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  • ado.net Concurrency violation

    - by Bicubic
    My first time using ADO.net. Trying to make database of Users. First I populate my DataSet: adapter.AcceptChangesDuringFill = true; adapter.AcceptChangesDuringUpdate = true; adapter.Fill(dataset); To create a user: User user = new User(); user.datarow = dataset.Users.NewUsersRow(); user.Name = username; user.PasswordHash = GetHash(password); user.Rights = UserRights.None; users.Add(user); dataset.Users.AddUsersRow(user.datarow); adapter.Update(dataset); When a user property is modified: adapter.Update(dataset); Creation by itself is fine. If I take an existing user and make multiple changes, fine. Multiple creations in a row, fine. Creation followed by a property change, I get this: "Concurrency violation: the UpdateCommand affected 0 of the expected 1 records." Any ideas?

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  • Poor DB4O performance - What am I doing wrong?

    - by Jon
    I read Rob Conery's post about Object databases and thought I'd give it a go. I have a class lets say Book with 15 properties mostly string, some int, one Datetime and 2 decimals. I used Rob's code to open the database file etc to test on a Winforms project not a Web project. So I did the following: for(int i = 0; i < 1000000; i++) { var Book = new Book(); //Assign variables s.Save(Book); } s.CommitChanges(); This took at least a couple of minutes. I then tried to retrieve all data to test speed: var spp = s.All<Passports>(); This one line was quick, however, then doing: sppp.Count() as well as a seperate test doing a foreach loop and incrementing a counter took a couple of minutes. This seems quite slow to me. Am I doing something wrong or am I expecting too much?

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  • [Qt] How to get rid of OCI.dll dependency when compiling static

    - by STL
    Hi, My application accesses an Oracle database through Qt's QSqlDatabase class. I'm compiling Qt as static for the release build, but I can't seem to be able to get rid of OCI.dll dependency. I'm trying to link against oci.lib (as available in Oracle's Instant Client with SDK). Here's my configure line : configure -qt-libjpeg -qt-zlib -qt-libpng -nomake examples -nomake demos -no-exceptions -no-stl -no-rtti -no-qt3support -no-scripttools -no-openssl -no-opengl -no-phonon -no-style-motif -no-style-cde -no-style-cleanlooks -no-style-plastique -static -release -opensource -plugin-sql-oci -plugin-sql-sqlite -platform win32-msvc2005 I link against oci.h and oci.lib in the SDK's folder by using : set INCLUDE=C:\oracle\instantclient\sdk\include;%INCLUDE% set LIB=C:\oracle\instantclient\sdk\lib\msvc;%LIB% Then, once Qt is compiled, I use the following lines in my *.pro file : QT += sql CONFIG += static LIBS += C:\oracle\instantclient\sdk\lib\msvc\oci.lib QTPLUGIN += qsqloci Then, in my main.cpp, I add the following commands to statically compile OCI plugin in the application : #include <QtPlugin> Q_IMPORT_PLUGIN(qsqloci) After compiling the project, I test it on my workstation and it works (as I have Oracle Instant Client installed). When I try on another workstation, I always get the message: This application has failed to start because OCI.dll was not found. Re-installing this application may fix this problem. I don't understand why I still need OCI.dll, as my statically linked application is supposed to link to oci.lib instead. Is there any Qt people here that might have a solution for me ? Thanks a lot ! STL

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  • Problems when I try to see databases in SQLite

    - by Sabau Andreea
    I created in code a database and two tables: static final String dbName="graficeCirculatie"; static final String ruteTable="Rute"; static final String colRuteId="RutaID"; static final String colRuta="Ruta"; static final String statiaTable="Statia"; static final String colStatiaID="StatiaID"; static final String colIdRuta="IdRuta"; static final String colStatia="Statia"; public DatabaseHelper(Context context) { super(context, dbName, null,33); } public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL("CREATE TABLE " + statiaTable + " (" + colStatiaID + " INTEGER PRIMARY KEY , " + colIdRuta + " INTEGER, " + colStatia + " TEXT)"); db.execSQL("CREATE TABLE " + ruteTable + "(" + colRuteId + " INTEGER PRIMARY KEY AUTOINCREMENT, " + colRuta + " TEXT);"); InsertDepts(db); } void InsertDepts(SQLiteDatabase db) { ContentValues cv = new ContentValues(); cv.put(colRuteId, 1); cv.put(colRuta, "Expres8"); db.insert(ruteTable, colRuteId, cv); cv.put(colRuteId, 2); cv.put(colRuta, "Expres2"); db.insert(ruteTable, colRuteId, cv); cv.put(colRuteId, 3); cv.put(colRuta, "Expres3"); db.insert(ruteTable, colRuteId, cv); } Now I want to see tables inputs from command line. I try in this way: C:\Program Files\Android\android-sdk\tools sqlite3 SQLite version 3.7.4 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite sqlite3 graficeCirculatie ... select * from ruteTable; And I got an error: Error: near "squlite3": syntax error. Can someone help me?

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  • Temporary users table or legitimate users table?

    - by John
    I have a freelance web application that lets users register for events. In my database, I have a t_events_applicants table with the column t_events_applications.user_id with a foreign key constraint linked to the t_users.user_id column. So this means only users who have registered with my web application can register for my web application's events. My client would now like to allow non-registered users, users who do not have an entry in my t_user table, to register for events. These non-registered users only need to provide their name and email address to register for events. Should I create a t_temporary_user table with columns name and email and then remove the t_events_applicants.user_id fk constraint? Or should I add un-registered users to the t_user table and then add a column called t_user.type where type can be 'registered' or 'non-registered'? How do I decide which approach to go with? A lot of times, I hesitate with either approach. I ask myself, "What if at a later time, a temporary user is allowed to become a fully registered user? Then maybe I should have only a t_user table. But then I also don't feel good about storing a lot of temporary users in t_user."

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  • How to store dynamic references to parts of a text

    - by Antoine L
    In fact, my question concerns an algorithm. I need to be able to attach annotations to certain parts of a text, like a word or a group of words. The first thing that came to me to do so is to store the position of this part (indexes) in the text. For instance, in the text 'The quick brown fox jumps over the lazy dog', I'd like to attach an annotation to 'quick brown fox', so the indexes of the annotation would be 4 - 14. But since the text is editable (other annotations could provoke a modification from text's author), the annoted part is likely to move (the indexes could change). In fact, I don't know how to update the indexes of the annoted part. What if the text becomes 'Everyday, the quick brown fox jumps over the lazy dog' ? I guess I have to watch every change of the text in the front-end application ? The front-end part of the application will be HTML with Javascript. I will be using PHP to develop the back-end part and every text and annotation will be stored in a database.

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  • ob_start() is partially capturing data

    - by AAA
    I am using the following code: PHP: // Generate Guid function NewGuid() { $s = strtoupper(uniqid(rand(),true)); $guidText = substr($s,0,8) . '-' . substr($s,8,4) . '-' . substr($s,12,4). '-' . substr($s,16,4). '-' . substr($s,20); return $guidText; } // End Generate Guid $Guid = NewGuid(); $alphabet = '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ'; function base_encode($num, $alphabet) { $base_count = strlen($alphabet); $encoded = ''; while ($num >= $base_count) { $div = $num/$base_count; $mod = ($num-($base_count*intval($div))); $encoded = $alphabet[$mod] . $encoded; $num = intval($div); } if ($num) $encoded = $alphabet[$num] . $encoded; return $encoded; } function base_decode($num, $alphabet) { $decoded = 0; $multi = 1; while (strlen($num) > 0) { $digit = $num[strlen($num)-1]; $decoded += $multi * strpos($alphabet, $digit); $multi = $multi * strlen($alphabet); $num = substr($num, 0, -1); } return $decoded; } ob_start(); echo base_encode($Guid, $alphabet); //should output: bUKpk $theid = ob_get_contents(); ob_get_clean(); The problem: When i echo $theid, it shows the complete entry, but as it is being inserted into the database, only the first entry in the sequence gets inserted, for example for the entry buKPK, only 'b' is being inserted not the rest.

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  • Schema-less design guidelines for Google App Engine Datastore and other NoSQL DBs

    - by jamesaharvey
    Coming from a relational database background, as I'm sure many others are, I'm looking for some solid guidelines for setting up / designing my datastore on Google App Engine. Are there any good rules of thumb people have for setting up these kinds of schema-less data stores? I understand some of the basics such as denormalizing since you can't do joins, but I was wondering what other recommendations people had. The particular simple example I am working with concerns storing searches and their results. For example I have the following 2 models defined in my Google App Engine app using Python: class Search(db.Model): who = db.StringProperty() what = db.StringProperty() where = db.StringProperty() createDate = db.DateTimeProperty(auto_now_add=True) class SearchResult(db.Model): title = db.StringProperty() content = db.StringProperty() who = db.StringProperty() what = db.StringProperty() where = db.StringProperty() createDate = db.DateTimeProperty(auto_now_add=True) I'm duplicating a bunch of properties between the models for the sake of denormalization since I can't join Search and SearchResult together. Does this make sense? Or should I store a search ID in the SearchResult model and effectively 'join' the 2 models in code when I retrieve them from the datastore? Please keep in mind that this is a simple example. Both models will have a lot more properties and the way I'm approaching this right now, I would put any property I put in the Search model in the SearchResult model as well.

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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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  • File Storage for Web Applications: Filesystem vs DB vs NoSQL engines

    - by El Yobo
    I have a web application that stores a lot of user generated files. Currently these are all stored on the server filesystem, which has several downsides for me. When we move "folders" (as defined by our application) we also have to move the files on disk (although this is more due to strange design decisions on the part of the original developers than a requirement of storing things on the filesystem). It's hard to write tests for file system actions; I have a mock filesystem class that logs actions like move, delete etc, without performing them, which more or less does the job, but I don't have 100% confidence in the tests. I will be adding some other jobs which need to access the files from other service to perform additional tasks (e.g. indexing in Solr, generating thumbnails, movie format conversion), so I need to get at the files remotely. Doing this over network shares seems dodgy... Dealing with permissions on the filesystem as sometimes given us problems in the past, although now that we've moved to a pure Linux environment this should be less of an issue. What are the downsides of storing files as BLOBs in MySQL? I guess that it would massively increase the database size and reduce the effectiveness of caches, but are there other problems? Do the same problems exist with NoSQL systems like Cassandra? Does anyone have any other suggestions that might be appropriate?

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  • Why qry.post executed with asynchronous mode?

    - by Ryan
    Recently I met a strange problem, see code snips as below: var sqlCommand: string; connection: TADOConnection; qry: TADOQuery; begin connection := TADOConnection.Create(nil); try connection.ConnectionString := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Test.MDB;Persist Security Info=False'; connection.Open(); qry := TADOQuery.Create(nil); try qry.Connection := connection; qry.SQL.Text := 'Select * from aaa'; qry.Open; qry.Append; qry.FieldByName('TestField1').AsString := 'test'; qry.Post; beep; finally qry.Free; end; finally connection.Free; end; end; First, Create a new access database named test.mdb and put it under the directory of this test project, we can create a new table named aaa in it which has only one text type field named TestField1. We set a breakpoint at line of "beep", then lunch the test application under ide debug mode, when ide stops at the breakpoint line (qry.post has been executed), at this time we use microsoft access to open test.mdb and open table aaa you will find there are no any changes in table aaa, if you let the ide continue running after pressing f9 you can find a new record is inserted in to table aaa, but if you press ctrl+f2 to terminate the application at the breakpoint, you will find the table aaa has no record been inserted, but in normal circumstance, a new record should be inserted in to the table aaa after qry.post executed. who can explain this problem , it troubles me so long time. thanks !!! BTW, the ide is delphi 2010, and the access mdb file is created by microsoft access 2007 under windows 7

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  • Finding the right terminology for a dictionary table

    - by Karl Forner
    My concern is about what I currently call "dictionary tables", that are database tables containing a list of controlled vocabulary. Let's use an example: Suppose you have a table User containing fields: user_id : primary key first_name last_name user_type_id : foreign key to the UserType table and another table UserType with just two fields: user_type_id : primary key name : the name/value of a particular type of user. For instance, the UserType table may contain (1, Administrator), (2, PowerUser), (3, Normal)... My question is: what is the canonical term for a table like UserType, that only contains a list of (dictinct) words. I want to publish some code that help managing this kind of tables, but first I have to name them ! Thanks for your help. Current state of thought: For now I feel Lookup Tables is a good term. It is also used with the same meaning in these posts: http://dbix-class.35028.n2.nabble.com/RFC-Component-for-Lookup-tables-td3504085.html http://tonyandrews.blogspot.de/2004/10/otlt-and-eav-two-big-design-mistakes.html Lookup Tables Best Practices: DB Tables... or Enumerations The only problem is that lookup table is also sometimes used to name a junction table.

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  • Select all points in a matrix within 30m of another point

    - by pinnacler
    So if you look at my other posts, it's no surprise I'm building a robot that can collect data in a forest, and stick it on a map. We have algorithms that can detect tree centers and trunk diameters and can stick them on a cartesian XY plane. We're planning to use certain 'key' trees as natural landmarks for localizing the robot, using triangulation and trilateration among other methods, but programming this and keeping data straight and efficient is getting difficult using just Matlab. Is there a technique for sub-setting an array or matrix of points? Say I have 1000 trees stored over 1km (1000m), is there a way to say, select only points within 30m radius of my current location and work only with those? I would just use a GIS, but I'm doing this in Matlab and I'm unaware of any GIS plugins for Matlab. I forgot to mention, this code is going online, meaning it's going on a robot for real-time execution. I don't know if, as the map grows to several miles, using a different data structure will help or if calculating every distance to a random point is what a spatial database is going to do anyway. I'm thinking of mirroring two arrays, one sorted by X and the other by Y. Then bubble sorting to determine the 30m range in that. I do the same for both arrays, X and Y, and then have a third cross link table that will select the individual values. But I don't know, what that's called, how to program that and I'm sure someone already has so I don't want to reinvent the wheel. Cartesian Plane GIS

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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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  • Modeling complex hierarchies

    - by jdn
    To gain some experience, I am trying to make an expert system that can answer queries about the animal kingdom. However, I have run into a problem modeling the domain. I originally considered the animal kingdom hierarchy to be drawn like -animal -bird -carnivore -hawk -herbivore -bluejay -mammals -carnivores -herbivores This I figured would allow me to make queries easily like "give me all birds", but would be much more expensive to say "give me all carnivores", so I rewrote the hierarchy to look like: -animal -carnivore -birds -hawk -mammals -xyz -herbivores -birds -bluejay -mammals But now it will be much slower to query "give me all birds." This is of course a simple example, but it got me thinking that I don't really know how to model complex relationships that are not so strictly hierarchical in nature in the context of writing an expert system to answer queries as stated above. A directed, cyclic graph seems like it could mathematically solve the problem, but storing this in a relational database and maintaining it (updates) would seem like a nightmare to me. I would like to know how people typically model such things. Explanations or pointers to resources to read further would be acceptable and appreciated.

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  • Primary key/foreign Key naming convention

    - by Jeremy
    In our dev group we have a raging debate regarding the naming convention for Primary and Foreign Keys. There's basically two schools of thought in our group: 1) Primary Table (Employee) Primary Key is called ID Foreign table (Event) Foreign key is called EmployeeID 2) Primary Table (Employee) Primary Key is called EmployeeID Foreign table (Event) Foreign key is called EmployeeID I prefer not to duplicate the name of the table in any of the columns (So I prefer option 1 above). Conceptually, it is consisted with a lot of the recommended practices in other languages, where you don't use the name of the object in its property names. I think that naming the foreign key EmployeeID (or Employee_ID might be better) tells the reader that it is the ID column of the Employee Table. Some others prefer option 2 where you name the primary key prefixed with the table name so that the column name is the same throughout the database. I see that point, but you now can not visually distinguish a primary key from a foreign key. Also, I think it's redundant to have the table name in the column name, because if you think of the table as an entity and a column as a property or attribute of that entity, you think of it as the ID attribute of the Employee, not the EmployeeID attribute of an employee. I don't go an ask my coworker what his PersonAge or PersonGender is. I ask him what his Age is. So like I said, it's a raging debate and we go on and on and on about it. I'm interested to get some new perspective.

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  • MySql Query lag time?

    - by Click Upvote
    When there are multiple PHP scripts running in parallel, each making an UPDATE query to the same record in the same table repeatedly, is it possible for there to be a 'lag time' before the table is updated with each query? I have basically 5-6 instances of a PHP script running in parallel, having been launched via cron. Each script gets all the records in the items table, and then loops through them and processes them. However, to avoid processing the same item more than once, I store the id of the last item being processed in a seperate table. So this is how my code works: function getCurrentItem() { $sql = "SELECT currentItemId from settings"; $result = $this->db->query($sql); return $result->get('currentItemId'); } function setCurrentItem($id) { $sql = "UPDATE settings SET currentItemId='$id'"; $this->db->query($sql); } $currentItem = $this->getCurrentItem(); $sql = "SELECT * FROM items WHERE status='pending' AND id > $currentItem'"; $result = $this->db->query($sql); $items = $result->getAll(); foreach ($items as $i) { //Check if $i has been processed by a different instance of the script, and if so, //leave it untouched. if ($this->getCurrentItem() > $i->id) continue; $this->setCurrentItem($i->id); // Process the item here } But despite of all the precautions, most items are being processed more than once. Which makes me think that there is some lag time between the update queries being run by the PHP script, and when the database actually updates the record. Is it true? And if so, what other mechanism should I use to ensure that the PHP scripts always get only the latest currentItemId even when there are multiple scripts running in parrallel? Would using a text file instead of the db help?

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  • table design for storing large number of rows

    - by hyperboreean
    I am trying to store in a postgresql database some unique identifiers along with the site they have been seen on. I can't really decide which of the following 3 option to choose in order to be faster and easy maintainable. The table would have to provide the following information: the unique identifier which unfortunately it's text the sites on which that unique identifier has been seen The amount of data that would have to hold is rather large: there are around 22 millions unique identifiers that I know of. So I thought about the following designs of the table: id - integer identifier - text seen_on_site - an integer, foreign key to a sites table This approach would require around 22 mil multiplied by the number of sites. id - integer identifier - text seen_on_site_1 - boolean seen_on_site_2 - boolean ............ seen_on_site_n - boolean Hopefully the number of sites won't go past 10. This would require only the number of unique identifiers that I know of, that is around 20 millions, but it would make it hard to work with it from an ORM perspective. one table that would store only unique identifiers, like in: id - integer unique_identifier - text, one table that would store only sites, like in: id - integer site - text and one many to many relation, like: id - integer, unique_id - integer (fk to the table storing identifiers) site_id - integer (fk to sites table) another approach would be to have a table that stores unique identifiers for each site So, which one seems like a better approach to take on the long run?

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  • insert data to table based on another table C#

    - by user1017315
    I wrote a code which takes some values from one table and inserts the other table in these values.(not just these values, but also these values(this values=values from the based on table)) and I get this error: System.Data.OleDb.OleDbException (0x80040E10): value wan't given for one or more of the required parameters.` here's the code. I don't know what i've missed. string selectedItem = comboBox1.SelectedItem.ToString(); Codons cdn = new Codons(selectedItem); string codon1; int index; if (this.i != this.counter) { //take from the DataBase the matching codonsCodon1 to codonsFullName codon1 = cdn.GetCodon1(); //take the serialnumber of the last protein string connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=C:\\Projects_2012\\Project_Noam\\Access\\myProject.accdb"; OleDbConnection conn = new OleDbConnection(connectionString); conn.Open(); string last= "SELECT proInfoSerialNum FROM tblProInfo WHERE proInfoScienceName = "+this.name ; OleDbCommand getSerial = new OleDbCommand(last, conn); OleDbDataReader dr = getSerial.ExecuteReader(); dr.Read(); index = dr.GetInt32(0); //add the amino acid to tblOrderAA using (OleDbConnection connection = new OleDbConnection(connectionString)) { string insertCommand = "INSERT INTO tblOrderAA(orderAASerialPro, orderAACodon1) " + " values (?, ?)"; using (OleDbCommand command = new OleDbCommand(insertCommand, connection)) { connection.Open(); command.Parameters.AddWithValue("orderAASerialPro", index); command.Parameters.AddWithValue("orderAACodon1", codon1); command.ExecuteNonQuery(); } } } EDIT:I put a messagebox after that line: index = dr.GetInt32(0); to see where is the problem, and i get the error before that.i don't see the messagebox

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  • Synchronizing DataGridView (DataTable) with the DB

    - by Ezekiel Rage
    Hi! I have the following situation: there is a table in the DB that is queried when the form loads and the retrieved data is filled into a DataGridView via the DataTable underneath. After the data is loaded the user is free to modify the data (add / delete rows, modify entries). The form has 2 buttons: Apply and Refresh. The first one sends the changes to the database, the second one re-reads the data from the DB and erases any changes that have been made by the user. My question is: is this the best way to keep a DataGridView synchronized with the DB (from a users point of view)? For now these are the downsides: the user must keep track of what he is doing and must press the button every while the modifications are lost if the form is closed / app crash / ... I tried sending the changes to the DB on CellEndEdit event but then the user also needs some Undo/Redo functionality and that is ... well ... a different story. So, any suggestions?

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  • What is a good automated data import method for SQL Server?

    - by Joel Potter
    I'm in the process of porting some SQL Server 2005 databases to SQL Server 2008. One of these databases has an associated import application (Windows task) which uses SSIS with a DTS package to import a large dataset from an MS Access database nightly. In upgrading to SQL Server 2008, I discovered that I can't run the same console application which has been performing the imports due to the missing manageddts DLL in SQL Server 2008. It's several years old and in need of a rewrite for various reason, plus, I've been fairly unhappy with DTS in general. The original reason DTS was chosen was for speed (5 min import time compared to 30+ for ADO.NET). The format of the data to import is out of my control (the client likes Access). I would also like to be able to run the import from a machine completely separate from the server hosting SQL Server and preferably with minimal SQL features installed. Options I've considered: Creating an Access application to connect to both databases (SQL Server and Access) and perform the import (Ugh!) Revisiting ADO.NET to see if the original implementation was poorly written. Updated SSIS packages. What other technologies should I be considering for this job?

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  • Which SQL statements to execute with intersection / junction tables

    - by user1455103
    Here a simplified database layout One condo can hold multiple properties (flats, garage boxes, etc) - 1->n relationship One owner can have multiple properties in the same condo and properties can have more than one owner (m->n changed to 1->n with the junction table) One condo can have multiple owners - 1->n Some additional clarification: A owner is a member of a condo. A condo is made of properties belonging to owners BUT a owner is not linked to a property directly (there can be no relation between a property and a owner for a certain time BUT there will ALWAYS be a relation between a owner and a condo). Reason for this: the agent managing the condo will first create a list of owners and a list of properties. It is only later thet he will "link" each property to one or multiple owners (or inversely) I'm quite new to SQL. What SQL statements should I execute to: SELECT, for a specific condo (WHERE condition), the properties and their respective owners (all properties should be listed even if owners are null) SELECT, for a specific condo (WHERE condition), the owners along with their properties (all owners should be listed even if properties are null) UPDATE / DELETE existing owners (I'm uncertain about how to handle the operation for the junction tables. Should I first check if there is an entry in the junction table or not ?) UPDATE / DELETE existing properties (same concern) INSERT new owners (should I use two different SQL statements depending if the owner should be linked to a property or NOT - IF condition ?) INSERT new properties (same question as above) Could you be as clear and generic as possible so that it can be reused ? :-)

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  • should i advocate migrating from access to (my)sql

    - by HotOil
    Hi: We have a windows MFC app that is written against an access database on a company server. The db is not that big: 19 MB. There are at most 2-3 users accessing it at any one time. It is used in a factory environment where access speed (or lack thereof) over the intranet becomes noticeable as it is part of the manufacturing time for our widgets. The scenario is this: as each widget is completed, it gets a record in the db.. by the end of the year, the db is larger and searching for a record takes longer and longer. The solution so far has been to manually move older records to an archival table about once a year. We are reworking other portions of this app right now, and it would be a good time to move to another db if we are going to do it. It is my understanding that if we were using sql, the search time would not go up as the table gets bigger because the entire .mdb does not have to be sent over the network each time. Is this correct? Does anyone have any insight about whether it could be worth it to go to the trouble (time and money) of migrating to a new db, or should I just add more functionality to the application we have now, and maybe automatically purge the older records from time to time, and add additional facilities to the app to get at the older records when needed? Thanks for any wisdom you can share..

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  • Saving tree-structures in Databases

    - by Nina Null
    Hello everyone. I use Hibernate/Spring and a MySQL Database for my data management. Currently I display a tree-structure in a JTable. A tree can have several branches, in turn a branch can have several branches (up to nine levels) again, or having leaves. Lately I have performanceproblemes, as soon as I want to create new branches on deeper levels. At this time a branch has a foreign key to its parent. The domainobject has access to its parent by calling getParent(), which returns the parent-branch. The deeper the level, the longer it takes to create a new branch. Microbenchmark results for creating a new branch are like: Level 1: 32 ms. Level 3: 80 ms. Level 9: 232 ms. Obviously the level (which means the number of parents) is responsible for this. So I wanted to ask, if there are any appendages to work around this kind of problem. I don’t understand why Hibernate needs to know about the whole object tree (all parents until the root) while creating a new branch. But as far as I know this can be the only reason for the delay while creating a new branch, because a branch doesn’t have any other relations to any other objects. I would be very thankful for any workarounds or suggestions. greets, jambusa

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  • PHP Function needed for GENERIC sorting of a recordset array

    - by donbriggs
    Somebody must have come up with a solution for this by now. I wrote a PHP class to display a recordset as an HTML table/datagrid, and I wish to expand it so that we can sort the datagrid by whichever column the user selects. In the below example data, we may need to sort the recordset array by Name, Shirt, Assign, or Age fields. I will take care of the display part, I just need help with sorting the data array. As usual, I query a database to get a result, iterate throught he result, and put the records into an assciateiave array. So, we end up with an array of arrays. (See below.) I need to be able to sort by any column in the dataset. However, I will not know the column names at design time, nor will I know if the colums will be string or numeric values. I have seen a ton of solutions to this, but I have not seen a GOOD and GENERIC solution Can somebody please suggest a way that I can sort the recordset array that is GENERIC, and will work on any recordset? Again, I will not know the fields names or datatypes at design time. The array presented below is ONLY an example. Array ( [0] = Array ( [name] = Kirk [shrit] = Gold [assign] = Bridge ) [1] => Array ( [name] => Spock [shrit] => Blue [assign] => Bridge ) [2] => Array ( [name] => Uhura [shrit] => Red [assign] => Bridge ) [3] => Array ( [name] => Scotty [shrit] => Red [assign] => Engineering ) [4] => Array ( [name] => McCoy [shrit] => Blue [assign] => Sick Bay ) )

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