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  • Table transformation / field parsing in PL/SQL

    - by IMHO
    I have de-normalized table, something like CODES ID | VALUE 10 | A,B,C 11 | A,B 12 | A,B,C,D,E,F 13 | R,T,D,W,W,W,W,W,S,S The job is to convert is where each token from VALUE will generate new record. Example: CODES_TRANS ID | VALUE_TRANS 10 | A 10 | B 10 | C 11 | A 11 | B What is the best way to do it in PL/SQL without usage of custom pl/sql packages, ideally with pure SQL? Obvious solution is to implement it via cursors. Any ideas?

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  • NHibernate Many to Many delete all my data in the table

    - by Daoming Yang
    I would love to thank @Stefan Steinegger and @David helped me out yesterday with many-to-many mapping. I have 3 tables which are "News", "Tags" and "News_Tags" with Many-To-Many relationship and the "News_Tags" is the link table. If I delete one of the news records, the following mappings will delete all my news records which have the same tags. One thing I need to notice, I only allowed unique tag stored in the "Tag" table. This mapping make sense for me, it will delete the tag and related News records, but how can I implement a tagging system with NHibernate? Can anyone give me some suggestion? Many thanks. Daoming. News Mapping: <class name="New" table="News" lazy="false"> <id name="NewID"> <generator class="identity" /> </id> <property name="Title" type="String"></property> <property name="Description" type="String"></property> <set name="TagsList" table="New_Tags" lazy="false" inverse="true" cascade="all"> <key column="NewID" /> <many-to-many class="Tag" column="TagID" /> </set> </class> Tag Mapping: <class name="Tag" table="Tags" lazy="false"> <id name="TagID"> <generator class="identity" /> </id> <property name="TagName" type="String"></property> <property name="DateCreated" type="DateTime"></property> <!--inverse="true" has been defined in the "News mapping"--> <set name="NewsList" table="New_Tags" lazy="false" cascade="all"> <key column="TagID" /> <many-to-many class="New" column="NewID" /> </set> </class>

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  • Focus Window by CGWindowID

    - by JustSid
    Is it possible to focus a NSWindow by its CGWindowID? And yes, how? I need to focus a Window of another application, but I have only its CGWindowID and I can only find sample code about retrieving the ID, but not how to focus a Window by its ID.

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  • Where should I put zoomIn in my MapActivity?

    - by Johny
    I'm writing an Android app, and I'd like to zoomIn as soon as the map has been loaded. I get the following error: java.lang.IllegalArgumentException: width and height must be > 0 This MapActivity - width and height must be > 0 question suggests the problem is the zoomIn() method is in the onCreate() method. But I get same error when I put it in the onResume() method. I've been searching for hours and I can't find anything about it at http://developer.android.com or anywhere else... Also I can't find a way to get the time point the map has been loaded. A "MapLoadedListener" or something like that... EDIT Here is my code: public class AMap extends MapActivity{ private final String LOG_TAG = this.getClass().getSimpleName(); private Context mContext; private Chronometer timer; private TextView tvCountdown; private RelativeLayout rl; private MapView mapView; private MapController mapController; private List<Overlay> mapOverlays; private PlayersOverlay playersOverlay; private Drawable drawable; private Builder endDialog; private ContextThemeWrapper ctw; private Handler mHandler = new Handler(); private Player player = new Player(); private StartTask startTask; private EndTask endTask; private MyDBAdapter mdba; private Cursor playersCursor; private UpdateBroadcastReceiver r; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.map_view); mContext = AMap.this; // set map mapView = (MapView) findViewById(R.id.mapview); mapView.setBuiltInZoomControls(true); mapView.setFocusable(true); // find the relative layout rl = (RelativeLayout) findViewById(R.id.rl); // set the chronometer timer = (Chronometer) findViewById(R.id.tv_timer); timer.setBackgroundColor(Color.DKGRAY); // set the countdown textview tvCountdown = (TextView) findViewById(R.id.tv_countdown); // Open DB connection and get players Cursor mdba = new MyDBAdapter(mContext); mdba.open(); playersCursor = mdba.getGame(); // Get this player's id and location Intent starter = this.getIntent(); player.setId(starter.getIntExtra("id", 0)); player.setLatitude(starter.getDoubleExtra("lat", 0)); player.setLongitude(starter.getDoubleExtra("lon", 0)); // Set this player's location as map's center GeoPoint geoPoint = new GeoPoint((int) (player.getLatitude()*1E6), (int) (player.getLongitude()*1E6)); mapController = mapView.getController(); mapController.setCenter(geoPoint); mapController.setZoom(15); Log.d(LOG_TAG, "My playersCursor has "+playersCursor.getCount()+" rows"); // drawable is needed but not used drawable = this.getResources().getDrawable(R.drawable.ic_launcher); // set PlayersOverlay (locations and statuses) playersOverlay = new PlayersOverlay(player.getId(), playersCursor, drawable, this); mapOverlays = mapView.getOverlays(); mapOverlays.add(playersOverlay); mHandler.postDelayed(mUpdateTimeTask, 100); } private Runnable mUpdateTimeTask = new Runnable() { public void run() { int h = mapView.getLayoutParams().height; int w = mapView.getLayoutParams().width; Log.d(LOG_TAG, "w = "+w+" , h = "+h); mHandler.postAtTime(this, System.currentTimeMillis() + 1000); } }; @Override public void onAttachedToWindow(){ Log.d(LOG_TAG, "Attached to Window"); int h = mapView.getLayoutParams().height; int w = mapView.getLayoutParams().width; Log.d(LOG_TAG, " Attached to window: w = "+w+" , h = "+h); //mapController.zoomInFixing(screenPoint.x, screenPoint.y); } public void onWindowFocusChanged(boolean hasFocus){ Log.d(LOG_TAG, "Focus changed to: "+hasFocus); int h = mapView.getLayoutParams().height; int w = mapView.getLayoutParams().width; Log.d(LOG_TAG, " Window focus changed: w = "+w+" , h = "+h); //mapController.zoomInFixing(screenPoint.x, screenPoint.y); } @Override protected void onStart(){ super.onStart(); // Create and register the broadcast receiver for messages from service IntentFilter filter = new IntentFilter(AppConstants.iGAME_UPDATE); r = new UpdateBroadcastReceiver(); registerReceiver(r, filter); // Create the dialog for end of game ctw = new ContextThemeWrapper(mContext, android.R.style.Theme_Translucent_NoTitleBar_Fullscreen); endDialog = new AlertDialog.Builder(ctw); endDialog.setMessage("End of Game"); endDialog.setCancelable(false); endDialog.setNeutralButton("OK", new OnClickListener(){ @Override public void onClick(DialogInterface dialog, int which) { Intent highScores = new Intent(AMap.this, HighScores.class); startActivity(highScores); playersCursor.close(); finish(); } }); } @Override protected void onStop() { if(!playersCursor.isClosed()) playersCursor.close(); unregisterReceiver(r); mdba.close(); super.onStop(); } @Override protected boolean isRouteDisplayed() { return false; } // Receives signal from NetworkService that DB has been updated public class UpdateBroadcastReceiver extends BroadcastReceiver { boolean startSignal, update, endSignal; @Override public void onReceive(Context context, Intent intent) { endSignal = intent.getBooleanExtra("endSignal", false); if(endSignal){ Log.d(LOG_TAG, "Game Update BroadcastReceiver received End Signal"); endTask = new EndTask(); endTask.execute(); return; } update = intent.getBooleanExtra("update", false); if(update){ Log.d(LOG_TAG, "Game Update BroadcastReceiver received game update"); playersCursor.requery(); mapView.invalidate(); return; } startSignal = intent.getBooleanExtra("startSignal", false); if(startSignal){ Log.d(LOG_TAG, "Game Update BroadcastReceiver received Start Signal"); startTask = new StartTask(); startTask.execute(); return; } } } class StartTask extends AsyncTask<Void,Integer,Void>{ private final ToneGenerator tg = new ToneGenerator(AudioManager.STREAM_NOTIFICATION, 100); private final long DELAY = 1200; @Override protected Void doInBackground(Void... params) { int i = 3; while(i>=0){ publishProgress(i); try { Thread.sleep(DELAY); } catch (InterruptedException e) { e.printStackTrace(); } i--; } return null; } @Override protected void onProgressUpdate(Integer... progress){ tg.startTone(ToneGenerator.TONE_PROP_PROMPT); tvCountdown.setText(""+progress[0]); } @Override protected void onPostExecute(Void result) { rl.removeView(tvCountdown); timer.setBase(SystemClock.elapsedRealtime()); timer.start(); //enable screen touches playersOverlay.setGameStarted(true); } } class EndTask extends AsyncTask<Void,Void,Void>{ @Override protected void onPreExecute(){ //disable screen touches playersOverlay.setEndOfGame(true); timer.stop(); } @Override protected Void doInBackground(Void... params) { return null; } @Override protected void onPostExecute(Void result) { try{ endDialog.show(); }catch(Exception e){ Toast.makeText(mContext, "End of game", Toast.LENGTH_LONG); Intent highScores = new Intent(AMap.this, HighScores.class); startActivity(highScores); playersCursor.close(); finish(); } mHandler.removeCallbacks(mUpdateTimeTask); } } }

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  • Deploy .net MVC 2 appication on IIS6

    - by munish
    I want to deploy my .net MVC 2 appication on IIS6.0. Will it require to change route path in global.asax file. In my application i have used html link, ajax request and Html.ActionLink. The code lines in the Global.asax file are: routes.MapRoute( "LogOn", "{controller}/{action}/{id}", new { controller = "Account", action = "Index", id = UrlParameter.Optional } ); Please suggest me. Thanks and Regards Munish

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  • Having a number in

    - by Wiika
    Can someone give me a query that will return as a result rows ID 1 & 3? ID Name Hidden 1 Mika 1,4,2 2 Loca 0 3 Nosta 4 4 Like 2 Something like this SELECT * FROM table WHERE Hidden HAVING(4)

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  • Is it possible to parse a URL into it's composite components?

    - by Paul Alexander
    I'd like to parse an incoming URL into it's component parts for some pre-processing before passing it into the standard MVC routing logic. For example given your standard route {controller}/{action}/{id} and the URL /user/show/10 Is there a way to have the Routing system return a dictionary containing controller, action and id keys with their corresponding values?

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  • how do i read strings from text files?

    - by ratty
    I like to read string from text file the text file consists of information below con = new MySqlConnection("server=localhost;user id=root; password=""; database=workplantype; pooling=false;"); i like to read server name such as"localhost" here and user id such as"root" here,how can i read this.

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  • Nhibernate - Getting Exception when run a simple join query

    - by Muhammad Akhtar
    hi, I am getting issue when I run sql Query having inner join, here is what I am doing very simple ISession session = NHibernateHelper.GetCurrentSession(); string query = string.Format("select Documents.TypeId from Documents inner join DocumentTrackingItems on Documents.Id = DocumentTrackingItems.DocumentId WHERE DocumentTrackingItems.ItemStepId = {0} order by Documents.TypeId asc", 13); System.Collections.ArrayList document = (System.Collections.ArrayList)session.CreateSQLQuery(query, "document", typeof(Document)).List(); I am getting this exception Exception Details: System.IndexOutOfRangeException: Id what's wrong in my query? --- thanks

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  • Ruby - Read file in batches

    - by Algorist
    Hi, I am reading a file that is 10mb in size and which contains some id's. I read them into a list in ruby. I am concerned that it might cause memory issues in the future, when the number of id's in file might increase. Is there a effective way of reading a large file in batches? Thank you

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  • Missing parameter error after running MySql query

    - by annelie
    Hello, I'm completely new to MySql and haven't used SqlDataSource with UpdateParameters before, so I'm probably missing something very obvious. When trying to update a record, the update does happen but then throws an error saying "'id' parameter is missing at the statement". So the query works and the database gets updated as it should, but an error is thrown afterwards. These are the update parameters: <UpdateParameters> <asp:Parameter Name="business_name" Type="string" Size="256" /> <asp:Parameter Name="addr_line_1" Type="string" Size="256" /> <asp:Parameter Name="addr_line_2" Type="string" Size="256" /> <asp:Parameter Name="addr_line_3" Type="string" Size="256" /> <asp:Parameter Name="postcode" Type="string" Size="32" /> <asp:Parameter Name="county" Type="string" Size="128" /> <asp:Parameter Name="town_city" Type="string" Size="256" /> <asp:Parameter Name="tl_url" Type="string" Size="256" /> <asp:Parameter Name="customer_id" Type="string" Size="16" /> <asp:Parameter Name="region_id" Type="Int16" /> <asp:Parameter Name="description" Type="string" Size="1024" /> <asp:Parameter Name="approval_status" Type="string" Size="1" /> <asp:Parameter Name="tl_user_name" Type="string" Size="256" /> <asp:Parameter Name="phone" Type="string" Size="50" /> <asp:Parameter Name="uploaders_own" Type="Int16" /> </UpdateParameters> Here's the update statement: UPDATE myTable SET business_name = ?, addr_line_1 = ?, addr_line_2 = ?, addr_line_3 = ?, postcode = ?, county = ?, town_city = ?, tl_url = ?, customer_id = ?, region_id = ?, description = ?, approval_status = ?, tl_user_name = ?, phone = ?, uploaders_own = ? WHERE id = " + id Here's the stack trace: [InvalidOperationException: 'id' parameter is missing at the statement] CoreLab.MySql.r.a() +775 CoreLab.MySql.r.a(Int32& A_0, ArrayList& A_1) +448 CoreLab.MySql.x.e() +398 CoreLab.MySql.x.o() +89 CoreLab.MySql.MySqlCommand.a(CommandBehavior A_0, IDisposable A_1, Int32 A_2, Int32 A_3) +1306 CoreLab.Common.DbCommandBase.ExecuteDbDataReader(CommandBehavior behavior) +310 System.Data.Common.DbCommand.ExecuteReader() +12 CoreLab.Common.DbCommandBase.ExecuteNonQuery() +64 System.Web.UI.WebControls.SqlDataSourceView.ExecuteDbCommand(DbCommand command, DataSourceOperation operation) +386 System.Web.UI.WebControls.SqlDataSourceView.ExecuteUpdate(IDictionary keys, IDictionary values, IDictionary oldValues) +325 System.Web.UI.DataSourceView.Update(IDictionary keys, IDictionary values, IDictionary oldValues, DataSourceViewOperationCallback callback) +92 System.Web.UI.WebControls.DetailsView.HandleUpdate(String commandArg, Boolean causesValidation) +837 System.Web.UI.WebControls.DetailsView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup) +509 System.Web.UI.WebControls.DetailsView.OnBubbleEvent(Object source, EventArgs e) +95 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.DetailsViewRow.OnBubbleEvent(Object source, EventArgs e) +113 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +118 System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +135 System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565 Does anyone know what I'm doing wrong? Thanks, Annelie

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  • mysql insert data from multiple select queries

    - by daulex
    What I've got working and it's what I need to improve on: INSERT form_data (id,data_id, email) SELECT fk_form_joiner_id AS data_id, value AS email FROM wp_contactform_submit_data WHERE form_key='your-email' This just gets the emails, now this is great, but not enough as I have a good few different values of form_key that I need to import into different columns, I'm aware that I can do it via php using foreach loops and updates, but this needs to be done purely in mysql. So how do I do something like: insert form_data(id,data,email,name,surname,etc) Select [..],Select [..].... Please help

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  • jQuery: form input values turns up undefined

    - by Seerumi
    Having problem with this bit of code qith jQuery. it should pick the values from current form and then submit them, but when I try to get them with jQuery they always turn up undefined. I know the SQL results are fine since they show correctly in HTML table, so it must be my inferior javascript skills. New with jQuery and I'm at loss :( PHP/HTML: echo "<table>\n" while ($row = odbc_fetch_array($query)) { echo "<form class='catForm'>\n"; echo "<input type=hidden class='catID' name='catID' value='".$row['running_id']."'/>\n"; echo "<tr>\n"; echo "<td>".$row['running_id']."</td>\n"; echo "<td>".$row['site_id']."</td>\n"; echo "<td>".$row['main_category']."</td>\n"; echo "<td>".$row['map_name']."</td>\n"; echo "<td><input type=textfield class='bCatID' value='".$row['mapping_id']."' size=6/></td>\n"; echo "<td><input type=submit class='saveCat' value='Save'/></td>\n"; echo "<td><input type=submit class='killCat' value='Delete' /></td>\n"; echo "</tr>\n"; echo "</form>\n"; } echo "</table>"; jQuery: $(".catForm").submit(function () { var id = $(this).find('.catID').val(); var bCatID = $(this).find('.bCatID').val(); var dataString = 'id='+id+'&bCatID='+bCatID; $.ajax({ type: "POST", url: 'adminUI/bin/updateSCategories.php', dataType : 'json', data: dataString, success: function(data) { if (data.error == true) $('.failure').html("Error, save failed.").show().fadeOut(2000); if (data.error == false) $('.success').html("Saved succesfully").show().fadeOut(2000); }, error: function(XMLHttpRequest, textStatus, errorThrown) { $('.failure').html("Error, save failed.").show().fadeOut(2000); } }); return false; }); RESULT: id: undefined bCatID: undefined

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  • ASP: button to input submit

    - by vishnu
    Hi All, I am trying to use literalcontrol to add a button as input type="submit" litLevelList.Text += string.Format(" &lt input type='submit' id='{0}' value='{1}' name='{2}' >", btnSave.ClientID, Lang.Trans("Save Changes " ) , btnSave. ??); I could get the button ID using CLientID but without the name the data doesnt seems to be submitted. Could anyone tell me how i could access the name value rendered by ASP for a button control. thanks, vishnu

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  • Pass a variable into a trigger

    - by Codesleuth
    I have a trigger which deals with some data for logging purposes like so: CREATE TRIGGER trgDataUpdated ON tblData FOR UPDATE AS BEGIN INSERT INTO tblLog ( ParentID, OldValue, NewValue, UserID ) SELECT deleted.ParentID, deleted.Value, inserted.Value, @intUserID -- how can I pass this in? FROM inserted INNER JOIN deleted ON inserted.ID = deleted.ID END How can I pass in the variable @intUserID into the above trigger, as in the following code: DECLARE @intUserID int SET @intUserID = 10 UPDATE tblData SET Value = @x PS: I know I can't literally pass in @intUserID to the trigger, it was just used for illustration purposes.

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  • Java Socket Connection is flooding network OR resulting in high ping

    - by user1461100
    i have a little problem with my java socket code. I'm writing an android client application which is sending data to a java multithreaded socket server on my pc through direct(!) wireless connection. It works fine but i want to improve it for mobile applications as it is very power consuming by now. When i remove two special lines in my code, the cpu usage of my mobile device (htc one x) is totally okay but then my connection seems to have high ping rates or something like that... Here is a server code snippet where i receive the clients data: while(true) { try { .... Object obj = in.readObject(); if(obj != null) { Class clazz = obj.getClass(); String className = clazz.getName(); if(className.equals("java.lang.String")) { String cmd = (String)obj; if(cmd.equals("dc")) { System.out.println("Client "+id+" disconnected!"); Server.connectedClients[id-1] = false; break; } if(cmd.substring(0,1).equals("!")) { robot.keyRelease(PlayerEnum.getKey(cmd,id)); } else { robot.keyPress(PlayerEnum.getKey(cmd,id)); } } } } catch .... Heres the client part, where i send my data in a while loop: private void networking() { try { if(client != null) { .... out.writeObject(sendQueue.poll()); .... } } catch .... when i write it this why, i send data everytime the while loop gets executed.. when sendQueue is empty, a null "Object" will be send. this results in "high" network traffic and in "high" cpu usage. BUT: all send comments are received nearly immediately. when i change the code to following: while(true) ... if(sendQueue.peek() != null) { out.writeObject(sendQueue.poll()); } ... the cpu usage is totally okay but i'm getting some laggs.. the commands do not arrive fast enough.. as i said, it works fine (besides cpu usage) if i'm sending data(with that null objects) every while execution. but i'm sure that this is very rough coding style because i'm kind of flooding the network. any hints? what am i doing wrong?? Thanks for your Help! Sincerly yours, maaft

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  • Lining up Divs, while using JQuery

    - by user630581
    I am trying to create a flash header like element in JQuery, that has three images that fade to other images. I have each group of images in a div, but the divs line up vertically down the page, I want them to line up horizontally in a row. Currently my css code is: div#demos{ width:940px; border:0; } .s1{ float:left; display:inline; background-color:#000000; width:225px; margin:0; } .s2{ float:right; display:inline; background-color:#000000; width:225px; margin:0; } .s3{ float:left; display:inline; background-color:#000000; width:225px; margin:0; } and my markup is: <div id="demos"> <div id="s1" class="pics"> <img src="Image1.jpeg" width="200" height="200" /> <img src="Image2.jpeg" width="200" height="200" /> <img src="Image3.jpeg" width="200" height="200" /> </div> <div id="s2" class="pics"> <img src="Image4.jpeg" width="200" height="200" /> <img src="Image5.jpeg" width="200" height="200" /> <img src="Image6.jpeg" width="200" height="200" /> </div> <div id="s3" class="pics"> <img src="Image7.jpeg" width="200" height="200" /> <img src="Image8.jpeg" width="200" height="200" /> <img src="Image9.jpeg" width="200" height="200" /> </div> <div style="clear:both"></div> </div>

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  • B-trees, databases, sequential inputs, and speed.

    - by IanC
    I know from experience that b-trees have awful performance when data is added to them sequentially (regardless of the direction). However, when data is added randomly, best performance is obtained. This is easy to demonstrate with the likes of an RB-Tree. Sequential writes cause a maximum number of tree balances to be performed. I know very few databases use binary trees, but rather used n-order balanced trees. I logically assume they suffer a similar fate to binary trees when it comes to sequential inputs. This sparked my curiosity. If this is so, then one could deduce that writing sequential IDs (such as in IDENTITY(1,1)) would cause multiple re-balances of the tree to occur. I have seen many posts argue against GUIDs as "these will cause random writes". I never use GUIDs, but it struck me that this "bad" point was in fact a good point. So I decided to test it. Here is my code: SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[T1]( [ID] [int] NOT NULL CONSTRAINT [T1_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO CREATE TABLE [dbo].[T2]( [ID] [uniqueidentifier] NOT NULL CONSTRAINT [T2_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO declare @i int, @t1 datetime, @t2 datetime, @t3 datetime, @c char(300) set @t1 = GETDATE() set @i = 1 while @i < 2000 begin insert into T2 values (NEWID(), @c) set @i = @i + 1 end set @t2 = GETDATE() WAITFOR delay '0:0:10' set @t3 = GETDATE() set @i = 1 while @i < 2000 begin insert into T1 values (@i, @c) set @i = @i + 1 end select DATEDIFF(ms, @t1, @t2) AS [Int], DATEDIFF(ms, @t3, getdate()) AS [GUID] drop table T1 drop table T2 Note that I am not subtracting any time for the creation of the GUID nor for the considerably extra size of the row. The results on my machine were as follows: Int: 17,340 ms GUID: 6,746 ms This means that in this test, random inserts of 16 bytes was almost 3 times faster than sequential inserts of 4 bytes. Would anyone like to comment on this? Ps. I get that this isn't a question. It's an invite to discussion, and that is relevant to learning optimum programming.

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  • Schema to support dynamic properties

    - by Johan Fredrik Varen
    Hi people. I'm working on an editor that enables its users to create "object" definitions in real-time. A definition can contain zero or more properties. A property has a name a type. Once a definition is created, a user can create an object of that definition and set the property values of that object. So by the click of a mouse-button, the user should ie. be able to create a new definition called "Bicycle", and add the property "Size" of type "Numeric". Then another property called "Name" of type "Text", and then another property called "Price" of type "Numeric". Once that is done, the user should be able to create a couple of "Bicycle" objects and fill in the "Name" and "Price" property values of each bike. Now, I've seen this feature in several software products, so it must be a well-known concept. My problem started when I sat down and tried to come up with a DB schema to support this data structure, because I want the property values to be stored using the appropriate column types. Ie. a numeric property value is stored as, say, an INT in the database, and a textual property value is stored as VARCHAR. First, I need a table that will hold all my object definitions: Table obj_defs id | name | ---------------- 1 | "Bicycle" | 2 | "Book" | Then I need a table for holding what sort of properties each object definition should have: Table prop_defs id | obj_def_id | name | type | ------------------------------------ 1 | 1 | "Size" | ? | 2 | 1 | "Name" | ? | 3 | 1 | "Price" | ? | 4 | 2 | "Title" | ? | 5 | 2 | "Author" | ? | 6 | 2 | "ISBN" | ? | I would also need a table that holds each object: Table objects id | created | updated | ------------------------------ 1 | 2011-05-14 | 2011-06-15 | 2 | 2011-05-14 | 2011-06-15 | 3 | 2011-05-14 | 2011-06-15 | Finally, I need a table that will hold the actual property values of each object, and one solution is for this table to have one column for each possible value type, such as this: Table prop_vals id | prop_def_id | object_id | numeric | textual | boolean | ------------------------------------------------------------ 1 | 1 | 1 | 27 | | | 2 | 2 | 1 | | "Trek" | | 3 | 3 | 1 | 1249 | | | 4 | 1 | 2 | 26 | | | 5 | 2 | 2 | | "GT" | | 6 | 3 | 2 | 159 | | | 7 | 4 | 3 | | "It" | | 8 | 5 | 3 | | "King" | | 9 | 6 | 4 | 9 | | | If I implemented this schema, what would the "type" column of the prop_defs table hold? Integers that each map to a column name, varchars that simply hold the column name? Any other possibilities? Would a stored procedure help me out here in some way? And what would the SQL for fetching the "name" property of object 2 look like?

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