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  • I'm looking for a constraint to prevent the insert of an empty string in MySQL

    - by Marga Keuvelaar
    Ok, in this question I learned how to prevent the insert of a NULL value. But, unfortunately, an empty string is being inserted anyway. Apart from preventing this on the PHP side, I'd like to use something like a database constraint to prevent this. Of course a check on the application side is necessary, but I'd like it to be on both sides. I am taught that whatever application is talking to your database, it should not be able to insert basically wrong data in it. So... CREATE TABLE IF NOT EXISTS tblFoo ( foo_id int(11) NOT NULL AUTO_INCREMENT, foo_test varchar(50) NOT NULL, PRIMARY KEY (foo_id) ); Would still allow me to do this insert: INSERT INTO tblFoo (foo_test) VALUES (''); Which I would like to prevent.

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  • C# debug vs release performance

    - by sagie
    Hi. I've encountered in the following paragraph: “Debug vs Release setting in the IDE when you compile your code in Visual Studio makes almost no difference to performance… the generated code is almost the same. The C# compiler doesn’t really do any optimisation. The C# compiler just spits out IL… and at the runtime it’s the JITer that does all the optimisation. The JITer does have a Debug/Release mode and that makes a huge difference to performance. But that doesn’t key off whether you run the Debug or Release configuration of your project, that keys off whether a debugger is attached.” The source is here and the podcast is here. Can someone direct me to a microsoft an article that can actualy prove this?

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  • Confusing Perl code

    - by titaniumdecoy
    I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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  • A B+tree simple implementation in C

    - by initpy
    Hi guys, I'm working on a fun project where I need a simple key/value store that uses B+Trees. I studied them some years ago, and to be honest, I don't want to reinvent the wheel, so I'm looking for a simple implementation in C of b+tree that I can just include in my project. I know of sqlite's, dbm's and tokyocabinet's ones but they're a little too "complicated" for my needs. Is there any (even pedagogical) work on this you can refer me to? Do you have some code to share? Thanks a lot!

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  • Search relevance from XML docs (XQuery?) vs MySQL

    - by Marius
    Hello there, I have a website where documents are saved in xml documents, all with the same structure. I need a search engine where I am able to choose documents with the highest relevance according to the key words given by a searching user. I thought it could (?) be a good idea to have one using XQuery rather than having the information stored twice (in XML docs + mysql database) and querying the mysql database for relevance searches. Is XQuery any good for this, and how, and what speed can I expect on +1000 documents of about 7kb each. Thank you for your time. Kind regards

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  • Sql: simultaneous aggregate from two tables

    - by Ash
    I have two tables: a Files table, which includes the file type, and a File Properties table, which references the file table via a foreign key. Sample Files table: | id | name | type | --------------------- | 1 | file1 | zip | | 2 | file2 | zip | | 3 | file3 | zip | | 4 | file4 | jpg | And the Properties table: | file_id | property | ----------------------- | 1 | x | | 2 | x | I want to make a query, which shows the count of each file type, and how many files of that type have a property. So in the example, the result would be | type | filecount | prop count | ---------------------------------- | zip | 3 | 2 | | jpg | 1 | 0 | I could accomplish this by select f.type, (select count(id) from files where type = f.type), count(fp.id) from files as f, file_properties as fp where f.id = fp.file_id group by f.type; But this seems very suboptimal and is very slow. Any better way to do this?

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  • Entity Framework: Setting EntityReference EntityKey causes exception on save

    - by NYSystemsAnalyst
    I have a table with a ModifiedUserID field that is a foreign key to a User table. In entity framework, I'm loading the first table, but not the users table. I have the user ID of the current user, and would like to set the ModifiedUserID to that value for all entities that have been modified prior to saving. Before calling SaveChanges(), I use the ObjectStateManager to get all modified entities. Since I do not have the user object, but I do have the user ID, I set the EntityReference.EntityKey property as follows: entity.UserReference.EntityKey = New EntityKey("MyContainer.User", "UserID", DatabaseUserID) This works fine, but when I execute SaveChanges(), I receive the following error: A relationship is being added or deleted from an AssociationSet 'FK_Table1_User'. With cardinality constraints, a corresponding 'Table1' must also be added or deleted. Now, I see that setting the EntityReference.EntityKey creates a new AssociationSet entry, but how to I prevent this error?

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  • Saving related model objects

    - by iHeartDucks
    I have two related models (one to many) in my django app and When I do something like this ObjBlog = Blog() objBlog.name = 'test blog' objEntry1 = Entry() objEntry1.title = 'Entry one' objEntry2 = Entry() objEntry2.title = 'Entry Two' objBlog.entry_set.add(objEntry1) objBlog.entry_set.add(objEntry2) I get an error which says "null value in column and it violates the foreign key not null constraint". None of my model objects have been saved. Do I have to save the "objBlog" before I could set the entries? I was hoping I could call the save method on objBlog to save it all. NOTE: I am not creating a blog engine and this is just an example.

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  • rsync useful w/ encrypted files?

    - by barrycarter
    Is rsync efficient for transferring encrypted files? More specifically: I encrypt 'x' with my public key and call the result 'y'. I rsync 'y' to my backup server. 'x' changes slightly I encrypt the modified 'x' and rsync the modified 'y' to my backup server. Is this efficient? I know a small change in 'x' yields a large change in 'y', but is the change localized? Or has 'y' changed so thoroughly that rsync is not much better than scp? I currently backup my "critical" files by tarring/bzipping them nightly, then encrypting the .tar.bz file and rsync'ing it to my backup server. Many of the individual files don't change, but, of course, the tar file changes if even one of the files change. Is this efficient? Should I be encrypting and backing up each file individually? That way, unchanged files will take no time to rsync.

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  • Mysql: create index on 1.4 billion records

    - by SiLent SoNG
    I have a table with 1.4 billion records. The table structure is as follows: CREATE TABLE text_page ( text VARCHAR(255), page_id INT UNSIGNED ) ENGINE=MYISAM DEFAULT CHARSET=ascii The requirement is to create an index over the column text. The table size is about 34G. I have tried to create the index by the following statement: ALTER TABLE text_page ADD KEY ix_text (text) After 10 hours' waiting I finally give up this approach. Is there any workable solution on this problem? UPDATE: the table is unlikely to be updated or inserted or deleted. The reason why to create index on the column text is because this kind of sql query would be frequently executed: SELECT page_id FROM text_page WHERE text = ?

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  • How do you use jQuery .data() to store html?

    - by Al
    Hi all - when I look up the syntax for .data(), it gives examples like this: $('body').data('foo', 52); I am doing AJAX loads and I was wondering if it is possible to store the incoming html using .data() so once the content is loaded, I would not need to do another AJAX load if the same link is clicked again - I would check to see if the .data key is empty. Would something like this work?: To load the contents of a #ajaxdiv into storage: $('body').data('storage', div#ajaxdiv.html()); To test if the data has already been loaded: if $('body').data('storage') != '' { div#ajaxdiv.html($('body').data('storage')); } Thanks in advance!! Al

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  • Howto check if a object is connected to another in hibernate

    - by codevourer
    Imagine two domain object classes, A and B. A has a bidirectional one-to-many relationship to B. A is related to thousands of B. The relations must be unique, it's not possible to have a duplicate. To check if an instance of B is already connected to a given instance of A, we could perform an easy INNER JOIN but this will only ensure the already persisted relations. What about the current transient relations? class A { @OneToMany private List<B> listOfB; } If we access the listOfB and perform a check of contains() this will fetch all the connected instances of B lazy from the datasource. I only want to validate them by their primary-key. Is there an easy solution where I can do things like "Does this instance of A is connected with this instance of B?" Without loading all these data into memory and perform a based on collections?

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  • Storing cvs data for further manipulation using Ruby

    - by ischnura
    I am dealing with a csv file that has some customer information (email, name, address, amount, [shopping_list: item 1, item 2]). I would like work with the data and produce some labels for printing... as well as to gather some extra information (total amounts, total items 1...) My main concern is to find the appropriate structure to store the data in ruby for future manipulation. For now I have thought about the following possibilities: multidimensional arrays: pretty simple to build, but pretty hard to access the data in a beautiful ruby way. hashes: having the email as key, and storing the information in different hashes (one hash for name, another hash for address, another hash for shopping list...) (getting the cvs data in to a Database and working with the data from ruby??) I would really appreciate your advice and guidance!!

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  • Get current session /process id from inside a mysql query

    - by Indra Ginanjar
    I'm trying to create a table for pseudo array variable. That looks like CREATE TABLE IF NOT EXISTS `MyArray`.`ArrayTable` ( `ID` INT UNSIGNED NOT NULL COMMENT 'Hash value of SessionID + ArrayName' , `SessionID` INT UNSIGNED NOT NULL , `ArrayName` CHAR(26) NOT NULL COMMENT '32 digit char - 6 digit longest process id (assumtion)' , `Index` INT UNSIGNED NOT NULL , `Value` TEXT NOT NULL , PRIMARY KEY (`ID`, `SessionID`) ) ENGINE = MyISAM; The table is not normalized yet, 'hope this will make it a little simpler to understand :) To avoid collission between client, there should be a differentiator between client session. For that reason i think need to know current session/process id (just like "SHOW PROCESSLIST") but really need to know IN WHICH process the query are?

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  • Problem with assembly loading in .NET

    - by Jamie
    Hi guys, I have got two projects in my solution: Silverlight and standard one. The standard one references System.Xml assembly (version 4.0.0.0), however the Silverlight one references System.Xml assembly (v. 2.0.5.0). I want to make an instance of XmlWriter in my Silverlight project. Here comes the problem - the exception is thrown (file not found for System.Xml assembly). I believe it is a matter of different assembly versions. Do you have any idea how to resolve this issue? Ive read something about the binding redirection - is it the key to the solution? If so, how to do this? Thank you in advance for the reply! Cheers.

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  • c# hierarchy collection library? - anyone know of one (e.g. GetDirectChildren, GetAllChildren, GetPa

    - by Greg
    Hi, Does anyone know of a solid C# library / approach to manage a hierarchy/web type collection? This would be a library that would basic consist of the concept of nodes & relationships, for example to model web pages/files linked under a URL, or modeling IT infrastructure. It would have key methods such as: Node.GetDirectParents() Node.GetRootParents() Node.GetDirectChildren() Node.GetAllChildren() So it's smarts would include the ability to "walk the tree" of nodes based on the relationships when someone does ask for "give me all the children under this node" for example. It ideally include a persistence layer, to save/retrieve such data to/from a databases (e.g. with a Nodes and Relationships table). Thanks

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  • Display fraction with numerator/denominator with empty fields for users to enter text

    - by Anil
    Hi all I have a scenario in which I need to design online keyboard with buttons implementing different mathematical functions in ASP.NET. For example 1) A button called "Fraction" Onclicking= should display A numerator and a denominator separated by '-' with empty fields. Just as we write fractions manually. Now when the user clicks on this button the cursor should focus on numerator displaying 'the division line' and then by pressing 'Down' arrow key(on computr keyboard) should focus on denominator allowing users to enter both fields. Keeping it simple the user should be able to toggle between numerator and denominator. Please help me with some sample code. I have got no idea. Thanks in advance

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  • Jquery Ajax not receiving php response correctly

    - by Theo
    I'm sending a JSON response from php to jquery: foreach ( $obj as $o ) { $a[ $o->key] = utf8_encode($o->id); } die(json_encode($a)); my html/jquery code is: $.ajax({ type:'POST', url: "imoveis/carrega_bairros", data: ({cidade:10}), dataType:"json", success: function(ret) { alert(ret) if(ret.success) { // ... } else alert("error"); } }); The json response is perfect (i get it on the console), but jquery is receiving a NULL ret object and it alerts "error". What's the problem???

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  • Is there anything like memcached, but for sorted lists?

    - by depesz
    I have a situation where I could really benefit from having system like memcached, but with the ability to store (per each key) sorted list of elements, and modifying the list by addition of values. For example: something.add_to_sorted_list( 'topics_list_sorted_by_title', 1234, 'some_title') something.add_to_sorted_list( 'topics_list_sorted_by_title', 5436, 'zzz') something.add_to_sorted_list( 'topics_list_sorted_by_title', 5623, 'aaa') Which I then could use like this: something.get_list_size( 'topics_list_sorted_by_title' ) // returns 3 something.get_list_elements( 'topics_list_sorted_by_title', 1, 10 ) // returns: 5623, 1234, 5436 Required system would allow me to easily get items count in every array, and fetch any number of values from the array, with the assumption that the values are sorted using attached value. I hope that the description is clear. And the question is relatively simple: is there any such system?

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  • How do I get the NextVal from an oracle Sequence thru NHibernate

    - by trainer
    I am working on c# .net 4.0 and using NHibernate to talk with an Oracle DB. You would think something as simple as this is already addressed somewhere but sadly its not. I need the NextVal from an Oracle sequence. I do not need to insert it a database as part of an Id or Primary key. I just need to use the next val on the c# side. Can somebody help me out with xml mapping and C# file(or a link) to achieve this. Thanks. Something like int NextValueOfSequence = GetNextValueofSequence(); public int GetNextValueOfSequence() { // Access NHibernate to return the next value of the sequence. }

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  • Data loss when converting from QString to QByteArray

    - by SleepyCod
    I'm using QPlainTextEdit as an HTML editor, saving the data through an HTTP post with QNetworkAccessManager. I experience data loss when using HTML special characters such as & (ampersand) I'm building a POST request with a QByteArray (as mentioned in the docs). QByteArray postData; QMapIterator<QString, QString> i(params); while(i.hasNext()) { i.next(); postData .append(i.key().toUtf8()) .append("=") .append(i.value().toUtf8()) .append("&"); } postData.remove(postData.length()-1, 1); //Do request QNetworkRequest postRequest = QNetworkRequest(res); oManager.post(postRequest, postData);

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  • Does introducing foreign keys to MySQL reduce performance

    - by Tam
    I'm building Ruby on Rails 2.3.5 app. By default, Ruby on Rails doesn't provide foreign key contraints so I have to do it manually. I was wondering if introducing foreign keys reduces query performance on the database side enough to make it not worth doing. Performance in this case is my first priority as I can check for data consistency with code. What is your recommendation in general? do you recommend using foreign keys? and how do you suggest I should measure this?

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  • How do I put all types implementing a certain generic interface in a dictionary?

    - by James Wenday
    Given a particular interface ITarget<T> and a particular type myType, here's how you would determine T if myType implements ITarget<T>. (This code snippet is taken from the answer to an earlier question.) foreach (var i in myType.GetInterfaces ()) if (i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ITarget<>)) return i.GetGenericArguments ()[0] ; However, this only checks a single type, myType. How would I create a dictionary of all such type parameters, where the key is T and the value is myType? I think it would look something like this: var searchTarget = typeof(ITarget<>); var dict = Assembly.GetExecutingAssembly().[???] .Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == searchTarget) .[???]; What goes in the blanks?

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  • DB2 Child Table - Auto Delete With Parent

    - by gamerzfuse
    I have a bit of a task before me. (DB2 Database) I need to create a table that will be a child table (is that what it is called in SQL?) I need it so that it has a foreign key constraint with my other table, so when the parent table is modified (record deleted) the child table also loses that record. Once I have the table, I also need to populate it with the data from the other table (if there is an easy way to UPDATE this). If you could point me in the right direction, this would help alot, as I do not even know what syntax to look for. Thanks in advance

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