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• building an ASP NET MVC site, should i go with linq to sql?

  - by aspm

  so i'm about to start a new website from scratch and i've spent about a week trying to figure out what technology to go with. i'm sold on ASP NET MVC. i'm 100% sure i'm going to love using that. but what i am not so sure about yet is using LINQ 2 SQL. so far i've gathered some data... 1) stack overflow uses it - can't be that bad 2) can be REALLY slow if you don't take advantage of compiled queries 3) will always be slower than ADO net, but can be almost just as fast if using #2 in the proper places 4) is NOT the preferred MS solution (there was a thread here on SO about dropping support) i'm itching to use it, but just want to make sure it's the best for me. i come from a heavy ADO/stored procedure and traditional asp net background (this will be my first experience with ASP MVC).

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• In Java how instance of and type cast(i.e (ClassName)) works on proxy object ?

  - by learner

  Java generates a proxy class for a given interface and provides the instance of the proxy class. But when we type cast the proxy object to our specific Object, how java handles this internally? Is this treated as special scenario? For example I have class 'OriginalClass' and it implements 'OriginalInterface', when I create proxy object by passing 'OriginalInterface' interface java created proxy class 'ProxyClass' using methods in the provided interface and provides object of this class(i.e ProxyClass). If my understanding is correct then can you please answer following queries 1) When I type cast object of ProxyClass to my class OriginalClass this works, but how java is allowing this? Same in case of instace of? 2) As my knowledge java creates a proxy class only with the methods, but what happen when I try to access attributes on this object? 3) Only interface methods are getting implemented in Proxy, but what happens when I try to access a method which not in interface and only mentioned in the class? Thanks, Student

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• Django - User account with multiple identities

  - by Scott Willman

  Synopsis: Each User account has a UserProfile to hold extended info like phone numbers, addresses, etc. Then, a User account can have multiple Identities. There are multiple types of identities that hold different types of information. The structure would be like so: User |<-FK- UserProfile | |<-FK- IdentityType1 |<-FK- IdentityType1 |<-FK- IdentityType2 |<-FK- IdentityType3 (current) |<-FK- IdentityType3 |<-FK- IdentityType3 The User account can be connected to n number of Identities of different types but can only use one Identity at a time. Seemingly, the Django way would be to collect all of the connected identities (user.IdentityType1_set.select_related()) into a QuerySet and then check each one for some kind of 'current' field. Question: Can anyone think of a better way to select the 'current' marked Identity than doing three DB queries (one for each IdentityType)?

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• Aggregate Functions in Index with IBMDB2

  - by Erkan

  Is there any way to pre aggregate results of aggregate functionts (f.i. count()) and store it in an index? The background is: i want to speed up count() queries. So that: Select count(users) from TE123 where region = 'A'; would be supported by an index like Region Count(Users) A 548 E 458 I know that MQTs would also help for this problem. However, in this case it is not possible to use MQT, as we use kind of an ORM and we don't want to define Entities on MQTs. I just slightly remember - one DBA told me - that there is such a function planned for DB2 V10.

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• Is there an open source repository for SQL code?

  - by morpheous

  I find myself writing SQL code (queries or stored procs) to solve problems that can definitely be defined as 'patterns' that occur frequently in business. Rather than having to wrack my brain each time I encounter a new problem (which must have been solved a countless times by other coders/db analysts, I wondered if there was a repository I could go to check out (peer reviewed) code - and maybe add my two pence every now and then. I know different db vendors tend to write slightly variant forms of SQL - but there could still be a repository with ANSI stuff and proprietary stuff. Hopefully, such a site would encourage more people to write standardized SQL. Is there such a site?. If no - why not? (would anyone else be interested in such a site?) If such a site exists, please provide link(s), as Google is not finding anything remotely useful.

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• Does Oracle 11g automatically index fields frequently used for full table scans?

  - by gustafc

  I have an app using an Oracle 11g database. I have a fairly large table (~50k rows) which I query thus: SELECT omg, ponies FROM table WHERE x = 4 Field x was not indexed, I discovered. This query happens a lot, but the thing is that the performance wasn't too bad. Adding an index on x did make the queries approximately twice as fast, which is far less than I expected. On, say, MySQL, it would've made the query ten times faster, at the very least. I'm suspecting Oracle adds some kind of automatic index when it detects that I query a non-indexed field often. Am I correct? I can find nothing even implying this in the docs.

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• How can I sqldump a huge database?

  - by meder

  SELECT count(*) from table gives me 3296869 rows. The table only contains 4 columns, storing dropped domains. I tried to dump the sql through: $backupFile = $dbname . date("Y-m-d-H-i-s") . '.gz'; $command = "mysqldump --opt -h $dbhost -u $dbuser -p $dbpass $dbname | gzip > $backupFile"; However, this just dumps an empty 20 KB gzipped file. My client is using shared hosting so the server specs and resource usage aren't top of the line. I'm not even given ssh access or access directly to the database so I have to make queries through PHP scripts I upload via FTP ( SFTP isn't an option, again ). Is there some way I can perhaps sequentially download portions of it, or pass an argument to mysqldump that will optimize it? I came across http://jeremy.zawodny.com/blog/archives/000690.html which mentions the -q flag and tried that but it didn't seem to do anything differently.

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• Is file_get_contents multi line?

  - by Abs

  Hello all, Does file_get_contents maintain line breaks? I thought it did but I have tried this: if($conn){ $tsql = file_get_contents('scripts/CreateTables/SLR05_MATCH_CREATETABLES.sql'); $row = sqlsrv_query($conn, $tsql); print_r(sqlsrv_errors()); } The errors I get is that SQL Server complains that there is incorrect syntax. I get the same errors when I run the SQL Script without any line breaks, which suggests file_get_contents removes them? When I run the script normally (open the file in SQL Server Management Studio) and execute it, it works perfectly. So is there something that I can use that maintains line breaks etc? Or is there another problem here in using queries from a file with the SQL Server PHP Driver from Microsoft? Thanks all for any help

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• how to handle db concurrency in client-server application in C#?

  - by RAJ K

  I am developing an application in C# WPF which will have Client-Server architecture (Client will do products sales billing). I am novice in this area and I asked this question to start my development process. Click here to view question. So, ultimately I have selected MySQl, WCf & WPF. Now I have one silly question. Do i need to handle DB concurrency explicitly in my application (like 3 clients inserting data same time) or MySQl will handle this without any conflict? To accomplish my project i thought, I will create a service in WCf which will do DB queries from client application. Do you have any suggestion to improve my application performance.

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• MySQL inner join different results

  - by Darryl at NetHosted

  I am trying to work out why the following two queries return different results: SELECT DISTINCT i.id, i.date FROM `tblinvoices` i INNER JOIN `tblinvoiceitems` it ON it.userid=i.userid INNER JOIN `tblcustomfieldsvalues` cf ON it.relid=cf.relid WHERE i.`tax` = 0 AND i.`date` BETWEEN '2012-07-01' AND '2012-09-31' and SELECT DISTINCT i.id, i.date FROM `tblinvoices` i WHERE i.`tax` = 0 AND i.`date` BETWEEN '2012-07-01' AND '2012-09-31' Obviously the difference is the inner join here, but I don't understand why the one with the inner join is returning less results than the one without it, I would have thought since I didn't do any cross table references they should return the same results. The final query I am working towards is SELECT DISTINCT i.id, i.date FROM `tblinvoices` i INNER JOIN `tblinvoiceitems` it ON it.userid=i.userid INNER JOIN `tblcustomfieldsvalues` cf ON it.relid=cf.relid WHERE cf.`fieldid` =5 AND cf.`value` REGEXP '[A-Za-z]' AND i.`tax` = 0 AND i.`date` BETWEEN '2012-07-01' AND '2012-09-31' But because of the different results that seem incorrect when I add the inner join (it removes some results that should be valid) it's not working at present, thanks.

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• Adding more OR searches with CONTAINS Brings Query to Crawl

  - by scolja

  I have a simple query that relies on two full-text indexed tables, but it runs extremely slow when I have the CONTAINS combined with any additional OR search. As seen in the execution plan, the two full text searches crush the performance. If I query with just 1 of the CONTAINS, or neither, the query is sub-second, but the moment you add OR into the mix the query becomes ill-fated. The two tables are nothing special, they're not overly wide (42 cols in one, 21 in the other; maybe 10 cols are FT indexed in each) or even contain very many records (36k recs in the biggest of the two). I was able to solve the performance by splitting the two CONTAINS searches into their own SELECT queries and then UNION the three together. Is this UNION workaround my only hope? Thanks. SELECT a.CollectionID FROM collections a INNER JOIN determinations b ON a.CollectionID = b.CollectionID WHERE a.CollrTeam_Text LIKE '%fa%' OR CONTAINS(a.*, '"*fa*"') OR CONTAINS(b.*, '"*fa*"') Execution Plan (guess I need more reputation before I can post the image):

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• SQL Query to select upcoming events with a start and end date

  - by Chris T

  I need to display upcoming events from a database. The problem is when I use the query I'm currently using any events with a start day that has passed will show up lower on the list of upcoming events regardless of the fact that they are current My table (yaml): columns: title: type: string(255) notnull: true default: Untitled Event start_time: type: time end_time: type: time start_day: type: date notnull: true end_day: type: date description: type: string(500) default: This event has no description category_id: integer My query (doctrine): $results = Doctrine_Query::create() ->from("sfEventItem e, e.Category c") ->select("e.title, e.start_day, e.description, e.category_id, e.slug") ->addSelect("c.title, c.slug") ->orderBy("e.start_day, e.start_time, e.title") ->limit(5) ->execute(array(), Doctrine_Core::HYDRATE_ARRAY); Basically I'd like any events that is currently going on (so if today is in between start_day and end_day) to be at the top of the list. How would I go about doing this if it's even possible? Raw sql queries are good answers too because they're pretty easy to turn into DQL.

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• Index for wildcard match of end of string

  - by Anders Abel

  I have a table of phone numbers, storing the phone number as varchar(20). I have a requirement to implement searching of both entire numbers, but also on only the last part of the number, so a typical query will be: SELECT * FROM PhoneNumbers WHERE Number LIKE '%1234' How can I put an index on the Number column to make those searchs efficient? Is there a way to create an index that sorts the records on the reversed string? Another option might be to reverse the numbers before storing them, which will give queries like: SELECT * FROM PhoneNumbers WHERE ReverseNumber LIKE '4321%' However that will require all users of the database to always reverse the string. It might be solved by storing both the normal and reversed number and having the reversed number being updated by a trigger on insert/update. But that kind of solution is not very elegant. Any other suggestions?

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• GQL Query with __key__ in List of KEYs

  - by bossylobster

  In the GQL reference [1], it is encouraged to use the IN keyword with a list of values, and to construct a Key from hand the GQL query SELECT * FROM MyModel WHERE __key__ = KEY('MyModel', 'my_model_key') will succeed. However, using the code you would expect to work: SELECT * FROM MyModel WHERE __key__ IN (KEY('MyModel', 'my_model_key1'), KEY('MyModel', 'my_model_key2')) in the Datastore Viewer, there is a complaint of "Invalid GQL query string." What is the correct way to format such a query? [1] http://code.google.com/appengine/docs/python/datastore/gqlreference.html PS I know there are more efficient ways to do this in Python (without constructing a GQL query) and using the remote_api, but each call to the remote_api counts against quota. In an environment where quota is not (necessarily) free, quick and dirty queries are very helpful.

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• Finding group maxes in SQL join result

  - by Gene

  Two SQL tables. One contestant has many entries: Contestants Entries Id Name Id Contestant_Id Score -- ---- -- ------------- ----- 1 Fred 1 3 100 2 Mary 2 3 22 3 Irving 3 1 888 4 Grizelda 4 4 123 5 1 19 6 3 50 Low score wins. Need to retrieve current best scores of all contestants ordered by score: Best Entries Report Name Entry_Id Score ---- -------- ----- Fred 5 19 Irving 2 22 Grizelda 4 123 I can certainly get this done with many queries. My question is whether there's a way to get the result with one, efficient SQL query. I can almost see how to do it with GROUP BY, but not quite. In case it's relevant, the environment is Rails ActiveRecord and PostgreSQL.

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• Do MySQL Locked Tables affect related Views?

  - by CogitoErgoSum

  So after reading http://stackoverflow.com/questions/1415602/performance-in-pdo-php-mysql-transaction-versus-direct-execution in regards to performance issues I was thinking about I did some research on locking tables in MySQL. On http://dev.mysql.com/doc/refman/5.0/en/table-locking.html Table locking enables many sessions to read from a table at the same time, but if a session wants to write to a table, it must first get exclusive access. During the update, all other sessions that want to access this particular table must wait until the update is done. This part struck me particularly becuase most of our queries will be updates rather than inserts. I was wondering if one created a table called foo on which all updates/inserts were carried out and then a view called foo_view (A copy of foo, or perhaps foo and a linkage of several other tables plus foo) on which all selects occured, would this locking issue still occur? That is, would SELECT quries on foo_view still have to wait for an update to finish on foo?

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• MS Access caching of reports / query results

  - by FrustratedWithFormsDesigner

  Is it possible to cache a query or report the first time it is run? It seems that opening a report will re-query the datasource. For certain queries, the data source does not change frequently enough that I'd be worried about a cache being out of date (users are notified when the database changes), and it would be much easier for the users to be able to open the report instantly rather than having to wait several minutes every time they want to see the data (though I realize if they close the file the caches will be lost - that's OK). Data comes from an ODBC connection to Oracle, using Access 2003.

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• Database Engine not appearing in SQL Server listing

  - by Jonn

  I don't know if I'm searching for the wrong queries in google but I can't seem to find an answer to this. I have SQL Server 2008 installed in my pc and according to services.msc, I've got 2 database engines running: SQLEXPRESS (probably one that came along with Visual Studio) and MSSQLSERVER. When I try to connect only SQLEXPRESS is visible in the Server Name drop down list. I tried to explicitly state MSSQLSERVER by typing in MYPCNAME\MSSQLSERVER Didn't work. The best solution I could find in the internet was to enable stuff at Configuration Manager. Didn't work either (although I did find that TCP/VIA and all other options were disabled for MSSQLSERVER). Anyone have any other ideas on what I should try next or probably something that I overlooked?

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• Is there a way to split the results of a select query into two equal halfs?

  - by Matthias

  I'd like to have a query returning two ResultSets each of which holding exactly half of all records matching a certain criteria. I tried using TOP 50 PERCENT in conjunction with an Order By but if the number of records in the table is odd, one record will show up in both resultsets. Example: I've got a simple table with TheID (PK) and TheValue fields (varchar(10)) and 5 records. Skip the where clause for now. SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID asc results in the selected id's 1,2,3 SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID desc results in the selected id's 3,4,5 3 is a dup. In real life of course the queries are fairly complicated with a ton of where clauses and subqueries.

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• Is directly executing SQL bad app design?

  - by Michael Lowman

  I'm developing an iOS application that's a manager/viewer for another project. The idea is the app will be able to process the data stored in a database into a number of visualizations-- the overall effect being similar to cacti. I'm making the visualizations fully user-configurable: the user defines what she wants to see and adds restrictions. She might specify, for instance, to graph a metric over the last three weeks with user accounts that are currently active and aren't based in the United States. My problem is that the only design I can think of is more or less passing direct SQL from the iOS app to the backend server to be executed against the database. I know it's bad practice and everything should be written in terms of stored procedures. But how else do I maintain enough flexiblity to keep fully user-defined queries? While the application does compose the SQL, direct SQL is never visible or injectable by the user. That's all abstracted away in UIDateTimeChoosers, UIPickerViews, and the like.

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• why LINQ 2 SQL sometime add a field like select 1 as test, others valid fields....

  - by Fredou

  I have to concat 2 linq2sql query and I have an issue since the 2 query doesn't return the same number of columns, what is weird is after a .ToList() on the queries, they can concat without problem. The reason is, for some linq2sql reason, I have 2 more column named test and test2 which come from 2 left outer join that linq2sql automatically create, something like "select 1 as test, tablefields" Is there any good reason for that? how to remove this extra "1 as test" field? here a few of examples of what it look like: google result for linq 2 sql "select 1 as test"

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• what good orm api will work well with scala or erlang

  - by Emotu Balogun

  I'm considering taking up scala programming but i'm really concerned about what will become of my ORM based applications. I currently use hibernate as my ORM and i find it a really reliable tool. I'd like to know if there's any ORM tool as efficient but written in scala, or will hibernate work seamlessly with it. i don't want to have to start writing endless sql queries again (like the days of JDBC). I also have the same thought about erlang. is there a good orm out there for erlang?? and can i use erlang with other DBMS like oracle and mysql with ORM

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• Why Does TFS Allow Orphaned Content and How Do I Get Rid of It?

  - by Chad

  My TfsVersionControl database has grown to 40+ GB in size. We recently did a TFS Destroy on a folder tree that should have cleared up at least 10 GB but instead it seemed to have no effect. When I look at the tables in TfsVersionControl, I am first shocked to see that there are no foreign keys at all in the database. Running a few queries, I see that there is some orphaning going on: tbl_Content has 13.9 GB of records that don't have a related tbl_File record tbl_File and tbl_Content have 2.4 GB that don't have a related tbl_Namespace record The cleanup job seems to be running nightly (prc_DeleteUnusedContent) and running it against the database manually doesn't remove any orphans. I see in the log for the cleanup job that it failed on 3/16, which is the morning after I destroyed the large amount of data. The error was due to a full transaction log. Could that error be the reason I'm left with all this orphaned data that can't be deleted? How can I permanently destroy this unneeded content?

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• DB management for Heroku apps

  - by zetarun

  Hi all, I'm fairly new to both Rails and Heroku but I'm seriously thinking of using it as a platform to deploy my Ruby/Rails applications. I want to use all the power of Heroku, so I prefer the "embedded" PostgreSQL managed by Heroku instead of the addon for Amazon RDS for MySQL, but I'm not so confident without the possibility to access my data in a SQL client... I know that in a well made app you have no need to access DB, but there are some situations (add rows to a config table, see data not mapped in a view, update some columns for debugging issues, performance monitoring, running queries for reporting, etc.) when this can be good... How do you solve this problem? What's you experience in a real life app powered by Heroku? Thanks!

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• Repository, Service or Domain object - where does logic belong?

  - by betitall

  Take this simple, contrived example: UserRepository.GetAllUsers(); UserRepository.GetUserById(); Inevitably, I will have more complex "queries", such as: //returns users where active=true, deleted=false, and confirmed = true GetActiveUsers(); I'm having trouble determining where the responsibility of the repository ends. GetActiveUsers() represents a simple "query". Does it belong in the repository? How about something that involves a bit of logic, such as: //activate the user, set the activationCode to "used", etc. ActivateUser(string activationCode);

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