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  • How can I synchronize one set of data with another?

    - by RenderIn
    I have an old database and a new database. The old records were converted to the new database recently. All our old applications continue to point to the old database, but the new applications point to the new database. Currently the old database is the only one being updated, so throughout the day the new database becomes out of sync. It is acceptable for the new database to be out of sync for a day, so until all our applications are pointed to the new database I just need to write a nightly cron job that will bring it up to date. I do not want to purge the new database and run the complete conversion script each night, as that would reduce uptime and would create a mess in our auditing of that table. I'm thinking about selecting all the data from the old database, converting it to the new database structure in memory, and then checking for the existence of each record before inserting it in the new database. After that's done, I'd select everything from the new database and check if it exists in the old one, and if not delete it. Is this the simplest way to do this?

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  • implementing dynamic query handler on historical data

    - by user2390183
    EDIT : Refined question to focus on the core issue Context: I have historical data about property (house) sales collected from various sources in a centralized/cloud data source (assume info collection is handled by a third party) Planning to develop an application to query and retrieve data from this centralized data source Example Queries: Simple : for given XYZ post code, what is average house price for 3 bed room house? Complex: What is estimated price for an house at "DD,Some Street,XYZ Post Code" (worked out from average values of historic data filtered by various characteristics of the house: house post code, no of bed rooms, total area, and other deeper insights like house building type, year of built, features)? In addition to average price, the application should support other property info ** maximum, or minimum price..etc and trend (graph) on a selected property attribute over a period of time**. Hence, the queries should not enforce the search based on a primary key or few fixed fields In other words, queries can be What is the change in 3 Bed Room house price (irrespective of location) over last 30 days? What kind of properties we can get for X price (irrespective of location or house type) The challenge I have is identifying the domain (BI/ Data Analytical or DB Design or DB Query Interface or DW related or something else) this problem (dynamic query on historic data) belong to, so that I can do further exploration My findings so far I could be wrong on the following, so please correct me if you think so I briefly read about BI/Data Analytics - I think it is heavy weight solution for my problem and has scalability issues. DB Design - As I understand RDBMS works well if you know Data model at design time. I am expecting attributes about property or other entity (user) that am going to bring in, would evolve quickly. hence maintenance would be an issue. As I am going to have multiple users executing query at same time, performance would be a bottleneck Other options like Graph DB (http://www.tinkerpop.com/) seems to be bit complex (they are good. but using those tools meant for generic purpose, make me think like assembly programming to solve my problem ) BigData related solution are to analyse data from multiple unrelated domains So, Any suggestion on the space this problem fit in ? (Especially if you have design/implementation experience of back-end for property listing or similar portals)

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  • Sqlite3 : "Database is locked" error

    - by Miraaj
    Hi all, In my cocoa application I am maintaining a SQLite db within resources folder and trying to do some select, delete operations in it but after some time it starts giving me 'Database is locked' error. The methods which I am using for select delete operations are as follows: // method to retrieve data if (sqlite3_open([databasePath UTF8String], &database) != SQLITE_OK) { sqlite3_close(database); NSAssert(0, @"Failed to open database"); } NSLog(@"mailBodyFor:%d andFlag:%d andFlag:%@",UId,x,Ffolder); NSMutableArray *recordsToReturn = [[NSMutableArray alloc] initWithCapacity:2]; NSString *tempMsg; const char *sqlStatementNew; NSLog(@"before switch"); switch (x) { case 9: // tempMsg=[NSString stringWithFormat:@"SELECT * FROM users_messages"]; tempMsg=[NSString stringWithFormat:@"SELECT message,AttachFileOriName as oriFileName,AttachmentFileName as fileName FROM users_messages WHERE id = (select message_id from users_messages_status where id= '%d')",UId]; NSLog(@"mail body query - %@",tempMsg); break; default: break; } sqlStatementNew = [tempMsg cStringUsingEncoding:NSUTF8StringEncoding]; sqlite3_stmt *compiledStatementNew; NSLog(@"before if statement"); if(sqlite3_prepare_v2(database, sqlStatementNew, -1, &compiledStatementNew, NULL) == SQLITE_OK) { NSLog(@"the sql is finalized"); while(sqlite3_step(compiledStatementNew) == SQLITE_ROW) { NSMutableDictionary *recordDict = [[NSMutableDictionary alloc] initWithCapacity:3]; NSString *message; if((char *)sqlite3_column_text(compiledStatementNew, 0)){ message = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatementNew, 0)]; } else{ message = @""; } NSLog(@"message - %@",message); NSString *oriFileName; if((char *)sqlite3_column_text(compiledStatementNew, 1)){ oriFileName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatementNew, 1)]; } else{ oriFileName = @""; } NSLog(@"oriFileName - %@",oriFileName); NSString *fileName; if((char *)sqlite3_column_text(compiledStatementNew, 2)){ fileName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatementNew, 2)]; } else{ fileName = @""; } NSLog(@"fileName - %@",fileName); [recordDict setObject:message forKey:@"message"]; [recordDict setObject:oriFileName forKey:@"oriFileName"]; [recordDict setObject:fileName forKey:@"fileName"]; [recordsToReturn addObject:recordDict]; [recordDict release]; } sqlite3_finalize(compiledStatementNew); sqlite3_close(database); NSLog(@"user messages return -%@",recordsToReturn); return recordsToReturn; } else{ NSLog(@"Error while creating retrieving mailBodyFor in messaging '%s'", sqlite3_errmsg(database)); sqlite3_close(database); } // method to delete data if (sqlite3_open([databasePath UTF8String], &database) != SQLITE_OK) { sqlite3_close(database); NSAssert(0, @"Failed to open database"); } NSString *deleteQuery = [[NSString alloc] initWithFormat:@"delete from users_messages_status where id IN(%@)",ids]; NSLog(@"users_messages_status msg deleteQuery - %@",deleteQuery); sqlite3_stmt *deleteStmnt; const char *sql = [deleteQuery cStringUsingEncoding:NSUTF8StringEncoding]; if(sqlite3_prepare_v2(database, sql, -1, &deleteStmnt, NULL) != SQLITE_OK){ NSLog(@"Error while creating delete statement. '%s'", sqlite3_errmsg(database)); } else{ NSLog(@"successful deletion from users_messages"); } if(SQLITE_DONE != sqlite3_step(deleteStmnt)){ NSLog(@"Error while deleting. '%s'", sqlite3_errmsg(database)); } sqlite3_close(database); Things are going wrong in this sequence Data is retrieved 'Database is locked' error arises on performing delete operation. When I retry to perform 1st step.. it now gives same error. Can anyone suggest me: If I am doing anything wrong or missing some check? Is there any way to unlock it when it gives locked error? Thanks, Miraaj

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  • What is the relation between database books by Ullman et al.?

    - by macias
    A First Course in Database Systems by Jeffrey D. Ullman, Jennifer Widom (Amazon links) Database System Implementation by Hector Garcia-Molina, Jeffrey D. Ullman, Jennifer D. Widom Database Systems: The Complete Book by Hector Garcia-Molina, Jeffrey D. Ullman, Jennifer Widom As far as I know the second one is the second "part" of the first one. But what about the third one -- is it just first+second published in one volume? I would like to buy them, but I don't want to get redundant reading. Thank you in advance for clarification.

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  • Map only certain parts of the class to a database using SQLAlchemy?

    - by Az
    When mapping an object using SQLAlchemy, is there a way to only map certain elements of a class to a database, or does it have to be a 1:1 mapping? Example: class User(object): def __init__(self, name, username, password, year_of_birth): self.name = name self.username = username self.password = password self.year_of_birth = year_of_birth Say, for whatever reason, I only wish to map the name, username and password to the database and leave out the year_of_birth. Is that possible and will this create problems? Edit - 25/03/2010 Additionally, say I want to map username and year_of_birth to a separate database. Will this database and the one above still be connected (via username)?

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  • SO what RDF database do i use for product attribute situation initially i thought about using EAV?

    - by keisimone
    Hi, i have a similar issue as espoused in http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters i am convinced to use RDF now. only because of one of the comments made by Bill Karwin in the answer to the above issue but i already have a database in mysql and the code is in php. 1) So what RDF database should I use? 2) do i combine the approach? meaning i have a class table inheritance in the mysql database and just the weird product attributes in the RDF? I dont think i should move everything to a RDF database since it is only just products and the wide array of possible attributes and value that is giving me the problem. 3) what php resources, articles should i look at that will help me better in the creation of this? 4) more articles or resources that helps me to better understand RDF in the context of the above challenge of building something that will better hold all sorts of products' attributes and values will be greatly appreciated. i tend to work better when i have a conceptual understanding of what is going on. Do bear in mind i am a complete novice to this and my knowledge of programming and database is average at best.

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  • How do I make software that preserves database integrity and correctness?

    - by user287745
    I have made an application project in Visual Studio 2008 C#, SQL Server from Visual Studio 2008. The database has like 20 tables and many fields in each. I have made an interface for adding deleting editing and retrieving data according to predefined needs of the users. Now I have to Make to project into software which I can deliver to my professor. That is, he can just double click the icon and the software simply starts. No Visual Studio 2008 needed to start the debugging. The database will be on one powerful computer (dual core latest everything Windows XP) and the user will access it from another computer connected using LAN. I am able to change the connection string to the shared database using Visual Studio 2008/ debugger whenever the server changes but how am I supposed to do that when it's software? There will by many clients. Am I supposed to give the same software to every one, so they all can connect to the database? How will the integrity and correctness of the database be maintained? I mean the db.mdf file will be in a folder which will be shared with read and write access. So it's not necessary that only one user will write at a time. So is there any coding for this or?

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  • How to use a c# datagridview to update a database file just like Access does?

    - by mackeyka
    I have googled everywhere and I am finally giving up and asking here. I am working in Visual Studio 2010 with C#. I have set up a form with a datagridview connected to a MSSQL database and I need to save changes made in the datagridview back to the physical database. I am having some success but I think that I am going about some of it completely wrong because I can not get it to save consistently. What I really want is for the updates to work just like they do when working with Access. When I edit a row in the datagridview and then leave that row, either by selecting another row or by selecting some other control on the form or even by changing to another form or quitting the application the row should be automatically pdated to the physical database. The first part of this question I think is, what is the proper event to use to trigger the save and then second what methods should be used to actually write the data to the database?

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  • PHP e-commerce site talking to internal database for stock / ordering?

    - by CitrusTree
    Hi. I'm working on an e-commerce site (either bespoke with PHP, or using Drupal/Ubercart), and I'd like to investigate the site interacting with an internal (filemaker) database we use to manage stock and orders. Currently we manually transfer orders from the web site to our own database, and the site does not check or record changes in stock. My plan to allow the 2 to interact is as follows: Make the internal database available externaly on a machine with a fixed IP Allow external access from the site only Connect to the internal database using ODBC (or similar) Use simple queries to check stock / record stock changes / record order details Am I missing something here as this sounds quite straight forward? Is there another solution I should be taking a look at? Thanks in advance for any help or comments.

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  • In Linux, what's the best way to delegate administration responsibilities, like for Apache, a database, or some other application?

    - by Andrew Banks
    In Linux, what's the best way to delegate administration responsibilities for Apache and other "applications"? File permissions? Sudo? A mix of both? Something else? At work we have two tiers of "administrators" Operating system administrators. These are your run-of-the-mill "server administrators." They are responsible for just the operating system. Application administrators. The people who build the web site. This includes not only writing the SQL, PHP, and HTML, but also setting up and running Apache and PostgreSQL or MySQL. The aforementioned OS admins will install this stuff, but it's mainly up to the app admins to edit all the config files, start and stop processes when needed, and so on. I am one of the app admins. This is different than what I am used to. I used to just write code. The sysadmin took care not only of the OS but also installing, setting up, and keeping up the server software. But he left. Now I'm in charge of setting up Apache and the database. The new sysadmins say they just handle the operating system. It's no problem. I welcome learning new stuff. But there is a learning curve, even for the OS admins. Apache, by default, seems to be set up for administration by root directly. All the config files and scripts are 644 and owned by root:root. I'm not given the root password, naturally, so the OS admins must somehow give my ordinary OS user account all the rights necessary to edit Apache's config files, start and stop it, read its log files, and so on. Right now they're using a mix of: (1) giving me certain sudo rights, (2) adding me to certain groups, and (3) changing the file permissions of various directories, to make them writable by one of the groups I'm in. This never goes smoothly. There's always a back-and-forth between me and the sysadmins. They say it's ready. Then I try certain things, and half of them I still can't do. So they make some more changes. Then finally I seem to be independent and can administer Apache and the database without pestering them anymore. It's the sheer complication and amount of changes that make me uncomfortable. Even though it finally works, more or less, it seems hackneyed. I feel like we're doing it wrong. It seems like the makers of the software would have anticipated this scenario (someone other than root administering it) and have a clean two- or three-step program to delegate responsibility to me. But it feels like we are really chewing up the filesystem and making it far and away from the default set-up. Any suggestions? Are we doing it the recommended way? P.S. For PostgreSQL it seems a little better. Its files are owned by a system user named postgres. So giving me the right to run sudo su - postgres gives me just about everything. I'm just now getting into MySQL, but it seems to be set up similarly. But it seems a little weird doing all my work as another user.

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  • What are the best practices for storing PHP session data in a database?

    - by undefined
    I have developed a web application that uses a web server and database hosted by a web host (on the ground) and a server running on Amazon Web Services EC2. Both servers may be used by a user during a session and both will need to know some session information about a user. I don't want to POST the information that is needed by both servers because I dont want it to be visible to browsers / Firebug etc. So I need my session data to persist across servers. And I think that this means that the best option is to store all / some of the data that I need in the database rather than in a session. The easiest thing to do seems to be to keep the sessions but to POST the session_id between servers and use this as the key to lookup the data I need from a 'user_session_data' table in the database. I have looked at Tony Marston's article "Saving PHP Session Data to a database" - should I use this or will a table with the session data that I need and session_id as key suffice? What would be the downside of creating my own table and set of methods for storing the data I need in the database?

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  • Retrieving data from database. Retrieve only when needed or get everything?

    - by RHaguiuda
    I have a simple application to store Contacts. This application uses a simple relational database to store Contact information, like Name, Address and other data fields. While designing it, I question came to my mind: When designing programs that uses databases, should I retrieve all database records and store them in objects in my program, so I have a very fast performance or I should always gather data only when required? Of course, retrieving all data can only be done if it`s not too many, but do you use this approach when you make sure that the database will be small (< 300 records for example)? I have designed once a similar application that fetches data only when needed, but that was slow (using a Access database). Thanks for all help.

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  • How do I make software that preserves database integrity and correctness? Please help, confused.

    - by user287745
    i have made an application project in vs 08 c#, sql server from vs 08. the database has like 20 tables and many fields in each have made an interface for adding deleting editting and retrieving data according to predefined needs of the users. now i have to 1) make to project in to a software which i can deliver to professor. that is he can just double click the icon and the software simply starts. no vs 08 needed to start the debugging 2) the database will be on one powerful computer (dual core latest everything win xp) and the user will access it from another computer connected using LAN i am able to change the connection string to the shared database using vs 08/ debugger whenever the server changes but how am i supposed to do that when its a software? 3)there will by many clients am i supposed to give the same software to every one, so they all can connect to the database, how will the integrity and correctness of the database be maintained? i mean the db.mdf file will be in a folder which will be shared with read and write access. so its not necessary that only one user will write at a time. so is there any coding for this or? please help me out here i am stuck do not know what to do i have no practical experience, would appreciate all the help thank you

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  • How do I put static data into an SQLite database in Android?

    - by sirconnorstack
    If I have a bunch of data that is never going to change (eg. an English language dictionary or the rgb values of a couple hundred color names), how do I use an SQLite database to store it? I know a database is faster than loading everything into memory when the app starts, but how do I make the database either the first time the app runs or "before" the apps ever runs?

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  • Which user account to assign as owner when attaching an SQL Server database?

    - by FreshCode
    This is a simple database security & performance question, but I've always used either a special user (eg. mydbuser), or Windows' built-in NETWORK SECURITY account as the owner when attaching databases to my SQL Server instances. When deploying my database to a production server, is there a specific user I should stick to or avoid? I would think that using an account with a set password could open the database up to a potential security issue.

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  • RSpec setup for an application that depends on an external database from another application.

    - by Chris Rittersdorf
    I've had to add features to an application that depends on a database from another application. I've been able to set up a connection to this external database and pull data from it. However, I'm not sure how to get my main application to create a test database for this external application. It would be awesome if there some way to pull in the schema for this database and create it in the same manner that 'rake db:test:prepare' does. Is there any configuration capabilities for RSpec to do this, or will I have to roll my own task?

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  • How to get stream to "in-memory" database created via H2DB?

    - by Reynevan
    I have to create such a mechanism: Create in-memory (H2DB) database; Create tables and fill them using some data; Get stream to that database; Send that stream via WebDAV or something else; I know everything except that "How to get stream to "in-memory" database created via H2DB"? And some explanations: I can't create file because of some server restrictions; I need that stream to create a file;

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  • Need Insight - What is the best practice for syncing up a production database that will be used on a

    - by james
    I have a site set up using CakePHP and MySQL and I want to work on a test database without disrupting my live site in case something goes wrong. I have another busy site, but my test site runs off the live database which can be occasionally nerve wracking. What do I do if I change a table name in the test db and I want it changed in the live database? Or if I remove a record from the test database. Is there a way to diff the changes? How do I even merge those changes? How does this interfere with live user edits and things of that nature? Hopefully some of you working devs can share some insight!

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  • What is the standard or best way to deal with database branching with Mercurial or Git branches?

    - by Chad Johnson
    This has been a big question mark on my mind. I'm moving to Mercurial or Git very soon for my web software, and sometimes my branches require significant database changes which other branches should not see. This, I can't always share the same database for my branches. Is there some standard way of dealing with database changes for branching and cloning? What do you all do? I'm using MySQL.

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  • Multiple connections to a MySQL database in a single PHP script.

    - by st3
    There are multiple times in one page where I need to connect and subsequently query a MySQL database, yet my code won't let me. I think it might be something to do with how my files are nested but it makes no sense. I am opening the SQL connection in the header file. The top of the offending page looks like the following: <?php $page_title = 'Dashboard'; include('templates/header.inc'); // includes a 'require_once('mysqli_connect.php') and a small query to the database; require_once('includes/functions.php'); require_once('includes/dashboard_sql.php'); // Contains functions which connect to database (which are failing.) ?> I get the PHP error Notice: Undefined variable: dbc in /Library/WebServer/Documents/pediatory_site/includes/dashboard_sql.php Where $dbc is the database connection defined in mysqli_connect.php. If anyone could help me out that would be great.

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  • How to automatically check out a database file in a source controlled web application ?

    - by TheRHCP
    Hello, I am working on an ASP.NET web application, we are a small team (4 students) and we do not have access to a dedicated server to host the database instance. So for this web application we decided just to put the database file in the App_Data folder. The problem is that our project is source controled on TFS, so every time you open the solution and try to launch the web application, we get an expcetion saying that database is read-only. That is logical because the databse file is not automatically checked-out. Is there a workaround to avoid a manual check-out of the database file everytime we open the solution ? Thanks.

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  • Should core application configuration be stored in the database, and if so what should be done to se

    - by Rl
    I'm writing an application around a lot of hierarchical data. Currently the hierarchy is fixed, but it's likely that new items will be added to the hierarchy in the future. (please let them be leaves) My current application and database design is fairly generic and nothing dealing with specific nodes in the hierarchy is hardcoded, with the exception of validation and lookup functions written to retrieve external data from each node's particular database. This pleases me from a design point of view, but I'm nervous at the realization that the entire application rests on a handful of records in the database. I'm also frustrated that I have to enforce certain aspects of data integrity with database triggers rather than by foreign key constraints (an example is where several different nodes in the hierarchy have their own proprietary IDs and I store them in a single column which, when coupled with the node ID can be used to locate the foreign data). I'm starting to wonder whether it may have been appropriate to simply hardcoded these known nodes into the system so that it would be more "type safe" and less generic. How does one know when something should be hardcoded, and when it should be a configuration item? Is it just a cost-benefit analysis of clarity/safety now vs less work later, or am I missing some metric I should be using to determine whether or not this is appropriate. The steps I'm taking to protect these valuable configurations are to add triggers that prevent updates/deletes. The database user that this application uses will only have the ability to manipulate data through stored procedures. What else can I do?

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