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  • SQL View with Data from two tables

    - by Alex
    Hello! I can't seem to crack this - I have two tables (Persons and Companies), and I'm trying to create a view that: 1) shows all persons 2) also returns companies by themselves once, regardless of how many persons are related to it 3) orders by name across both tables To clarify, some sample data: (Table: Companies) Id Name 1 Banana 2 ABC Inc. 3 Microsoft 4 Bigwig (Table: Persons) Id Name RelatedCompanyId 1 Joe Smith 3 2 Justin 3 Paul Rudd 4 4 Anjolie 5 Dustin 4 The output I'm looking for is something like this: Name PersonName CompanyName RelatedCompanyId ABC Inc. NULL ABC Inc. NULL Anjolie Anjolie NULL NULL Banana NULL Banana NULL Bigwig NULL Bigwig NULL Dustin Dustin Bigwig 4 Joe Smith Joe Smith Microsoft 3 Justin Justin NULL NULL Microsoft NULL Microsoft NULL Paul Rudd Paul Rudd Bigwig 4 As you can see, the new "Name" column is ordered across both tables (the company names appear correctly in between the person names), and each company appears exactly once, regardless of how many people are related to it. Can this even be done in SQL?! P.S. I'm trying to create a view so I can use this later for easy data retrieval, fulltext indexing and make the programming side simpler by just querying the view.

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  • Dynamic SQL Server stored procedure

    - by Pinu
    ALTER PROCEDURE [dbo].[GetDocumentsAdvancedSearch] @SDI CHAR(10) = NULL ,@Client CHAR(4) = NULL ,@AccountNumber VARCHAR(20) = NULL ,@Address VARCHAR(300) = NULL ,@StartDate DATETIME = NULL ,@EndDate DATETIME = NULL ,@ReferenceID CHAR(14) = NULL AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- DECLARE DECLARE @Sql NVARCHAR(4000) DECLARE @ParamList NVARCHAR(4000) SELECT @Sql = 'SELECT DISTINCT ISNULL(Documents.DocumentID, '') ,Person.Name1 ,Person.Name2 ,Person.Street1 ,Person.Street2 ,Person.CityStateZip ,ISNULL(Person.ReferenceID,'') ,ISNULL(Person.AccountNumber,'') ,ISNULL(Person.HasSetPreferences,0) ,Documents.Job ,Documents.SDI ,Documents.Invoice ,ISNULL(Documents.ShippedDate,'') ,ISNULL(Documents.DocumentPages,'') ,Documents.DocumentType ,Documents.Description FROM Person LEFT OUTER JOIN Documents ON Person.PersonID = Documents.PersonID LEFT OUTER JOIN DocumentType ON Documents.DocumentType = DocumentType.DocumentType LEFT OUTER JOIN Addressess ON Person.PersonID = Addressess.PersonID' SELECT @Sql = @Sql + ' WHERE Documents.SDI IN ( '+ QUOTENAME(@sdi) + ') OR (Person.AssociationID = ' + ''' 000000 + ''' + 'AND Person.Client = ' + QUOTENAME(@Client) IF NOT (@AccountNumber IS NULL) SELECT @Sql = @Sql + 'AND Person.AccountNumber LIKE' + QUOTENAME(@AccountNumber) IF NOT (@Address IS NULL) SELECT @Sql = @Sql + 'AND Person.Name1 LIKE' +QUOTENAME(@Address)+ 'AND Person.Name2 LIKE' +QUOTENAME(@Address)+ 'AND Person.Street1 LIKE' +QUOTENAME(@Address)+ 'AND Person.Street2 LIKE' +QUOTENAME(@Address)+ 'AND Person.CityStateZip LIKE' +QUOTENAME(@Address) IF NOT (@StartDate IS NULL) SELECT @Sql = @Sql + 'AND Documents.ShippedDate >=' +@StartDate IF NOT (@EndDate IS NULL) SELECT @Sql = @Sql + 'AND Documents.ShippedDate <=' +@EndDate IF NOT (@ReferenceID IS NULL) SELECT @Sql = @Sql + 'AND Documents.ReferenceID =' +QUOTENAME(@ReferenceID) -- Insert statements for procedure here -- PRINT @Sql SELECT @ParamList = '@Psdi CHAR(10),@PClient CHAR(4),@PAccountNumber VARCHAR(20),@PAddress VARCHAR(300),@PStartDate DATETIME ,@PEndDate DATETIME,@PReferenceID CHAR(14)' EXEC SP_EXECUTESQL @Sql,@ParamList,@Sdi,@Client,@AccountNumber,@Address,@StartDate,@EndDate,@ReferenceID --PRINT @Sql END ERROR Msg 102, Level 15, State 1, Line 23 Incorrect syntax near '000000'. Msg 105, Level 15, State 1, Line 23 Unclosed quotation mark after the character string 'AND Person.Client = [1 ]AND Person.AccountNumber LIKE[1]'.

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  • Require help in Writing Query

    - by harigm
    The following image have been uploaded to show what I am trying to do and what I wanted out of it Can any one help me write the Query to get the results what I want Please check the following SELECT * FROM KPT WHERE PROPERTY_ID IN (SELECT PROPERTY_ID FROM khata_header WHERE DIV_ID = 3 and RECORD_STATUS = 0) and CHALLAN_NO > 42646 The above is the query I have written and I have got the following result set ID CHALLAN_NO PROPERTY_ID SITE_NO TOTAL_AMOUNT ----- ------------- -------------- ------------------- --------------- 1242 42757 3103010141 296 595 1243 63743 3204190257 483 594 1244 63743 3204190257 483 594 1334 43395 3217010223 1088 576 1421 524210 3320050416 (null) (null) 1422 524210 3320050416 (null) (null) 1560 564355 3320021408 (null) (null) 1870 516292 3320040420 (null) (null) 1940 68357 3217100104 139 1153 1941 68357 3217100104 139 1153 2002 56256 3320100733 511 4430 2003 56256 3320100733 511 4430 2004 66488 3217040869 293 3094 2005 66488 3217040869 293 3094 2016 64571 3217040374 (null) (null) 2036 523122 3320020352 (null) (null) 2039 65682 3217040021 273 919 In my resultset, I am getting the PropertyId repeated, since there are multilple entries, How Can I know How many have been repeated What are those Property Id which have repeated more than 2 times. Little Back ground about the tables are PROPERTY_ID is the FK in the KPT PROPERTY_ID is the PK in KH I am writing a subquery to get the Result, so I am stuck I dont know how to get my results Please help

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  • Select highest rated, oldest track

    - by Blair McMillan
    I have several tables: CREATE TABLE [dbo].[Tracks]( [Id] [uniqueidentifier] NOT NULL, [Artist_Id] [uniqueidentifier] NOT NULL, [Album_Id] [uniqueidentifier] NOT NULL, [Title] [nvarchar](255) NOT NULL, [Length] [int] NOT NULL, CONSTRAINT [PK_Tracks_1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[TrackHistory]( [Id] [int] IDENTITY(1,1) NOT NULL, [Track_Id] [uniqueidentifier] NOT NULL, [Datetime] [datetime] NOT NULL, CONSTRAINT [PK_TrackHistory] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] INSERT INTO [cooltunes].[dbo].[TrackHistory] ([Track_Id] ,[Datetime]) VALUES ("335294B0-735E-4E2C-8389-8326B17CE813" ,GETDATE()) CREATE TABLE [dbo].[Ratings]( [Id] [int] IDENTITY(1,1) NOT NULL, [Track_Id] [uniqueidentifier] NOT NULL, [User_Id] [uniqueidentifier] NOT NULL, [Rating] [tinyint] NOT NULL, CONSTRAINT [PK_Ratings] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] INSERT INTO [cooltunes].[dbo].[Ratings] ([Track_Id] ,[User_Id] ,[Rating]) VALUES ("335294B0-735E-4E2C-8389-8326B17CE813" ,"C7D62450-8BE6-40F6-80F1-A539DA301772" ,1) Users User_Id|Guid Other fields Links between the tables are pretty obvious. TrackHistory has each track added to it as a row whenever it is played ie. a track will appear in there many times. Ratings value will either be 1 or -1. What I'm trying to do is select the Track with the highest rating, that is more than 2 hours old, and if there is a duplicate rating for a track (ie a track receives 6 +1 ratings and 1 - rating, giving that track a total rating of 5, another track also has a total rating of 5), the track that was last played the longest ago should be returned. (If all tracks have been played within the last 2 hours, no rows should be returned) I'm getting somewhere doing each part individually using the link above, SUM(Value) and GROUP BY Track_Id, but I'm having trouble putting it all together. Hopefully someone with a bit more (MS)SQL knowledge will be able to help me. Many thanks!

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  • No whitespace between a cast and a namespace operator?

    - by Pod
    Hello. Could anyone please explain the following line of code, found on http://docs.openttd.org/ai__cargo_8cpp_source.html return (AICargo::TownEffect)::CargoSpec::Get(cargo_type)->town_effect; If this line was: return (AICargo::TownEffect) ::CargoSpec::Get(cargo_type)->town_effect; (note the space between TownEffect) and the ::) then I would understand it fine. However there is no whitespace in that document*, which would mean (AICargo::TownEffect) is the left operand of the :: operator. How does this code work/compile? Or are the two things equivilent due to some obscure C++ rule? *It's the same in the cpp file as well.

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  • How to implement progressbar(to show progress) using threading concept in win 32?

    - by Rakesh
    I am trying to show a progress bar while my process is going on...in my application there will be a situation where I gotta read files and manipulate them(it will take some time to complete)..want to display a progress bar during this operation..the particular function I am calling is an win 32 ...so if you check my code below i am upto the point of creating the progress bar in a dialog window and creating a thread Now I dont know how to post the message and where to get the message and handle...Please help me..thanks in advance //my function int Myfunction(....) { HWND dialog = CreateWindowEx(0,WC_DIALOG,L"Proccessing...",WS_OVERLAPPEDWINDOW|WS_VISIBLE, 600,300,280,120,NULL,NULL,NULL,NULL); HWND pBar = CreateWindowEx(NULL,PROGRESS_CLASS,NULL,WS_CHILD|WS_VISIBLE,40,20,200, 20, dialog,(HMENU)IDD_PROGRESS,NULL,NULL); HANDLE getHandle = CreateThread(NULL,NULL,(LPTHREAD_START_ROUTINE)SetFilesForOperation(...), NULL,NULL,0); } LPARAM SetFilesForOperation(...) { for(int index = 0;index < noOfFiles; index++) { *checkstate = *(checkState + index); if(*checkstate == -1) { *(getFiles+i) = new TCHAR[MAX_PATH]; wcscpy(*(getFiles+i),*(dataFiles +index)); i++; } else { (*tempDataFiles)->Add(*(dataFiles+index)); *(checkState + localIndex) = *(checkState + index); localIndex++; } //SendMessage(pBar,PBM_SETSTEP,1,0); } }

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  • Why does resolveBinding() return null even though I setResolveBindings(true) on my ASTParser?

    - by Woody Zenfell III
    I am writing an Eclipse plug-in that uses JDT AST's ASTParser to parse a method. I am looking within that method for the creation of a particular type of object. When I find a ClassInstanceCreation, I call getType() on it to see what type is being instantiated. I want to be sure that the fully-resolved type being dealt with there is the one I think it is, so I tell the resultant Type object to resolveBinding(). I get null back even though there are no compilation errors and even though I called setResolveBindings(true) on my ASTParser. I gave my ASTParser (via setSource()) the ICompilationUnit that contains my method, so the parser has access to the entire workspace context. final IMethod method = ...; final ASTParser parser = ASTParser.newParser(AST.JLS3); parser.setResolveBindings(true); parser.setSource(method.getCompilationUnit()); parser.setSourceRange(method.getSourceRange().getOffset(), method.getSourceRange().getLength()); parser.setKind(ASTParser.K_CLASS_BODY_DECLARATIONS); final TypeDeclaration astRoot = (TypeDeclaration) parser.createAST(null); final ClassInstanceCreation classInstanceCreation = walkAstAndFindMyExpression(astRoot); final Type instantiatedType = classInstanceCreation.getType(); System.out.println("BINDING: " + instantiatedType.resolveBinding()); Why does resolveBinding() return null? How can I get the binding information?

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  • Storing float numbers as strings in android database

    - by sandis
    So I have an app where I put arbitrary strings in a database and later extract them like this: Cursor DBresult = myDatabase.query(false, Constant.DATABASE_NOTES_TABLE_NAME, new String[] {"myStuff"}, where, null, null, null, null, null); DBresult.getString(0); This works fine in all cases except for when the string looks like a float number, for example "221.123123123". After saving it to the database I can extract the database to my computer and look inside it with a DB-viewer, and the saved number is correct. However, when using cursor.getString() the string "221.123" is returned. I cant for the life of me understand how I can prevent this. I guess I could do a cursor.getDouble() on every single string to see if this gives a better result, but that feels sooo ugly and inefficient. Any suggestions? Cheers, edit: I just made a small test program. This program prints "result: 123.123", when I would like it to print "result: 123.123123123" SQLiteDatabase database = openOrCreateDatabase("databas", Context.MODE_PRIVATE, null); database.execSQL("create table if not exists tabell (nyckel string primary key);"); ContentValues value = new ContentValues(); value.put("nyckel", "123.123123123"); database.insert("tabell", null, value); Cursor result = database.query("tabell", new String[]{"nyckel"}, null, null, null, null, null); result.moveToFirst(); Log.d("TAG","result: " + result.getString(0));

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  • MySQL "OR MATCH" hangs (very slow) on multiple tables

    - by Kerry
    After learning how to do MySQL Full-Text search, the recommended solution for multiple tables was OR MATCH and then do the other database call. You can see that in my query below. When I do this, it just gets stuck in a "busy" state, and I can't access the MySQL database. SELECT a.`product_id`, a.`name`, a.`slug`, a.`description`, b.`list_price`, b.`price`, c.`image`, c.`swatch`, e.`name` AS industry, MATCH( a.`name`, a.`sku`, a.`description` ) AGAINST ( '%s' IN BOOLEAN MODE ) AS relevance FROM `products` AS a LEFT JOIN `website_products` AS b ON (a.`product_id` = b.`product_id`) LEFT JOIN ( SELECT `product_id`, `image`, `swatch` FROM `product_images` WHERE `sequence` = 0) AS c ON (a.`product_id` = c.`product_id`) LEFT JOIN `brands` AS d ON (a.`brand_id` = d.`brand_id`) INNER JOIN `industries` AS e ON (a.`industry_id` = e.`industry_id`) WHERE b.`website_id` = %d AND b.`status` = %d AND b.`active` = %d AND MATCH( a.`name`, a.`sku`, a.`description` ) AGAINST ( '%s' IN BOOLEAN MODE ) OR MATCH ( d.`name` ) AGAINST ( '%s' IN BOOLEAN MODE ) GROUP BY a.`product_id` ORDER BY relevance DESC LIMIT 0, 9 Any help would be greatly appreciated. EDIT All the tables involved are MyISAM, utf8_general_ci. Here's the EXPLAIN SELECT statement: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY a ALL NULL NULL NULL NULL 16076 Using temporary; Using filesort 1 PRIMARY b ref product_id product_id 4 database.a.product_id 2 1 PRIMARY e eq_ref PRIMARY PRIMARY 4 database.a.industry_id 1 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 23261 1 PRIMARY d eq_ref PRIMARY PRIMARY 4 database.a.brand_id 1 Using where 2 DERIVED product_images ALL NULL NULL NULL NULL 25933 Using where I don't know how to make that look neater -- sorry about that UPDATE it returns the query after 196 seconds (I think correctly). The query without multiple tables takes about .56 seconds (which I know is really slow, we plan on changing to solr or sphinx soon), but 196 seconds?? If we could add a number to the relevance if it was in the brand name ( d.name ), that would also work

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  • How is the ">" operator implemented (on 32 bit integers)?

    - by Ron Klein
    Let's say that the environment is x86. How do compilers compile the "" operator on 32 bit integers. Logically, I mean. Without any knowledge of Assembly. Let's say that the high level language code is: int32 x, y; x = 123; y = 456; bool z; z = x > y; What does the compiler do for evaluating the expression x > y? Does it perform something like (assuming that x and y are positive integers): w = sign_of(x - y); if (w == 0) // expression is 'false' else if (w == 1) // expression is 'true' else // expression is 'false' Is there any reference for such information?

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  • Syntax for documenting JSON structure

    - by Roman A. Taycher
    So I'm trying to document the format of the json returned by an api I am writing against and I'd like to know if there is any popular format for the documentation of json structure. Note I'm not trying to to test or validate anything, I'm just using this for documentation. Also some ways to add comments to non-constants(items always returned w/ the same value) would be nice. This the not totally thought out scheme I'm currently using: Plain names refer to identifiers or types. Some types have type-comment Strings that appear to be constant(always returned for that type of request) strings are "str" Constant Numbers would be just the number Constant null is null Booleans are true/false for constant booleans or Boolean otherwise [a,b,c] are lists with 3 items a,b,c [... ...] is a list of repeating elements of some types/constants/patterns {a:A,b:B,c:c} and {... ...} is the same for a dictionary. example: story := [header,footer] header := {"data":realHeader,"kind":"Listing"} realHeader := {"after": null, "before": null, "children": [{"data": realRealHeader, "kind": "t3"}], "modhash": ""} footer := {"data":AlmostComments,"kind":"Listing"} AlmostComments := {"data": {"after": null, "before": null, "children": comments, "modhash": ""}, "kind": "t1"} comments := [...{"data":comment, "kind":"t1"}...] realRealHeader := {"author": string, "clicked": boolean, "created": int, "created_utc": int, "domain": "code.reddit.com", "downs": int, "hidden": boolean, "id": string-id, "is_self": boolean, "levenshtein": null, "likes": null, "media": null, "media_embed": { }, "name": string-id, "num_comments": int, "over_18": false, "permalink": string-urlLinkToStoryStartingFrom/r, "saved": false, "score": int, "selftext": string, "selftext_html": string-html, "subreddit": string-subredditname, "subreddit_id": string-id, "thumbnail": "", "title": string, "ups": int, "url": "http://code.reddit.com/" } comments := { "author": string, "body": string-body_html-wout-html, "body_html": string-html-formated, "created": int, "created_utc": int, "downs": int, "id": string-id, "levenshtein": null, "likes": null, "link_id": string-id, "name": string-id", "parent_id": string-id, "replies": AlmostComments or null, "subreddit": string-subredditname, "subreddit_id": string-id, "ups": int }

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  • Simple Scala syntax - trying to define "==" operator - what am I missing?

    - by Alex R
    While experimenting with some stuff on the REPL, I got to a point where I needed something like this: scala class A(x:Int) { println(x); def ==(a:A) : Boolean = { this.x == a.x; } } Just a simple class with an "==" operator. Why doesn't it work??? Here's the result: :10: error: type mismatch; found : A required: ?{val x: ?} Note that implicit conversions are not applicable because they are ambiguous: both method any2ArrowAssoc in object Predef of type [A](x: A)ArrowAssoc[A] and method any2Ensuring in object Predef of type [A](x: A)Ensuring[A] are possible conversion functions from A to ?{val x: ?} class A(x:Int) { println(x); def ==(a:A) : Boolean = { this.x == a.x; } } ^ This is scala 2.8 RC1. Thanks

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  • netbeans autocompletion when using singleton to retrieve object instead of new operator?

    - by fayer
    when i use the 'new' operator to instantiate a class, netbeans has no problem to autocomplete the members of the object. $instance = new Singleton(); $instance-> // shows test() method but when i use a singleton to retrieve an object it cannot autocomplete the members in the object retrieved. the getInstance code looks like this: public function test() { echo "hello"; } public static function getInstance() { if ( ! is_object(self::$_instance)) { self::$_instance = new self(); self::$_instance->initialize(); } return self::$_instance; } so i use: $instance = Singleton::getInstance(); $instance-> // no autocompletion! does anyone have the same problem? how do i work around it? thanks!

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  • C# Bug or Brain Teaser? Cast working only with Coalesce (??) Operator

    - by Alex
    This is very strange, maybe someone can explain what's happening, or this is a bug (though I tend to think that this is probably just something intricate about C#). The following code throws the error "Cannot implicitly convert type 'uint?' to 'uint'.": public void Test(UInt32? p) { UInt32 x = p; } However, this code works without error: public void Test(UInt32? p) { UInt32 x = p ?? 1; } Huh? Why does this work? Why would the coalesce operator cause implicit conversion of UInt32? (nullable) to UInt32 (non-nullable), while the first error message says that there is no implicit conversion between those types?

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  • C# string equality operator returns false, but I'm pretty sure it should be true... What?!

    - by Daniel Schaffer
    I'm trying to write a unit test for a piece of code that generates a large amount of text. I've run into an issue where the "expected" and "actual" strings appear to be equal, but Assert.AreEqual throws, and both the equality operator and Equals() return false. The result of GetHashCode() is different for both values as well. However, putting both strings into text files and comparing with DiffMerge tells me they're the same. Additionally, using Encoding.ASCII.GetBytes() on both values and then using SequenceEquals to compare the resulting byte arrays returns true. The values are 34KB each, so I'll hold off putting them here for now. Any ideas? I'm completely stumped.

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  • Avoiding repeated subqueries when 'WITH' is unavailable

    - by EloquentGeek
    MySQL v5.0.58. Tables, with foreign key constraints etc and other non-relevant details omitted for brevity: CREATE TABLE `fixture` ( `id` int(11) NOT NULL auto_increment, `competition_id` int(11) NOT NULL, `name` varchar(50) NOT NULL, `scheduled` datetime default NULL, `played` datetime default NULL, PRIMARY KEY (`id`) ); CREATE TABLE `result` ( `id` int(11) NOT NULL auto_increment, `fixture_id` int(11) NOT NULL, `team_id` int(11) NOT NULL, `score` int(11) NOT NULL, `place` int(11) NOT NULL, PRIMARY KEY (`id`) ); CREATE TABLE `team` ( `id` int(11) NOT NULL auto_increment, `name` varchar(50) NOT NULL, PRIMARY KEY (`id`) ); Where: A draw will set result.place to 0 result.place will otherwise contain an integer representing first place, second place, and so on The task is to return a string describing the most recently played result in a given competition for a given team. The format should be "def Team X,Team Y" if the given team was victorious, "lost to Team X" if the given team lost, and "drew with Team X" if there was a draw. And yes, in theory there could be more than two teams per fixture (though 1 v 1 will be the most common case). This works, but feels really inefficient: SELECT CONCAT( (SELECT CASE `result`.`place` WHEN 0 THEN "drew with" WHEN 1 THEN "def" ELSE "lost to" END FROM `result` WHERE `result`.`fixture_id` = (SELECT `fixture`.`id` FROM `fixture` LEFT JOIN `result` ON `result`.`fixture_id` = `fixture`.`id` WHERE `fixture`.`competition_id` = 2 AND `result`.`team_id` = 1 ORDER BY `fixture`.`played` DESC LIMIT 1) AND `result`.`team_id` = 1), ' ', (SELECT GROUP_CONCAT(`team`.`name`) FROM `fixture` LEFT JOIN `result` ON `result`.`fixture_id` = `fixture`.`id` LEFT JOIN `team` ON `result`.`team_id` = `team`.`id` WHERE `fixture`.`id` = (SELECT `fixture`.`id` FROM `fixture` LEFT JOIN `result` ON `result`.`fixture_id` = `fixture`.`id` WHERE `fixture`.`competition_id` = 2 AND `result`.`team_id` = 1 ORDER BY `fixture`.`played` DESC LIMIT 1) AND `team`.`id` != 1) ) Have I missed something really obvious, or should I simply not try to do this in one query? Or does the current difficulty reflect a poor table design?

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  • How does C++ free the memory when a constructor throws an exception and a custom new is used

    - by Joshua
    I see the following constructs: new X will free the memory if X constructor throws. operator new() can be overloaded. The canonical definition of an operator new overload is void *operator new(heap h) and the corrisponding operator delete. The most common operator new overload is pacement new, which is void *operator new(void *p) { return p; } You almost always cannot call delete on the pointer given to placement new. This leads to a single question. How is memory cleaned up when X constructor throws and an overloaded new is used?

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  • Is it possible to have a mysql table accept a null value for a primary_key column referencing a diff

    - by Dr.Dredel
    I have a table that has a column which holds the id of a row in another table. However, when table A is being populated, table B may or may not have a row ready for table A. My question is, is it possible to have mysql prevent an invalid value from being entered but be ok with a NULL? or does a foreign key necessitate a valid related value? So... what I'm looking for (in pseudo code) is this: Table "person" id | name Table "people" id | group_name | person_id (foreign key id from table person) insert into person (1, 'joe'); insert into people (1, 'foo', 1)//kosher insert into people (1, 'foo', NULL)//also kosher insert into people(1, 'foo', 7)// should fail since there is no id 7 in the person table. The reason I need this is that I'm having a chicken and egg issue where it makes perfect sense for the rows in the people table to be created before hand (in this example, I'm creating the groups and would like them to pre-exist the people who join them). And I realize that THIS example is silly and I would just put the group id in the person table rather than vice-versa, but in my real-world problem that is not workable. Just curious if I need to allow any and all values in order to make this work, or if there's some way to allow for null.

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  • Template class + virtual function = must implement?

    - by sold
    This code: template <typename T> struct A { T t; void DoSomething() { t.SomeFunction(); } }; struct B { }; A<B> a; is easily compiled without any complaints, as long as I never call a.DoSomething(). However, if I define DoSomething as a virtual function, I will get a compile error saying that B doesn't declare SomeFunction. I can somewhat see why it happens (DoSomething should now have an entry in the vtable), but I can't help feeling that it's not really obligated. Plus it sucks. Is there any way to overcome this? EDIT 2: Okay. I hope this time it makes sence: Let's say I am doing intrusive ref count, so all entities must inherit from base class Object. How can I suuport primitive types too? I can define: template <typename T> class Primitive : public Object { T value; public: Primitive(const T &value=T()); operator T() const; Primitive<T> &operator =(const T &value); Primitive<T> &operator +=(const T &value); Primitive<T> &operator %=(const T &value); // And so on... }; so I can use Primitive<int>, Primitive<char>... But how about Primitive<float>? It seems like a problem, because floats don't have a %= operator. But actually, it isn't, since I'll never call operator %= on Primitive<float>. That's one of the deliberate features of templates. If, for some reason, I would define operator %= as virtual. Or, if i'll pre-export Primitive<float> from a dll to avoid link errors, the compiler will complain even if I never call operator %= on a Primitive<float>. If it would just have fill in a dummy value for operator %= in Primitive<float>'s vtable (that raises an exception?), everything would have been fine.

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  • slow mysql count because of subselect

    - by frgt10
    how to make this select statement more faster? the first left join with the subselect is making it slower... mysql> SELECT COUNT(DISTINCT w1.id) AS AMOUNT FROM tblWerbemittel w1 JOIN tblVorgang v1 ON w1.object_group = v1.werbemittel_id INNER JOIN ( SELECT wmax.object_group, MAX( wmax.object_revision ) wmaxobjrev FROM tblWerbemittel wmax GROUP BY wmax.object_group ) AS wmaxselect ON w1.object_group = wmaxselect.object_group AND w1.object_revision = wmaxselect.wmaxobjrev LEFT JOIN ( SELECT vmax.object_group, MAX( vmax.object_revision ) vmaxobjrev FROM tblVorgang vmax GROUP BY vmax.object_group ) AS vmaxselect ON v1.object_group = vmaxselect.object_group AND v1.object_revision = vmaxselect.vmaxobjrev LEFT JOIN tblWerbemittel_has_tblAngebot wha ON wha.werbemittel_id = w1.object_group LEFT JOIN tblAngebot ta ON ta.id = wha.angebot_id LEFT JOIN tblLieferanten tl ON tl.id = ta.lieferant_id AND wha.zuschlag = (SELECT MAX(zuschlag) FROM tblWerbemittel_has_tblAngebot WHERE werbemittel_id = w1.object_group) WHERE w1.flags =0 AND v1.flags=0; +--------+ | AMOUNT | +--------+ | 1982 | +--------+ 1 row in set (1.30 sec) Some indexes has been already set and as EXPLAIN shows they were used. +----+--------------------+-------------------------------+--------+----------------------------------------+----------------------+---------+-----------------------------------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+-------------------------------+--------+----------------------------------------+----------------------+---------+-----------------------------------------------+------+----------------------------------------------+ | 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 2072 | | | 1 | PRIMARY | v1 | ref | werbemittel_group,werbemittel_id_index | werbemittel_group | 4 | wmaxselect.object_group | 2 | Using where | | 1 | PRIMARY | <derived3> | ALL | NULL | NULL | NULL | NULL | 3376 | | | 1 | PRIMARY | w1 | eq_ref | object_revision,or_og_index | object_revision | 8 | wmaxselect.wmaxobjrev,wmaxselect.object_group | 1 | Using where | | 1 | PRIMARY | wha | ref | PRIMARY,werbemittel_id_index | werbemittel_id_index | 4 | dpd.w1.object_group | 1 | | | 1 | PRIMARY | ta | eq_ref | PRIMARY | PRIMARY | 4 | dpd.wha.angebot_id | 1 | | | 1 | PRIMARY | tl | eq_ref | PRIMARY | PRIMARY | 4 | dpd.ta.lieferant_id | 1 | Using index | | 4 | DEPENDENT SUBQUERY | tblWerbemittel_has_tblAngebot | ref | PRIMARY,werbemittel_id_index | werbemittel_id_index | 4 | dpd.w1.object_group | 1 | | | 3 | DERIVED | vmax | index | NULL | object_revision_uq | 8 | NULL | 4668 | Using index; Using temporary; Using filesort | | 2 | DERIVED | wmax | range | NULL | or_og_index | 4 | NULL | 2168 | Using index for group-by | +----+--------------------+-------------------------------+--------+----------------------------------------+----------------------+---------+-----------------------------------------------+------+----------------------------------------------+ 10 rows in set (0.01 sec) The main problem while the statement above takes about 2 seconds seems to be the subselect where no index can be used. How to write the statement even more faster? Thanks for help. MT

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  • How to call operator<< on "this" in a descendant of std::stringstream?

    - by romkyns
    class mystream : public std::stringstream { public: void write_something() { this << "something"; } }; This results in the following two compile errors on VC++10: error C2297: '<<' : illegal, right operand has type 'const char [10]' error C2296: '<<' : illegal, left operand has type 'mystream *const ' Judging from the second one, this is because what this points at can't be changed, but the << operator does (or at least is declared as if it does). Correct? Is there some other way I can still use the << and >> operators on this?

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  • C++ volatile required when spinning on boost::shared_ptr operator bool()?

    - by JaredC
    I have two threads referencing the same boost::shared_ptr: boost::shared_ptr<Widget> shared; On thread is spinning, waiting for the other thread to reset the boost::shared_ptr: while(shared) boost::thread::yield(); And at some point the other thread will call: shared.reset(); My question is whether or not I need to declare the shared pointer as volatile to prevent the compiler from optimizing the call to shared.operator bool() out of the loop and never detecting the change? I know that if I were simply looping on a variable, waiting for it to reach 0 I would need volatile, but I'm not sure if boost::shared_ptr is implemented in such a way that it is not necessary here.

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  • Why does my SQL database not work in Android?

    - by user1426967
    In my app a click on an image button brings you to the gallery. After clicking on an image I want to call onActivityResult to store the image path. But it does not work. In my LogCat it always tells me that it crashes when it tries to save the image path. Can you find the problem? My onActivityResult method: mImageRowId = savedInstanceState != null ? savedInstanceState.getLong(ImageAdapter.KEY_ROWID) : null; @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if(requestCode == PICK_FROM_FILE && data != null && data.getData() != null) { Uri uri = data.getData(); if(uri != null) { Cursor cursor = getContentResolver().query(uri, new String[] { android.provider.MediaStore.Images.ImageColumns.DATA}, null, null, null); cursor.moveToFirst(); String image = cursor.getString(0); cursor.close(); if(image != null) { // HERE IS WHERE I WANT TO SAVE THE IMAGE. HERE MUST BE THE ERROR! if (mImageRowId == null) { long id = mImageHelper.createImage(image); if (id > 0) { mImageRowId = id; } } // Set the image and display it in the edit activity Bitmap bitmap = BitmapFactory.decodeFile(image); mImageButton.setImageBitmap(bitmap); } } } } This is my onSaveInstanceState method: private static final Long DEF_ROW_ID = 0L; @Override protected void onSaveInstanceState(Bundle outState) { outState.putLong(ImageAdapter.KEY_ROWID, mImageRowId != null ? mImageRowId : DEF_ROW_ID); super.onSaveInstanceState(outState); } This is a part from my DbAdapter: public long createImage(String image) { ContentValues cv = new ContentValues(); cv.put(KEY_IMAGE, image); return mImageDb.insert(DATABASE_TABLE, null, cv); }

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  • Shortcut to get all private field names combined with && operator as a generated line of code?

    - by burak ozdogan
    Hi, Is it possible to use reflection when we write a code-template? I was just thinking if it is possible to write a piece of code-template that will return me a list of all private field in the class separated by && operator in Visual Stuudio? Let's say, I will enter "getAllPrivates&&" (or press a shortcut key) in the VS editor and it will return me something like this: private bool _privateFiel1 = false; private bool _privateFiel2 = true; private bool _privateFiel3 = false; private bool _privateFiel4 = false; private bool _privateFiel5 = true; // Here I press the shortcut or call the code-template and get his: _privateFiel1 && _privateFiel2 && _privateFiel3 && _privateFiel4 && _privateFiel5

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  • How to implement copy operator for such C++ structure?

    - by Kabumbus
    So having struct ResultStructure { ResultStructure(const ResultStructure& other) { // copy code in here ? using memcpy ? how??? } ResultStructure& operator=(const ResultStructure& other) { if (this != &other) { // copy code in here ? } return *this } int length; char* ptr; }; How to implement copy? (sorry - I am C++ nube)

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