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  • What is the corrrect way to increment a field making up part of a composit key

    - by Tr1stan
    I have a bunch of tables whose primary key is made up of the foreign keys of other tables (Composite key). Therefore for example the attributes (as a very cut down version) might look like this: A[aPK, SomeFields] 1:M B[bPK, aFK, SomeFields] 1:M C[cPK, bFK, aFK, SomeFields] as data this could look like: A[aPK, SomeFields]: 1, Foo 2, Bar B[bPK, aFK, SomeFields]: 1, 1, FooData1 2, 1, FooData2 1, 2, BarData1 2, 2, BarData2 C[cPK, bFK, aFK, SomeFields]: 1, 1, 1, FooData1More 2, 1, 1, FooData1More 1, 2, 1, FooData2More 2, 2, 1, FooData2More 1, 1, 2, BarData1More 2, 1, 2, BarData1More 1, 2, 2, BarData2More 2, 2, 2, BarData2More I've got this running in a MSSQL DBMS and I'm looking for the best way to increment the left most column, in each table when a new tuple is added to it. I can't use the Auto Increment Identity Specification option as that has no idea that it is part of a composite key. I also don't want to use any aggregate function such as: MAX(field)+1 as this will have adverse affects with multiple users inputting data, rolling back etc. There might however be a nice trigger based option here, but I'm not sure. This must be a common issue so I'm hoping that someone has a lovely solution. As a side which may or may not affect the answer, I'm using Entity Framework 1.0 as my ORM, within a c# MVC application.

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  • mysql subquery strangely slow

    - by aviv
    I have a query to select from another sub-query select. While the two queries look almost the same the second query (in this sample) runs much slower: SELECT user.id ,user.first_name -- user.* FROM user WHERE user.id IN (SELECT ref_id FROM education WHERE ref_type='user' AND education.institute_id='58' AND education.institute_type='1' ); This query takes 1.2s Explain on this query results: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY user index first_name 152 141192 Using where; Using index 2 DEPENDENT SUBQUERY education index_subquery ref_type,ref_id,institute_id,institute_type,ref_type_2 ref_id 4 func 1 Using where The second query: SELECT -- user.id -- user.first_name user.* FROM user WHERE user.id IN (SELECT ref_id FROM education WHERE ref_type='user' AND education.institute_id='58' AND education.institute_type='1' ); Takes 45sec to run, with explain: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY user ALL 141192 Using where 2 DEPENDENT SUBQUERY education index_subquery ref_type,ref_id,institute_id,institute_type,ref_type_2 ref_id 4 func 1 Using where Why is it slower if i query only by index fields? Why both queries scans the full length of the user table? Any ideas how to improve? Thanks.

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  • T-SQL MERGE - finding out which action it took

    - by IanC
    I need to know if a MERGE statement performed an INSERT. In my scenario, the insert is either 0 or 1 rows. Test code: DECLARE @t table (C1 int, C2 int) DECLARE @C1 INT, @C2 INT set @c1 = 1 set @c2 = 1 MERGE @t as tgt USING (SELECT @C1, @C2) AS src (C1, C2) ON (tgt.C1 = src.C1) WHEN MATCHED AND tgt.C2 != src.C2 THEN UPDATE SET tgt.C2 = src.C2 WHEN NOT MATCHED BY TARGET THEN INSERT VALUES (src.C1, src. C2) OUTPUT deleted.*, $action, inserted.*; SELECT inserted.* The last line doesn't compile (no scope, unlike a trigger). I can't get access to @action, or the output. Actually, I don't want any output meta data. How can I do this?

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  • Self-relation messes up contents in fetching

    - by holographix
    Hi folks, I'm dealing with an annoying problem in core data I've got a table named Character, which is made as follows I'm filling the table in various steps: 1) fill the attributes of the table 2) fill the Character Relation (charRel) FYI charRel is defined as follows I'm feeding the contents by pulling the data from an xml, the feeding code is this curStr = [[NSMutableString stringWithString:[curStr stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]] retain]; NSLog(@"Parsing relation within these keys %@, in order to get'em associated",curStr); NSArray *chunks = [curStr componentsSeparatedByString: @","]; for( NSString *relId in chunks ) { NSLog(@"Associating %@ with id %@",[currentCharacter valueForKey:@"character_id"], relId); NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"character_id == %@", relId]; [request setEntity:[NSEntityDescription entityForName:@"Character" inManagedObjectContext:[self managedObjectContext] ]]; [request setPredicate:predicate]; NSerror *error = nil; NSArray *results = [[self managedObjectContext] executeFetchRequest:request error:&error]; // error handling code if(error != nil) { NSLog(@"[SYMBOL CORRELATION]: retrieving correlated symbol error: %@", [error localizedDescription]); } else if([results count] > 0) { Character *relatedChar = [results objectAtIndex:0]; // grab the first result in the stack, could be done better! [currentCharacter addCharRelObject:relatedChar]; //VICE VERSA RELATIONS NSArray *charRels = [relatedChar valueForKey:@"charRel"]; BOOL alreadyRelated = NO; for(Character *charRel in charRels) { if([[charRel valueForKey:@"character_id"] isEqual:[currentCharacter valueForKey:@"character_id"]]) { alreadyRelated = YES; break; } } if(!alreadyRelated) { NSLog(@"\n\t\trelating %@ with %@", [relatedChar valueForKey:@"character_id"], [currentCharacter valueForKey:@"character_id"]); [relatedChar addCharRelObject:currentCharacter]; } } else { NSLog(@"[SYMBOL CORRELATION]: related symbol was not found! ##SKIPPING-->"); } [request release]; } NSLog(@"\t\t### TOTAL OF REALTIONS FOR ID %@: %d\n%@", [currentCharacter valueForKey:@"character_id"], [[currentCharacter valueForKey:@"charRel"] count], currentCharacter); error = nil; /* SAVE THE CONTEXT */ if (![managedObjectContext save:&error]) { NSLog(@"Whoops, couldn't save the symbol record: %@", [error localizedDescription]); NSArray* detailedErrors = [[error userInfo] objectForKey:NSDetailedErrorsKey]; if(detailedErrors != nil && [detailedErrors count] > 0) { for(NSError* detailedError in detailedErrors) { NSLog(@"\n################\t\tDetailedError: %@\n################", [detailedError userInfo]); } } else { NSLog(@" %@", [error userInfo]); } } at this point when I print out the values of the currentCharacter, everything looks perfect. every relation is in its place. in example in this log we can clearly see that this element has got 3 items in charRel: <Character: 0x5593af0> (entity: Character; id: 0x55938c0 <x-coredata://67288D50-D349-4B19-B7CB-F7AC4671AD61/Character/p86> ; data: { catRel = "<relationship fault: 0x9a29db0 'catRel'>"; charRel = ( "0x9a1f870 <x-coredata://67288D50-D349-4B19-B7CB-F7AC4671AD61/Character/p74>", "0x9a14bd0 <x-coredata://67288D50-D349-4B19-B7CB-F7AC4671AD61/Character/p109>", "0x558ba00 <x-coredata://67288D50-D349-4B19-B7CB-F7AC4671AD61/Character/p5>" ); "character_id" = 254; examplesRel = "<relationship fault: 0x9a29df0 'examplesRel'>"; meaning = "\n Left"; pinyin = "\n zu\U01d2"; "pronunciation_it" = "\n zu\U01d2"; strokenumber = 5; text = "\n \n <p>The most ancient form of this symbol"; unicodevalue = "\n \U5de6"; }) then when I'm in need of retrieving this item I perform an extraction, like this: // at first I get the single Character record NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSError *error; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"character_id == %@", self.char_id ]; [request setEntity:[NSEntityDescription entityForName:@"Character" inManagedObjectContext:_context ]]; [request setPredicate:predicate]; NSArray *fetchedObjs = [_context executeFetchRequest:request error:&error]; when, for instance, I print out in NSLog the contents of charRel NSArray *correlations = [singleCharacter valueForKey:@"charRel"]; NSLog(@"CHARACTER OBJECT \n%@", correlations); I get this Relationship fault for (<NSRelationshipDescription: 0x5568520>), name charRel, isOptional 1, isTransient 0, entity Character, renamingIdentifier charRel, validation predicates (), warnings (), versionHashModifier (null), destination entity Character, inverseRelationship (null), minCount 1, maxCount 99 on 0x6937f00 hope that I made myself clear. this thing is driving me insane, I've googled all over world, but I couldn't find a solution (and this make me think to as issue related to bad coding somehow :P). thank you in advance guys. k

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  • What is the most efficient procedure for implementing a sortable ajax list on the backend?

    - by HenryL
    The most common method is to assign a sequential order field for each item in the list and do an update that maintains the sequence with every ajax sort operation. Unfortunately, this requires an update to each item of the list every time someone sorts. This is fine for small lists, but what's the best way to implement sorting for larger lists that are constantly updated? I am looking for something that minimizes DB IO.

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  • MySQL Table structure of thumb UP & DOWN for comments system ?

    - by Axel
    Hello, i already created a table for comments but i want to add the feature of thumb Up and Down for comments like Digg and Youtube, i use php & mysql and i'm wondering What's the best table scheme to implement that so comments with many likes will be on the top. This is my current comments table : comments(id,user,article,comment,stamp) Note: Only registred will be able to vote, so there isn't need to restrict the votes by IP Thanks

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  • In SQL server, to convert a varchar which have this format (nnn:nn:nn)

    - by user1688917
    I have this varchar format as time accumulation and i want to convert it to an integer to do a SUM and get the total time for a group. The fist part which may be 1, 2, 3, 4 or even five digits represent the accumulation of Hours and then seperated by a colon. then come the second part which is accumulation of minutes and last accumulation of seconds (2 digits each). How to convert this to integer in one query if possile.

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  • Search sort by parameter match count in the query? PostgreSQL

    - by Ben Dauphinee
    I am working on a search query in PostgreSQL, and one of the things I do is sort my query results by the number of parameters matched. I have no clue how this can be done. Does anyone have a suggestion or solution? Table brand color type engine Ford Blue 4-door V8 Maserati Blue 2-door V12 Saturn Green 4-door V8 GM Yellow 1-door V4 Current Query SELECT brand FROM table WHERE color = 'Blue' or type = '4-door' or engine = 'V8' Result Should Be Ford (3 match) Saturn (2 match) Maserati (1 match)

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  • Hierarchical Hibernate, how many queries are executed?

    - by ghost1
    So I've been dealing with a home brew DB framework that has some seriously flaws, the justification for use being that not using an ORM will save on the number of queries executed. If I'm selecting all possibile records from the top level of a joinable object hierarchy, how many separate calls to the DB will be made when using an ORM (such as Hibernate)? I feel like calling bullshit on this, as joinable entities should be brought down in one query , right? Am I missing something here? note: lazy initialization doesn't matter in this scenario as all records will be used.

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  • How do I perform 'WHERE' on groups of rows?

    - by Drew
    I have a table, which looks like: +-----------+----------+ + person_id + group_id + +-----------+----------+ + 1 + 10 + + 1 + 20 + + 1 + 30 + + 2 + 10 + + 2 + 20 + + 3 + 10 + +-----------+----------+ I need a query such that only person_ids with groups 10 AND 20 AND 30 are returned (only person_id: 1). I am not sure how to do this, as from what I can see it would require me to group the rows by person_id and then select the rows which contain all group_ids. I'm looking for something which will preserve the use of keys without resorting to string operations on group_concat() or such.

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  • How to store a scaleable sized extensible event log?

    - by firoso
    Hello everyone! I've been contemplating writing a simple "event log" that takes a paramater list and stores event messages in a log file, trouble is, I forsee this file growing to be rather large (assume 1M entries or more) the question is, how can I implement this system without pulling teeth, I know that SQL would be a possible way to go. XML would be ideal but not really practical for scaleability if i'm not going nuts. Example Log Entry -----Time Date-------- ---------Sender----------------------- ---------Tags---------- --Message---------- 12/24/2008 24:00:00 $DOMAIN\SYSTEM\Application$ :Trivial: :Notification: It's Christmas in 1s

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  • Desimal data Type Display scale part as zero

    - by Wael Dalloul
    I have Decimal field in SQLserver 2005 table, Price decimal(18, 4) if I write 12 it will be converted to 12.0000, if I write 12.33 it will be converted into 12.3300. Always it's putting zero to the right of the decimal point in the count of Scale Part(4). I was using these in SQL Server 2000, it was not behaving like this, in SQL Server 2000 if I put 12.5 it will be stored as 12.5 not as 12.5000 what SQLServer2005 do. My Question is how to stop SQL Server 2005 from putting zeros to the right of the decimal point?

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  • Can somebody suggest good source for IMS?

    - by Raja Reddy
    I would like to learn working with IMS, can somebody suggest me a good source? I'm not sure if it matters to say that I have quite good exposure and experience with INSYNC DB2 and QMF. So anything that can depict and explain the advantages and disadvantages over IMS would be really helpful. Thanks for your help beforehand..

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  • Advantage Data Architect doesn't accept 'output to', are there any other options for outputting a ta

    - by likesalmon
    I'm trying to output the results of a SELECT query to a tab delimited text file in Advantage Data Architect. I know I can use the 'Export to' feature to do this, but there are a lot of tables and that is going to take forever. I would rather use the SQL editor, but I found out it does not accept the OUTPUT TO argument, even though that command is part of Sybase SQL. I would like to do this: SELECT * FROM tablename; OUTPUT TO 'C:/ExportDirectory' DELIMITED BY '\t' FORMAT TEXT; Is there another way?

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  • Keeping DB Table sorted using multi-field formula (Microsoft SQL)

    - by user298167
    Hello Everybody. I have a Job Table which has two interesting columns: Creation Date and Importance (high - 3, medium 2, low - 1). Job's priority calculated like this: Priority = Importance * (time passed since creation). The problem is, Every time I would like to pick 200 jobs with highest priority, I dont want to resort the table. Is there a way to keep rows sorted? I was also thinking about having three tables one for High, Medium and Low and then sort those by Creation Date. Thanks

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  • top-k selection/merge

    - by tcurdt
    I have n sorted lists. These lists are quite long (300000+ tuples). Selecting the top 10 of the individual lists is of course trivial - they are right at the head of the lists. Where it gets more interesting is when I want the top 10 of all the sorted lists. The question is whether there is an algorithm to calculate the combined top 10 having the correct order while cutting off the long tail of the lists. The goal is to reduce the required space. And if there is: How does one find the limit where is is safe to cut? Note: The actual counts are not important. Only the order is.

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  • Language/Framework support for Interacting With CouchDB

    - by Gordon
    I am interested in knowing if there are any server-side web application frameworks which integrate nicely with CouchDB? Does anyone have any experience in doing this? It seems like a dynamic language would be well-suited for playing with the JSON, but I am more interested in hearing about how it would fit in with the framework and the application's design.

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  • Join Where Rows Don't Exist or Where Criteria Matches...?

    - by Greg
    I'm trying to write a query to tell me which orders have valid promocodes. Promocodes are only valid between certain dates and optionally certain packages. I'm having trouble even explaining how this works (see psudo-ish code below) but basically if there are packages associated with a promocode then the order has to have one of those packages and be within a valid date range otherwise it just has to be in a valid date range. The whole "if PrmoPackage rows exist" thing is really throwing me off and I feel like I should be able to do this without a whole bunch of Unions. (I'm not even sure if that would make it easier at this point...) Anybody have any ideas for the query? if `OrderPromoCode` = `PromoCode` then if `OrderTimestamp` is between `PromoStartTimestamp` and `PromoEndTimestamp` then if `PromoCode` has packages associated with it //yes then if `PackageID` is one of the specified packages //yes code is valid //no invalid //no code is valid Order: OrderID* | OrderTimestamp | PackageID | OrderPromoCode 1 | 1/2/11 | 1 | ABC 2 | 1/3/11 | 2 | ABC 3 | 3/2/11 | 2 | DEF 4 | 4/2/11 | 3 | GHI Promo: PromoCode* | PromoStartTimestamp* | PromoEndTimestamp* ABC | 1/1/11 | 2/1/11 ABC | 3/1/11 | 4/1/11 DEF | 1/1/11 | 1/11/13 GHI | 1/1/11 | 1/11/13 PromoPackage: PromoCode* | PromoStartTimestamp* | PromoEndTimestamp* | PackageID* ABC | 1/1/11 | 2/1/11 | 1 ABC | 1/1/11 | 2/1/11 | 3 GHI | 1/1/11 | 1/11/13 | 1 Desired Result: OrderID | IsPromoCodeValid 1 | 1 2 | 0 3 | 1 4 | 0

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  • What are the best ways to store Graphs in persistent storage

    - by nicoslepicos
    I am wondering what the best ways to store graphs in persistent storage are, for later analysis, search, clustering, etc. I see neo4j being an option, I am curious if there are also other graph databases available. Does anyone have any insights into how larger social networks store their graph based data (or other sites that require the storage of graph like models, e.g. RDF). What about options like Cassandra, or MySQL?

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  • select for update with ruby oci8

    - by ash34
    how do I do a 'select for update' and then 'update' the row using ruby oci8. I have two fields counter1 and counter2 in a table which has only 1 record. I want to select the values from this table and then increment them by locking the row using select for update. thanks.

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