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  • Storing Preferences/One-to-One Relationships in Database

    - by LnDCobra
    What is the best way to store settings for certain objects in my database? Method one: Using a single table Table: Company {CompanyID, CompanyName, AutoEmail, AutoEmailAddress, AutoPrint, AutoPrintPrinter} Method two: Using two tables Table Company {CompanyID, COmpanyName} Table2 CompanySettings{CompanyID, utoEmail, AutoEmailAddress, AutoPrint, AutoPrintPrinter}

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  • Database migrations for MS SQL Server

    - by Art
    I need a database migration framework for MS SQL Server, capable of managing both schema changes and data migrations. I guess I am looking for something similar to django's South framework here. given the fact that South is tightly coupled with django's ORM, and the fact that there's so many ORMs for MS SQL I guess having just a generic migration framework, enabling you to write and execute in controlled and sequential manner SQL data/schema change scripts should be sufficient. Thanks!

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  • What is a columnar database?

    - by Raj More
    I have been working with warehousing for a while now. I am intrigued by Columnar Databases and the speed that they have to offer for data retrievals. I have multi-part question: How do Columnar Databases work? How do they differ from relational databases? Is there a trial version of a columnar database I can install to play around? (I am on Windows 7)

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  • Best books for SQL Server / database design.

    - by ioannis
    I have some really good books for SQL Server, like: SQL Server 2008 Bible Pro SQL Server 2008 - Relational Database Design and Implementation SQL Server 2008 for Developers. Can you suggest/recommend some other titles, that may address other topics perhaps, that you found truly useful?

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  • Database Table of Boolean Values

    - by guazz
    What's the best method of storing a large number of booleans in a database table? Should I create a column for each boolean value or is there a more optimal method? Employee Table IsHardWorking IsEfficient IsCrazy IsOverworked IsUnderpaid ...etc.

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  • Database design for heavy timed data logging

    - by user293995
    Hi, I have an application where I receive each data 40.000 rows. I have 5 million rows to handle (500 Mb MySQL 5.0 database). Actually, thoses rows are stored in the same table = slow to update, hard to backup, ... Which king of scheme is used in such application to allow long term accessibility to the datas without problems with too big tables, easy backup, fast read / write ? Is postgresql better than mysql for such purpose ? Thanks in advance BEst regards

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  • Good tool to visualise database schema?

    - by Mat
    Are there any good tools for visualising a pre-existing database schema? I'm using MySQL if it matters. I'm currently using MySQL Workbench to process an SQL create script dump, but it's clunky, slow and a manual process to drag all the tables about (which would be okay if it wasn't so slow).

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  • internal implementation of database Queries

    - by harigm
    In my experience I have used many queries like select, order by, where clause etc.. in mysql, sql-server, oracle etc For a moment i have thought, 1)how is this internally written to implement the above queries 2) which language do they use? 3) is that programming language? if yes which language? 4)what kind of environment required to implement this kind of complex database

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  • MultiOS "Jet Database" for C++/Qt?

    - by Airjoe
    Hopefully I can articulate this well: I'm porting an application I made years ago from VB6 (I know, I know!) to C++/Qt. In my original application, one thing I liked was that I didn't need an actual SQL server running, I could just use MS Access .mdb files. I was wondering if something similar exists for Qt that will work on multiple OSes - a database stored in a file, pretty much, but that I can still run SQL queries with. Not sure if something like this exists or not, but any help appreciated, thanks!

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  • (database design):Which tables should be created for all kindes files (images, attached email files,

    - by meyosef
    Hi, I new in database design: I have question with my own few solution,what do you thinks?: Which tables should be created for all kinds files (images, attached email files,text files for store email body, etc..) that stored in my online store? *option 1:use seperate table for files types * files{ id files_types_id FK file_path file_extension } files_types{ id type_name (unique) } *option 2: use bool field for each file type * files{ id file_path file_extension is_image_main is_image_icon is_image_logo is_pdf_file is_text_file } **option 3: use 1 enum field 'file_type' for each file type ** files{ id file_path file_extension file_type (image_main,image_icon,image_logo,image_main,pdf,text) **enum** } Thanks you, Yosef

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  • Database Owner Conundrum

    - by Johnm
    Have you ever restored a database from a production environment on Server A into a development environment on Server B and had some items, such as Service Broker, mysteriously cease functioning? You might want to consider reviewing the database owner property of the database. The Scenario Recently, I was developing some messaging functionality that utilized the Service Broker feature of SQL Server in a development environment. Within the instance of the development environment resided two databases: One was a restored version of a production database that we will call "RestoreDB". The second database was a brand new database that has yet to exist in the production environment that we will call "DevDB". The goal is to setup a communication path between RestoreDB and DevDB that will later be implemented into the production database. After implementing all of the Service Broker objects that are required to communicate within a database as well as between two databases on the same instance I found myself a bit confounded. My testing was showing that the communication was successful when it was occurring internally within DevDB; but the communication between RestoreDB and DevDB did not appear to be working. Profiler to the rescue After carefully reviewing my code for any misspellings, missing commas or any other minor items that might be a syntactical cause of failure, I decided to launch Profiler to aid in the troubleshooting. After simulating the cross database messaging, I noticed the following error appearing in Profiler: An exception occurred while enqueueing a message in the target queue. Error: 33009, State: 2. The database owner SID recorded in the master database differs from the database owner SID recorded in database '[Database Name Here]'. You should correct this situation by resetting the owner of database '[Database Name Here]' using the ALTER AUTHORIZATION statement. Now, this error message is a helpful one. Not only does it identify the issue in plain language, it also provides a potential solution. An execution of the following query that utilizes the catalog view sys.transmission_queue revealed the same error message for each communication attempt: SELECT     * FROM        sys.transmission_queue; Seeing the situation as a learning opportunity I dove a bit deeper. Reviewing the database properties  The owner of a specific database can be easily viewed by right-clicking the database in SQL Server Management Studio and selecting the "properties" option. The owner is listed on the "General" page of the properties screen. In my scenario, the database in the production server was created by Frank the DBA; therefore his server login appeared as the owner: "ServerName\Frank". While this is interesting information, it certainly doesn't tell me much in regard to the SID (security identifier) and its existence, or lack thereof, in the master database as the error suggested. I pulled together the following query to gather more interesting information: SELECT     a.name     , a.owner_sid     , b.sid     , b.name     , b.type_desc FROM        master.sys.databases a     LEFT OUTER JOIN master.sys.server_principals b         ON a.owner_sid = b.sid WHERE     a.name not in ('master','tempdb','model','msdb'); This query also helped identify how many other user databases in the instance were experiencing the same issue. In this scenario, I saw that there were no matching SIDs in server_principals to the owner SID for my database. What login should be used as the database owner instead of Frank's? The system stored procedure sp_helplogins will provide a list of the valid logins that can be used. Here is an example of its use, revealing all available logins: EXEC sp_helplogins;  Fixing a hole The error message stated that the recommended solution was to execute the ALTER AUTHORIZATION statement. The full statement for this scenario would appear as follows: ALTER AUTHORIZATION ON DATABASE:: [Database Name Here] TO [Login Name]; Another option is to execute the following statement using the sp_changedbowner system stored procedure; but please keep in mind that this stored procedure has been deprecated and will likely disappear in future versions of SQL Server: EXEC dbo.sp_changedbowner @loginname = [Login Name]; .And They Lived Happily Ever After Upon changing the database owner to an existing login and simulating the inner and cross database messaging the errors have ceased. More importantly, all messages sent through this feature now successfully complete their journey. I have added the ownership change to my restoration script for the development environment.

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  • Save object using variable with object name

    - by FBE
    I'm wondering what an easy way is to save an object in R, using a variable objectName with the name of the object to be saved. I want this to easy save objects, with their name in the file name. I tried to use get, but I didn't manage to save the object with it's original object name. Example: If I have the object called "temp", which I want to save in the directory "dataDir". I put the name of the object in the variable "objectName". Attempt 1: objectName<-"temp" save(get(objectName), file=paste(dataDir, objectName, ".RData", sep="")) load(paste(dataDir, objectName, ".RData", sep="")) This didn't work, because R tries to save an object called get(objectName), instead of the result of this call. So I tried the following: Attempt 2: objectName<-"temp" object<-get(objectName) save(object, file=paste(dataDir, objectName, ".RData", sep="")) load(paste(dataDir, objectName, ".RData", sep="")) This obviously didn't work, because R saves the object with name "object", and not with name "temp". After loading I have a copy of "object", instead of "temp". (Yes, with the same contents...but that is not what I want :) ). So I thought it should be something with pointers. So tried the following: Attempt 3: objectName<-"temp" object<<-get(objectName) save(object, file=paste(dataDir, objectName, ".RData", sep="")) load(paste(dataDir, objectName, ".RData", sep="")) Same result as attempt 2. But I'm not sure I'm doing what I think I'm doing. What is the solution for this?

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  • Database - Designing an "Events" Table

    - by Alix Axel
    After reading the tips from this great Nettuts+ article I've come up with a table schema that would separate highly volatile data from other tables subjected to heavy reads and at the same time lower the number of tables needed in the whole database schema, however I'm not sure if this is a good idea since it doesn't follow the rules of normalization and I would like to hear your advice, here is the general idea: I've four types of users modeled in a Class Table Inheritance structure, in the main "user" table I store data common to all the users (id, username, password, several flags, ...) along with some TIMESTAMP fields (date_created, date_updated, date_activated, date_lastLogin, ...). To quote the tip #16 from the Nettuts+ article mentioned above: Example 2: You have a “last_login” field in your table. It updates every time a user logs in to the website. But every update on a table causes the query cache for that table to be flushed. You can put that field into another table to keep updates to your users table to a minimum. Now it gets even trickier, I need to keep track of some user statistics like how many unique times a user profile was seen how many unique times a ad from a specific type of user was clicked how many unique times a post from a specific type of user was seen and so on... In my fully normalized database this adds up to about 8 to 10 additional tables, it's not a lot but I would like to keep things simple if I could, so I've come up with the following "events" table: |------|----------------|----------------|--------------|-----------| | ID | TABLE | EVENT | DATE | IP | |------|----------------|----------------|--------------|-----------| | 1 | user | login | 201004190030 | 127.0.0.1 | |------|----------------|----------------|--------------|-----------| | 1 | user | login | 201004190230 | 127.0.0.1 | |------|----------------|----------------|--------------|-----------| | 2 | user | created | 201004190031 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 2 | user | activated | 201004190234 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 2 | user | approved | 201004190930 | 217.0.0.1 | |------|----------------|----------------|--------------|-----------| | 2 | user | login | 201004191200 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | created | 201004191230 | 127.0.0.1 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | impressed | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 15 | user_ads | clicked | 201004191231 | 127.0.0.2 | |------|----------------|----------------|--------------|-----------| | 2 | user | blocked | 201004200319 | 217.0.0.1 | |------|----------------|----------------|--------------|-----------| | 2 | user | deleted | 201004200320 | 217.0.0.1 | |------|----------------|----------------|--------------|-----------| Basically the ID refers to the primary key (id) field in the TABLE table, I believe the rest should be pretty straightforward. One thing that I've come to like in this design is that I can keep track of all the user logins instead of just the last one, and thus generate some interesting metrics with that data. Due to the nature of the events table I also thought of making some optimizations, such as: #9: Since there is only a finite number of tables and a finite (and predetermined) number of events, the TABLE and EVENTS columns could be setup as ENUMs instead of VARCHARs to save some space. #14: Store IPs as UNSIGNED INT with INET_ATON() instead of VARCHARs. Store DATEs as TIMESTAMPs instead of DATETIMEs. Use the ARCHIVE (or the CSV?) engine instead of InnoDB / MyISAM. Overall, each event would only consume 14 bytes which is okay for my traffic I guess. Pros: Ability to store more detailed data (such as logins). No need to design (and code for) almost a dozen additional tables (dates and statistics). Reduces a few columns per table and keeps volatile data separated. Cons: Non-relational (still not as bad as EAV): SELECT * FROM events WHERE id = 2 AND table = 'user' ORDER BY date DESC(); 6 bytes overhead per event (ID, TABLE and EVENT). I'm more inclined to go with this approach since the pros seem to far outweigh the cons, but I'm still a little bit reluctant.. Am I missing something? What are your thoughts on this? Thanks!

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  • Service-Oriented Architecture and Web Services

    Service oriented architecture is an architectural model for developing distributed systems across a network or the Internet. The main goal of this model is to create a collection of sub-systems to function as one unified system. This approach allows applications to work within the context of a client server relationship much like a web browser would interact with a web server. In this relationship a client application can request an action to be performed on a server application and are returned to the requesting client. It is important to note that primary implementation of service oriented architecture is through the use of web services. Web services are exposed components of a remote application over a network. Typically web services communicate over the HTTP and HTTPS protocols which are also the standard protocol for accessing web pages on the Internet.  These exposed components are self-contained and are self-describing.  Due to web services independence, they can be called by any application as long as it can be accessed via the network.  Web services allow for a lot of flexibility when connecting two distinct systems because the service works independently from the client. In this case a web services built with Java in a UNIX environment not will have problems handling request from a C# application in a windows environment. This is because these systems are communicating over an open protocol allowed by both environments. Additionally web services can be found by using UDDI. References: Colan, M. (2004). Service-Oriented Architecture expands the vision of web services, Part 1. Retrieved on August 21, 2011 from http://www.ibm.com/developerworks/library/ws-soaintro/index.html W3Schools.com. (2011). Web Services Introduction - What is Web Services. Retrieved on August 21, 2011 from http://www.w3schools.com/webservices/ws_intro.asp

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  • Does command/query separation apply to a method that creates an object and returns its ID?

    - by Gilles
    Let's pretend we have a service that calls a business process. This process will call on the data layer to create an object of type A in the database. Afterwards we need to call again on another class of the data layer to create an instance of type B in the database. We need to pass some information about A for a foreign key. In the first method we create an object (modify state) and return it's ID (query) in a single method. In the second method we have two methods, one (createA) for the save and the other (getId) for the query. public void FirstMethod(Info info) { var id = firstRepository.createA(info); secondRepository.createB(id); } public void SecondMethod(Info info) { firstRepository.createA(info); var key = firstRepository.getID(info); secondRepository.createB(key); } From my understanding the second method follows command query separation more fully. But I find it wasteful and counter-intuitive to query the database to get the object we have just created. How do you reconcile CQS with such a scenario? Does only the second method follow CQS and if so is it preferable to use it in this case?

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  • How can I design my classes to include calendar events stored in a database?

    - by Gianluca78
    I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine. At this moment, I have two classes: a class "Calendar" and a class "CalendarCell". Here you are the two classes properties and method declarations. class Calendar { private $month; private $monthName; private $year; private $calendarCellList = array(); private $translator; public function __construct($month, $year, $translator) {} public function getCalendarCellList() {} public function getMonth() {} public function getMonthName() {} public function getNextMonth() {} public function getNextYear() {} public function getPreviousMonth() {} public function getPreviousYear() {} public function getYear() {} private function calculateDaysPreviousMonth() {} private function calculateNumericDayOfTheFirstDayOfTheWeek() {} private function isCurrentDay(\DateTime $dateTime) {} private function isDifferentMonth(\DateTime $dateTime) {} } class CalendarCell { private $day; private $month; private $dayNameAbbreviation; private $numericDayOfTheWeek; private $isCurrentDay; private $isDifferentMonth; private $translator; public function __construct(array $parameters) {} public function getDay() {} public function getMonth() {} public function getDayNameAbbreviation() {} public function isCurrentDay() {} public function isDifferentMonth() {} } Each calendar day can includes many calendar events (such as appointments or schedules) stored in a database. My question is: which is the best way to manage these calendar events in my classes? I think to add a eventList property in CalendarCell and populate it with an array of CalendarEvent objects fetched by the database. This kind of solution doesn't allow other coders to reuse the classes without db (because I should inject at least a repository services also) just to create and visualize a calendar... so maybe it could be better to extend CalendarCell (for instance in CalendarCellEvent) and add the database features? I feel like I'm missing some crucial design pattern! Any suggestion will be very appreciated!

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  • How can I design my classes for a calendar based on database events?

    - by Gianluca78
    I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine. At this moment, I have two classes: a class "Calendar" and a class "CalendarCell". Here you are the two classes properties and method declarations. class Calendar { private $month; private $monthName; private $year; private $calendarCellList = array(); private $translator; public function __construct($month, $year, $translator) {} public function getCalendarCells() {} public function getMonth() {} public function getMonthName() {} public function getNextMonth() {} public function getNextYear() {} public function getPreviousMonth() {} public function getPreviousYear() {} public function getYear() {} private function calculateDaysPreviousMonth() {} private function calculateNumericDayOfTheFirstDayOfTheWeek() {} private function isCurrentDay(\DateTime $dateTime) {} private function isDifferentMonth(\DateTime $dateTime) {} } class CalendarCell { private $day; private $month; private $dayNameAbbreviation; private $numericDayOfTheWeek; private $isCurrentDay; private $isDifferentMonth; private $translator; public function __construct(array $parameters) {} public function getDay() {} public function getMonth() {} public function getDayNameAbbreviation() {} public function isCurrentDay() {} public function isDifferentMonth() {} } Each calendar day can includes many events stored in a database. My question is: which is the best way to manage these events in my classes? I think to add a eventList property in CalendarCell and populate it with an array of CalendarEvent objects fetched by the database. This kind of solution doesn't allow other coders to reuse the classes without db (because I should inject at least a repository services also) just to create and visualize a calendar... so maybe it could be better to extend CalendarCell (for instance in CalendarCellEvent) and add the database features? I feel like I'm missing some crucial design pattern! Any suggestion will be very appreciated!

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  • If an entity is composed, is it still a god object?

    - by Telastyn
    I am working on a system to configure hardware. Unfortunately, there is tons of variety in the hardware, which means there's a wide variety of capabilities and configurations depending on what specific hardware the software connects to. To deal with this, we're using a Component Based Entity design where the "hardware" class itself is a very thin container for components that are composed at runtime based on what capabilities/configuration are available. This works great, and the design itself has worked well elsewhere (particularly in games). The problem is that all this software does is configure the hardware. As such, almost all of the code is a component of the hardware instance. While the consumer only ever works against the strongly typed interfaces for the components, it could be argued that the class that represents an instance of the hardware is a God Object. If you want to do anything to/with the hardware, you query an interface and work with it. So, even if the components of an object are modular and decoupled well, is their container a God Object and the downsides associated with the anti-pattern?

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  • Ha a hutés nem elég a gépteremben: Sun Cooling Door a Database Machine-hoz

    - by Fekete Zoltán
    A Database Machine hatalmas teljesítménye miatt általában jóval kevesebb hutésre van szükség, mintha egy külön high-end servert és külön high-end storage-ot hutenénk! Ha viszont a géptermünk maradék hutési kapacitása nem elegendo, és nem elégszünk meg a "hagyományos mosóporral", akkor újabb hutési trükkre van szükség. Erre kínálnak megoldást a Sun Cooling Door modellek, például az 5200-as és az 5600-as modellek.

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