to learn whatever is actually needed. I hope this question is answerable and not open-ended since I really like to know if there is a default way to check for the ability to get further programming skills on the job. If something is not clear to you please give me some comments and let me improve my question.

  Read the article

• Custom filtering in Android using ArrayAdapter

  - by Alxandr

  I'm trying to filter my ListView which is populated with this ArrayAdapter: package me.alxandr.android.mymir.adapters; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.Iterator; import java.util.Set; import me.alxandr.android.mymir.R; import me.alxandr.android.mymir.model.Manga; import android.content.Context; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ArrayAdapter; import android.widget.Filter; import android.widget.SectionIndexer; import android.widget.TextView; public class MangaListAdapter extends ArrayAdapter<Manga> implements SectionIndexer { public ArrayList<Manga> items; public ArrayList<Manga> filtered; private Context context; private HashMap<String, Integer> alphaIndexer; private String[] sections = new String[0]; private Filter filter; private boolean enableSections; public MangaListAdapter(Context context, int textViewResourceId, ArrayList<Manga> items, boolean enableSections) { super(context, textViewResourceId, items); this.filtered = items; this.items = filtered; this.context = context; this.filter = new MangaNameFilter(); this.enableSections = enableSections; if(enableSections) { alphaIndexer = new HashMap<String, Integer>(); for(int i = items.size() - 1; i >= 0; i--) { Manga element = items.get(i); String firstChar = element.getName().substring(0, 1).toUpperCase(); if(firstChar.charAt(0) > 'Z' || firstChar.charAt(0) < 'A') firstChar = "@"; alphaIndexer.put(firstChar, i); } Set<String> keys = alphaIndexer.keySet(); Iterator<String> it = keys.iterator(); ArrayList<String> keyList = new ArrayList<String>(); while(it.hasNext()) keyList.add(it.next()); Collections.sort(keyList); sections = new String[keyList.size()]; keyList.toArray(sections); } } @Override public View getView(int position, View convertView, ViewGroup parent) { View v = convertView; if(v == null) { LayoutInflater vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); v = vi.inflate(R.layout.mangarow, null); } Manga o = items.get(position); if(o != null) { TextView tt = (TextView) v.findViewById(R.id.MangaRow_MangaName); TextView bt = (TextView) v.findViewById(R.id.MangaRow_MangaExtra); if(tt != null) tt.setText(o.getName()); if(bt != null) bt.setText(o.getLastUpdated() + " - " + o.getLatestChapter()); if(enableSections && getSectionForPosition(position) != getSectionForPosition(position + 1)) { TextView h = (TextView) v.findViewById(R.id.MangaRow_Header); h.setText(sections[getSectionForPosition(position)]); h.setVisibility(View.VISIBLE); } else { TextView h = (TextView) v.findViewById(R.id.MangaRow_Header); h.setVisibility(View.GONE); } } return v; } @Override public void notifyDataSetInvalidated() { if(enableSections) { for (int i = items.size() - 1; i >= 0; i--) { Manga element = items.get(i); String firstChar = element.getName().substring(0, 1).toUpperCase(); if(firstChar.charAt(0) > 'Z' || firstChar.charAt(0) < 'A') firstChar = "@"; alphaIndexer.put(firstChar, i); } Set<String> keys = alphaIndexer.keySet(); Iterator<String> it = keys.iterator(); ArrayList<String> keyList = new ArrayList<String>(); while (it.hasNext()) { keyList.add(it.next()); } Collections.sort(keyList); sections = new String[keyList.size()]; keyList.toArray(sections); super.notifyDataSetInvalidated(); } } public int getPositionForSection(int section) { if(!enableSections) return 0; String letter = sections[section]; return alphaIndexer.get(letter); } public int getSectionForPosition(int position) { if(!enableSections) return 0; int prevIndex = 0; for(int i = 0; i < sections.length; i++) { if(getPositionForSection(i) > position && prevIndex <= position) { prevIndex = i; break; } prevIndex = i; } return prevIndex; } public Object[] getSections() { return sections; } @Override public Filter getFilter() { if(filter == null) filter = new MangaNameFilter(); return filter; } private class MangaNameFilter extends Filter { @Override protected FilterResults performFiltering(CharSequence constraint) { // NOTE: this function is *always* called from a background thread, and // not the UI thread. constraint = constraint.toString().toLowerCase(); FilterResults result = new FilterResults(); if(constraint != null && constraint.toString().length() > 0) { ArrayList<Manga> filt = new ArrayList<Manga>(); ArrayList<Manga> lItems = new ArrayList<Manga>(); synchronized (items) { Collections.copy(lItems, items); } for(int i = 0, l = lItems.size(); i < l; i++) { Manga m = lItems.get(i); if(m.getName().toLowerCase().contains(constraint)) filt.add(m); } result.count = filt.size(); result.values = filt; } else { synchronized(items) { result.values = items; result.count = items.size(); } } return result; } @SuppressWarnings("unchecked") @Override protected void publishResults(CharSequence constraint, FilterResults results) { // NOTE: this function is *always* called from the UI thread. filtered = (ArrayList<Manga>)results.values; notifyDataSetChanged(); } } } However, when I call filter('test') on the filter nothing happens at all (or the background-thread is run, but the list isn't filtered as far as the user conserns). How can I fix this?

  Read the article

• Solr Multicore Admin Problem

  - by Daniel M

  Im trying to add a url based security constraint to solr deployed in websphere 6.1. If I specify the core name in the url of the constraint then the admin url for that core gives a 404. Has anyone had any success with this or any suggestions? Cheers Cross-posted with stackoverflow

  Read the article

• Is this information about me as a programmer concise and good enough?

  - by Nick Rosencrantz

  I not only want you to review my resume but please tell me what you think Google means when they answered me: "We don't look at personal letters and we like your resume and we can recommend you internally but we need measurable experience. What is meant with "measurable" here? Do they mean like O(1) compared to O(n), selling an entire company, grades or what? This is what I sent: Curriculum vitae Nick Rosencrantz Competence: System development, web development Technical competence: Java, Javascript, HTML, XML, CSS, AJAX, PHP, SQL, Python Employments: 2012- Mobile Innovation AB System Developer IT consultant (Java programmer) 2011-2012 Bnano International Ltd System Developer Python programming in Google App Engine 2008-2009 Sweden Island AB System Developer Programming C++ and Java EE components 2003-2007 Studies Stockholm School of Economics During studies worked as network technician at Effnet AB 2000-2002 Jadestone AB System Developer System development in Java/J2EE. In 2001: KTH, Assistant. Teaching application server programming in Java Enterprise + weblogic + Informix. 1999-2000 Studies KTH 1996-1998 Spray.se System development, Researcher 1995-1995 Finance broker Backoffice work with financial instruments 1993-1994 Computer & Audio-Technical Systems AB Programming, sommer job Education/Courses: Stockholm School of Economics, Master of Science diploma, KTH, Computer Science undergraduate studies Languages Swedish, English, also some German and French Born 1973, Swedish citizen I also have a project-based CS which is several pages long but the above is about what I was aiming for in the beginning when I was looking for a job, now I have employment as an IT consultant in central Stockholm and I want to make my resume concise and also know what Google meant with their answer (It was a Swedish Google employee that via linkedin recruited from my Stockholm School of Economics groups since that is a small elite economics school where I took my M.Sc. and KTH is one of the largest universities in northern Europe so I sent her a link with my CV and she said she could promote me internally if I added "measurable experience" and I've been thinking for weeks what that may mean?

  Read the article

• Ruby or Python?

  - by Bobby Tables

  Hi all, This question is extremely subjective and open-ended. It might even sound like something I should just research for myself and make my own decision. But I'd like to put it out there and get some thoughts from others. Long story short - I burned out with the rat race and am on a self-funded sabbatical this year. Much of it is to take a break from the corporate grind and travel around, but I also want to play around with new technologies and do some self-learning projects, to stay up to speed on programming, and well - I just love tinkering with programming, when there's no pressure! Here's the thing: I am a lifetime C/C++/Java programmer. I'm a bit of a squiggly bracket snob since I've been working with this family of languages for my entire programming career. So I'd like to learn a language which isn't so closely syntactically related to this group. What I'm basically looking for is a language which is relatively general purpose, fun to learn, has some new concepts that are different from C++/Java, and has a good community. A secondary consideration is that it has good web development frameworks. A tertiary consideration is that it's not totally academic (read: there are real world jobs out there using it). I've narrowed it down to Ruby or Python. My impression of Ruby is that it is extremely web oriented - that the only real application of it is as a server side scripting language for doing web stuff (mainly Ruby on Rails). For Python I'm not so sure. TL;DR and to put it as succinctly as possible: which of these would be better for a C++/Java guy to learn to get some new perspectives on programming? And which is more open and general purpose and applicable to a wider set of applications? I'm leaning towards Ruby at the moment, but I worry to an extent that it looks like it's used as nothing but a server side web language.

  Read the article

• Moving from windows to linux

  - by rincewind

  I need to reconcile these 2 facts: I don't feel comfortable working on Linux; I need to develop software for Linux. Some background: I have a 10+ years of programming experience on Windows (almost exclusively C/C++, but some .NET as well), I was a user of FreeBSD at home for about 3 years or so (then had to go back to Windows), and I've never had much luck with Linux. And now I have to develop software for Linux. I need a plan. On Windows, you can get away with just knowing a programming language, an API you're coding against, your IDE (VisualStudio) and some very basic tools for troubleshooting (Depends, ProcessExplorer, DebugView, WinDbg). Everything else comes naturally. On Linux, it's a very different story. How the hell would I know what DLL (sorry, Shared Object) would load, if I link to it from Firefox plugin? What's the Linux equivalent of inserting __asm int 3/DebugBreak() in the source and running the program, and then letting the OS call a debugger? Why the hell release builds use something, called appLoader, while debug builds work somehow different? Worst of all: how to provision Linux development environment? So, taking into account that hatred is usually associated with not knowing enough, what would you recommend? I'm ok with Emacs and GCC. I need to educate myself as a Linux admin/user, and I need to learn proper troubleshooting tools (strace is cool, btw), equivalents to the ones I mentioned above. Do I need to do Linux From Scratch? Or do I need to just read some books (I've read "UNIX programming enviornment" by Kernighan and "Advanced Programming..." by Stevens, but I need to learn something more practical)? Or do I need to have some Linux distro on my home computer?

  Read the article

• The road to become a programmer [closed]

  - by user68991

  I'm looking for a 'career' change, I don't actually have a career at the moment since I haven't been able to find a job since I graduated with a degree in Materials Engineering. One of my loves has always been computers and programming, though I have never studied it seriously. When I was 11 I wrote a very basic graphical 'game' using notepad and HTML, where I drew each possible position of the main character on the different 'maze' level in MSPaint, using pictures of arrows as links to a new page with the character in a new position, and various other buttons would pop up 'search box', 'press button' etc. At the time I thought this was an amazing achievement of my programming skills. I've used a little bit of FORTRAN 90 whilst I was at university, which rekindled my interest in programming. When I was a kid I mainly used C and HTML, but only very basically as my 'game' suggests. I want to learn a new programming language, I'm not entirely sure where I want to go with it, but the number one contender at the moment is android apps. I'm looking at learning Java, but I've read that it's a difficult place to begin with; so I've also looked at learning Visual Basic, which I believe is also object oriented(?) but a little easier to understand? (not that I know what an object is anyway). Any information people could give me regarding which language to learn, and if there are any good online tutorial for that language I'd really appreciate it. Some of the tutorials I've used so far are full or jargon I can't understand. Also, I'm not afraid of maths having got an engineering degree. Thanks in advance for any help/advice. James

  Read the article

• Is this kind of Design by Contract useless?

  - by Charlie Pigarelli

  I've just started informatics university and I'm attending a programming course about C(++). The programming professor prefers to teach very few things (in 3 month we have just reached the functions topic) and connect every topic with a type of programming design that somehow is similar to the Design by Contract design. Basically what he ask us to do is to write every exercise with comments Pre-conditions, Post-conditions and Invariants that should prove the correctness of each program we write. But this doesn't make any sense to me. I mean, ok: maybe writing down your thoughts prevent you from doing some mistakes, but if this is all an abstract thing, then if your program intuition is wrong you'll write your program wrong and then you'll also write pre and post conditions wrong probably auto convincing your self about its correctness. Most of the time, both me and other students have written programs that seemed ok and that had correct pre and post condition too. But at the moment of testing it was just completely wrong. I had some experience before this course of programming and I had written a lot of line of code before and I found myself comfortably with just writing a program and unit test it. It take less time to accomplish and is less "abstract" than just thinking about what every single piece of your program should do in every case (which is kinda like mentally testing it). Finally, all this pre and post conditions takes me like 80% of the total time of the exercise. It's harder to think about putting down this pre and post correct than to write the program itself. Since we are like the only course of the only university probably in the entire world that makes this things, could someone please tell me how should I manage this thing? Am I right thinking that this doesn't worth anything? Should I change university? (there are like double of the people attending that course and it seems that usually very few people passes the exam the first year). Should I convince myself it's method is right?

  Read the article

• How to learn the math behind the code?

  - by Solomon Wise

  I am a 12 year old who has recently gotten into programming. (Although I know that the number of books you have read does not determine your programming competency or ability, just to paint a "map" of where I am in terms of the content I know...) I've finished the books: Python 3 For Absolute Beginners Pro Python Python Standard Library by Example Beautiful Code Agile Web Development With Rails and am about halfway into Programming Ruby. I have written many small programs (One that finds which files have been updated and deleted in a directory, one that compares multiple players' fantasy baseball value, and some text based games, and many more). Obviously, as I'm not some sort of child prodigy, I can't take a formal Computer Science course until high school. I really want to learn computer science to increase my knowledge about the code, and the how the code runs. I've really become interested in the math part after reading the source code for Python's random module. Is there a place where I can learn CS, or programming math online for free, at a level that would be at least partially understandable to a person my age?

  Read the article

• Ways to break the "Syndrome of the perfect programmer"

  - by Rushino

  I am probably not the only one that feel that way. But I have what I tend to call "The syndrome of the perfect programmer" which many might say is the same as being perfectionist but in this case it's in the domain of programming. However, the domain of programming is a bit problematic for such a syndrome. Have you ever felt that when you are programming you're not confident or never confident enought that your code is clean and good code that follows most of the best practices ? There so many rules to follow that I feel like being overwhelmed somehow. Not that I don't like to follow the rules of course I am a programmer and I love programming, I see this as an art and I must follow the rules. But I love it too, I mean I want and I love to follow the rules in order to have a good feeling of what im doing is going the right way.. but I only wish I could have everything a bit more in "control" regarding best practices and good code. Maybe it's a lack of organization? Maybe it's a lack of experience? Maybe a lack of practice? Maybe it's a lack of something else someone could point out? Is there any way to get rid of that syndrome somehow ?

  Read the article

< Previous Page | 225 226 227 228 229 230 231 232 233 234 235 236  | Next Page >