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• Need help tuning a SQL statement

  - by jeffself

  I've got a table that has two fields (custno and custno2) that need to be searched from a query. I didn't design this table, so don't scream at me. :-) I need to find all records where either the custno or custno2 matches the value returned from a query on the same table based on a titleno. In other words, the user types in 1234 for the titleno. My query searches the table to find the custno associated with the titleno. It also looks for the custno2 for that titleno. Then it needs to do a search on the same table for all other records that have either the custno or custno2 returned in the previous search in the custno or custno2 fields for those other records. Here is what I've come up with: SELECT BILLYR, BILLNO, TITLENO, VINID, TAXPAID, DUEDATE, DATEPIF, PROPDESC FROM TRCDBA.BILLSPAID WHERE CUSTNO IN (select custno from trcdba.billspaid where titleno = '1234' union select custno2 from trcdba.billspaid where titleno = '1234' and custno2 != '') OR CUSTNO2 IN (select custno from trcdba.billspaid where titleno = '1234' union select custno2 from trcdba.billspaid where titleno = '1234' and custno2 != '') The query takes about 5-10 seconds to return data. Can it be rewritten to work faster?

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• deleting object with template for int and object

  - by Yokhen

  Alright so Say I have a class with all its definition, bla bla bla... template <class DT> class Foo{ private: DT* _data; //other stuff; public: Foo(DT* data){ _data = data } virtual ~Foo(){ delete _data } //other methods }; And then I have in the main method: int main(){ int number = 12; Foo<anyRandomClass>* noPrimitiveDataObject = new Foo<anyRandomClass>(new anyRandomClass()); Foo<int>* intObject = new Foo<int>(number); delete noPrimitiveDataObject; //Everything goes just fine. delete intObject; //It messes up here, I think because primitive data types such as int are allocated in a different way. return 0; } My question is: What could I do to have both delete statements in the main method work just fine? P.S.: Although I have not actually compiled/tested this specific code, I have reviewed it extensively (as well as indented. You're welcome.), so if you find a mistake, please be nice. Thank you.

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• Setting Nullable Integer to String Containing Nothing yields 0

  - by Brian MacKay

  I've been pulling my hair out over some unexpected behavior from nullable integers. If I set an Integer to Nothing, it becomes Nothing as expected. If I set an Integer? to a String that is Nothing, it becomes 0! Of course I get this whether I explicitly cast the String to Integer? or not. I realize I could work around this pretty easily but I want to know what I'm missing. Dim NullString As String = Nothing Dim NullableInt As Integer? = CType(NullString, Integer?) 'Expected NullableInt to be Nothing, but it's 0! NullableInt = Nothing 'This works -- NullableInt now contains Nothing. How is this EDIT: Previously I had my code up here so without the explicit conversion to 'Integer?' and everyone seemed to be fixated on that. I want to be clear that this is not an issue that would have been caught by Option Strict On -- check out the accepted answer. This is a quirk of the string-to-integer conversion rules which predate nullable types, but still impact them.

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• How can I restore the "auto" values with for list-style-type in nested unordered lists with CSS?

  - by Michael

  By default, an unstyled set of nested <ul> lists looks like this (in Chrome, Firefox, and IE at least): The top level has a list-style-type of disc, the next level is circle, and subsequent levels are square. If I include a stylesheet that changes the list-style-type to none, is there a simple way to revert back to the "automatic bullet types" later in the document? (e.g., override with a subsequent CSS definition or JavaScript style change) Basically, I'm looking for something like list-style-type: auto; (which is apparently not valid and has no effect): <style type="text/css"> ul { list-style-type: none; } ul { list-style-type: auto; } /* Does not work */ </style> Setting the list-style-type back to disc changes every bullet in the list and I no longer see different bullets at different levels, so that doesn't work either. Is the only way to accomplish this by explicitly defining styles for every level? e.g.: <style type="text/css"> ul { list-style-type: disc; } ul ul { list-style-type: circle; } ul ul ul { list-style-type: square; } </style>

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• Evaluating expressions using Visual Studio 2005 SDK rather than automation's Debugger::GetExpression

  - by brone

  I'm looking into writing an addin (or package, if necessary) for Visual Studio 2005 that needs watch window type functionality -- evaluation of expressions and examination of the types. The automation facilities provide Debugger::GetExpression, which is useful enough, but the information provided is a bit crude. From looking through the docs, it sounds like an IDebugExpressionContext2 would be more useful. With one of these it looks as if I can get more information from an expression -- detailed information about the type and any members and so on and so forth, without having everything come through as strings. I can't find any way of actually getting a IDebugExpressionContext2, though! IDebugProgramProvider2 sort of looks relevant, in that I could start with IDebugProgramProvider2::GetProviderProcessData and then slowly drill down until reaching something that can supply my expression context -- but I'll need to supply a port to this, and it's not clear how to retrieve the port corresponding to the current debug session. (Even if I tried every port, it's not obvious how to tell which port is the right one...) I'm becoming suspicious that this simply isn't a supported use case, but with any luck I've simply missed something crashingly obvious. Can anybody help?

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• Is it poor design to create objects that only execute code during the constructor?

  - by Curtix

  In my design I am using objects that evaluate a data record. The constructor is called with the data record and type of evaluation as parameters and then the constructor calls all of the object's code necessary to evaluate the record. This includes using the type of evaluation to find additional parameter-like data in a text file. There are in the neighborhood of 250 unique evaluation types that use the same or similar code and unique parameters coming from the text file. Some of these evaluations use different code so I benefit a lot from this model because I can use inheritance and polymorphism. Once the object is created there isn't any need to execute additional code on the object (at least for now) and it is used more like a struct; its kept on a list and 3 properties are used later. I think this design is the easiest to understand, code, and read. A logical alternative I guess would be using functions that return score structs, but you can't inherit from methods so it would make it kind of sloppy imo. I am using vb.net and these classes will be used in an asp.net web app as well as in a distributed app. thanks for your input

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• Generic validate input data via regex. Input error when match.count == 0

  - by Valamas

  Hi, I have a number of types of data fields on an input form, for example, a web page. Some fields are like, must be an email address, must be a number, must be a number between, must have certain characters. Basically, the list is undefinable. I wish to come up with a generic way of validating the data inputed. I thought I would use regex to validate the data. The fields which need validation would be related to a "regex expression" and a "regex error message" stating what the field should contain. My current mock up has that when the match count is zero, that would signify an error and to display the message. While still a white belt regex designer I have come to understand that in certain situations that it is difficult to write a regex which results in a match count of zero for every case. A complex regex case I looked for help on was Link Here. The forum post was a disaster because I confused people helping me. But one of the statements said that it was difficult to make a regex with a match count of zero meaning the input data was invalid; that the regex was very difficult to write that for. Does anyone have comments or suggestions on this generic validation system I am trying to create? thanks

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• Java Function Analysis

  - by khan

  Okay..I am a total Python guy and have very rarely worked with Java and its methods. The condition is that I have a got a Java function that I have to explain to my instructor and I have got no clue about how to do so..so if one of you can read this properly, kindly help me out in breaking it down and explaining it. Also, i need to find out any flaw in its operation (i.e. usage of loops, etc.) if there is any. Finally, what is the difference between 'string' and 'string[]' types? public static void search(String findfrom, String[] thething){ if(thething.length > 5){ System.err.println("The thing is quite long"); } else{ int[] rescount = new int[thething.length]; for(int i = 0; i < thething.length; i++){ String[] characs = findfrom.split("[ \"\'\t\n\b\f\r]", 0); for(int j = 0; j < characs.length; j++){ if(characs[j].compareTo(thething[i]) == 0){ rescount[i]++; } } } for (int j = 0; j < thething.length; j++) { System.out.println(thething[j] + ": " + rescount[j]); } } }

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• Surely a foolish error, but I can't see it

  - by dnagirl

  I have a form (greatly simplified): <form action='http://example.com/' method='post' name='event_form'> <input type='text' name='foo' value='3'/> <input type='submit' name='event_submit' value='Edit'/> </form> And I have a class "EventForm" to process the form. The main method, process() looks like this: public function process($submitname=false){ $success=false; if ($submitname && isset($_POST[$submitname])){ //PROBLEM: isset($_POST[$submitname] is always FALSE for some reason if($success=$this->ruler->validate()){//check that dependancies are honoured and data types are correct if($success=$this->map_fields()){//divide input data into Event, Schedule_Element and Temporal_Expression(s) $success=$this->eventholder->save(); } } } else {//get the record from the db based on event_id or schedule_element_id foreach($this->gets as $var){//list of acceptable $_GET keys if(isset($_GET[$var])){ if($success= $this->__set($var,$_GET[$var])) break; } } } $this->action=(empty($this->eventholder->event_id))? ADD : EDIT; return $success; } When the form is submitted, this happens: $form->process('event_submit'); For some reason though, isset($_POST['event_submit']) always evaluates to FALSE. Can anyone see why?

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• Tokenizing numbers for a parser

  - by René Nyffenegger

  I am writing my first parser and have a few questions conerning the tokenizer. Basically, my tokenizer exposes a nextToken() function that is supposed to return the next token. These tokens are distinguished by a token-type. I think it would make sense to have the following token-types: SYMBOL (such as <, :=, ( and the like REMARK (or a comment) NUMBER IDENT (such as the name of a function or a variable) STRING (Something enclosed between "....") Now, do you think this makes sense? Also, I am struggling with the NUMBER token-type. Do you think it makes more sense to further split it up into a NUMBER and a FLOAT token-type? Without a FLOAT token-type, I'd receive NUMBER (eg 402), a SYMBOL (.) followed by another NUMBER (eg 203) if I were about to parse a float. Finally, what do you think makes more sense for the tokenizer to return when it encounters a -909? Should it return the SYMBOL - first, followed by the NUMBER 909 or should it return a NUMBER -909 right away?

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• passing an "unknown enumeration" to a method

  - by firoso

  I'm currently trying to make a class that can register strings as identifiers and accociate them with different types of Enumerations, these enumerations are being evaluated only in so much that I am ensuring that when it's used, that the parameter passed to broadcast (messageType) is an instance of the associated Enum Type. This would work something like this: Diagnostics.RegisterIdentifier("logger", typeof(TestEnum)); Diagnostics.Broadcast("logger", TestEnum.Info, null, "Hello World", null); here's the code I currently have, I need to be able to verify that messageTypesEnum is contained in messageTypesFromIdentifier. private static Dictionary<string, Type> identifierMessageTypeMapping = new Dictionary<string, Type>(); private static List<IListener> listeners = new List<IListener>(); public static void RegisterIdentifier(string identifier, Type messageTypesEnum) { if (messageTypesEnum.BaseType.FullName == "System.Enum") { identifierMessageTypeMapping.Add(identifier, messageTypesEnum); } else { throw new ArgumentException("Expected type of messageTypesEnum to derive from System.Enum", "messageTypesEnum"); } } public static void Broadcast(string identifier, object messageType, string metaIdentifier, string message, Exception exception) { if (identifierMessageTypeMapping.ContainsKey(identifier)) { Type messageTypesFromIdentifier = identifierMessageTypeMapping[identifier]; foreach (var listener in listeners) { DiagnosticsEvent writableEvent = new DiagnosticsEvent(identifier, messageType, metaIdentifier, message, exception); listener.Write(writableEvent); } } }

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• What do I name classes whose only purpose is to act as a structure?

  - by Sergio Tapia

  For example, take my Actor class: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Drawing; namespace FreeIMDB { class Actor { public string Name { get; set; } public Image Portrait { get; set; } public DateTime DateOfBirth { get; set; } public List<string> ActingRoles { get; set; } public List<string> WritingRoles { get; set; } public List<string> ProducingRoles { get; set; } public List<string> DirectingRoles { get; set; } } } This class will only be used to stuff information into it, and allow other developers to get their values. What are these types of classes officially called? What is the correct nomenclature?

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• Remove this URL string when login fails and simply show div error

  - by Anagio

  My developer built our registration page to display a div when logins failed based on a string in the URL. When logins fail this is added to the URL /login?msg=invalid The PHP in my login.phtml which displays the error messages based on the msg= parameter is <?php $msg = ""; $msg = $_GET['msg']; if($msg==""){ $showMsg = ""; } elseif($msg=="invalid"){ $showMsg = ' <div class="alert alert-error"> <a class="close" data-dismiss="alert">×</a> <strong>Error!</strong> Login or password is incorrect! </div>'; } elseif($msg=="disabled"){ $showMsg = "Your account has been disabled."; } elseif($msg==2){ $showMsg = "Your account is not activated. Please check your email."; } ?> In the controller the redirect to that URL is else //email id does not exist in our database { //redirecting back with invalid email(invalid) msg=invalid. $this->_redirect($url."?msg=invalid"); } I know there are a few other validation types for disabled accounts etc. I'm in the process of redesigning the entire interface and would like to get rid of this kind of validation so that the div tags display when logins fail but not show the URL strings. If it matters the new div I want to display is <div class="alert alert-error alert-login"> Email or password incorrect </div> I'd like to replace the php my self in my login.phtml and controller but not a good programmer. What can I replace $this->_redirect($url."?msg=invalid"); with so that no strings are added to the URL and display the appropriate div tags? Thanks

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• UIImagePickerController crashes on rapid scrolling, slower than photos app

  - by vvanhee

  Most of the time, my image picker works perfectly (iOS 4.2.1). However, if I scroll very rapidly up and down about 4-6 times through my camera roll of about 300 photos, I get a crash. This never happens with the "photos" app on the same iPhone 3Gs. Also, I'm noticing that the stock "photos" app scrolls much more smoothly than my image picker. Has anyone else noticed this behavior? I'd be interested if others could attempt this in their own apps and see if they crash. I don't think it's related to other objects hogging memory on my iPhone because it's a simple app, and this happens right after I start the app. It also doesn't seem to be related to messages sent to other released objects or overreleasing of other objects in viewdidunload, based on my crash logs and the fact that the simulator responds well to simulated memory warnings. I think it might be a bug in the internal implementation of the UIImagePickerController... This is how I start the picker. I've done this multiple ways (including setting a retain property for the UIImagePickerController in my header and releasing on dealloc). This seems to be the best way (crashes least): UIImagePickerController *picker = [[UIImagePickerController alloc] init]; picker.delegate = self; picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum; picker.allowsEditing = YES; [self presentModalViewController:picker animated:YES]; [picker release]; This is the crashed thread (I get various exception types): Exception Type: SIGSEGV Exception Codes: SEGV_ACCERR at 0xfffffffff4faafa4 Crashed Thread: 8 ... Thread 8 Crashed: 0 CoreFoundation 0x000494ea -[__NSArrayM replaceObjectAtIndex:withObject:] + 98 1 PhotoLibrary 0x00008e0f -[PLImageTable _segmentAtIndex:] + 527 2 PhotoLibrary 0x00008a21 -[PLImageTable _mappedImageDataAtIndex:] + 221 3 PhotoLibrary 0x0000893f -[PLImageTable dataForEntryAtIndex:] + 15 4 PhotoLibrary 0x000087e7 PLThumbnailManagerImageDataAtIndex + 35 5 PhotoLibrary 0x00008413 -[PLThumbnailManager _dataForPhoto:format:width:height:bytesPerRow:dataWidth:dataHeight:imageDataOffset:imageDataFormat:preheat:] + 299 6 PhotoLibrary 0x000b6c13 __-[PLThumbnailManager preheatImageDataForImages:withFormat:]_block_invoke_1 + 159 7 libSystem.B.dylib 0x000d6680 _dispatch_call_block_and_release + 20 8 libSystem.B.dylib 0x000d6ba0 _dispatch_worker_thread2 + 128 9 libSystem.B.dylib 0x0007b251 _pthread_wqthread + 265

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• How to convert Big Endian and how to flip the highest bit?

  - by Robert Frank

  I am using a TStream to read binary data (thanks to this post: http://stackoverflow.com/questions/2878180/how-to-use-a-tfilestream-to-read-2d-matrices-into-dynamic-array). My next problem is that the data is Big Endian. From my reading, the Swap() method is seemingly deprecated. How would I swap the types below? 16-bit two's complement binary integer 32-bit two's complement binary integer 64-bit two's complement binary integer IEEE single precision floating-point - Are IEEE affected by Big Endian? And, finally, since the data is unsigned, the creators of this dataset have stored the unsigned values as signed integers (excluding the IEEE). They instruct that one need only add an offset (2^15, 2^31, and 2^63) to recover the unsigned data. But, they note that flipping the most significant bit is the fastest way to do that. How does one efficiently flip the most significant bit of a 16, 32, or 64-bit integer? So, if the data on disk (16-bit) is "85 FB" - the desired result after reading the data and swapping and bit flipping would be 1531. Is there a way to accomplish the swapping and bit flipping with generics so it fits into the generic answer at the link above? Yes, kids, THIS is how scientific astronomical data is stored by NASA, ESO, and all professional astronomers. This FITS standard is considered by some to be one of the most successful standards ever created in its proliferation and flexibility!

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• GWT: creating a text widget for highly customized data entry

  - by Caffeine Coma

  I'm trying to implement a kind of "guided typing" widget for data entry, in which the user's text entry is highly controlled and filtered. When the user types a particular character I need to intercept and filter it before displaying it in the widget. Imagine if you will, a Unix shell embedded as a webapp; that's the kind of thing I'm trying to implement. I've tried two approaches. In the first, I extend a TextArea, and add a KeyPressHandler to filter the characters. This works, but the browser-provided spelling correction is totally inappropriate, and I don't see how to turn it off. I've tried: DOM.setElementProperty(textArea.getElement(), "spellcheck", "false"); But that seems to have no effect- I still get the red underlines over "typos". In the second approach I use a FocusWidget to get KeyPress events, and a separate Label or HTML widget to present the filtered characters back to the user. This avoids the spelling correction issue, but since the FocusWidget is not a TextArea, the browser tends to intercept certain typed characters for internal use; e.g. FireFox will use the "/" character to begin a "Quick Find" on the page, and hitting Backspace will load the previous web page. Is there a better way to accomplish what I'm trying to do?

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• Arrays not matching correctly

  - by Nick Gibson

  userAnswer[] holds the string of the answer the user types in and is comparing it to answers[] to see if they match up and then spits out correct or wrong. j is equal to the question number. So if j was question 6, answers[j] should refer to answers[6] right? Then userAnswer[6] should compare to answers[6] and match if its correct. But its giving me wrong answers and displaying the answer I typed as correct. int abc, loopCount = 100; int j = quesNum, overValue, forLoop = 100; for (int loop = 1; loop < loopCount; loop++) { aa = r.nextInt(10+1); abc = (int) aa; String[] userAnswer = new String[x]; JOptionPane.showMessageDialog(null,abc); if(abc < x) { userAnswer[j] = JOptionPane.showInputDialog(null,"Question "+quesNum+"\n"+questions[abc]+"\n\nA: "+a[abc]+"\nB: "+b[abc]+"\nC: "+c[abc]+"\nD: "+d[abc]); if(userAnswer[j].equals(answers[j])) { JOptionPane.showMessageDialog(null,"Correct. \nThe Correct Answer is "+answers[abc]); } else { JOptionPane.showMessageDialog(null,"Wrong. \n The Correct Answer is "+answers[abc]); }//else }//if }//for

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• Solr : how do i index and search several fields?

  - by sbrattla

  Hi, I've set up my first 'installation' of Solr, where each index (document) represents a musical work (with properties like number (int), title (string), version (string), composers (string) and keywords (string)). I've set the field 'title' as the default search field. However, what do I do when I would like to do a query on all fields? I'd like to give users the opportunity to search in all fields, and as far as I've understood there is at least two options for this: (1) Specify which fields the query should be made against. (2) Set up the Solr configuration with copyfields, so that values added to each of the fields will be copied to a 'catch-all'-like field which can be used for searching. However, in this case, i am uncertain how things would turn out when i take into consideration that the data types are not all the same for the various fields (the various fields will to a lesser og greater degree go through filters, but as copyfield values are taken from their original fields before the values have been run through their original fields' filters, i would have to apply one single filter to all values on the copyfield. This, again, would result in integers being 'filtered' just as strings would). Is this a case where i should use copyfields? At first glance, it seems a bit more 'flexible' to rather just search on all fields. However, maybe there's a cost? All feedback appreciated! Thanks!

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• How do I select dynamic ids in this format?

  - by sjsc

  I'm trying to select dynamic ids when a user types something into the input fields. My app spits out the input fields in the following format: <input id="student_1_first_name" /> <input id="student_1_last_name" /> <input id="student_2_first_name" /> <input id="student_2_last_name" /> <input id="student_3_first_name" /> <input id="student_3_last_name" /> etc. For example, I tried doing this to select the end of the id string: <script type="text/javascript"> $(document).ready( function (){ $("input[id$=_first_name]").bind("keyup", run_some_function_here); run_some_function_here(); $("input[id$=_last_name]").bind("keyup", run_some_function_here); run_some_function_here(); } ); </script> When I do that, Jquery can't seem to select the input ids, so the functions don't run. Do you have any ideas on how I can select the ids correctly?

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• ASP.NET enum dropdownlist validation

  - by Arun Kumar

  I have got a enum public enum TypeDesc { [Description("Please Specify")] PleaseSpecify, Auckland, Wellington, [Description("Palmerston North")] PalmerstonNorth, Christchurch } I am binding this enum to drop down list using the following code on page_Load protected void Page_Load(object sender, EventArgs e) { if (TypeDropDownList.Items.Count == 0) { foreach (TypeDesc newPatient in EnumToDropDown.EnumToList<TypeDesc>()) { TypeDropDownList.Items.Add(EnumToDropDown.GetEnumDescription(newPatient)); } } } public static string GetEnumDescription(Enum value) { FieldInfo fi = value.GetType().GetField(value.ToString()); DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false); if (attributes != null && attributes.Length > 0) return attributes[0].Description; else return value.ToString(); } public static IEnumerable<T> EnumToList<T>() { Type enumType = typeof(T); // Can't use generic type constraints on value types, // so have to do check like this if (enumType.BaseType != typeof(Enum)) throw new ArgumentException("T must be of type System.Enum"); Array enumValArray = Enum.GetValues(enumType); List<T> enumValList = new List<T>(enumValArray.Length); foreach (int val in enumValArray) { enumValList.Add((T)Enum.Parse(enumType, val.ToString())); } return enumValList; } and my aspx page use the following code to validate <asp:DropDownList ID="TypeDropDownList" runat="server" > </asp:DropDownList> <asp:RequiredFieldValidator ID="TypeRequiredValidator" runat="server" ControlToValidate="TypeDropDownList" ErrorMessage="Please Select a City" Text="<img src='Styles/images/Exclamation.gif' />" ValidationGroup="city"></asp:RequiredFieldValidator> But my validation is accepting "Please Specify" as city name. I want to stop user to submit if the city is not selected.

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• Best way to migrate export/import from SQL Server to oracle

  - by matao

  Hi guys! I'm faced with needing access for reporting to some data that lives in Oracle and other data that lives in a SQL Server 2000 database. For various reasons these live on different sides of a firewall. Now we're looking at doing an export/import from sql server to oracle and I'd like some advice on the best way to go about it... The procedure will need to be fully automated and run nightly, so that excludes using the SQL developer tools. I also can't make a live link between databases from our (oracle) side as the firewall is in the way. The data needs to be transformed in the process from a star schema to a de-normalised table ready for reporting. What I'm thinking about is writing a monster query for SQL Server (which I mostly have already) that will denormalise and read out the data from SQL Server into a flat file using the sql server equivalent of sqlplus as a scheduled task, dump into a Well Known Location, then on the oracle side have a cron job that copies down the file and loads it with sql loader and rebuilds indexes etc. This is all doable, but very manual. Is there one or a combination of FOSS or standard oracle/SQL Server tools that could automate this for me? the Irreducible complexity is the query on one side and building indexes on the other, but I would love to not have to write the CSV dumping detail or the SQL loader script, just say dump this view out to CSV on one side, and on the other truncate and insert into this table from CSV and not worry about mapping column names and all other arcane sqlldr voodoo... best practices? thoughts? comments? edit: I have about 50+ columns all of varying types and lengths in my dataset, which is why I'd prefer to not have to write out how to generate and map each single column...

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• Set service dependencies after install

  - by Dennis

  I have an application that runs as a Windows service. It stores various things settings in a database that are looked up when the service starts. I built the service to support various types of databases (SQL Server, Oracle, MySQL, etc). Often times end users choose to configure the software to use SQL Server (they can simply modify a config file with the connection string and restart the service). The problem is that when their machine boots up, often times SQL Server is started after my service so my service errors out on start up because it can't connect to the database. I know that I can specify dependencies for my service to help guide the Windows service manager to start the appropriate services before mine. However, I don't know what services to depend upon at install time (when my service is registered) since the user can change databases later on. So my question is: is there a way for the user to manually indicate the service dependencies based on the database that they are using? If not, what is the proper design approach that I should be taking? I've thought about trying to do something like wait 30 seconds after my service starts up before connecting to the database but this seems really flaky for various reasons. I've also considered trying to "lazily" connect to the database; the problem is that I need a connection immediately upon start up since the database contains various pieces of vital info that my service needs when it first starts. Any ideas?

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• Sync two SqlExpress using NHibernate

  - by Christian

  Hello, I am creating a simple project management system which uses NHibernate for object storage. The underlying database is SQL express (at least currently for development). The client runs on either the desktop or laptop. I know I could use web-services and store the DB only on the desktop, but this would force the desktop to be available all the time. I am currently thinking about duplicating the DB, having two instances with "different data". To clarify, we are not talking about a productive app here, its a prototype. One way to achieve this very simple would be the following process: Client: Check if desktop DB is available (through web service) Client: If yes, use desktop storage, no problem here Client: If not, use own DB as storage Client: Poll desktop regulary, as soon as it comes on, sync Client: Switch to desktop storage ... Desktop: Do not attempt any DB operation before checking for required sync Desktop: If sync needed, do it... My question is now, how would you sync? Assume 4 or 5 types of objects, all have GUID as identifiers. Would you always manually "lazy load" all objects of a certain type and feed them to the DB. Would you always drop the whole desktop DB in case the client DB may be newer and out of sync? Again, I want to stress out, I am not assuming any conflicts or stale data, I basically just want to "copy the whole DB from the client". Would you use NHibernate for this? Or would you separate the copy process? When I think about it, my questions comes down to this: Is there any function from NHibernate: SyncDBs_SourceWins_(SourceDB, TargetDB) Thanks for help, Chris

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• Scala: Correcting type inference of representation type over if statement

  - by drhagen

  This is a follow-up to two questions on representation types, which are type parameters of a trait designed to represent the type underlying a bounded type member (or something like that). I've had success creating instances of classes, e.g ConcreteGarage, that have instances cars of bounded type members CarType. trait Garage { type CarType <: Car[CarType] def cars: Seq[CarType] def copy(cars: Seq[CarType]): Garage def refuel(car: CarType, fuel: CarType#FuelType): Garage = copy( cars.map { case `car` => car.refuel(fuel) case other => other }) } class ConcreteGarage[C <: Car[C]](val cars: Seq[C]) extends Garage { type CarType = C def copy(cars: Seq[C]) = new ConcreteGarage(cars) } trait Car[C <: Car[C]] { type FuelType <: Fuel def fuel: FuelType def copy(fuel: C#FuelType): C def refuel(fuel: C#FuelType): C = copy(fuel) } class Ferrari(val fuel: Benzin) extends Car[Ferrari] { type FuelType = Benzin def copy(fuel: Benzin) = new Ferrari(fuel) } class Mustang(val fuel: Benzin) extends Car[Mustang] { type FuelType = Benzin def copy(fuel: Benzin) = new Mustang(fuel) } trait Fuel case class Benzin() extends Fuel I can easily create instances of Cars like Ferraris and Mustangs and put them into a ConcreteGarage, as long as it's simple: val newFerrari = new Ferrari(Benzin()) val newMustang = new Mustang(Benzin()) val ferrariGarage = new ConcreteGarage(Seq(newFerrari)) val mustangGarage = new ConcreteGarage(Seq(newMustang)) However, if I merely return one or the other, based on a flag, and try to put the result into a garage, it fails: val likesFord = true val new_car = if (likesFord) newFerrari else newMustang val switchedGarage = new ConcreteGarage(Seq(new_car)) // Fails here The switch alone works fine, it is the call to ConcreteGarage constructor that fails with the rather mystical error: error: inferred type arguments [this.Car[_ >: this.Ferrari with this.Mustang <: this.Car[_ >: this.Ferrari with this.Mustang <: ScalaObject]{def fuel: this.Benzin; type FuelType<: this.Benzin}]{def fuel: this.Benzin; type FuelType<: this.Benzin}] do not conform to class ConcreteGarage's type parameter bounds [C <: this.Car[C]] val switchedGarage = new ConcreteGarage(Seq(new_car)) // Fails here ^ I have tried putting those magic [C <: Car[C]] representation type parameters everywhere, but without success in finding the magic spot.

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• Basic problems (type inference or something else?) in Objective-C/Cocoa.

  - by Matt

  Hi, Apologies for how basic these questions are to some. Just started learning Cocoa, working through Hillegass' book, and am trying to write my first program (a GUI Cocoa app that counts the number of characters in a string). I tried this: NSString *string = [textField stringValue]; NSUInteger *stringLength = [string length]; NSString *countString = (@"There are %u characters",stringLength); [label setStringValue:countString]; But I'm getting errors like: Incompatible pointer conversion initializing 'NSUInteger' (aka 'unsigned long'), expected 'NSUInteger *'[-pedantic] for the first line, and this for the second line: Incompatible pointer types initializing 'NSUInteger *', expected 'NSString *' [-pedantic] I did try this first, but it didn't work either: [label setStringValue:[NSString stringWithFormat:@"There are %u characters",[[textField stringValue] length]]] On a similar note, I've only written in easy scripting languages before now, and I'm not sure when I should be allocing/initing objects and when I shouldn't. For example, when is it okay to do this: NSString *myString = @"foo"; or int *length = 5; instead of this: NSString *myString = [[NSString alloc] initWithString:"foo"]; And which ones should I be putting into the header files? I did check Apple's documentation, and CocoaDev, and the book I'm working for but without luck. Maybe I'm looking in the wrong places.. Thanks to anyone who takes the time to reply this: it's appreciated, and thanks for being patient with a beginner. We all start somewhere. EDIT Okay, I tried the following again: [label setStringValue:[NSString stringWithFormat:@"There are %u characters",[[textField stringValue] length]]] And it actually worked this time. Not sure why it didn't the first time, though I think I might have typed %d instead of %u by mistake. However I still don't understand why the code I posted at the top of my original post doesn't work, and I have no idea what the errors mean, and I'd very much like to know because it seems like I'm missing something important there.

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