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  • Connect android to database

    - by danny
    I am doing a school project where we need to create an android application which needs to connect to a database. the application needs to gain and store information for people's profiles on the database. But unfortunatly we are a little bit stuck at this point because there are numerous ways to link the application such as http request through apache or through the SOAP/REST protocol. But it's really hard to find good instructions or tutorials on the problem since I can't really find them. Maybe that's cause i'm probably using the wrong words on google. Unfortunately I have little relevant information. So if anyone can help me with finding relevant links to good online tutorials or howto's than those are very welcome.

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  • What are performance limits of a database?

    - by Tommy
    What are some rough performance limits (read/s, write/s) for a single database server (no master-slave architecture), assuming storage on disk? How many read/s, write/s, depending on the kind of disk? (SSD vs non-SSD) , assuming simple operations (select one row by primary key, update one row, correctly indexed). I assume this limit is dependent on disk seek/write. EDIT: My question is more about getting rough metrics of the number of operations a database supports: to be able to know for example, if a new feature triggering 300 inserts/s can be supported without scaling out with additional servers.

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  • Postgres pg_dump dumps database in a different order every time

    - by behrk2
    Hello, I am writing a PHP script (which also uses linux bash commands) which will run through test cases by doing the following: I am using a PostgreSQL database (8.4.2)... 1.) Create a DB 2.) Modify the DB 3.) Store a database dump of the DB (pg_dump) 4.) Do regression testing by doing steps 1.) and 2.), and then take another database dump and compare it (diff) with the original database dump from step number 3.) However, I am finding that pg_dump will not always dump the database in the same way. It will dump things in a different order every time. Therefore, when I do a diff on the two database dumps, the comparison will result in the two files being different, when they are actually the same, just in a different order. Is there a different way I can go about doing the pg_dump? Thanks!

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  • Storing n-grams in database in < n number of tables.

    - by kurige
    If I was writing a piece of software that attempted to predict what word a user was going to type next using the two previous words the user had typed, I would create two tables. Like so: == 1-gram table == Token | NextWord | Frequency ------+----------+----------- "I" | "like" | 15 "I" | "hate" | 20 == 2-gram table == Token | NextWord | Frequency ---------+------------+----------- "I like" | "apples" | 8 "I like" | "tomatoes" | 12 "I hate" | "tomatoes" | 20 "I hate" | "apples" | 2 Following this example implimentation the user types "I" and the software, using the above database, predicts that the next word the user is going to type is "hate". If the user does type "hate" then the software will then predict that the next word the user is going to type is "tomatoes". However, this implimentation would require a table for each additional n-gram that I choose to take into account. If I decided that I wanted to take the 5 or 6 preceding words into account when predicting the next word, then I would need 5-6 tables, and an exponentially increase in space per n-gram. What would be the best way to represent this in only one or two tables, that has no upper-limit on the number of n-grams I can support?

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  • Writing datatable to database file, one record at a time

    - by Kevin
    I want to write a C# program that will read a row from a datatable (named loadDT) and update a database file (named Forecasts.mdb). My datatable looks like this (each day's value is a number representing kilowatts usage forecast): Hour Day1 Day2 Day3 Day4 Day5 Day6 Day7 1 519 520 524 498 501 476 451 My database file looks like this: Day Hour KWForecast 1 1 519 2 1 520 3 1 524 ... and so on. Basically, I want to be able to read one row from the datatable, and then extrapolate that out to my database file, one record at a time. Each row from the datatable will result in seven records written to the database file. Any ideas on how to go about this? I can connect to my database, the connection string works, and I can update and delete from the database. I just can't wrap my head around how to do this one record at a time.

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  • hosting site on one web server and accessing a database on another

    - by tombull89
    I'm fairly sure this is the right place for this question, but if not please move it to the the right site. I have a number of sites on a 1and1 package (yeah, I know...) and I also have a subdomian that belongs to a college tutor. I have been playing around with PHP and MySQL databases on the subdomian site and would like to know if it is possible to run a database driven (i.e. blog) on one of my 1and1 sites. I could upgrade my package but if I'm only going to gain database functionality I'm not sure if I want to do it. Also, as 1and1 don't use cPanel I'm wondering how the databases would be managed...but I'll worry about that when (if) the time comes. Cheers!

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  • How to Script a backup for each database on an MSSQL Engine?

    - by Geo
    We need to backup 40 databases inside an MS SQL Server Engine. We backup each database with the following script: BACKUP DATABASE [dbname1] TO DISK = N'J:\SQLBACKUPS\dbname1.bak' WITH NOFORMAT, INIT, NAME = N'dbname1-Full Database Backup', SKIP, NOREWIND, NOUNLOAD, STATS = 10 GO declare @backupSetId as int select @backupSetId = position from msdb..backupset where database_name=N'dbname1' and backup_set_id=(select max(backup_set_id) from msdb..backupset where database_name=N'dbname1' ) if @backupSetId is null begin raiserror(N'Verify failed. Backup information for database ''dbname1'' not found.', 16, 1) end RESTORE VERIFYONLY FROM DISK = N'J:\SQLBACKUPS\dbname1.bak' WITH FILE = @backupSetId, NOUNLOAD, NOREWIND GO We will like to add to the script the functionality of taking each database and replacing it in the above script. Basically a script that will create and verify each database backup from an engine. I am looking for something like this: For each database in database-list sp_backup(database) // this is the call to the script above. End For any ideas?

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  • Writing datatable to database file, one record at a time in C#

    - by Kevin
    Hi! I want to write a C# program that will read a row from a datatable (named loadDT) and update a database file (named Forecasts.mdb). My datatable looks like this (each day's value is a number representing kilowatts usage forecast): Hour Day1 Day2 Day3 Day4 Day5 Day6 Day7 1 519 520 524 498 501 476 451 My database file looks like this: Day Hour KWForecast 1 1 519 2 1 520 3 1 524 ... and so on. Basically, I want to be able to read one row from the datatable, and then extrapolate that out to my database file, one record at a time. Each row from the datatable will result in seven records written to the database file. Any ideas on how to go about this? I can connect to my database, the connection string works, and I can update and delete from the database. I just can't wrap my head around how to do this one record at a time. Thanks in advance for any help and advice.

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  • Two radically different queries against 4 mil records execute in the same time - one uses brute force.

    - by IanC
    I'm using SQL Server 2008. I have a table with over 3 million records, which is related to another table with a million records. I have spent a few days experimenting with different ways of querying these tables. I have it down to two radically different queries, both of which take 6s to execute on my laptop. The first query uses a brute force method of evaluating possibly likely matches, and removes incorrect matches via aggregate summation calculations. The second gets all possibly likely matches, then removes incorrect matches via an EXCEPT query that uses two dedicated indexes to find the low and high mismatches. Logically, one would expect the brute force to be slow and the indexes one to be fast. Not so. And I have experimented heavily with indexes until I got the best speed. Further, the brute force query doesn't require as many indexes, which means that technically it would yield better overall system performance. Below are the two execution plans. If you can't see them, please let me know and I'll re-post then in landscape orientation / mail them to you. Brute-force query: Index-based exception query: My question is, based on the execution plans, which one look more efficient? I realize that thing may change as my data grows.

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  • MySQL date query only returns one year, when multiple exist

    - by Bowman
    I'm a part-time designer/developer with a part-time photography business. I've got a database of photos with various bits of metadata attached. I want to query the database and return a list of the years that photos were taken, and the quantity of photos that were taken in that year. In short, I want a list that looks like this: 2010 (35 photos) 2009 (67 photos) 2008 (48 photos) Here's the query I'm using: SELECT YEAR(date) AS year, COUNT(filename) as quantity FROM photos WHERE visible='1' GROUP BY 'year' ORDER BY 'year' DESC Instead of churning out all the possible years (the database includes photos from 2010-2008), this is the sole result: 2010 (35 photos) I've tried a lot of different syntax but at this point I'm giving in and asking for help!

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  • Connect to Oracle database on a different server from PHP

    - by macha
    Hello I have a database engine sitting on a remote server, while my webserver is present locally. I have worked pretty much with client-server architecture, where the server has both the webserver and the database engine. Now I need to connect to an Oracle database which is situated on a different server. Can anybody give me any suggestions?? I believe ODBC_CONNECT might not work. Do I use OCI8 drivers?? How would I connect to my database server. Also I would have a very high number of database calls going back and forth, so is it good to go with persistent connection or do I still use individual database calls?

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  • How to structure a database with questions and answers?

    - by Andreas Johannessen
    Hi I am going to make a simple application that uses a database. I could need some guidance on how to structure it. I shall make question program. What I have in mind is. One table with questions One table with the difficulity of the question One table with the category of the question However, what do I do with the answers? Have them as seperate columns in the question-table? It sounds like a bad practice.(Also, where do I have the correct answer) Each question will have 5 answers where only one of them is correct.

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  • Trouble creating a SQL query

    - by JoBu1324
    I've been thinking about how to compose this SQL query for a while now, but after thinking about it for a few hours I thought I'd ask the SO community to see if they have any ideas. Here is a mock up of the relevant portion of the tables: contracts id date ar (yes/no) term payments contract_id payment_date The object of the query is to determine, per month, how many payments we expect, vs how many payments we received. conditions for expecting a payment Expected payments begin on contracts.term months after contracts.date, if contracts.ar is "yes". Payments continue to be expected until the month after the first missed payment. There is one other complication to this: payments might be late, but they need to show up as if they were paid on the date expected. The data is all there, but I've been having trouble wrapping my head around the SQL query. I am not an SQL guru - I merely have a decent amount of experience handling simpler queries. I'd like to avoid filtering the results in code, if possible - but without your help that may be what I have to do. Expected Output Month Expected Payments Received Payments January 500 450 February 498 478 March 234 211 April 987 789 ... SQL Fiddle I've created an SQL Fiddle: http://sqlfiddle.com/#!2/a2c3f/2

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  • Get Rails to save a record to the database in a non-UTC time

    - by Shaun
    Is there a way to get Rails to save records to the database without it automagically converting the timestamp into UTC before saving? The problem is that I have a few models that pull data from a legacy database that saves everything in Mountain Time and occasionally I have to have my Rails app write to that database. The problem is that every time it does, it converts the time I give it from Mountain Time to UTC, which is 6-7 hours ahead (depending on DST)! Needless to say, this really messes with reporting on that database. If I could get around doing this, I would. Unfortunately, I can't do anything about the fact that this other database uses a different timezone, nor can I really get away from the need for this app to save to that database occasionally. If I could just get Rails to stop trying to help me, it'd be great.

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  • how to query an embedded entity by using a query builder

    - by user577719
    I've searched quite a time for an answer to this question. Following Codesmell: @Entity public class Person { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) protected Integer id; @Column(nullable = true, length = 50) @Size(max = 50) private String name; @Embedded @Valid protected Adress adress; public void setId(Integer id) { this.id = id; } public Integer getId() { return this.id; } public void setName(String name) { this.name = name; } public void getName() { return this.name; } public void setAdress(Adress adress) { this.adress = adress; } public void getAdress() { return this.adress; } } @Embeddable public class Adress { @Column(nullable = false, length = 50) @Size(max = 50) @NotNull private String place; public void setPlace(String place) { this.place = place; } public void getPlace() { return this.place; } } public class PersonDaoJpa { public List<Ort> findByPerson(final Person person) { CriteriaBuilder builder = this.entityManager.getCriteriaBuilder(); CriteriaQuery<Person> query = builder.createQuery(Person.class); Root<Person> rootPerson = query.from(Person.class); List<Predicate> wherePredicates = new ArrayList<Predicate>(); if (person.getName() != null) { wherePredicates.add( builder.like(builder.lower(rootPerson.<String>get("name")), ort.getName().toLowerCase()) ); } Adresse adresse = ort.getAdresse(); if (adresse != null) { if(adresse.getPlace() != null) { // this won't work wherePredicates.add( builder.like(builder.lower(rootPerson.<String>get("person.adress.place")), adresse.getPlace().toLowerCase()) ); } } Predicate whereClause = builder.and(wherePredicates.toArray(new Predicate[0])); query.where(whereClause); return this.entityManager.createQuery(query).getResultList(); } } How can I access the Adress.place through rootPerson? rootPerson.get("place"), or rootPerson.get("adress.place") won't work...

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  • Ultra-grand super acts_as_tree rails query

    - by Bloudermilk
    Right now I'm dealing with an issue regarding an intense acts_as_tree MySQL query via rails. The model I am querying is Foo. A Foo can belong to any one City, State or Country. My goal is to query Foos based on their location. My locations table is set up like so: I have a table in my database called locations I use a combination of acts_as_tree and polymorphic associations to store each individual location as either a City, State or Country. (This means that my table consists of the rows id, name, parent_id, type) Let's say for instance, I want to query Foos in the state "California". Beside Foos that directly belong to "California", I should get all Foos that belong every City in "California" like Foos in "Los Angeles" and "San Francisco". Not only that, but I should get any Foos that belong to the Country that "California" is in, "United States". I've tried a few things with associations to no avail. I feel like I'm missing some super-helpful Rails-fu here. Any advice?

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  • Question about Benchmark funcion in Mysql ( Incredible results ).

    - by xRobot
    I have 2 tables: author with 3 millions of rows. book with 20 miles rows. . So I have benchmarked this query with a join: SELECT BENCHMARK(100000000, 'SELECT book.title, author.name FROM `book` , `author` WHERE book.id = author.book_id ') And this is the result: Query took 0.7438 sec ONLY 0.7438 seconds for 100 millions of query with a join ??? Do I make some mistakes or this is the right result ?

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  • Why doesn't this CompiledQuery give a performance improvement?

    - by Grammarian
    I am trying to speed up an often used query. Using a CompiledQuery seemed to be the answer. But when I tried the compiled version, there was no difference in performance between the compiled and non-compiled versions. Can someone please tell me why using Queries.FindTradeByTradeTagCompiled is not faster than using Queries.FindTradeByTradeTag? static class Queries { // Pre-compiled query, as per http://msdn.microsoft.com/en-us/library/bb896297 private static readonly Func<MyEntities, int, IQueryable<Trade>> mCompiledFindTradeQuery = CompiledQuery.Compile<MyEntities, int, IQueryable<Trade>>( (entities, tag) => from trade in entities.TradeSet where trade.trade_tag == tag select trade); public static Trade FindTradeByTradeTagCompiled(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = mCompiledFindTradeQuery(entities, tag); return tradeQuery.FirstOrDefault(); } public static Trade FindTradeByTradeTag(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = from trade in entities.TradeSet where trade.trade_tag == tag select trade; return tradeQuery.FirstOrDefault(); } }

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  • SQL Server 2008 database Backup

    - by TaraWalsh
    Hi guys, today I was trying to restore a database with a backup I had made previously on another computer, however I kept getting the following error message: the media loaded on "filepath" is formatted to support 2 media families, but 1 media families are expected according to the device specification I didn't look into it at the time, I just figured it was a bad backup and I'd redo it when I got home. So now I'm trying to do another backup, and I'm getting the above error message for that too. I did backup to a different location at one point, however that no longer exists now. Is there a way i can get passed this error and just do a fresh backup of the database? any pointers would be much appreciated :)

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  • Entity framework 4.0 compiled query with Where() clause issue

    - by Andrey Salnikov
    Hello, I encountered with some strange behavior of System.Data.Objects.CompiledQuery.Compile function - here is my code for compile simple query: private static readonly Func<DataContext, long, Product> productQuery = CompiledQuery.Compile((DataContext ctx, long id) => ctx.Entities.OfType<Data.Product>().Where(p => p.Id == id) .Select(p=>new Product{Id = p.Id}).SingleOrDefault()); where DataContext inherited from ObjectContext and Product is a projection of POCO Data.Product class. My data context in first run contains Data.Product {Id == 1L} and in second Data.Product {Id == 2L}. First using of compilled query productQuery(dataContext, 1L) works perfect - in result I have Product {Id == 1L} but second run productQuery(dataContext, 2L) always returns null, instead of context in second run contains single product with id == 2L. If I remove Where clause I will get correct product (with id == 2L). It seems that first id value caching while first run of productQuery, and therefore all further calls valid only when dataContext contains Data.Product {id==1L}. This issue can't be reproduced if I've used direct query instead of its precompiled version. Also, all tests I've performed on test mdf base using SQL Server 2008 express and Visual studio 2010 final from my ASP.net application.

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  • Visual Studio 2010 Database Project does not understand Schema Names anymore?

    - by Xenan
    I just tried to upgrade a Visual Studio 2008 Database project to VS2010 and actually it is quite a mess. Hundreds of warnings, all unsolved references. It seems to boil down to Visual Studio not to understand Schema Names (aka Ownership) anymore. For example, the standard dbo schema: [$(MyDataBase)].dbo.MyTable is fine but: [$(MyDataBase)].myschema.MyTable gives an unsolved reference. It did work in VS2008. Also the abbreviation for dbo, the double dot: [$(MyDataBase)]..MyTable Doesn't work anymore. In the project property windows I restored the references to the correct servers (which were lost after the conversion) but that didn't help. This seems pretty basic but I don't have a clue how to solve this. Any help is appreciated.

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  • Help converting subquery to query with joins

    - by Tim
    I'm stuck on a query with a join. The client's site is running mysql4, so a subquery isn't an option. My attempts to rewrite using a join aren't going too well. I need to select all of the contractors listed in the contractors table who are not in the contractors2label table with a given label ID & county ID. Yet, they might be listed in contractors2label with other label and county IDs. Table: contractors cID (primary, autonumber) company (varchar) ...etc... Table: contractors2label cID labelID countyID psID This query with a subquery works: SELECT company, contractors.cID FROM contractors WHERE contractors.complete = 1 AND contractors.archived = 0 AND contractors.cID NOT IN ( SELECT contractors2label.cID FROM contractors2label WHERE labelID <> 1 AND countyID <> 1 ) I thought this query with a join would be the equivalent, but it returns no results. A manual scan of the data shows I should get 34 rows, which is what the subquery above returns. SELECT company, contractors.cID FROM contractors LEFT OUTER JOIN contractors2label ON contractors.cID = contractors2label.cID WHERE contractors.complete = 1 AND contractors.archived = 0 AND contractors2label.labelID <> 1 AND contractors2label.countyID <> 1 AND contractors2label.cID IS NULL

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  • Searching for online database software/cms

    - by ButterdBread
    I am searching for a software or CMS that manages and displays large online databases, as some kind of frontend to MySQL or any other database. It should be accessible through the browser, be as secure as possible (offering login). The data I'd like to store would be personal information such as name, adress and birthday - also I'd need to be able to add custom fields as well. Also forms and the possibility to download the data in an excel? table would be great. PHPmyadmin is not an option, it should be similar to a CRM but more closely adapted to managing database tables, searching for entries and filtering data. It should be possible to have many user accounts with different rights, with each of them being able to acces certain parts of the data and entering own data. Is there something out there, that might get close to what I imagine? I appreciate any help!

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