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  • What's the "best" database for embedded?

    - by mawg
    I'm an embedded guy, not a database guy. I've been asked to redesign an existing system which has bottlenecks in several places. The embedded device is based around an ARM 9 processor running at 220mHz. There should be a database of 50k entries (may increase to 250k) each with 1k of data (max 8 filed). That's approximate - I can try to get more precise figures if necessary. They are currently using SqlLite 2 and planning to move to SqlLite 3. Without starting a flame war - I am a complete d/b newbie just seeking advice - is that the "best" decision? I realize that this might be a "how long is a piece of string?" question, but any pointers woudl be greatly welcomed. I don't mind doing a lot of reading & research, but just hoped that you could get me off to a flying start. Thanks. p.s Again, a total rewrite, might not even stick with embedded Linux, but switch to eCos, don't worry too much about one time conversion between d/b formats. Oh, and accesses should be infrequent, at most one every few seconds. edit: ok, it seems they have 30k entries (may reach 100k or more) of only 5 or 6 fields each, but at least 3 of them can be a search key for a record. They are toying with "having no d/b at all, since the data are so simple", but it seems to me that with multiple keys, we couldn't use fancy stuff like a quicksort() type search (recursive, binary search). Any thoughts on "no d/b", just data-structures? Btw, one key is 800k - not sure how well SqlLite handles that (maybe with "no d/b" I have to hash that 800k to something smaller?)

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  • Database Design Question regaurding duplicate information.

    - by galford13x
    I have a database that contains a history of product sales. For example the following table CREATE TABLE SalesHistoryTable ( OrderID, // Order Number Unique to all orders ProductID, // Product ID can be used as a Key to look up product info in another table Price, // Price of the product per unit at the time of the order Quantity, // quantity of the product for the order Total, // total cost of the order for the product. (Price * Quantity) Date, // Date of the order StoreID, // The store that created the Order PRIMARY KEY(OrderID)); The table will eventually have millions of transactions. From this, profiles can be created for products in different geographical regions (based on the StoreID). Creating these profiles can be very time consuming as a database query. For example. SELECT ProductID, StoreID, SUM(Total) AS Total, SUM(Quantity) QTY, SUM(Total)/SUM(Quantity) AS AvgPrice FROM SalesHistoryTable GROUP BY ProductID, StoreID; The above query could be used to get the Information based on products for any particular store. You could then determine which store has sold the most, has made the most money, and on average sells for the most/least. This would be very costly to use as a normal query run anytime. What are some design descisions in order to allow these types of queries to run faster assuming storage size isn’t an issue. For example, I could create another Table with duplicate information. Store ID (Key), Product ID, TotalCost, QTY, AvgPrice And provide a trigger so that when a new order is received, the entry for that store is updated in a new table. The cost for the update is almost nothing. What should be considered when given the above scenario?

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  • Saving Abstract and Sub classes to database

    - by bretddog
    Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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  • Database design: Calculating the Account Balance

    - by 001
    How do I design the database to calculate the account balance? 1) Currently I calculate the account balance from the transaction table In my transaction table I have "description" and "amount" etc.. I would then add up all "amount" values and that would work out the user's account balance. I showed this to my friend and he said that is not a good solution, when my database grows its going to slow down???? He said I should create separate table to store the calculated account balance. If did this, I will have to maintain two tables, and its risky, the account balance table could go out of sync. Any suggestion? EDIT: OPTION 2: should I add an extra column to my transaction tables "Balance". now I do not need to go through many rows of data to perform my calculation. Example John buys $100 credit, he debt $60, he then adds $200 credit. Amount $100, Balance $100. Amount -$60, Balance $40. Amount $200, Balance $240.

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  • 10 Steps to access Oracle stored procedures from Crystal Reports

    Requirements to access Oracle stored procedures from CR The following requirements must be met in order for CR to access an Oracle stored procedure: 1. You must create a package that defines the REF CURSOR. This REF CURSOR must be strongly bound to a static pre-defined structure (see Strongly Bound REF CURSORs vs Weakly Bound REF CURSORs). This package must be created separately and before the creation of the stored procedure. NOTE Crystal Reports 9 native connections will support Oracle stored procedures created within packages as well as Oracle stored procedures referencing weakly bound REF CURSORs. Crystal Reports 8.5 native connections will support Oracle stored procedures referencing weakly bound REF CURSORs. 2. The procedure must have a parameter that is a REF CURSOR type. This is because CR uses this parameter to access and define the result set that the stored procedure returns. 3. The REF CURSOR parameter must be defined as IN OUT (read/write mode). After the procedure has opened and assigned a query to the REF CURSOR, CR will perform a FETCH call for every row from the query's result. This is why the parameter must be defined as IN OUT. 4. Parameters can only be input (IN) parameters. CR is not designed to work with OUT parameters. 5. The REF CURSOR variable must be opened and assigned its query within the procedure. 6. The stored procedure can only return one record set. The structure of this record set must not change, based on parameters. 7. The stored procedure cannot call another stored procedure. 8. If using an ODBC driver, it must be the CR Oracle ODBC driver (installed by CR). Other Oracle ODBC drivers (installed by Microsoft or Oracle) may not function correctly. 9. If you are using the CR ODBC driver, you must ensure that in the ODBC Driver Configuration setup, under the Advanced Tab, the option 'Procedure Return Results' is checked ON. 10. If you are using the native Oracle driver and using hard-coded date selection within the procedure, the date selection must use either a string representation format of 'YYYY-DD-MM' (i.e. WHERE DATEFIELD = '1999-01-01') or the TO_DATE function with the same format specified (i.e. WHERE DATEFIELD = TO_DATE ('1999-01-01','YYYY-MM-DD'). For more information, refer to kbase article C2008023. 11. Most importantly, this stored procedure must execute successfully in Oracle's SQL*Plus utility. If all of these conditions are met, you must next ensure you are using the appropriate database driver. Please refer to the sections in this white paper for a list of acceptable database drivers. span.fullpost {display:none;}

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  • 10 Steps to access Oracle stored procedures from Crystal Reports

    Requirements to access Oracle stored procedures from CR The following requirements must be met in order for CR to access an Oracle stored procedure: 1. You must create a package that defines the REF CURSOR. This REF CURSOR must be strongly bound to a static pre-defined structure (see Strongly Bound REF CURSORs vs Weakly Bound REF CURSORs). This package must be created separately and before the creation of the stored procedure. NOTE Crystal Reports 9 native connections will support Oracle stored procedures created within packages as well as Oracle stored procedures referencing weakly bound REF CURSORs. Crystal Reports 8.5 native connections will support Oracle stored procedures referencing weakly bound REF CURSORs. 2. The procedure must have a parameter that is a REF CURSOR type. This is because CR uses this parameter to access and define the result set that the stored procedure returns. 3. The REF CURSOR parameter must be defined as IN OUT (read/write mode). After the procedure has opened and assigned a query to the REF CURSOR, CR will perform a FETCH call for every row from the query's result. This is why the parameter must be defined as IN OUT. 4. Parameters can only be input (IN) parameters. CR is not designed to work with OUT parameters. 5. The REF CURSOR variable must be opened and assigned its query within the procedure. 6. The stored procedure can only return one record set. The structure of this record set must not change, based on parameters. 7. The stored procedure cannot call another stored procedure. 8. If using an ODBC driver, it must be the CR Oracle ODBC driver (installed by CR). Other Oracle ODBC drivers (installed by Microsoft or Oracle) may not function correctly. 9. If you are using the CR ODBC driver, you must ensure that in the ODBC Driver Configuration setup, under the Advanced Tab, the option 'Procedure Return Results' is checked ON. 10. If you are using the native Oracle driver and using hard-coded date selection within the procedure, the date selection must use either a string representation format of 'YYYY-DD-MM' (i.e. WHERE DATEFIELD = '1999-01-01') or the TO_DATE function with the same format specified (i.e. WHERE DATEFIELD = TO_DATE ('1999-01-01','YYYY-MM-DD'). For more information, refer to kbase article C2008023. 11. Most importantly, this stored procedure must execute successfully in Oracle's SQL*Plus utility. If all of these conditions are met, you must next ensure you are using the appropriate database driver. Please refer to the sections in this white paper for a list of acceptable database drivers. span.fullpost {display:none;}

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  • Access ADP - For/Against?

    - by webworm
    I have been tasked with taking an Access 97 application and moving the back-end data to SQL Server while moving the front end to Access 2003 (using Access Data Projects). In the process of this migration the back-end data structures will be changed significantly to support new functionality. If I had my wish we would not be using Access as the front end. I think our application would be much better served by WinForms, WPF, or a web application. We have the time needed to properly plan a business logic layer and implement an excellent solution but powers above me want to stay with Access because that is what they are familiar with. What I could use help with is pros/cons of continuing down this path of Access development. What are some legitimate arguments for and against using Access 2003? Here is what I have come up with so far. Pro Access: Already own Access 2003 licenses Easy GUI development Reports look nice Against Access Having to use VBA (Visual Basic for Applications) ADO vs DAO. Didn't Microsoft change things from Access 2002 to Access 2003? Not tied to Access runtime Choice in front end (WPF, WinForms, even ASP.NET) Maintainability True separation of logic from UI not possible Does Microsoft still support Access ADP? Perhaps there are other issues I am not aware off both for and against Access for application development. I am trying to keep an open mind while at the same time trying to maintain my sanity. I have been using C# since .NET was released and the thought of going back to VBA for six months makes my head hurt. Especially when I feel I could offer so much more if allowed to develop with modern languages and tools?

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  • Struggling to create correct relationships in MS Access

    - by Yandawl
    http://img714.imageshack.us/img714/7820/croppercapture1.png Basically: an award(course) has many units, which can be either optional or core(mandatory), depending on the award. So for example: the unit 'Advanced Software Engineering' maybe a core unit for the award 'Software Engineering BSc' but only an optional unit for the course 'Web Technology BSc'. I've used flags for that purpose. A student is enrolled on an award so I need to get a complete list of core and optional units (bearing in mind that a student chooses 1 out of many possible optional units). Also, these units have events, e.g, a lecture, workshop or seminar, etc. and those events have sessions or instances of events where students enrolled on that particular unit are required to attend, and those attendances are stored in a separate table to form a register. So I need a hierarchy of expanding the tables something like this I guess: Awards - Students - Units - Sessions - Attendances Any help with this would be appreciated... It's blowing my mind and I'm really close to going insane! My tutor didn't spot I'd got it wrong when I showed my original data model to him and it's due in next week! Thank you :D

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  • How can I display images on a MS Access 2007+ form with a hyperlink source?

    - by Yaaqov
    I am looking improve the efficiency of an Access 2010 database by using a web server with images and only storing the hyperlink source (i.e, http://www.images.com/images/image1.jpg) in the table. I know that one can save images as "attachements", using a "blob" object type, but when you're dealing with thousands of images, queries are bogged down, and performance suffers. So in short, is there are relatively simple way of displaying images on MS Access forms with a source that is a hyperlink address (storing files locally and using filepaths is not preferable). Thanks.

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  • build a Database from Ms Word list information...

    - by Jayron Soares
    Please someone can advise me how to approach a given problem: I have a sequential list of metadata in a document in MS Word. The basic idea is create a python algorithm to iterate over of the information, retrieving just the name of PROCESS, when is made a queue, from a database. for example. Process: Process Walker (1965) Exact reference: Walker Process Equipment., nc. v. Food Machinery Corp.. Link: http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=US&vol=382&invol= Type of procedure: Certiorari To The United States Court of Appeals for the SeventhCircuit. Parties: Walker Process Equipment, Inc. Sector: Systems is … Start Date: October 12-13 Arguedas, 1965 Summary: Food Machinery Company has initiated a process to stop or slow the entry of competitors through the use of a patent obtained by fraud. The case concerned a patenton "knee ction swing diffusers" used in aeration equipment for sewage treatment systems, and the question was whether "the maintenance and enforcement of a patent obtained by fraud before the patent office" may be a basis for antitrust punishment. Report of the evolution process: petitioner, in answer to respond .. Importance: a) First case which established an analysis for the diagnosis of dispute… There are about 200 pages containing the information above. I have in mind the idea of creating an algorithm in python to be able to break this information sequenced and try to store them in a web database[open source application that I’m looking for] in order to allow for free consultations ...

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  • Announcing: Oracle Enterprise Manager 12c Delivers Advanced Self-Service Automation for Oracle Database 12c Multitenant

    - by Scott McNeil
    New Self-Service Driven Provisioning of Pluggable Databases Today Oracle announced new capabilities that support managing the full lifecycle of pluggable database as a service in Oracle Enterprise Manager 12c Release 3 (12.1.0.3). This latest release builds on the existing capabilities to provide advanced automation for deploying database as a service using Oracle Database 12c Multitenant option. It takes it one step further by offering pluggable database as a service through Oracle Enterprise Manager 12c self-service portal providing customers with fast provisioning of database cloud services with minimal time and effort. This is a significant addition to Oracle Enterprise Manager 12c’s existing portfolio of cloud services that includes infrastructure as a service, database as a service, testing as a service, and Java platform as a service. The solution provides a self-service mechanism to provision pluggable databases allowing users to request and access database(s) on-demand. The self-service operations are also enabled through REST APIs allowing customers to integrate with third-party automation systems or their custom enterprise portals. Benefits Self-service provisioning allows rapid access to pluggable database as a service for hosting or certifying applications on Oracle Database 12c Self-service driven migration to pluggable database as a service in order to migrate a pre-Oracle Database 12c database to a pluggable database as a service model and test the consolidation strategy Single service catalog for all approved pluggable database as a service configurations which helps customers achieve standardization while catering to all applications and users in the enterprise Resource guarantee via database resource manager (and IORM on Oracle Exadata) that enables deployment of mixed workloads in a shared environment Quota, role based access, and policy based management that enforces governance and reduces administrative overhead Chargeback or showback which improves metering and accountability for services consumed by each pluggable database Comprehensive REST APIs that support integration with ticketing or change management systems, and or with other self-service portals Minimal administrative and maintenance overhead through self-managing automation that allows for intelligent placement of pluggable databases To understand how pluggable database as a service works, watch this quick demo: Stay Connected: Twitter | Facebook | YouTube | Linkedin | Newsletter Download the Oracle Enterprise Manager Cloud Control12c Mobile app

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  • Handling changes to data types and entries in a database migration

    - by jandjorgensen
    I'm fully redesigning a site that indexes a number of articles with basic search functionality. The previous site was written about a decade ago, and I'm salvaging about 30,000 entries with data stored in less-than-ideal formats. While I'm moving from MSSQL to MySQL, I don't need to make any "live" changes, so this is not a production-level migration issue so much as a redesign. For instance, dates are stored the same as tags/subjects about the articles, but in strings as "YYYYMMDDd" (the lowercase d stands for "date" in the string). Essentially, before or after I move from the previous database format to a new one, I'm going to need to do a lot of replacement of individual entries. While I understand how to do operations with regular expressions in non-database issues, my database experience isn't robust enough to know the best way to handle this. What is the best (or standard) way to handle major changes like this? Is there an SQL operation I should be looking into? Please let me know if the problem isn't clear--I'm not entirely sure what kind of answer I'm looking for.

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  • Staying OO and Testable while working with a database

    - by Adam Backstrom
    What are some OOP strategies for working with a database but keeping thing testable? Say I have a User class and my production environment works against MySQL. I see a couple possible approaches, shown here using PHP: Pass in a $data_source with interfaces for load() and save(), to abstract the backend source of data. When testing, pass a different data store. $user = new User( $mysql_data_source ); $user-load( 'bob' ); $user-setNickname( 'Robby' ); $user-save(); Use a factory that accesses the database and passes the result row to User's constructor. When testing, manually generate the $row parameter, or mock the object in UserFactory::$data_source. (How might I save changes to the record?) class UserFactory { static $data_source; public static function fetch( $username ) { $row = self::$data_source->get( [params] ); $user = new User( $row ); return $user; } } I have Design Patterns and Clean Code here next to me, but I'm struggling to find applicable concepts.

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  • Android Card Game Database for Deck Building

    - by Singularity222
    I am making a card game for Android where a player can choose from a selection of cards to build a deck that would contain around 60 cards. Currently, I have the entire database of cards created that the user can browse. The next step is allowing the user to select cards and create a deck with whatever cards they would like. I have a form where the user can search for specific cards based off a few different attributes. The search results are displayed in a List Activity. My thought about deck creation is to add the primary key of each card the user selects to a SQLite Database table with the amount they would like in the deck. This way as the user performs searches for cards they can see the state of the deck. Once the user decides to save the deck. I'll export the card list to XML and wipe the contents of the table. If the user wanted to make changes to the deck, they would load it, it would be parsed back into the table so they could make the changes. A similar situation would occur when the eventually load the deck to play a game. I'm just curious what the rest of you may think of this method. Currently, this is a personal project and I am the only one working on it. If I can figure out the best implementation before I even begin coding I'm hoping to save myself some time and trouble.

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  • Looking to create website that can have custom GUI and database per user

    - by riley3131
    I have developed an MS Access database for a company to track data in regards to production of a certain commodity. It has many many tables, forms, reports, etc. These were all done as the user requested, and resemble the users previously used system, mostly printed worksheets and excel workbooks. This has created a central location for all information and has allowed the company to compare data in a new way. I am now looking to do this for other companies, but would like to switch it to a web application. Here is my question. What is the best way to create unique solutions for individual companies that can have around 100 users each? I would love to create one site that would serve all parties, but that would ruin the customizable nature of what I am developing. I love the ability to create reports, excel sheets, pdf, graphs, etc with access, but am tired of relying on my customers software, servers, etc. I have some experience with WAMP, but I am far better at VBA. I was okay at PHP, and was getting a grasp on JavaScript a few years back. I am also trying to decide whether to go with WAMP or LAMP, if web is the best choice. Also, should I try set up one site for all users that after log-in goes to company specific pages, or individual sites for each company? Should I host or use a service?

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  • Choosing the Database Solution for Large Data Application

    - by GµårÐïåñ
    I have been tasked to write an application that will be a combination of document and inventory management in VB.net which will be used to store document images in TIFF, PDF, XPS, TXT, DOC, PPT and so on as binary data that can be retrieved for viewing, printing, and possible OCR to be searchable as well along with meta data such as sender, recipient, type of document, date, source, etc. So the table would probably be something like: DOC_NAME, DOC_DATE, NOTES, ... DOC_BINARY (where the actual document will be put inside) What my concern is finding a database solution that will not become unstable due to size restrictions, records limitations and performance. Some of the options are MS_SQL, SQL Express, SQLite, mySQL, and Access. Now I can pretty much eliminate Access right off the bat as it is just too limiting and not scalable. I can further eliminate SQL Express because of the 2 GB limit and again scalability. So that leaves me with MS_SQL, SQLite and mySQL (although if anyone has other options they think would be good as well, please feel free to share them, by no means am I set on these only). So this brings me to what you guys think is the best option for what I have described. The goal is that the data is all in one place (a single file) that will make backup and portability easier. For small volume usage, pretty much any solution will hold for a while, but my goal is to think ahead and make sure its able to withstand heavy large volume usage as well. Another consideration is also the interoperability with .NET and stability of such code to avoid errors and memory leaks. Your feedback would be greatly appreciated.

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  • How to quickly search through a very large list of strings / records on a database

    - by Giorgio
    I have the following problem: I have a database containing more than 2 million records. Each record has a string field X and I want to display a list of records for which field X contains a certain string. Each record is about 500 bytes in size. To make it more concrete: in the GUI of my application I have a text field where I can enter a string. Above the text field I have a table displaying the (first N, e.g. 100) records that match the string in the text field. When I type or delete one character in the text field, the table content must be updated on the fly. I wonder if there is an efficient way of doing this using appropriate index structures and / or caching. As explained above, I only want to display the first N items that match the query. Therefore, for N small enough, it should not be a big issue loading the matching items from the database. Besides, caching items in main memory can make retrieval faster. I think the main problem is how to find the matching items quickly, given the pattern string. Can I rely on some DBMS facilities, or do I have to build some in-memory index myself? Any ideas? EDIT I have run a first experiment. I have split the records into different text files (at most 200 records per file) and put the files in different directories (I used the content of one data field to determine the directory tree). I end up with about 50000 files in about 40000 directories. I have then run Lucene to index the files. Searching for a string with the Lucene demo program is pretty fast. Splitting and indexing took a few minutes: this is totally acceptable for me because it is a static data set that I want to query. The next step is to integrate Lucene in the main program and use the hits returned by Lucene to load the relevant records into main memory.

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  • Database migrations for SQL Server

    - by Art
    I need a database migration framework for 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 SQL Server 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.

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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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  • 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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  • 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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