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• mailing system DB structure, need help

  - by Anna

  i have a system there user(sender) can write a note to friends(receivers), number of receivers=0. Text of the message is saved in DB and visible to sender and all receivers then they login to system. Sender can add more receivers at any time. More over any of receivers can edit the message and even remove it from DB. For this system i created 3 tables, shortly: users(userID, username, password) messages(messageID, text) list(id, senderID, receiverID, messageID) in table "list" each row corresponds to pair sender-receiver, like sender_x_ID -- receiver_1_ID -- message_1_ID sender_x_ID -- receiver_2_ID -- message_1_ID sender_x_ID -- receiver_3_ID -- message_1_ID Now the problem is: 1. if user deletes the message from table "messages" how to automatically delete all rows from table "list" which correspond to deleted message. Do i have to include some foreign keys? More important: 2. if sender has let say 3 receivers for his message1 (username1, username2 and username3) and at certain moment decides to add username4 and username5 and at the same time exclude username1 from the list of receivers. PHP code will get the new list of receivers (username2, username3, username4, username5) That means insert to table "list" sender_x_ID -- receiver_4_ID -- message_1_ID sender_x_ID -- receiver_5_ID -- message_1_ID and also delete from table "list" the row corresponding to user1 (which is not in the list or receivers any more) sender_x_ID -- receiver_1_ID -- message_1_ID which sql query to send from PHP to make it in an easy and intelligent way? Please help! Examples of sql queries would be perfect!

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• Is it possible to load an entire SQL Server CE database into RAM?

  - by DanM

  I'm using LinqToSql to query a small SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table via a foreign key, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of the appeal of LinqToSql. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view.

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• Entity Framework 4 Entity with EntityState of Unchanged firing update

  - by Andy

  I am using EF 4, mapping all CUD operations for my entities using sprocs. I have two tables, ADDRESS and PERSON. A PERSON can have multiple ADDRESS associated with them. Here is the code I am running: Person person = (from p in context.People where p.PersonUID == 1 select p).FirstOrDefault(); Address address = (from a in context.Addresses where a.AddressUID == 51 select a).FirstOrDefault(); address.AddressLn2 = "Test"; context.SaveChanges(); The Address being updated is associated with the Person I am retrieveing - although they are not explicitly linked in any way in the code. When the context.SaveChanges() executes not only does the Update sproc for my Address entity get fired (like you would expect), but so does the Update sproc for the Person entity - even though you can see there was no change made to the Person entity. When I check the EntityState of both objects before the context.SaveChanges() call I see that my Address entity has an EntityState of "Modified" and my Person enity has an EntityState of "Unchanged". Why is the Update sproc being called for the Person entity? Is there a setting of some sort that I can set to prevent this from happening?

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• Update table using SSIS

  - by thursdaysgeek

  I am trying to update a field in a table with data from another table, based on a common key. If it were in straight SQL, it would be something like: Update EHSIT set e.IDMSObjID = s.IDMSObjID from EHSIT e, EHSIDMS s where e.SITENUM = s.SITE_CODE However, the two tables are not in the same database, so I'm trying to use SSIS to do the update. Oh, and the sitenum/site_code are varchar in one and nvarchar in the other, so I'll have to do a data conversion so they'll match. How do I do it? I have a data flow object, with the source as EHSIDMS and the destination as EHSIT. I have a data conversion to convert the unicode to non-unicode. But how do I update based on the match? I've tried with the destination, using a SQL Command as the Data Access mode, but it doesn't appear to have the source table. If I just map the field to be updated, how does it limit it based on fields matching? I'm about to export my source table to Excel or something, and then try inputting from there, although it seems that all that would get me would be to remove the data conversion step. Shouldn't there be an update data task or something? Is it one of those Data Flow transformation tasks, and I'm just not figuring out which it is?

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• Is there unresizable space in latex? Pictures in good looking grid.

  - by drasto

  I've created latex macro to typeset guitar chords diagrams(using picture environment). Now I want to make diagrams of different appear in good looking grid when typeset one next to each other as the picture shows: The picture. (on the picture: Labeled "First" bad layout of diagrams, labeled "Second" correct layout when equal number of diagrams in line) I'm using \hspace to make some skips between diagrams, otherwise they would be too near to each other. As you can see in second case when latex arrange pictures in so that there is same number of them in each line it works. However if there is less pictures in the last line they become "shifted" to the right. I don't want this. I guess is because latex makes the space between diagrams in first line a little longer for the line to exactly fit the page width. How do I tell latex not to resize spaces created by \hspace ? Or is there any other way ? I guess I cannot use tables because I don't know how many diagrams will fit in one line... This is current state of code: \newcommand{\spaceForChord}{1.7cm} \newcommnad{\chordChart}[1]{% %calculate dimensions xdim and ydim according to setings \begin{picture}(xdim, ydim){% %draw the diagram inside defined area }% \hspace*{\spaceForChord}% \hspace*{-\xdim}% }% %end preambule and begin document \begin{document} First:\\* \\* \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} %...above line is repeated 12 more times to produce result shown at the picture \end{document} Thanks for any help.

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• iPhone - Using sql database - insert statement failing

  - by Satyam svv

  Hi, I'm using sqlite database in my iphone app. I've a table which has 3 integer columns. I'm using following code to write to that database table. -(BOOL)insertTestResult { NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString* documentsDirectory = [paths objectAtIndex:0]; NSString* dataBasePath = [documentsDirectory stringByAppendingPathComponent:@"test21.sqlite3"]; BOOL success = NO; sqlite3* database = 0; if(sqlite3_open([dataBasePath UTF8String], &database) == SQLITE_OK) { BOOL res = (insertResultStatement == nil) ? createStatement(insertResult, &insertResultStatement, database) : YES; if(res) { int i = 1; sqlite3_bind_int(insertResultStatement, 0, i); sqlite3_bind_int(insertResultStatement, 1, i); sqlite3_bind_int(insertResultStatement, 2, i); int err = sqlite3_step(insertResultStatement); if(SQLITE_ERROR == err) { NSAssert1(0, @"Error while inserting Result. '%s'", sqlite3_errmsg(database)); success = NO; } else { success = YES; } sqlite3_finalize(insertResultStatement); insertResultStatement = nil; } } sqlite3_close(database); return success;} The command sqlite3_step is always giving err as 19. I'm not able to understand where's the issue. Tables are created using following queries: CREATE TABLE [Patient] (PID integer NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,PFirstName text NOT NULL,PLastName text,PSex text NOT NULL,PDOB text NOT NULL,PEducation text NOT NULL,PHandedness text,PType text) CREATE TABLE PatientResult(PID INTEGER,PFreeScore INTEGER NOT NULL,PForcedScore INTEGER NOT NULL,FOREIGN KEY (PID) REFERENCES Patient(PID)) I've only one entry in Patient table with PID = 1 BOOL createStatement(const char* query, sqlite3_stmt** stmt, sqlite3* database){ BOOL res = (sqlite3_prepare_v2(database, query, -1, stmt, NULL) == SQLITE_OK); if(!res) NSLog( @"Error while creating %s => '%s'", query, sqlite3_errmsg(database)); return res;}

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• How to use Transaction in Entity FrameWork?

  - by programmerist

  How to use Transaction in Entity FrameWork? i read some links on Stackoverflow : http://stackoverflow.com/questions/815586/entity-framework-using-transactions-or-savechangesfalse-and-acceptallchanges BUT; i have 3 table so i have 3 entities: CREATE TABLE Personel (PersonelID integer PRIMARY KEY identity not null, Ad varchar(30), Soyad varchar(30), Meslek varchar(100), DogumTarihi datetime, DogumYeri nvarchar(100), PirimToplami float); Go create TABLE Prim (PrimID integer PRIMARY KEY identity not null, PersonelID integer Foreign KEY references Personel(PersonelID), SatisTutari int, Prim float, SatisTarihi Datetime); Go CREATE TABLE Finans (ID integer PRIMARY KEY identity not null, Tutar float); Personel, Prim,Finans my tables. if you look Prim table you can see Prim value float value if i write a textbox not float value my transaction must run. using (TestEntities testCtx = new TestEntities()) { using (TransactionScope scope = new TransactionScope()) { // do someyihng... testCtx.Personel.SaveChanges(); // do someyihng... testCtx.Prim.SaveChanges(); // do someyihng... testCtx.Finans.SaveChanges(); scope .Complete(); success = true; } } How can i do that?

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• C programming - How to print numbers with a decimal component using only loops?

  - by californiagrown

  I'm currently taking a basic intro to C programming class, and for our current assignment I am to write a program to convert the number of kilometers to miles using loops--no if-else, switch statements, or any other construct we haven't learned yet are allowed. So basically we can only use loops and some operators. The program will generate three identical tables (starting from 1 kilometer through the input value) for one number input using the while loop for the first set of calculations, the for loop for the second, and the do loop for the third. I've written the entire program, however I'm having a bit of a problem with getting it to recognize an input with a decimal component. Here is what I have for the while loop conversions: #include <stdio.h> #define KM_TO_MILE .62 main (void) { double km, mi, count; printf ("This program converts kilometers to miles.\n"); do { printf ("\nEnter a positive non-zero number"); printf (" of kilometers of the race: "); scanf ("%lf", &km); getchar(); }while (km <= 1); printf ("\n KILOMETERS MILES (while loop)\n"); printf (" ========== =====\n"); count = 1; while (count <= km) { mi = KM_TO_MILE * count; printf ("%8.3lf %14.3lf\n", count, mi); ++count; } getchar(); } The code reads in and converts integers fine, but because the increment only increases by 1 it won't print a number with a decimal component (e.g. 3.2, 22.6, etc.). Can someone point me in the right direction on this? I'd really appreciate any help! :)

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• Best way to build an application based on R?

  - by Prasad Chalasani

  I'm looking for suggestions on how to go about building an application that uses R for analytics, table generation, and plotting. What I have in mind is an application that: displays various data tables in different tabs, somewhat like in Excel, and the columns should be sortable by clicking. takes user input parameters in some dialog windows. displays plots dynamically (i.e. user-input-dependent) either in a tab or in a new pop-up window/frame Note that I am not talking about a general-purpose fron-end/GUI for exploring data with R (like say Rattle), but a specific application. Some questions I'd like to see addressed are: Is an entirely R-based approach even possible ( on Windows ) ? The following passage from the Rattle article in R-Journal intrigues me: It is interesting to note that the first implementation of Rattle actually used Python for implementing the callbacks and R for the statistics, using rpy. The release of RGtk2 allowed the interface el- ements of Rattle to be written directly in R so that Rattle is a fully R-based application If it's better to use another language for the GUI part, which language is best suited for this? I'm looking for a language where it's relatively "painless" to build the GUI, and that also integrates very well with R. From this StackOverflow question How should I do rapid GUI development for R and Octave methods (possibly with Python)? I see that Python + PyQt4 + QtDesigner + RPy2 seems to be the best combo. Is that the consensus ? Anyone have pointers to specific (open source) applications of the type I describe, as examples that I can learn from?

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• Does this query fetch unnecessary information? Should I change the query?

  - by Camran

  I have this classifieds website, and I have about 7 tables in MySql where all data is stored. I have one main table, called "classifieds". In the classifieds table, there is a column called classified_id. This is not the PK, or a key whatsoever. It is just a number which is used for me to JOIN table records together. Ex: classifieds table: fordon table: id => 33 id => 12 classified_id => 10 classified_id => 10 ad_id => 'bmw_m3_92923' This above is linked together by the classified_id column. Now to the Q, I use this method to fetch all records WHERE the column ad_id matches any of the values inside an array, called in this case $ad_arr: SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*, hem_inredning.*, hobby.* FROM classified mt LEFT JOIN fordon ON fordon.classified_id = mt.classified_id LEFT JOIN boende ON boende.classified_id = mt.classified_id LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id LEFT JOIN business ON business.classified_id = mt.classified_id LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id LEFT JOIN hobby ON hobby.classified_id = mt.classified_id WHERE mt.ad_id IN ('$ad_arr')"; Is this good or would this actually fetch unnecessary information? Check out this Q I posted couple of days ago. In the comments HLGEM is commenting that it is wrong etc etc. What do you think? http://stackoverflow.com/questions/2782275/another-rookie-question-how-to-implement-count-here Thanks

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• How do i map this in NHibernate

  - by Andrew Smith

  I Have two classes, Survey and Poll classes. Also I have Question and Question Choice classes. How do I map these so I come out with particular table formats. here is the classes involved. public class Survey { public IList<Question> Questions { get; private set; } } public class Poll { public Question Question { get; set; } } public class Question { public string Text { get; set; } public IList<QuestionChocie> Choices { get; private set; } } public class QuestionChoice { public string Text { get; set; } } The resulting tables that I'm shooting for include the following Surveys- a table of survey information. Polls - a table of polls information. SurveyQuestions -a table of survey questions. PollQuestions - a table of poll questions. SurveyChoices - a table of the question choices for the surveys. PollChoices - a table of the question choices for the survey. preferably i really want to know for fluent nhibernate, or just mapping xml is fine too.

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• Find whether a particular cell of a table has an img tag

  - by SilentPro

  I am generating a table dynamically using Django. The same table template is used to generate a variety of tables depending on the data supplied. In one scenario a particular column contains image tags. Since my table is editable (using jquery) the image cell also becomes editable and removes my content. I want some special behavior on double click of such cells like say upload an image. How do I accomplish this with a jquery? My script for making the table editable is given below. $(function() { $("td").dblclick(function() { var OriginalContent = $(this).text(); $(this).addClass("cellEditing"); $(this).html("<input type='text' value='" + OriginalContent + "' />"); $(this).children().first().focus(); $(this).children().first().keypress(function(e) { if (e.which == 13) { var newContent = $(this).val(); $(this).parent().text(newContent); $(this).parent().removeClass("cellEditing"); } }); $(this).children().first().blur(function() { $(this).parent().text(OriginalContent); $(this).parent().removeClass("cellEditing"); }); }); });

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• How to use multiple identity numbers in one table?

  - by vincer

  I have an web application that creates printable forms, these forms have a unique number on them, the problem is I have 2 forms that separate numbers need to be created for them. ie) Form1- Numbered 2000000-2999999 Form2- Numbered 3000000-3999999 dbo.test2 - is my form information table Tsel - is my autoinc table for the 3000000 series numbers Tadv - is my autoinc table for the 2000000 series numbers What I have done is create 2 tables with just autoinc row (one for 2000000 series numbers and one for 3000000 series numbers), I then created a trigger to add a record to the coresponding table, read back the autoinc number and add it to my table that stores the form information including the just created autoinc number for the right series of forms. Although it does work, I'm concerned that the numbers will get messed up under load. I'm not sure the @@IDENTITY will always return the right value when many people are using the system. (I cannot have duplicates and I need to use the numbering form show above. See code below. ** TRIGGER ** CREATE TRIGGER MAKEANID2 ON dbo.test2 AFTER INSERT AS SET NOCOUNT ON declare @someid int declare @someid2 int declare @startfrom int declare @test1 varchar(10) select @someid=@@IDENTITY select @test1 = (Select name1 from test2 where sysid = @someid ) if @test1 = 'select' begin insert into Tsel Default values select @someid2 = @@IDENTITY end if @test1 = 'adv' begin insert into Tadv Default values select @someid2 = @@IDENTITY end update test2 set name2=(@someid2) where sysid = @someid SET NOCOUNT OFF

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• How to delete a row from a typed dataset and save it to a database?

  - by Zingam

  I am doing this as a small project to learn about disconnected and connected models in .NET 4.0 and SQL Server 2008 R2. I have three tables: Companies (PK CompanyID) Addresses (PK AddressID, FK CompanyID) ContactPersons (PK ContactPersonID, FK CompanyID) CompanyID is assigned manually by the users. The other IDs are auto-generated. Companies has a one-to-many relationship with ContactPerson. I have set any changes to cascade. I display all records in Companies in a DataGridView and when a row is clicked, the corresponding records in ContactPersons are displayed in a second DataGridView. I have successfully implemented updating and inserting new records but I completely fail in my attempts to delete rows and save the changes to the database. I us a typed dataset. If I use this: DataRow[] contactPersonRows = m_SoldaCompaniesFileDataSet.ContactPersons.Select("ContactPersonID = " + this.m_CurrentContactPerson.ContactPersonID); m_SoldaCompaniesFileDataSet.ContactPersons.Rows.Remove(contactPersonRows[0]); The records are displayed properly in the DataGridView but are not saved in the database later. If I use this: DataRow row = m_SoldaCompaniesFileDataSet.ContactPersons.Rows.Find(this.m_CurrentContactPerson.ContactPersonID); row.Delete(); The records are set but I get an exeception: DeletedRowInaccessibleException, when I try to refresh the DataGridView. The exception pop-s up in the auto-generated dataset.design file. I am pretty much stuck at this point since yesterday. I cannot find anything anywhere that remotely resembles my problem. And I cannot understand actually what is going on.

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• Subquery with multiple results combined into a single field?

  - by Todd

  Assume I have these tables, from which i need to display search results in a browser: Table: Containers id | name 1 Big Box 2 Grocery Bag 3 Envelope 4 Zip Lock Table: Sale id | date | containerid 1 20100101 1 2 20100102 2 3 20091201 3 4 20091115 4 Table: Items id | name | saleid 1 Barbie Doll 1 2 Coin 3 3 Pop-Top 4 4 Barbie Doll 2 5 Coin 4 I need output that looks like this: itemid itemname saleids saledates containerids containertypes 1 Barbie Doll 1,2 20100101,20100102 1,2 Big Box, Grocery Bag 2 Coin 3,4 20091201,20091115 3,4 Envelope, Zip Lock 3 Pop-Top 4 20091115 4 Zip Lock The important part is that each item type only gets one record/row in the return on the screen. I accomplished this in the past by returning multiple rows of the same item and using a scripting language to limit the output. However, this makes the ui overly complicated and loopy. So, I'm hoping I can get the database to spit out only as many records as there are rows to display. This example may be a bit extreme because of the 2 joins needed to get to the container from the item (through the sale table). I'd be happy for just an example query that outputs this: itemid itemname saleids saledates 1 Barbie Doll 1,2 20100101,20100102 2 Coin 3,4 20091201,20091115 3 Pop-Top 4 20091115 I can only return a single result in a subquery, so I'm not sure how to do this.

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• How to translate the fields of a database model?

  - by Tõnis M

  I have some tables/models in a web app that will have multilingual content. For example a university, with it's description in a default language(english) and the user wants he can see the same information in another language( if the object has it's fields translated). If there were only a few languages then I would just add fields like name_en and name_de and so on, but the number of languages isn't fixed, so that' would create a mess. I could also just create a new object with the translated data but then foreign keys wouldn't work, and only some of the fields can be translated so that would create duplicate data. Storing the translations in a file and using gettext or something similar is also not an option since the objects fields can be translated by the website user, not only developers/admins. What would be the best way to design/architect such a database? Searching from the translated data should also be not too complex - as it should not require creating complex joins which would make the queries slower I'm using PostgreSQL and Ruby of Rails but I'm not looking for a technical solution but for a general idea how to design it.

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• Entity framework self referencing loop detected

  - by Lyd0n

  I have a strange error. I'm experimenting with a .NET 4.5 Web API, Entity Framework and MS SQL Server. I've already created the database and set up the correct primary and foreign keys and relationships. I've created a .edmx model and imported two tables: Employee and Department. A department can have many employees and this relationship exists. I created a new controller called EmployeeController using the scaffolding options to create an API controller with read/write actions using Entity Framework. In the wizard, selected Employee as the model and the correct entity for the data context. The method that is created looks like this: // GET api/Employee public IEnumerable<Employee> GetEmployees() { var employees = db.Employees.Include(e => e.Department); return employees.AsEnumerable(); } When I call my API via /api/Employee, I get this error: ...The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; ...System.InvalidOperationException","StackTrace":null,"InnerException":{"Message":"An error has occurred.","ExceptionMessage":"Self referencing loop detected with type 'System.Data.Entity.DynamicProxies.Employee_5D80AD978BC68A1D8BD675852F94E8B550F4CB150ADB8649E8998B7F95422552'. Path '[0].Department.Employees'.","ExceptionType":"Newtonsoft.Json.JsonSerializationException","StackTrace":" ... Why is it self referencing [0].Department.Employees? That doesn't make a whole lot of sense. I would expect this to happen if I had circular referencing in my database but this is a very simple example. What could be going wrong?

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• Best way to limit results in MySQL with user subcategories

  - by JM4

  I am trying to essentially solve for the following: 1) Find all users in the system who ONLY have programID 1. 2) Find all users in the system who have programID 1 AND any other active program. My tables structures (in very simple terms are as follows): users userID | Name ================ 1 | John Smith 2 | Lewis Black 3 | Mickey Mantle 4 | Babe Ruth 5 | Tommy Bahama plans ID | userID | plan | status --------------------------- 1 | 1 | 1 | 1 2 | 1 | 2 | 1 3 | 1 | 3 | 1 4 | 2 | 1 | 1 5 | 2 | 3 | 1 6 | 3 | 1 | 0 7 | 3 | 2 | 1 8 | 3 | 3 | 1 9 | 3 | 4 | 1 10 | 4 | 2 | 1 11 | 4 | 4 | 1 12 | 5 | 1 | 1 I know I can easily find all members with a specific plan with something like the following: SELECT * FROM users a JOIN plans b ON (a.userID = b.userID) WHERE b.plan = 1 AND b.status = 1 but this will only tell me which users have an 'active' plan 1. How can I tell who ONLY has plan 1 (in this case only userID 5) and how to tell who has plan 1 AND any other active plan? Update: This is not to get a count, I will actually need the original member information, including all the plans they have so a COUNT(*) response may not be what I'm trying to achieve.

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• Java: over-typed structures?

  - by HH

  Term over-type structure = a data structure that accepts different types, can be primitive or user-defined. I think ruby supports many types in structures such as tables. I tried a table with types 'String', 'char' and 'File' in Java but errs. How can I have over-typed structure in Java? How to show types in declaration? What about in initilization? Suppose a structure: INDEX VAR FILETYPE //0 -> file FILE //1 -> lineMap SizeSequence //2 -> type char //3 -> binary boolean //4 -> name String //5 -> path String Code import java.io.*; import java.util.*; public class Object { public static void print(char a) { System.out.println(a); } public static void print(String s) { System.out.println(s); } public static void main(String[] args) { Object[] d = new Object[6]; d[0] = new File("."); d[2] = 'T'; d[4] = "."; print(d[2]); print(d[4]); } } Errors Object.java:18: incompatible types found : java.io.File required: Object d[0] = new File("."); ^ Object.java:19: incompatible types found : char required: Object d[2] = 'T'; ^

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• Unable to delete inherited entity class in EF4

  - by Coding Gorilla

  I have two entities in an EF4 model (using Model First), let's call them EntityA and EntityB. EntityA is marked as abstract, and EntityB inherits from EntityA. They are similar to the following: public class EntityA { public Guid Id; public string Name; public string Uri; } public class EntityB : EntityA { public string AnotherProperty; } The generated database tables look as I would expect them, with EntityA as on table, and then another table like: EntityA_EntityB Id (PK, FK, uniqueidentifier) AnotherProperty (varchar) There is a foreign key constraint on EntityA_EntityB that references EntityA's Id property, no cascades are configured (although I did try changing these myself). The problem is that when I attempt to do something like: Context.DeleteObject(EntityA_EntityB); EF attempts to delete the EntityA_EntityB table record before deleting the EntityA table record, which of course violates the foreign key constraint on EntityA_EntityB table. Using EFProfiler I see the following commands being sent to the database: delete [dbo].[EntityA_EntityB] where (([Id] = '5c02899f-09ea-2ed9-d44b-01aef80f6b64' /* @0 */) followed by delete [dbo].[EntityA] where ([Id] = '5c02899f-09ea-2ed9-d44b-01aef80f6b64' /* @0 */) I'm completely stumped as to how to get around this problem. I would think the EF should know that it needs to delete the base class first, before deleting the inherited class. I know I could do some triggers or other database type solutions, but I'd rather avoid doing that if I can. All my classes are POCO built using some customized T4 templates. I don't want to paste in a lot of extraneous code, but if you need more information I'll provide what I can.

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• Index question: Select * with WHERE clause. Where and how to create index

  - by Mestika

  Hi, I’m working on optimizing some of my queries and I have a query that states: select * from SC where c_id ="+c_id” The schema of ** SC** looks like this: SC ( c_id int not null, date_start date not null, date_stop date not null, r_t_id int not null, nt int, t_p decimal, PRIMARY KEY (c_id, r_t_id, date_start, date_stop)); My immediate bid on how the index should be created is a covering index in this order: INDEX(c_id, date_start, date_stop, nt, r_t_id, t_p) The reason for this order I base on: The WHERE clause selects from c_id thus making it the first sorting order. Next, the date_start and date_stop to specify a sort of “range” to be defined in these parameters Next, nt because it will select the nt Next the r_t_id because it is a ID for a specific type of my r_t table And last the t_p because it is just a information. I don’t know if it is at all necessary to order it in a specific way when it is a SELECT ALL statement. I should say, that the SC is not the biggest table. I can say how many rows it contains but a estimate could be between <10 and 1000. The next thing to add is, that the SC, in different queries, inserts the data into the SC, and I know that indexes on tables which have insertions can be cost ineffective, but can I somehow create a golden middle way to effective this performance. Don't know if it makes a different but I'm using IBM DB2 version 9.7 database Sincerely Mestika

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• How to configure a NSPopupButton for displaying multiple values in a TableView?

  - by jekmac

  Hi there! I'm using two entities A and B with to-many-to-many relationship. Lets say I got an entity A with attribute aAttrib and a to-many relationship aRelat to another entity B with attribute bAttrib and a to-many relationship bRelat with entity A. Now I am building an interface with two tables one for entity A and another for entity B. The table for entity B has two columns one for bAttrib and one for the relationship aRelat. The aRelat-column should be a NSPopupButtonCell to display multiple aAttrib values. I'd like to set all the bindings in InterfaceBuilder in Table Column Bindings: -- I have two NSArrayController each for one entity: Object Controller Mode:Entity Array Controller Bindings: Parameters Managed Object Context bind to File's Owner -- One Table Cloumn with a PopUpButtonCell: TableCloumnBindings Content bind to Entity A with ControllerKey arrangedObjects; Content Values bind to Entity A with ModelKeyPath aAttrib Selected Object bind to Entity B with ModelKeyPath bRelat I know that this configuration doesn't allow multiple value setting. But I don't know how to do the right one. Getting the following message: HIToolbox: ignoring exception 'Unacceptable type of value for to-many relationship: property = "bRelat"; desired type = NSSet; given type = NSCFString; value = testValue.' that raised inside Carbon event dispatch... Does anyone have any idea?

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• Mixing together Connect by, inner join and sum with Oracle

  - by François

  Hey there, I need help with a oracle query. Excuse me in advance for my english. Here is my setup: I have 2 tables called respectively "tasks" and "timesheets". The "tasks" table is a recursive one, that way each task can have multiple subtasks. Each timesheet is associated with a task (not necessarily the "root" task) and contains the number of hours worked on it. Example: Tasks id:1 | name: Task A | parent_id: NULL id:2 | name: Task A1 | parent_id: 1 id:3 | name: Task A1.1 | parent_id: 2 id:4 | name: Task B | parent_id: NULL id:5 | name: Task B1 | parent_id: 4 Timesheets id:1 | task_id: 1 | hours: 1 id:2 | task_id: 2 | hours: 3 id:3 | task_id:3 | hours: 1 id:5 | task_id:5 | hours:1 ... What I want to do: I want a query that will return the sum of all the hours worked on a "task hierarchy". If we take a look at the previous example, It means I would like to have the following results: task A - 5 hour(s) | task B - 1 hour(s) At first I tried this SELECT TaskName, Sum(Hours) "TotalHours" FROM ( SELECT replace(sys_connect_by_path(decode(level, 1, t.name), '~'), '~') As TaskName, ts.hours as hours FROM tasks t INNER JOIN timesheets ts ON t.id=ts.task_id START WITH PARENTOID=-1 CONNECT BY PRIOR t.id = t.parent_id ) GROUP BY TaskName Having Sum(Hours) > 0 ORDER BY TaskName And it almost work. THe only problem is that if there are no timesheet for a root task, it will skip the whole hieararchy... but there might be timesheets for the child rows and it is exactly what happens with Task B1. I know it is the "inner join" part that is causing my problem but I'm not sure how can I get rid of it. Any idea how to solve this problem? Thank you

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• SELECT product from subclass: How many queries do I need?

  - by Stefano

  I am building a database similar to the one described here where I have products of different type, each type with its own attributes. I report a short version for convenience product_type ============ product_type_id INT product_type_name VARCHAR product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id ... (common attributes to all product) magazine ======== magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id ... (magazine-specific attributes) web_site ======== web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id ... (web-site specific attributes) This way I do not need to make a huge table with a column for each attribute of different product types (most of which will then be NULL) How do I SELECT a product by product.product_id and see all its attributes? Do I have to make a query first to know what type of product I am dealing with and then, through some logic, make another query to JOIN the right tables? Or is there a way to join everything together? (if, when I retrieve the information about a product_id there are a lot of NULL, it would be fine at this point). Thank you

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• Best way to update/insert into a table based on a remote table.

  - by martilyo

  I have two very large enterprise tables in an Oracle 10g database. One table keeps the historical information of the other table. The problem is, I'm getting to the point where the records are just too many that my insert update is taking too long and my session is getting killed by the governor. Here's a pseudocode of my update process: sqlsel := 'SELECT col1, col2, col3, sysdate FROM table2@remote_location dpi WHERE (col1, col2, col3) IN ( SELECT col1, col2, col3 FROM table2@remote_location MINUS SELECT DISTINCT col1, col2, col3 FROM table1 mpc WHERE facility = '''||load_facility||''' )'; EXECUTE IMMEDIATE sqlsel BULK COLLECT INTO table1; I've tried the MERGE statement: MERGE INTO table1 t1 USING ( SELECT col1, col2, col3 FROM table2@remote_location ) t2 ON ( t1.col1 = t2.col1 AND t1.col2 = t2.col2 AND t1.col3 = t2.col3 ) WHEN NOT MATCHED THEN INSERT (t1.col1, t1.col2, t1.col3, t1.update_dttm ) VALUES (t2.col1, t2.col2, t2.col3, sysdate ) But there seems to be a confirmed bug on versions prior to Oracle 10.2.0.4 on the merge statement when doing a merge using a remote database. The chance of getting an enterprise upgrade is slim so is there a way to further optimize my first query or write it in another way to have it run best performance wise? Thanks.

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