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  • Display another field in the referenced table for multiple columns with performance issues in mind

    - by israkir
    I have a table of edge like this: ------------------------------- | id | arg1 | relation | arg2 | ------------------------------- | 1 | 1 | 3 | 4 | ------------------------------- | 2 | 2 | 6 | 5 | ------------------------------- where arg1, relation and arg2 reference to the ids of objects in another object table: -------------------- | id | object_name | -------------------- | 1 | book | -------------------- | 2 | pen | -------------------- | 3 | on | -------------------- | 4 | table | -------------------- | 5 | bag | -------------------- | 6 | in | -------------------- What I want to do is that, considering performance issues (a very big table more than 50 million of entries) display the object_name for each edge entry rather than id such as: --------------------------- | arg1 | relation | arg2 | --------------------------- | book | on | table | --------------------------- | pen | in | bag | --------------------------- What is the best select query to do this? Also, I am open to suggestions for optimizing the query - adding more index on the tables etc... EDIT: Based on the comments below: 1) @Craig Ringer: PostgreSQL version: 8.4.13 and only index is id for both tables. 2) @andrefsp: edge is almost x2 times bigger than object.

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  • Selecting rows without a value for Date/Time columns

    - by Ross
    I'm running this query: SELECT TOP 1 [DVD Copy].[Stock No] FROM [DVD Copy] WHERE [DVD Copy].[Catalogue No] =[Forms]![New Rental]![Catalogue No] And [Issue Date] = Null; Which works fine without the null check for Issue Date. I'm trying to select rows without a Date in the Issue Date column. Is Null the wrong kind of value to use for here?

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  • Linq2Sql Best Practices

    - by this. __curious_geek
    I'm recently migrating to Linq2Sql and all my future projects will be using Linq2Sql. Having said that, I researched a lot on how to properly plug-in Linq2Sql in application design. what to put at what layer ? How do you design your repositories and business layer services ? Should I use DTOs over Linq2Sql entities on interaction layer ? what things should I be careful about ? what problems did you face ? I did not find any rock-solid material that really talked about one single thing and everyone have their own opinions. I'm looking forward to your ideas on how to integrate/use Linq2Sql in projects. My priority is maintenance[it should be maintenable and when multiple people work on same project] and scalabilty [it should have scope of evolution]. Thanks.

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  • USing Min/Max with conditional operator

    - by user638501
    Hello All, I am trying to run a query to find max and min values, and then use a conditional operator. however when I try to run the following query, it gives me error - "misuse of aggregate: min()". My query is: SELECT a.prim_id, min(b.new_len*36) as min_new_len, max(b.new_len*36) as max_new_len FROM tb_first a, tb_second b WHERE a.sec_id = b.sec_id AND min_new_len > 1900 AND max_new_len < 75000 GROUP BY a.prim_id ORDER BY avg(b.new_len*36); Any suggestions ?

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  • How to save multiple column in database

    - by shamim
    I have a text file.I need to get data from this text file and show on grid , 1)After this user can update information from gridview, 2)Click on save button save data on database. Before clicking on button data don't save on database.How to do that?

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  • How can I use a php array in a mysql search query?

    - by ThinkingInBits
    I was going to use the scuttle solution on: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html for handling searches on my website. I was wondering how I could take the search input from a user and turn it into a single query. For instance, let's say a user inputted 'blue dogs' in their search query... How could I dynamically update the query to include ('blue', 'dogs') in union and intersection queries?

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  • WPF/.NET data access models - resource recommendations

    - by jasonk
    We're in the early design/prep phases of transferring/updating a rather large "legacy" 3 tier client-server app to a new version. We’re looking at doing WPF over Winforms as it appears to be the direction Microsoft is pushing development of the future and we’d like the maximize the life cycle/span of the apps. That said during the rewrite we’d like to make as many changes to our data access/presentation model to improve performance as much as possible up front as many. I’ve been doing some research along that vein but the vast majority of the resources I've found that discuss WPF focus only simple data tracking apps or focus on the very basics UI design/controls. The few items that even discuss data presentation are fairly elementary in depth. Are there any books/articles/recommended reading/other resources recommended for development related to large enterprise level business apps? Any “gotchas” that should/could be avoided? General advice to minimize the time underwater

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  • How to ensure DB security for a Windows Forms application?

    - by Vilx-
    The basic setup is classic - you're creating a Windows Forms application that connects to a DB and does all kinds of enterprise-y stuff. Naturally, such an application will have many users with different access rights in the DB, and each with their own login name and password. So how do you implement this? One way is to create a DB login for every application user, but that's a pretty serious thing to do, which even requires admin rights on the DB server, etc. If the DB server hosts several applications, the admins are quite likely not to be happy with this. In the web world typically one creates his own "Users" table which contains all the necessary info, and uses one fixed DB login for all interaction. That is all nice for a web app, but a windows forms can't hide this master login information, negating security altogether. (It can try to hide, but all such attempts are easily broken with a bit of effort). So... is there some middle way? Perhaps logging in with a fixed login, and then elevating priviledges from a special stored procedure which checks the username and password?

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  • Can't add domain users to Reporting Services 2008

    - by Jeremy
    I have SSRS 2008 setup on the database server. The server is part of the domain. Reporting Services is running under NetworkService. When I try to add a domain user using the web interface (Site Settings -- Security -- New Role Assignment), the page posts back but the user is not in the list. The server's log file contains the following Unhandled Exception: ui!ReportManager_0-1!954!01/12/2009-10:14:52:: Unhandled exception: System.Security.Principal.IdentityNotMappedException: Some or all identity references could not be translated. at System.Security.Principal.SecurityIdentifier.Translate(IdentityReferenceCollection sourceSids, Type targetType, Boolean forceSuccess) at System.Security.Principal.SecurityIdentifier.Translate(Type targetType) at System.Security.Principal.WindowsIdentity.GetName() at System.Security.Principal.WindowsIdentity.get_Name() at ReportingServicesHttpRuntime.RsWorkerRequest.GetServerVariable(String name) at System.Web.Security.WindowsAuthenticationModule.OnEnter(Object source, EventArgs eventArgs) at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Any one have an idea on how to fix this?

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  • Insert multiple records from a XML string differing on one parameter in SQL SERVER 2008

    - by Rohit
    Below in a query which inserts records to SimpleDictationProfileMapping table after reading it from a XML string. Now this query inserts a single record in which DictationCaptureProfileID is @dictationCaptureProfileId . Now i want to insert multiple rows in which @dictationCaptureProfileId is different and other 2 values are same. What i want to achieve by this is in case parent changes all child values should also change. INSERT INTO SimpleDictationProfileMapping ( DictationCaptureProfileID, DictationProfileMappingAttributeID, DictationProfileMappingAttributeValue ) SELECT @dictationCaptureProfileId, row.value('@attrId','varchar(max)'), row.value('@value', 'varchar(max)') FROM @simpleDictationCaptureProfileMappings.nodes('/simpleMappingAtribute/attribute') AS d ( row ) ; I want INSERT INTO SimpleDictationProfileMapping ( DictationCaptureProfileID OR (SELECT DictationCaptureProfileID FROM DictationCaptureProfile WHERE SystemDictationCaptureProfileID = @systemDictationCaptureProfileID), DictationProfileMappingAttributeID, DictationProfileMappingAttributeValue ) SELECT @dictationCaptureProfileId , row.value('@attrId','varchar(max)'), row.value('@value', 'varchar(max)') FROM @simpleDictationCaptureProfileMappings.nodes ('/simpleMappingAtribute/attribute') AS d ( row ) ; Please tell how to achieve this.

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  • MSSQL in ASP.NET application getting unstable after a certain period

    - by Barslett
    Hello, I have an ASP.NET 2.0 application that I made to keep track of disruption reports about our public transport system. The architecture is pretty straight-forward; an MSSQL Express 2008 database, ADO.NET and a DataSet/DAL with a few methods to access the database. There is a set of .aspx pages for the UI in use by our dispatchers and on our public website, as well as a set of SOAP and REST webservices and an RSS feed. Everything worked just fine for more than a year, until two weeks ago. Now and then, it seems as the database enters an unstable mode, and the application starts responding something right, something wrong. The typical error is that apparently, an empty DataTable is returned to the public disruption overview or to the RSS generator. Thus, the user gets e.g. an empty GridView, but no exception is thrown AFAIK, and nothing is written to the Windows Application log. After a restart of the MSSQL Express service, the situation is back to normal. It has to be said that the situation first time appeared a few days after I made a new minor upgrade of the application. The RSS generator was slightly rewritten, and I added a WCF REST service. But the DAL and the database schema were untouched... Any hints of how we could keep the database stable? It is a bit annoying not to have a clue ;-)

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  • COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better?

    - by zneak
    Hello guys, I often find these three variants: SELECT COUNT(*) FROM Foo; SELECT COUNT(1) FROM Foo; SELECT COUNT(PrimaryKey) FROM Foo; As far as I can see, they all do the same thing, and I find myself using the three in my codebase. However, I don't like to do the same thing different ways. To which one should I stick? Is any one of them better than the two others?

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  • Can't combine "LINQ Join" with other tables

    - by FullmetalBoy
    The main problem is that I recieve the following message: "base {System.SystemException} = {"Unable to create a constant value of type 'BokButik1.Models.Book-Author'. Only primitive types ('such as Int32, String, and Guid') are supported in this context."}" based on this LinQ code: IBookRepository myIBookRepository = new BookRepository(); var allBooks = myIBookRepository.HamtaAllaBocker(); IBok_ForfattareRepository myIBok_ForfattareRepository = new Bok_ForfattareRepository(); var Book-Authors = myIBok_ForfattareRepository.HamtaAllaBok_ForfattareNummer(); var q = from booknn in allBooks join Book-Authornn in Book-Authors on booknn.BookID equals Book-Authornn.BookID select new { booknn.title, Book-AuthorID }; How shall I solve this problem to get a class instance that contain with property title and Book-AuthorID? // Fullmetalboy I also have tried making some dummy by using "allbooks" relation with Code Samples from the address http://www.hookedonlinq.com/JoinOperator.ashx. Unfortunately, still same problem. I also have taken account to Int32 due to entity framework http://msdn.microsoft.com/en-us/library/bb896317.aspx. Unfortunatley, still same problem. Using database with 3 tables and one of them is a many to many relationship. This database is used in relation with entity framework Book-Author Book-Author (int) BookID (int) Forfattare (int) Book BookID (int) title (string) etc etc etc

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  • About to migrate :string but I'm thinking :text might be better. Performance/Purpose?

    - by Sam
    class CreateScrapes < ActiveRecord::Migration def self.up create_table :scrapes do |t| t.text :saved_characters t.text :sanitized_characters t.string :href t.timestamps end end def self.down drop_table :scrapes end end I'm about to rake db:migrate and I'm think about the attribute type if I should be using text or string. Since saved_characters and sanitized_characters will be arrays with thousands of unicode values, its basically comma delimited data, I'm not sure if `:text' is really the right way to go here. What would you do?

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  • Find the highest number of occurences in a column in SQL

    - by Ronnie
    Given this table: Order custName description to_char(price) A desa $14 B desb $14 C desc $21 D desd $65 E dese $21 F desf $78 G desg $14 H desh $21 I am trying to display the whole row where prices have the highest occurances, in this case $14 and $21 I believe there needs to be a subquery. So i started out with this: select max(count(price)) from orders group by price which gives me 3. after some time i didn't think that was helpful. i believe i needed the value 14 and 21 rather the the count so i can put that in the where clause. but I'm stuck how to display that. any help?

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  • Non-Access or -base QBE tool?

    - by idbin.cath0br0
    Hello. I'm currently looking for a QBE tool that can execute queries on PostgreSQL or MySQL. OS doesn't really matter. Reason is that we've got to do QBE at school but I don't want to use neither Microsoft Access nor OpenOffice.org Base (lack of features). Any help would be appreciated.

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  • Nested joins hide table names

    - by Sergio
    Hi: I have three tables: Suppliers, Parts and Types. I need to join all of them while discriminating columns with the same name (say, "id") in the three tables. I would like to successfully run this query: CREATE VIEW Everything AS SELECT Suppliers.name as supplier, Parts.id, Parts.description, Types.typedesc as type FROM Suppliers JOIN (Parts JOIN Types ON Parts.type_id = Types.id) ON Suppliers.id = Parts.supplier_id; My DBMS (sqlite) complains that "there is not such a column (Parts.id)". I guess it forgets table names once the JOIN is done but then how can I refer to the column id that belongs to the table Parts?

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  • IN statement performance in PostgreSQL (and in general)

    - by Vasil
    I know this has probably been asked before, but I can't find it with SO's search. Lets say i've TABLE1 and TABLE2, who should I expect the performance of a query such as this: SELECT * FROM TABLE1 WHERE id IN SUBQUERY_ON_TABLE2; as the number of rows in TABLE1 and TABLE2 grow and id is a primary key on TABLE1. Yes, I know using IN is such a n00b mistake, but TABLE2 has a generic relation (django generic relation) to multiple other tables so I can't think of another way to filter the data. At what (aproximate) ammount of rows in TABLE1 and TABLE2 should I expect to notice performance issues because of this? Will performance degrade linearly, exponentially etc. depending on the number of rows?

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  • what is the question for the query?

    - by Kevinniceguy
    Sorry...I mean what question will be for this query? SELECT SUM(price) FROM Room r, Hotel h WHERE r.hotelNo = h.hotelNo and hotelName = 'Paris Hilton' and roomNo NOT IN (SELECT roomNo FROM Booking b, Hotel h WHERE (dateFrom <= CURRENT_DATE AND dateTo >= CURRENT_DATE) AND b.hotelNo = h.hotelNo AND hotelName = 'Paris Hilton');

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  • Why does this MySQL function return null?

    - by Shore
    Description: the query actually run have 4 results returned,as can be see from below, what I did is just concate the items then return, but unexpectedly,it's null. I think the code is self-explanatory: DELIMITER | DROP FUNCTION IF EXISTS get_idiscussion_ask| CREATE FUNCTION get_idiscussion_ask(iask_id INT UNSIGNED) RETURNS TEXT DETERMINISTIC BEGIN DECLARE done INT DEFAULT 0; DECLARE body varchar(600); DECLARE created DATETIME; DECLARE anonymous TINYINT(1); DECLARE screen_name varchar(64); DECLARE result TEXT; DECLARE cur1 CURSOR FOR SELECT body,created,anonymous,screen_name from idiscussion left join users on idiscussion.uid=users.id where idiscussion.iask_id=iask_id; DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1; SET result = ''; OPEN cur1; REPEAT FETCH cur1 INTO body, created, anonymous, screen_name; SET result = CONCAT(result,'<comment><body><![CDATA[',body,']]></body>','<replier>',if(screen_name is not null and !anonymous,screen_name,''),'</replier>','<created>',created,'</created></comment>'); UNTIL done END REPEAT; CLOSE cur1; RETURN result; END | DELIMITER ; mysql> DELIMITER ; mysql> select get_idiscussion_ask(1); +------------------------+ | get_idiscussion_ask(1) | +------------------------+ | NULL | +------------------------+ 1 row in set (0.01 sec) mysql> SELECT body,created,anonymous,screen_name from idiscussion left join users on idiscussion.uid=users.id where idiscussion.iask_id=1; +------+---------------------+-----------+-------------+ | body | created | anonymous | screen_name | +------+---------------------+-----------+-------------+ | haha | 2009-05-27 04:57:51 | 0 | NULL | | haha | 2009-05-27 04:57:52 | 0 | NULL | | haha | 2009-05-27 04:57:52 | 0 | NULL | | haha | 2009-05-27 04:57:53 | 0 | NULL | +------+---------------------+-----------+-------------+ 4 rows in set (0.00 sec) For those who don't think the code is self-explanatory: Why the function returns NULL?

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  • Should I catch exceptions thrown when closing java.sql.Connection

    - by jb
    Connection.close() may throw SqlException, but I have always assumed that it is safe to ignore any such exceptions (and I have never seen code that does not ignore them). Normally I would write: try{ connection.close(); }catch(Exception e) {} Or try{ connection.close(); }catch(Exception e) { logger.log(e.getMessage(), e); } The question is: Is it bad practice (and has anyone had problems when ignoring such exeptions). When Connection.close() does throw any exception. If it is bad how should I handle the exception. Comment: I know that discarding exceptions is evil, but I'm reffering only to exceptions thrown when closing a connection (and as I've seen this is fairly common in this case). Does anyone know when Connection.close() may throw anything?

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  • Postgre database ignoring created index ?!

    - by drasto
    I have an Postgre database and a table called my_table. There are 4 columns in that table (id, column1, column2, column3). The id column is primary key, there are no other constrains or indexes on columns. The table has about 200000 rows. I want to print out all rows which has value of column column2 equal(case insensitive) to 'value12'. I use this: SELECT * FROM my_table WHERE column2 = lower('value12') here is the execution plan for this statement(result of set enable_seqscan=on; EXPLAIN SELECT * FROM my_table WHERE column2 = lower('value12')): Seq Scan on my_table (cost=0.00..4676.00 rows=10000 width=55) Filter: ((column2)::text = 'value12'::text) I consider this to be to slow so I create an index on column column2 for better prerformance of searches: CREATE INDEX my_index ON my_table (lower(column2)) Now I ran the same select: SELECT * FROM my_table WHERE column2 = lower('value12') and I expect it to be much faster because it can use index. However it is not faster, it is as slow as before. So I check the execution plan and it is the same as before(see above). So it still uses sequential scen and it ignores the index! Where is the problem ?

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  • What's wrong with this SQL query?

    - by ThinkingInBits
    I have two tables: photographs, and photograph_tags. Photograph_tags contains a column called photograph_id (id in photographs). You can have many tags for one photograph. I have a photograph row related to three tags: boy, stream, and water. However, running the following query returns 0 rows SELECT p.* FROM photographs p, photograph_tags c WHERE c.photograph_id = p.id AND (c.value IN ('dog', 'water', 'stream')) GROUP BY p.id HAVING COUNT( p.id )=3 Is something wrong with this query?

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