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  • Java library to partially export a database while respecting referential integrity constraints

    - by Mwanji Ezana
    My production database is several GB's uncompressed and it's getting to be a pain to download and run locally when trying to reproduce a bug or test a feature with real data. I would like to be able to select the specific records that interest me, then have the library figure out what other records are necessary to produce a dataset that respects the databases integrity constraints and finally print it out as a list of insert statements or dump that I can restore. For example: given Author, Blog and Comment tables when I select comments posted after a certain date I should get inserts for the Blog records the comments have foreign keys to and the Author records those Blogs have foreign keys to.

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  • Using Cases to change background colour | Visual Studio 2008

    - by Simon
    I really need help working with cases, I'm only learning it so far, but just can't get a drop down menu to work that would change the background of a Textbox. Private Sub cbColours_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbColours.SelectedIndexChanged Select Case colours Case Is = "Red" txtSpace.BackColor = Color.Red Case Is = "Blue" txtSpace.BackColor = Color.Blue Case Is = "Green" txtSpace.BackColor = Color.Green End Select End Sub It isn't doing anything at all... In the dropdown menu, it has Red, Blue and Green one per line When the value (e.g. Green) is clicked, it will then change the Textbox to the colour selected. Many help appreciated :)

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  • How can I use linq to build an object from 1 row of data?

    - by Hcabnettek
    Hi All, I have a quick linq question. I have a stored proc that should return one row of data. I would like to use a lambda to build an object. Here's what I'm currently doing which works, but I know I should be able to use First instead of Select except I can't seem to get the syntax correct. Can anyone straighten me out here? Thanks for any help. var location = new GeoLocationDC(); DataSet ds = db.ExecuteDataSet(dbCommand); if(ds.Tables[0].Rows.Count == 1) { var rows = ds.Tables[0].AsEnumerable(); var x = rows.Select( c => new GeoLocationDC { Latitude = Convert.ToInt32(c.Field<string>("LATITUDE")), Longitude = Convert.ToInt32(c.Field<string>("LONGITUDE")) }).ToList(); if(x.Count > 0 ) { location = x[0]; } Cheers, ~ck }

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  • Split table and insert with identity link

    - by The King
    Hi.. I have 3 tables similar to the sctructure below CREATE TABLE [dbo].[EmpBasic]( [EmpID] [int] IDENTITY(1,1) NOT NULL Primary Key, [Name] [varchar](50), [Address] [varchar](50) ) CREATE TABLE [dbo].[EmpProject]( [EmpID] [int] NOT NULL primary key, // referencing column with EmpBasic [EmpProject] [varchar](50) ) CREATE TABLE [dbo].[EmpFull_Temp]( [ObjectID] [int] IDENTITY(1,1) NOT NULL Primary Key, [T1Name] [varchar](50) , [T1Address] [varchar](50) , [T1EmpProject] [varchar](50) ) The EmpFull_Temp table has the records with a dummy object ID column... I want to populate the first 2 tables with the records in this table... But with EmpID as a reference between the first 2 tables. I tried this in a stored procedure... Create Table #IDSS (EmpID bigint, objID bigint) Insert into EmpBasic output Inserted.EmpID, EmpFull_Temp.ObjectID into #IDSS Select T1Name, T1Address from EmpFull_Temp Where ObjectID < 106 Insert into EmpProject Select A.EmpID, B.T1EmpProject from #IDSS as A, EmpFull_Temp as B Where A.ObjID = B.ObjectID But it says.. The multi-part identifier "EmpFull_Temp.ObjectID" could not be bound. Could you please help me in achieving this...

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  • Copy email to the clipboard with Outlook VBA

    - by Arlen Beiler
    How do I copy an email to the clipboard and then paste it into excel with the tables intact? I am using Outlook 2007 and I want to do the equivalent of "Click on email > Select All > Copy > Switch to Excel > Select Cell > Paste". I have the Excel Object Model pretty well figured out, but have no experience in Outlook other than the following code. Dim mapi As NameSpace Dim msg As Outlook.MailItem Set mapi = Outlook.Application.GetNamespace("MAPI") Set msg = mapi.Folders.Item(1).Folders.Item("Posteingang").Folders.Item(1).Folders.Item(7).Items.Item(526)

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  • Simulating an identity column within an insert trigger

    - by William Jens
    I have a table for logging that needs a log ID but I can't use an identity column because the log ID is part of a combo key. create table StuffLogs { StuffID int LogID int Note varchar(255) } There is a combo key for StuffID & LogID. I want to build an insert trigger that computes the next LogID when inserting log records. I can do it for one record at a time (see below to see how LogID is computed), but that's not really effective, and I'm hoping there's a way to do this without cursors. select @NextLogID = isnull(max(LogID),0)+1 from StuffLogs where StuffID = (select StuffID from inserted) The net result should allow me to insert any number of records into StuffLogs with the LogID column auto computed. StuffID LogID Note 123 1 foo 123 2 bar 456 1 boo 789 1 hoo Inserting another record using StuffID: 123, Note: bop will result in the following record: StuffID LogID Note 123 3 bop

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  • Selecting based on __key__ (a unique identifier) in google appengine [Java]

    - by Stavros
    I have public class QuantityType { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; @Persistent private String type; } I am trying to setup a query to get the right QuantityType by it's key gql = "select * from QuantityType where __key__='aght52oobW1hIHTWVzc2FnZRiyAQw'"; But its not working because BadFilterError: BadFilterError: invalid filter: key filter value must be a Key; received aght52oobW1hIHTWVzc2FnZRiyAQw (a str). I have also tried to use gql = "select * from QuantityType where __key__=='" + KeyFactory.stringToKey(qTypeKey)+"'"; but it's now working.. How can I get a specific object from my datastore by it's key?

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  • Mysql table data problem?

    - by DaTeNtImE
    I'm new to mysql and was wondering how can I add the users birthdate in the following HTML format to the MYSQL table data listed below? How would the structure look like for example email VARCHAR(80) NOT NULL,? Here is the HTML code below. <li><label>Date of Birth: </label> <label for="month">Month: </label> <select name="month" id="month"> <option value="January">January</option> <option value="February">February</option> <option value="March">March</option> <option value="April">April</option> <option value="May">May</option> <option value="June">June</option> <option value="July">July</option> <option value="August">August</option> <option value="September">September</option> <option value="October">October</option> <option value="November">November</option> <option value="December">December</option> </select> <label for="day">Day: </label> <select id="day" name="day"> <option value="0" selected="selected">Day</option> <option value="1">1</option> <option value="2">2</option> <option value="3">3</option> <option value="4">4</option> <option value="5">5</option> <option value="6">6</option> <option value="7">7</option> <option value="8">8</option> <option value="9">9</option> <option value="10">10</option> <option value="11">11</option> <option value="12">12</option> <option value="13">13</option> <option value="14">14</option> <option value="15">15</option> <option value="16">16</option> <option value="17">17</option> <option value="18">18</option> <option value="19">19</option> <option value="20">20</option> <option value="21">21</option> <option value="22">22</option> <option value="23">23</option> <option value="24">24</option> <option value="25">25</option> <option value="26">26</option> <option value="27">27</option> <option value="28">28</option> <option value="29">29</option> <option value="30">30</option> <option value="31">31</option> </select> <label for="year">Year: </label><input type="text" name="year" id="year" /></li> Here is the MySQL table data. CREATE TABLE users ( user_id INT UNSIGNED NOT NULL AUTO_INCREMENT, first_name VARCHAR(20) NOT NULL, last_name VARCHAR(40) NOT NULL, email VARCHAR(80) NOT NULL, pass CHAR(40) NOT NULL, user_level TINYINT(1) UNSIGNED NOT NULL DEFAULT 0, active CHAR(32), registration_date DATETIME NOT NULL, PRIMARY KEY (user_id), UNIQUE KEY (email), INDEX login (email, pass) );

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  • problem in counting two fields in one query

    - by Mac Taylor
    hey guys i need to count new private messages and old one from a table so first thing come to mind is using mysql_num_rows and easy thing to do // check new pms $user_id = $userinfo['user_id']; $sql = "SELECT author_id FROM bb3privmsgs_to WHERE user_id='$user_id' AND (pm_new='1' OR pm_unread='1')"; $result = $db->sql_query($sql) ; $new_pms = $db->sql_numrows($result); $db->sql_freeresult($result); // check old pms $sql = "SELECT author_id FROM bb3privmsgs_to WHERE user_id='$user_id' AND (pm_new='0' OR pm_unread='0')"; $result = $db->sql_query($sql) ; $old_pms = $db->sql_numrows($result); $db->sql_freeresult($result); but how can i count these two fields just in one statement and shorter lines ?~

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  • Where to put conditionals in ANSI-syntax SQL queries

    - by RenderIn
    What's the difference between these two queries? I've been resistant to jumping on the ANSI-syntax bandwagon because I have not been able to unravel various syntactical ambiguities. Is 1) returning the product of the join and only then filtering out those joined records which have weight = 500? And is 2) filtering out those prior to the join? Is 2 bad syntax? Why might I use that? 1: SELECT SOMETHING FROM FOO INNER JOIN BAR ON FOO.NAME = BAR.NAME WHERE BAR.WEIGHT < 500 2: SELECT SOMETHING FROM FOO INNER JOIN BAR ON FOO.NAME = BAR.NAME AND BAR.WEIGHT < 500

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  • SQLite Transaction fills a table BEFORE the transaction is commited

    - by user1500403
    Halo I have a code that creates a datatable (in memory) from a select SQL statement. However I realised that this datatable is filling during the procedure rather as a result of the transaction comit statment, it does the job but its slow. WHat amI doing wrong ? Inalready.Clear() 'clears a dictionary Using connection As New SQLite.SQLiteConnection(conectionString) connection.Open() Dim sqliteTran As SQLite.SQLiteTransaction = connection.BeginTransaction() Try oMainQueryR = "SELECT * FROM detailstable Where name= :name AND Breed= :Breed" Dim cmdSQLite As SQLite.SQLiteCommand = connection.CreateCommand() Dim oAdapter As New SQLite.SQLiteDataAdapter(cmdSQLite) With cmdSQLite .CommandType = CommandType.Text .CommandText = oMainQueryR .Parameters.Add(":name", SqlDbType.VarChar) .Parameters.Add(":Breed", SqlDbType.VarChar) End With Dim c As Long = 0 For Each row As DataRow In list.Rows 'this is the list with 500 names If Inalready.ContainsKey(row.Item("name")) Then Else c = c + 1 Form1.TextBox1.Text = " Fill .... " & c Application.DoEvents() Inalready.Add(row.Item("name"), row.Item("Breed")) cmdSQLite.Parameters(":name").Value = row.Item("name") cmdSQLite.Parameters(":Breed").Value = row.Item("Breed") oAdapter.Fill(newdetailstable) End If Next oAdapter.FillSchema(newdetailstable, SchemaType.Source) Dim z = newdetailstable.Rows.Count 'At this point the newdetailstable is already filled up and I havent even comited the transaction ' sqliteTran.Commit() Catch ex As Exception End Try End Using

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  • Cursors vs Procedures in SQL

    - by CogitoErgoSum
    So, I just learned about CURSORS but still don't exactly grasp them. What is the difference between a cursor and procedure or even a function? So far from the various examples (DECLARE CURSOR ... SELECT ... FROM ...) It seems at most its a variable to hold a query. Is the data real time, or a snapshot of when the cursor was declared? i.e. I have a table with one row and one col with a value of 2. I do DECLARE CURSOR ... SELECT * FROM table1 I then insert a new row with a value of 3. When I run the cursor, would I Just get the one row from before the cursor was declared, or both rows? Thanks

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  • T-SQL to PL/SQL (IDENTITY)

    - by folone
    I've got a T-SQL script, that converts field to IDENTITY (in a weird way). How do I convert it to PL/SQL? (and, probably, figure out, if there is a simpler way to do this - without creating a temporary table). The T-SQL script: -- alter table ts_changes add TS_THREADID VARCHAR(100) NULL; -- Change Field TS_ID TS_NOTIFICATIONEVENTS to IDENTITY BEGIN TRANSACTION GO CREATE TABLE dbo.Tmp_TS_NOTIFICATIONEVENTS ( TS_ID int NOT NULL IDENTITY (1, 1), TS_TABLEID int NOT NULL, TS_CASEID int NULL, TS_WORKFLOWID int NULL, TS_NOTIFICATIONID int NULL, TS_PRIORITY int NULL, TS_STARTDATE int NULL, TS_TIME int NULL, TS_WAITSTATUS int NULL, TS_RECIPIENTID int NULL, TS_LASTCHANGEDATE int NULL, TS_ELAPSEDCYCLES int NULL ) ON [PRIMARY] SET IDENTITY_INSERT dbo.Tmp_TS_NOTIFICATIONEVENTS ON GO IF EXISTS(SELECT * FROM dbo.TS_NOTIFICATIONEVENTS) EXEC('INSERT INTO dbo.Tmp_TS_NOTIFICATIONEVENTS (TS_ID, TS_TABLEID, TS_CASEID, TS_WORKFLOWID, TS_NOTIFICATIONID, TS_PRIORITY, TS_STARTDATE, TS_TIME, TS_WAITSTATUS, TS_RECIPIENTID, TS_LASTCHANGEDATE, TS_ELAPSEDCYCLES) SELECT TS_ID, TS_TABLEID, TS_CASEID, TS_WORKFLOWID, TS_NOTIFICATIONID, TS_PRIORITY, TS_STARTDATE, TS_TIME, TS_WAITSTATUS, TS_RECIPIENTID, TS_LASTCHANGEDATE, TS_ELAPSEDCYCLES FROM dbo.TS_NOTIFICATIONEVENTS WITH (HOLDLOCK TABLOCKX)') GO SET IDENTITY_INSERT dbo.Tmp_TS_NOTIFICATIONEVENTS OFF GO DROP TABLE dbo.TS_NOTIFICATIONEVENTS GO EXECUTE sp_rename N'dbo.Tmp_TS_NOTIFICATIONEVENTS', N'TS_NOTIFICATIONEVENTS', 'OBJECT' GO ALTER TABLE dbo.TS_NOTIFICATIONEVENTS ADD CONSTRAINT aaaaaTS_NOTIFICATIONEVENTS_PK PRIMARY KEY NONCLUSTERED ( TS_ID ) WITH( STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO COMMIT

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  • EF4: common interface for EF entities

    - by Feryt
    Hi. I have public interface: public interface IEntity { int ID { get; set; } string Name { get; set; } bool IsEnabled { get; set; } } ehich some EF entities implements(thanks to partial class) and extesion method: public static IEnumerable<SelectListItem> ToSelectListItems<T>(this IQueryable<T> entities, int? selectedID = null) where T : IEntity { return entities.Select(c => new { c.Name, c.ID }).ToList().Select(c => new SelectListItem { Text = c.Name, Value = c.ID.ToString(), Selected = (c.ID == selectedID) }); } Calling ToSelectListItems return exception: Unable to cast the type '<EF entity name>' to type 'IEntity'. LINQ to Entities only supports casting Entity Data Model primitive types. Why, any ideas? Thank you.

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  • Is this postgres function cost efficient or still have to clean

    - by kiranking
    There are two tables in postgres db. english_all and english_glob First table contains words like international,confidential,booting,cooler ...etc I have written the function to get the words from english_all then perform for loop for each word to get word list which are not inserted in anglish_glob table. Word list is like I In Int Inte Inter .. b bo boo boot .. c co coo cool etc.. for some reason zwnj(zero-width non-joiner) is added during insertion to english_all table. But in function I am removing that character with regexp_replace. Postgres function for_loop_test is taking two parameter min and max based on that I am selecting words from english_all table. function code is like DECLARE inMinLength ALIAS FOR $1; inMaxLength ALIAS FOR $2; mviews RECORD; outenglishListRow english_word_list;--custom data type eng_id,english_text BEGIN FOR mviews IN SELECT id,english_all_text FROM english_all where wlength between inMinLength and inMaxLength ORDER BY english_all_text limit 30 LOOP FOR i IN 1..char_length(regexp_replace(mviews.english_all_text,'(?)$','')) LOOP FOR outenglishListRow IN SELECT distinct on (regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','')) mviews.id, regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') where regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') not in(select english_glob.english_text from english_glob where i=english_glob.wlength) order by regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') LOOP RETURN NEXT outenglishListRow; END LOOP; END LOOP; END LOOP; END; Once I get the word list I will insert that into another table english_glob. My question is is there any thing I can add to or remove from function to make it more efficient. edit Let assume english_all table have words like footer,settle,question,overflow,database,kingdom If inMinLength = 5 and inmaxLength=7 then in the outer loop footer,settle,kingdom will be selected. For above 3 words inner two loop will apply to get words like f,fo,foo,foot,foote,footer,s,se,set,sett,settl .... etc. In the final process words which are bold will be entered into english_glob with another parameter like 1 to denote it is a proper word and stored in the another filed of english_glob table. Remaining word will be stored with another parameter 0 because in the next call words which are saved in database should not be fetched again. edit2: This is a complete code CREATE TABLE english_all ( id serial NOT NULL, english_all_text text NOT NULL, wlength integer NOT NULL, CONSTRAINT english_all PRIMARY KEY (id), CONSTRAINT english_all_kan_text_uq_id UNIQUE (english_all_text) ) CREATE TABLE english_glob ( id serial NOT NULL, english_text text NOT NULL, is_prop integer default 1, CONSTRAINT english_glob PRIMARY KEY (id), CONSTRAINT english_glob_kan_text_uq_id UNIQUE (english_text) ) insert into english_all(english_text) values ('ant'),('forget'),('forgive'); on function call with parameter 3 and 6 fallowing rows should fetched a an ant f fo for forg forge forget next is insert to another table based on above row insert into english_glob(english_text,is_prop) values ('a',1),('an',1), ('ant',1),('f',0), ('fo',0),('for',1), ('forg',0),('forge',1), ('forget',1), on function call next time with parameter 3 and 7 fallowing rows should fetched.(because f,fo,for,forg are all entered in english_glob table) forgi forgiv forgive

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  • SQl Server: serializable level not working

    - by Zé Carlos
    I have the following SP: CREATE PROCEDURE [dbo].[sp_LockReader] AS BEGIN SET NOCOUNT ON; begin try set transaction isolation level serializable begin tran select * from teste commit tran end try begin catch rollback tran set transaction isolation level READ COMMITTED end catch set transaction isolation level READ COMMITTED END The table "test" has many values, so "select * from teste" takes several seconds. I run the sp_LockReader at same time in two diferent query windows and the second one starts showing test table contents without the first one terminates. Shouldn't serializeble level forces the second query to wait? How do i get the described behaviour? Thanks

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  • NeoAxis 3D disponible en version 1.3, le moteur de jeu ajoute le SSAO et une meilleure gestion du terrain

    NeoAxis 3D et maintenant disponible en version 1.3 La nouvelle version du moteur de jeu apporte le SSAO, des améliorations sur le terrain et plein d'autres surprises C'est en cette période de Noël que NeoAxis 3D, le moteur de jeu multi-plateforme revient avec une hotte fournit en cadeau pour nous, les développeurs. Tout d'abord, cette version estampillée 1.3 apporte le Screen Space Ambient Occlusion (SSAO). Une technique de rendu temps réel qui est grandement utilisée dans l'industrie pour permettre une approximation efficace de l'ambient occlusion (des ombres sont rajoutés selon le buffer de profondeur).. Celui-ci est implémenté tel un effet après rendu (post processing) afin de garder une bonne synergi...

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  • delphi "Invalid use of keyword" in TQuery

    - by Baldric
    I'm trying to populate a TDBGrid with the results of the following TQuery against the file Journal.db: select * from Journal where Journal.where = "RainPump" I've tried both Journal."Where" and Journal.[Where] to no avail. I've also tried: select Journal.[Where] as "Location" - with the same result. Journal.db is a file created by a third party and I am unable to change the field names. The problem is that the field I'm interested in is called 'where' and understandably causes the above error. How do I reference this field without causing the BDE (presumably) to explode?

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  • LINQ Except operator and object equality

    - by Abhijeet Patel
    Here is an interesting issue I noticed when using the Except Operator: I have list of users from which I want to exclude some users: The list of users is coming from an XML file: The code goes like this: interface IUser { int ID { get; set; } string Name { get; set; } } class User: IUser { #region IUser Members public int ID { get; set; } public string Name { get; set; } #endregion public override string ToString() { return ID + ":" +Name; } public static IEnumerable<IUser> GetMatchingUsers(IEnumerable<IUser> users) { IEnumerable<IUser> localList = new List<User> { new User{ ID=4, Name="James"}, new User{ ID=5, Name="Tom"} }.OfType<IUser>(); var matches = from u in users join lu in localList on u.ID equals lu.ID select u; return matches; } } class Program { static void Main(string[] args) { XDocument doc = XDocument.Load("Users.xml"); IEnumerable<IUser> users = doc.Element("Users").Elements("User").Select (u => new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType<IUser>(); //still a query, objects have not been materialized var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes should contain 6 users but here it contains 8 users } } When I call User.GetMatchingUsers(users) I get 2 matches as expected. The issue is that when I call users.Except(matches) The matching users are not being excluded at all! I am expecting 6 users ut "excludes" contains all 8 users instead. Since all I'm doing in GetMatchingUsers(IEnumerable users) is taking the IEnumerable and just returning the IUsers whose ID's match( 2 IUsers in this case), my understanding is that by default "Except" will use reference equality for comparing the objects to be excluded. Is this not how "Except" behaves? What is even more interesting is that if I materialize the objects using .ToList() and then get the matching users, and call "Except", everything works as expected! Like so: IEnumerable users = doc.Element("Users").Elements("User").Select (u = new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType().ToList(); //explicity materializing all objects by calling ToList() var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes now contains 6 users as expected I don't see why I should need to materialize objects for calling "Except" given that its defined on IEnumerable? Any suggesstions / insights would be much appreciated.

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  • Coherence Data Guarantees for Data Reads - Basic Terminology

    - by jpurdy
    When integrating Coherence into applications, each application has its own set of requirements with respect to data integrity guarantees. Developers often describe these requirements using expressions like "avoiding dirty reads" or "making sure that updates are transactional", but we often find that even in a small group of people, there may be a wide range of opinions as to what these terms mean. This may simply be due to a lack of familiarity, but given that Coherence sits at an intersection of several (mostly) unrelated fields, it may be a matter of conflicting vocabularies (e.g. "consistency" is similar but different in transaction processing versus multi-threaded programming). Since almost all data read consistency issues are related to the concept of concurrency, it is helpful to start with a definition of that, or rather what it means for two operations to be concurrent. Rather than implying that they occur "at the same time", concurrency is a slightly weaker statement -- it simply means that it can't be proven that one event precedes (or follows) the other. As an example, in a Coherence application, if two client members mutate two different cache entries sitting on two different cache servers at roughly the same time, it is likely that one update will precede the other by a significant amount of time (say 0.1ms). However, since there is no guarantee that all four members have their clocks perfectly synchronized, and there is no way to precisely measure the time it takes to send a given message between any two members (that have differing clocks), we consider these to be concurrent operations since we can not (easily) prove otherwise. So this leads to a question that we hear quite frequently: "Are the contents of the near cache always synchronized with the underlying distributed cache?". It's easy to see that if an update on a cache server results in a message being sent to each near cache, and then that near cache being updated that there is a window where the contents are different. However, this is irrelevant, since even if the application reads directly from the distributed cache, another thread update the cache before the read is returned to the application. Even if no other member modifies a cache entry prior to the local near cache entry being updated (and subsequently read), the purpose of reading a cache entry is to do something with the result, usually either displaying for consumption by a human, or by updating the entry based on the current state of the entry. In the former case, it's clear that if the data is updated faster than a human can perceive, then there is no problem (and in many cases this can be relaxed even further). For the latter case, the application must assume that the value might potentially be updated before it has a chance to update it. This almost aways the case with read-only caches, and the solution is the traditional optimistic transaction pattern, which requires the application to explicitly state what assumptions it made about the old value of the cache entry. If the application doesn't want to bother stating those assumptions, it is free to lock the cache entry prior to reading it, ensuring that no other threads will mutate the entry, a pessimistic approach. The optimistic approach relies on what is sometimes called a "fuzzy read". In other words, the application assumes that the read should be correct, but it also acknowledges that it might not be. (I use the qualifier "sometimes" because in some writings, "fuzzy read" indicates the situation where the application actually sees an original value and then later sees an updated value within the same transaction -- however, both definitions are roughly equivalent from an application design perspective). If the read is not correct it is called a "stale read". Going back to the definition of concurrency, it may seem difficult to precisely define a stale read, but the practical way of detecting a stale read is that is will cause the encompassing transaction to roll back if it tries to update that value. The pessimistic approach relies on a "coherent read", a guarantee that the value returned is not only the same as the primary copy of that value, but also that it will remain that way. In most cases this can be used interchangeably with "repeatable read" (though that term has additional implications when used in the context of a database system). In none of cases above is it possible for the application to perform a "dirty read". A dirty read occurs when the application reads a piece of data that was never committed. In practice the only way this can occur is with multi-phase updates such as transactions, where a value may be temporarily update but then withdrawn when a transaction is rolled back. If another thread sees that value prior to the rollback, it is a dirty read. If an application uses optimistic transactions, dirty reads will merely result in a lack of forward progress (this is actually one of the main risks of dirty reads -- they can be chained and potentially cause cascading rollbacks). The concepts of dirty reads, fuzzy reads, stale reads and coherent reads are able to describe the vast majority of requirements that we see in the field. However, the important thing is to define the terms used to define requirements. A quick web search for each of the terms in this article will show multiple meanings, so I've selected what are generally the most common variations, but it never hurts to state each definition explicitly if they are critical to the success of a project (many applications have sufficiently loose requirements that precise terminology can be avoided).

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  • How can I provide values for non-grouped columns in NHibernate?

    - by ddc0660
    I have a criteria query: Session.CreateCriteria<Sell043Report>() .SetProjection(.ProjectionList() .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.location)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.agent)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.cusip)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.SettlementDate)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.salePrice)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.foreignFx)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.batchNumber)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.origSaleDate)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.planName)) .Add(LambdaProjection.GroupProperty<Sell043Report>(r => r.dateTimeAdded)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.shares)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.netMoney)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.grossMoney)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.taxWithheld)) .Add(LambdaProjection.Sum<Sell043Report>(r => r.fees))) .List<Sell043Report>(); that generates the following SQL: SELECT this_.location as y0_, this_.agent as y1_, this_.cusip as y2_, this_.SettlementDate as y3_, this_.salePrice as y4_, this_.foreignFx as y5_, this_.batchNumber as y6_, this_.origSaleDate as y7_, this_.planName as y8_, this_.dateTimeAdded as y9_, sum(this_.shares) as y10_, sum(this_.netMoney) as y11_, sum(this_.grossMoney) as y12_, sum(this_.taxWithheld) as y13_, sum(this_.fees) as y14_ FROM MIS_IPS_Sell043Report this_ GROUP BY this_.location, this_.agent, this_.cusip, this_.SettlementDate, this_.salePrice, this_.foreignFx, this_.batchNumber, this_.origSaleDate, this_.planName, this_.dateTimeAdded however the Sell043Report table has additional columns than those listed in the SELECT statement so I'm receiving this error when attempting to get a list of Sell043Reports: System.ArgumentException: The value "System.Object[]" is not of type "xyz.Sell043Report" and cannot be used in this generic collection. I suspect the problem is that I'm not selecting all of the columns for a Sell043Report and so it doesn't know how to map the dataset to the object. I'm trying to achieve something like this: SELECT this_.location as y0_, this_.agent as y1_, this_.cusip as y2_, this_.SettlementDate as y3_, this_.salePrice as y4_, this_.foreignFx as y5_, this_.batchNumber as y6_, this_.origSaleDate as y7_, this_.planName as y8_, this_.dateTimeAdded as y9_, sum(this_.shares) as y10_, sum(this_.netMoney) as y11_, sum(this_.grossMoney) as y12_, sum(this_.taxWithheld) as y13_, sum(this_.fees) as y14_, '' as Address1, '' as Address2 // etc FROM MIS_IPS_Sell043Report this_ GROUP BY this_.location, this_.agent, this_.cusip, this_.SettlementDate, this_.salePrice, this_.foreignFx, this_.batchNumber, this_.origSaleDate, this_.planName, this_.dateTimeAdded How can I do this using NHibernate?

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  • Moving to OOP hopefully!

    - by Luke
    So I am trying to understand OOP more and use it. The following code was written before i started using OOP. //loop through all the users $game = "$_POST[Game]_teams"; $result = mysql_query("SELECT username FROM `users`") or die(mysql_error()); while( $row=mysql_fetch_assoc($result) ) { $u[] = $row['username']; } I have put the query into my database page like following: function selectAllUsers() { $q = "SELECT username FROM ".TBL_USERS.""; mysql_query($q, $this->connection); } I'm a little confused about how the rest could be different? Would it be? Is it possible for anyone to help me without more code or understanding of my structure?

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  • Some facebook friends' birthdays returning as null but I have the correct API permissions

    - by Andrei Radulescu
    I'm tring to get my friends' birthdays in my app and some of them are null. I thought that those people don't have a birthday set, but they actually do. My fql query is: SELECT uid,name,birthday_date FROM user WHERE uid IN (SELECT uid2 from friend where uid1=me()) My app has the "friends_birthday" permission set. I also tried with "birthday" instead of "birthday_date". Same result. I imagine that this happens because they opted out somehow, but I don't know how. Is there an alternate solution to actually get their birthdays from facebook? Thanks!

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  • jQuery Form plugin - no data from file upload?

    - by pojo
    I've been struggling a bit with the jQuery Form plugin. I want to create a file upload form that posts the data (JSON, from the chosen file) into a REST service exposed by a servlet. The URL for the POST is calculated from what the user chooses in a SELECT dropdown. When the upload is complete, I want to notify the user immediately, AJAX-style. The problem is that the POST header has a Content-Length of 0 and contains no data. I would appreciate any help! <html> <head> <script type="text/javascript" src="js/jquery-1.4.2.min.js">/* ppp */</script> <script type="text/javascript" src="js/jquery.form.js">/* ppp */</script> <script type="text/javascript"> function cb_beforesubmit (arr, $form, options) { // This should override the form's action attribute options.url = "/rest/services/" + $('#selectedaction')[0].value; return true; } function cb_success (rt, st, xhr, wf) { $('#response').html(rt + '<br>' + st + '<br>' + xhr); } $(document).ready(function () { var options = { beforeSubmit: cb_beforesubmit, success: cb_success, dataType: 'json', contentType: 'application/json', method: 'POST', }; $('#myform').ajaxForm(options); $.getJSON('/rest/services', function (data, ts) { for (var property in data) { if (typeof property == 'string') { $('#selectedaction').append('<option>' + property + '</option>'); } } }); }); </script> </head> <body> <form id="myform" action="/rest/services/foo1" method="POST" enctype="multipart/form-data"> <!-- The form does not seem to submit at all if I don't set action to a default value? !--> <select id="selectedaction"> <script type="text/javascript"> </script> </select> <input type="file" value="Choose"/> <input type="submit" value="Submit" /> </form> <div id="response"> </div> </body> </html>

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