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  • Database design and foreign keys: Where should they be added in related tables?

    - by Carvell Fenton
    I have a relatively simple subset of tables in my database for tracking something called sessions. These are academic sessions (think offerings of a particular program). The tables to represent a sessions information are: sessions session_terms session_subjects session_mark_item_info session_marks All of these tables have their own primary keys, and are like a tree, in that sessions have terms, terms have subjects, subjects have mark items, etc. So each on would have at least its "parent's" foreign key. My question is, design wise is it a good idea to include the sessions primary key in the other tables as a foreign key to easily select related session items, or is that too much redundency? If I include the session foreign key (or all parent foreign keys from tables up the heirarchy) in all the tables, I can easily select all the marks for a session. As an example, something like SELECT mark FROM session_marks WHERE sessionID=... If I don't, then I would have to combine selects with something like WHERE something IN (SELECT... Which approach is "more correct" or efficient? Thanks in advance!

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  • Creating 3DES key from bytes

    - by AO
    I create a triple DES key from the a byte array ("skBytes") but when calling getEncoded on the triple DES key ("sk") and comparing it to the byte array, they differ! They are almost the same if you look at the console output, though. How would I create a triple DES key that is exactly as "skBytes"? byte[] skBytes = {(byte) 0x41, (byte) 0x0B, (byte) 0xF0, (byte) 0x9B, (byte) 0xBC, (byte) 0x0E, (byte) 0xC9, (byte) 0x4A, (byte) 0xB5, (byte) 0xCE, (byte) 0x0B, (byte) 0xEA, (byte) 0x05, (byte) 0xEF, (byte) 0x52, (byte) 0x31, (byte) 0xD7, (byte) 0xEC, (byte) 0x2E, (byte) 0x75, (byte) 0xC3, (byte) 0x1D, (byte) 0x3E, (byte) 0x61}; DESedeKeySpec keySpec = new DESedeKeySpec(skBytes); SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DESede"); SecretKey sk = keyFactory.generateSecret(keySpec); for(int i = 0; i < skBytes.length; i++) { System.out.println("(sk.getEncoded()[i], skBytes[i]) = (" + sk.getEncoded()[i] +", " + skBytes[i] + ")"); } Console output: (sk.getEncoded()[i], skBytes[i]) = (64, 65) (sk.getEncoded()[i], skBytes[i]) = (11, 11) (sk.getEncoded()[i], skBytes[i]) = (-15, -16) (sk.getEncoded()[i], skBytes[i]) = (-101, -101) (sk.getEncoded()[i], skBytes[i]) = (-68, -68) (sk.getEncoded()[i], skBytes[i]) = (14, 14) (sk.getEncoded()[i], skBytes[i]) = (-56, -55) (sk.getEncoded()[i], skBytes[i]) = (74, 74) (sk.getEncoded()[i], skBytes[i]) = (-75, -75) (sk.getEncoded()[i], skBytes[i]) = (-50, -50) (sk.getEncoded()[i], skBytes[i]) = (11, 11) (sk.getEncoded()[i], skBytes[i]) = (-22, -22) (sk.getEncoded()[i], skBytes[i]) = (4, 5) (sk.getEncoded()[i], skBytes[i]) = (-17, -17) (sk.getEncoded()[i], skBytes[i]) = (82, 82) (sk.getEncoded()[i], skBytes[i]) = (49, 49) (sk.getEncoded()[i], skBytes[i]) = (-42, -41) (sk.getEncoded()[i], skBytes[i]) = (-20, -20) (sk.getEncoded()[i], skBytes[i]) = (47, 46) (sk.getEncoded()[i], skBytes[i]) = (117, 117) (sk.getEncoded()[i], skBytes[i]) = (-62, -61) (sk.getEncoded()[i], skBytes[i]) = (28, 29) (sk.getEncoded()[i], skBytes[i]) = (62, 62) (sk.getEncoded()[i], skBytes[i]) = (97, 97)

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  • Fastest way to convert a list of doubles to a unique list of integers?

    - by javanix
    I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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  • Fastest way to modify a decimal-keyed table in MySQL?

    - by javanix
    I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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  • How to configure SHIFT+LEFT, SHIFT+RIGHT, SHIFT+HOME and SHIFT+END keys in terminal on Mac?

    - by Misha Moroshko
    To configure the Home and End keys in terminal on MacBook Air (OS X 10.7.2) I defined in Terminal -> Preferences -> Keyboard: Key Action ---- ------ Home \033OH End \033OF What are the codes to configure the following combinations so that they will work like in Windows? Shift+Left (should select the character on the left) Shift+Right (should select the character on the right) Shift+Home (should select all the characters on the left) Shift+End (should select all the characters on the right)

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  • Strange behaviour when posting CGEvent to PSN

    - by Ben Packard
    If I set up a loop that posts some keyboard events to a PSN, I find that it works fine except for when first launched. The event only seems to post when i do something with the mouse manually - even just moving it slightly. Here's the details, if they help. An external application has a list box of text lines, which I am reading by posting copy commands (and checking the pasteboard). Unfortunately this is my only way to get this text. Sometimes, the application pulls focus away from the list, which I can detect. When this happens, the most reliable way to return focus is by sending a mouse event to click on a text field directly above the list, then send a 'tab' keyboard event to shift the focus onto the list. So at launch, the loop runs fine, scrolling down the list and copying the text. When focus is shifted away, its is detected fine, and the events are sent to move focus back to the list. But nothing seems to happen. The loop continues detecting that focus has changed, but the events only work once I move the mouse. Or even just use the scroll wheel. Strange. Once this has happened the first time, it works fine - each time focus moves, the PSN events switch it back without me having to do anything at all. Here's the code that runs in the loop - verified as working: //copy to pasteboard - CMD-V e3 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)8, true); CGEventSetFlags(e3, kCGEventFlagMaskCommand); CGEventPostToPSN(&psn, e3); CFRelease(e3); e4 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)8, false); CGEventPostToPSN(&psn, e4); CFRelease(e4); //move cursor down e1 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)125, true); CGEventPostToPSN(&psn, e1); CFRelease(e1); e2 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)125, false); CGEventPostToPSN(&psn, e2); CFRelease(e2); And here's where I switch focus, also working (except when first required): //click in text input box - point is derived earlier e6 = CGEventCreateMouseEvent(NULL, kCGEventLeftMouseDown, point, 0); CGEventPostToPSN(&psn, e6); CFRelease(e6); e7 = CGEventCreateMouseEvent(NULL, kCGEventLeftMouseUp, point, 0); CGEventPostToPSN(&psn, e7); CFRelease(e7); //press tab key to move to chat log table CGEventRef e = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)48, true); //CGEventPost(kCGSessionEventTap, e); CGEventPostToPSN(&psn, e); CFRelease(e); CGEventRef e11 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)48, false); CGEventPostToPSN(&psn, e11); CFRelease(e11);

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  • Accepting more simultaneous keyboard inputs

    - by unknownthreat
    Sometimes, a normal computer keyboard will only accept user's inputs up to a certain key simultaneously. I got a logitech keyboard that can accept up to 3-4 key presses at the same time. The computer does not accept any more input if you press more than 4 keys for this keyboard. And it also depends on certain areas of your keyboard as well. Some locations allow more key to be pressed (like the arrow keys), while some locations permit you to press only 1-2 keys. This also differs from keyboard to keyboard as well. Some older keyboards only accept up 1-2 keys. This isn't problematic with usual office work, but when it comes to gaming. For instance, imagine a platform game, where you have to jump, attack, and control direction at the same time. This implies several key presses and some keyboards cannot accept such simultaneous input. However, I've tried this on several games and the amount of possible keyboard inputs seem to be also different. Therefore, we have two issues: Keyboards have different amount of simultaneous inputs. Some games can accept more keyboard inputs than other games. At first, I thought this is hardware only problem, but why do some programs behave differently? Why some programs can accept more keyboard inputs than other programs? So how can we write our programs to accept more keyboard inputs?

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  • What is Erlang's concurrency model actually ?

    - by arun_suresh
    I was reading a paper recently Why Events are Bad. The paper is a comparative study of Event based and thread based highly concurrent servers and finally concludes stating that Threads are better than events in that scenario. I find that I am not able to classify what sort of concurrency model erlang exposes. Erlang provides Light Weight Processes, but those processes are suspended most of the time until it has received some event/message of some sort. /Arun

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  • NHibernate One to One Foreign Key ON DELETE CASCADE

    - by xll
    I need to implement One-to-one association between Project and ProjecSettings using fluent NHibernate: public class ProjectMap : ClassMap<Project> { public ProjectMap() { Id(x => x.Id) .UniqueKey(MapUtils.Col<Project>(x => x.Id)) .GeneratedBy.HiLo("NHHiLoIdentity", "NextHiValue", "1000", string.Format("[EntityName] = '[{0}]'", MapUtils.Table<Project>())) .Not.Nullable(); HasOne(x => x.ProjectSettings) .PropertyRef(x => x.Project); } } public class ProjectSettingsMap : ClassMap<ProjectSettings> { public ProjectSettingsMap() { Id(x => x.Id) .UniqueKey(MapUtils.Col<ProjectSettings>(x => x.Id)) .GeneratedBy.HiLo("NHHiLoIdentity", "NextHiValue", "1000", string.Format("[EntityName] = '[{0}]'", MapUtils.Table<ProjectSettings>())); References(x => x.Project) .Column(MapUtils.Ref<ProjectSettings, Project>(p => p.Project, p => p.Id)) .Unique() .Not.Nullable(); } } This results in the following sql for Project Settings: CREATE TABLE ProjectSettings ( Id bigint PRIMARY KEY NOT NULL, Project_Project_Id bigint NOT NULL UNIQUE, /* Foreign keys */ FOREIGN KEY (Project_Project_Id) REFERENCES Project() ON DELETE NO ACTION ON UPDATE NO ACTION ); What I am trying to achieve is to have ON DELETE CASCADE for the FOREIGN KEY (Project_Project_Id), so that when the project is deleted through sql query, it's settings are deleted too. How can I achieve this ? EDIT: I know about Cascade.Delete() option, but it's not what I need. Is there any way to intercept the FK statement generation?

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  • A GUID as the MySQL table's Primary Key or as a separate column

    - by Ben
    I have a multi-process program that performs, in a 2 hour period, 5-10 million inserts to a 34GB table within a single Master/Slave MySQL setup (plus an equal number of reads in that period). The table in question has only 5 fields and 3 (single field) indexes. The primary key is auto-incrementing. I am far from a DBA, but the database appears to be crippled during this two hour period. So, I have a couple of general questions. 1) How much bang will I get out of batching these writes into units of 10? Currently, I am writing each insert serially because, after writing, I immediately need to know, in my program, the resulting primary key of each insert. The PK is the only unique field presently and approximating the order of insertion with something like a Datetime field or a multi-column value is not acceptable. If I perform a bulk insert, I won't know these IDs, which is a problem. So, I've been thinking about turning the auto-increment primary key into a GUID and enforcing uniqueness. I've also been kicking around the idea of creating a new column just for the purposes of the GUID. I don't really see the what that achieves though, that the PK approach doesn't already offer. As far as I can tell, the big downside to making the PK a randomly generated number is that the index would take a long time to update on each insert (since insertion order would not be sequential). Is that an acceptable approach for a table that is taking this number of writes? Thanks, Ben

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  • SQL Server problems reading columns with a foreign key

    - by illdev
    I have a weird situation, where simple queries seem to never finish for instance SELECT top 100 ArticleID FROM Article WHERE ProductGroupID=379114 returns immediately SELECT top 1000 ArticleID FROM Article WHERE ProductGroupID=379114 never returns SELECT ArticleID FROM Article WHERE ProductGroupID=379114 never returns SELECT top 1000 ArticleID FROM Article returns immediately By 'returning' I mean 'in query analyzer the green check mark appears and it says "Query executed successfully"'. I sometimes get the rows painted to the grid in qa, but still the query goes on waiting for my client to time out - 'sometimes': SELECT ProductGroupID AS Product23_1_, ArticleID AS ArticleID1_, ArticleID AS ArticleID18_0_, Inventory_Name AS Inventory3_18_0_, Inventory_UnitOfMeasure AS Inventory4_18_0_, BusinessKey AS Business5_18_0_, Name AS Name18_0_, ServesPeople AS ServesPe7_18_0_, InStock AS InStock18_0_, Description AS Descript9_18_0_, Description2 AS Descrip10_18_0_, TechnicalData AS Technic11_18_0_, IsDiscontinued AS IsDisco12_18_0_, Release AS Release18_0_, Classifications AS Classif14_18_0_, DistributorName AS Distrib15_18_0_, DistributorProductCode AS Distrib16_18_0_, Options AS Options18_0_, IsPromoted AS IsPromoted18_0_, IsBulkyFreight AS IsBulky19_18_0_, IsBackOrderOnly AS IsBackO20_18_0_, Price AS Price18_0_, Weight AS Weight18_0_, ProductGroupID AS Product23_18_0_, ConversationID AS Convers24_18_0_, DistributorID AS Distrib25_18_0_, type AS Type18_0_ FROM Article AS articles0_ WHERE (IsDiscontinued = '0') AND (ProductGroupID = 379121) shows this behavior. I have no idea what is going on. Probably select is broken ;) I got a foreign key on ProductGroups ALTER TABLE [dbo].[Article] WITH CHECK ADD CONSTRAINT [FK_ProductGroup_Articles] FOREIGN KEY([ProductGroupID]) REFERENCES [dbo].[ProductGroup] ([ProductGroupID]) GO ALTER TABLE [dbo].[Article] CHECK CONSTRAINT [FK_ProductGroup_Articles] there are some 6000 rows and IsDiscontinued is a bit, not null, but leaving this condition out does not change the outcome. Anyone can tell me how to handle such a situation? More info, anyone? Additional Info: this does not seem to be restricted to this Foreign Key, but all/some referencing this entity.

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  • What is the corrrect way to increment a field making up part of a composit key

    - by Tr1stan
    I have a bunch of tables whose primary key is made up of the foreign keys of other tables (Composite key). Therefore for example the attributes (as a very cut down version) might look like this: A[aPK, SomeFields] 1:M B[bPK, aFK, SomeFields] 1:M C[cPK, bFK, aFK, SomeFields] as data this could look like: A[aPK, SomeFields]: 1, Foo 2, Bar B[bPK, aFK, SomeFields]: 1, 1, FooData1 2, 1, FooData2 1, 2, BarData1 2, 2, BarData2 C[cPK, bFK, aFK, SomeFields]: 1, 1, 1, FooData1More 2, 1, 1, FooData1More 1, 2, 1, FooData2More 2, 2, 1, FooData2More 1, 1, 2, BarData1More 2, 1, 2, BarData1More 1, 2, 2, BarData2More 2, 2, 2, BarData2More I've got this running in a MSSQL DBMS and I'm looking for the best way to increment the left most column, in each table when a new tuple is added to it. I can't use the Auto Increment Identity Specification option as that has no idea that it is part of a composite key. I also don't want to use any aggregate function such as: MAX(field)+1 as this will have adverse affects with multiple users inputting data, rolling back etc. There might however be a nice trigger based option here, but I'm not sure. This must be a common issue so I'm hoping that someone has a lovely solution. As a side which may or may not affect the answer, I'm using Entity Framework 1.0 as my ORM, within a c# MVC application.

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  • Fetching just the Key/id from a ReferenceProperty in App Engine

    - by ozone
    Hi SO, I could use a little help in AppEngine land... Using the [Python] API I create relationships like this example from the docs: class Author(db.Model): name = db.StringProperty() class Story(db.Model): author = db.ReferenceProperty(Author) story = db.get(story_key) author_name = story.author.name As I understand it, that example will make two datastore queries. One to fetch the Story and then one to deference the Author inorder to access the name. But I want to be able to fetch the id, so do something like: story = db.get(story_key) author_id = story.author.key().id() I want to just get the id from the reference. I do not want to have to deference (therefore query the datastore) the ReferenceProperty value. From reading the documentation it says that the value of a ReferenceProperty is a Key Which leads me to think that I could just call .id() on the reference's value. But it also says: The ReferenceProperty model provides features for Key property values such as automatic dereferencing. I can't find anything that explains when this referencing takes place? Is it safe to call .id() on the ReferenceProperty's value? Can it be assumed that calling .id() will not cause a datastore lookup?

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  • google maps marker draggable doesn't work

    - by ArmenGrigoryan
    I try all methods but in my google map on the marker doesn't work events, I try enable events and write (clickable: true), but it did not help, in test server working good, but on phpfox marker not clickable, help me please correct it go to it http://iguansystems.com/phpfoxdev/index.php?do=/pages/24/quickstart/step2/ link login - [email protected], and pass- tryuser in center frontend right at "Primary Venue" have "Can't find venue? Add New" click on "Add New" and window with a map open

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  • wpf mvvm datagrid selectedrow

    - by 2Fast4YouBR
    Hi, after some google around, I just figured out that there is no one that is using 100% MvvM pattern to get the ToolKit DataGrid events ! Is that impossible or what ? I see too much people using the code-behind... How can I get the SelectedRow or dblClick events using mvvm ? cheers

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  • Dictionaries with more than one key per value in Python

    - by nickname
    I am attempting to create a nice interface to access a data set where each value has several possible keys. For example, suppose that I have both a number and a name for each value in the data set. I want to be able to access each value using either the number OR the name. I have considered several possible implementations: Using two separate dictionaries, one for the data values organized by number, and one for the data values organized by name. Simply assigning two keys to the same value in a dictionary. Creating dictionaries mapping each name to the corresponding number, and vice versa Attempting to create a hash function that maps each name to a number, etc. (related to the above) Creating an object to encapsulate all three pieces of data, then using one key to map dictionary keys to the objects and simply searching the dictionary to map the other key to the object. None of these seem ideal. The first seems ugly and unmaintainable. The second also seems fragile. The third/fourth seem plausible, but seem to require either much manual specification or an overly complex implementation. Finally, the fifth loses constant-time performance for one of the lookups. In C/C++, I believe that I would use pointers to reference the same piece of data from different keys. I know that the problem is rather similar to a database lookup problem by a non-key column, however, I would like (if possible), to maintain the approximate O(1) performance of Python dictionaries. What is the most Pythonic way to achieve this data structure?

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  • Updating a composite primary key

    - by VBCSharp
    I am struggling with the philosophical discussions about whether or not to use composite primary keys on my SQL Server database. I have always used the surrogate keys in the past and I am challenging myself by leaving my comfort zone to try something different. I have read many discussion but can't come to any kind of solution yet. The struggle I am having is when I have to update a record with the composite PK. For example, the record in questions is like this: ContactID, RoleID, EffectiveDate, TerminationDT. The PK in this case is the ContactID, RoleID, and EffectiveDate. TerminationDT can be null. If in my UI, the user changes the RoleID and then I need to update the record. Using the surrogate key I can do an Update Table Set RoleID = 1 WHERE surrogateID = Z. However, using the Composite Key way, once one of the fields in the composite key changes I have no way to reference the old record to update it without now maintaining somewhere in the UI a reference to the old values. I do not bind datasources in my UI. I open a connection, get the data and store it in a bucket, then close the connection. What are everyone's opinions? Thanks.

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  • INSERT..ON DUPLICATE KEY UPDATE - but NOT using the duplicate key to compare.

    - by calumbrodie
    I am trying to solve a problem I have inherited with poor treatment of different data sources. I have a user table that contains BOTH good and evil users. create table `users`( `user_id` int(13) NOT NULL AUTO_INCREMENT , `email` varchar(255) , `name` varchar(255) , PRIMARY KEY (`user_id`) ); In this table the primary key is currently set to be user_id. I have another table ('users_evil') which contains ONLY the evil users (all the users from this table are included in the first table) - the user_id's on this table do NOT correspond to those in the first table. I want to have all my users in one table, and simply flag which are good and which are evil. What I want to do is alter the user table and add a column ('evil') which defaults to 0. I then want to dump the data from my 'users_evil') table and then run an INSERT..ON DUPLICATE KEY UPDATE with this data into the first table (setting 'evil'=1 where the emails match) The problem is that the 'PK' is set to the user_id and not the 'email'. Any suggestions, or even another strategy to successfully achive this. Can I run this statement but treat another column as PK only for the duration of the statement.

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  • Where is a good javascript reference for object event handlers?

    - by GregH
    I am relatively new to Javascript and constantly need to look up how to handle various events for objects. For example, I have a table containing a few text fields and need to know when somebody starts typing in any of the text boxes. Is there any good concise reference on the web anyplace that documents all of the objects and event handlers associated with all objects? I'd like to be able to look up the object and see all of the events I can handle for that object.

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  • Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

    - by TX_
    Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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  • NHibernate with string primary key and relationships

    - by John_
    I've have just been stumped with this problem for an hour and I annoyingly found the problem eventually. THE CIRCUMSTANCES I have a table which users a string as a primary key, this table has various many to one and many to many relationships all off this primary key. When searching for multiple items from the table all relationships were brought back. However whenever I tried to get the object by the primary key (string) it was not bringing back any relationships, they were always set to 0. THE PARTIAL SOLUTION So I looked into my logs to see what the SQL was doing and that was returning the correct results. So I tried various things in all sorts of random ways and eventually worked out it was. The case of the string being passed into the get method was not EXACTLY the same case as it was in the database, so when it tried to match up the relationship items with the main entity it was finding nothing (Or at least NHIbernate wasn't because as I stated above the SQL was actually returning the correct results) THE REAL SOLUTION Has anyone else come across this? If so how do you tell NHibernate to ignore case when matching SQL results to the entity? It is silly because it worked perfectly well before now all of a sudden it has started to pay attention to the case of the string.

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  • Handling primary key duplicates in a data warehouse load

    - by Meff
    I'm currently building an ETL system to load a data warehouse from a transactional system. The grain of my fact table is the transaction level. In order to ensure I don't load duplicate rows I've put a primary key on the fact table, which is the transaction ID. I've encountered a problem with transactions being reversed - In the transactional database this is done via a status, which I pick up and I can work out if the transaction is being done, or rolled back so I can load a reversal row in the warehouse. However, the reversal row will have the same transaction ID and so I get a primary key violation. I've solved this for now by negating the primary key, so transaction ID 1 would be a payment, and transaction ID -1 (In the warehouse only) would be the reversal. I have considered an alternative of generating a BIT column, where 0 is normal and 1 is reversal, then making the PK the transaction ID and the BIT column. My question is, is this a good practice, and has anyone else encountered anything like this? For reference, this is a payment processing system, so values will not be modified, so there will only ever be transactions and reversals.

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  • HTML form with single text field + preventing postback in Internet Explorer

    - by SudheerKovalam
    I have noticed a rather strange behaviour in IE. I have a HTML form with a single input text field and a submit button On Submit click I need to execute a client side JavaScript function that does the necessary. Now when I want to prevent the postback in the text field (on enter key press) I have added a key press JavaScript function that looks like this: <input type=text onkeypress="return OnEnterKeyPress(event)" /> function OnEnterKeyPress(event) { var keyNum = 0; if (window.event) // IE { keyNum = event.keyCode; } else if (event.which) // Netscape/Firefox/Opera { keyNum = event.which; } else return true; if (keyNum == 13) // Enter Key pressed, then start search, else do nothing. { OnButtonClick(); return false; } else return true; } Strangly this doesn't work. But if I pass the text field to the function : <input type=text onkeypress="return OnEnterKeyPress(this,event);" /> function OnEnterKeyPress(thisForm,event) { var keyNum = 0; if (window.event) // IE { keyNum = event.keyCode; } else if (event.which) // Netscape/Firefox/Opera { keyNum = event.which; } else return true; if (keyNum == 13) // Enter Key pressed, then start search, else do nothing. { OnButtonClick(); return false; } else return true; } I am able to prevent the postback. Can anyone confirm what is exactly happening here?? the HTML form has just one text box and a submit button The resultant o/p of the JavaScript function executed on submit is displayed in a HTML text area in a separate div.

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