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• Database structure - is mySQL the right choice?

  - by Industrial

  Hi everyone, We are currently planning the database structure of a quite complex e-commerce web app that has flexibility as it's main cornerstone. Our app features a large amount of data (products) and we have run into a slight headache trying to keep performance high without compromizing normalization rules in the database, or leaving our highly beloved flexibility concept behind when integrating product options (also widely known as product attributes or parameters). Based on various references and sources available, we have made up lists on pros and cons of all major and well known database patterns to solve this. After comparing these, we have come up with two final alternatives: EAV (Entity-attribute-value model) : Pros: Database is used for all sorting. Cons: All related queries will include a number of joins between multiple tables in order to complete the collection of data. SLOB (Serialized LOB, also known as Facade?) : Pros: Very flexible. Keeping the number of necessary joins low compared to a EAV design pattern. Easy to update/add/remove data from each product. Cons: All sorting will be done by the application instead of the database. Will use lots of performance (memory?) when big datasets is processed by a large number of users. Our main questions: Which pattern/structure would you use, or maybe even a different solution? Is there better databases besides mySQL available nowadays to accomplish what we want? Thanks a lot! Reference: http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters

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• Video learning for database design

  - by donpal

  I'm trying to learn good relational database design (using mysql and php if that makes any difference). I've already done some database work, so I'm not totally clueless, but I suspect that my solutions may not have adhered to best practices for efficient searching, optimization, etc. Can someone suggest a good set of videos on the topic? If you know something is superb or has really made a difference in your own learning, please post your suggestion. Prefer videos, but books (as long as they're not too huge) are ok too. But prefer videos. Thank you

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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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• Process for beginning a Ruby on Rails project

  - by Daniel Beardsley

  I'm about to begin a Ruby on Rails project and I'd love to hear how others go through the process of starting an application design. I have quite a bit of experience with RoR, but don't have that many starting from scratch with only a vision experiences and would appreciate the wisdom of others who've been there. I'm looking for an order of events, reasons for the order, and maybe why each part is important. I can think of a few starting points, but I'm not sure where it's best to begin Model design and relationships (entities, how they relate, and their attributes) Think of user use-cases (or story-boards) and implement the minimum to get these done Create Model unit-tests then create the necessary migrations and AR models to get the tests to pass Hack out the most basic version of the simplest part of your application and go from there Start with a template for a rails app (like http://github.com/thoughtbot/suspenders) Do the boring gruntwork first (User auth, session management, ...) ...

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• DB design : save different details of payment (credit or check)

  - by haim evgi

  my question is: i have a member that can pay in 3 different way credit card check transfer from bank account how design the table that contain the history of payment. the fields of every way is different . if i save all in one table , i have lot of blank field ? what the right way to deal it ?

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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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• C# Design Reduce a Long List of Methods

  - by guazz

  I have a simple application that loads data from an XML file to a database. public class EmployeeLoader() { public void LoadEmpoyees() {...} public void LoadSalaries() {...} public void LoadRegistrationData() {...} public void LoadTaxData() {...} } Is it a good idea to have multiple "Load" methods as this looks like a code smell as I have about tweney Load methods? If so, how do I make my code more readable? Each Load method loads data to the corresponding table in the database via a repository?

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• basic database design table on rails

  - by runcode

  I am confuse on a concept. I am doing this on rails. Is that Entity set equal to a table in the database? Is that Relationship set equal to a table in the database? Let say we have Entity set "USER" and Entity set "POST" and Entity set "COMMENT" User- can post many posts and comments as they want Post- belong to users Comments-belong to posts ,users, so comment is weak entity. SCHEMA ====== USER -id -name POST -id -user_id(FK) -comment_id (FK) COMMENT -id -user_id (FK) -post_id (FK) so USER,POST,COMMENT are tables I think. And what else is a table? And do I need a table for the relationship??

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• Updating access 2000 database through code in VB6

  - by Mark

  I have an application that uses an access 2000 database currently in distribution. I need to update one of the recordsets with additional fields on my customer's computers. My data controls work fine as I have them set to connect in access 2000 format but when I try to open the database in code, I get an unrecognized data format error. What is the best way to replace or add to the database on their machines? Any help is greatly appreciated.

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• Formatting data from management database

  - by bVector

  I've got some data that goes like this: Config_Name Question Answer Cisco WAN Sensitivity: High Cisco WAN Authorized Users: Brent, Charles Cisco WAN Last Audited: n/a Cisco WAN Next Audit: 3/30/2012 Cisco WAN Audit Signature: Cisco WAN Username: MYCOMPANY Cisco WAN Password: Cisco WAN Encrypted-A ENCRYPTED DATA Cisco WAN Encrypted-B Cisco WAN Encrypted-C vCenter server Sensitivity: High vCenter server Authorized Users: Brent, Charles vCenter server Last Audited: vCenter server Next Audit: 3/30/2012 vCenter server Audit Signature: ENCRYPTED DATA vCenter server Username: administrator vCenter server Password: vCenter server Encrypted-A ENCRYPTED DATA vCenter server Encrypted-B vCenter server Encrypted-C AKSC-NE01 IPMI Sensitivity: High AKSC-NE01 IPMI Authorized Users: Brent, Charles AKSC-NE01 IPMI Last Audited: AKSC-NE01 IPMI Next Audit: 3/30/2012 AKSC-NE01 IPMI Audit Signature: ENCRYPTED DATA AKSC-NE01 IPMI Username: MYCOMPANY AKSC-NE01 IPMI Password: AKSC-NE01 IPMI Encrypted-A ENCRYPTED DATA AKSC-NE01 IPMI Encrypted-B AKSC-NE01 IPMI Encrypted-C and I need it to be in this format: Config_Name Sensitivity: Authorized Users: Last Audited: Next Audit: Audit Signature: Username: Password: Encrypted-A Encrypted-B Encrypted-C AKSC-NE01 IPMI High Brent, Charles 3/30/2012 ENCRYPTED DATA MYCOMPANY ENCRYPTED DATA Cisco ASA5505 WAN High Brent, Charles n/a 3/30/2012 ENCRYPTED DATA MYCOMPANY ENCRYPTED DATA vCenter server High Brent, Charles 3/30/2012 ENCRYPTED DATA administrator ENCRYPTED DATA the tabs get messed up on here but hopefully you get my drift. does anyone know an easy way to do this? I haven't found one with excel just yet.

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• Design practice for securing data inside Azure SQL

  - by Sid

  Update: I'm looking for a specific design practice as we try to build-our-own database encryption. Azure SQL doesn't support many of the encryption features found in SQL Server (Table and Column encryption). We need to store some sensitive information that needs to be encrypted and we've rolled our own using AesCryptoServiceProvider to encrypt/decrypt data to/from the database. This solves the immediate issue (no cleartext in db) but poses other problems like Key rotation (we have to roll our own code for this, walking through the db converting old cipher text into new cipher text) metadata mapping of which tables and which columns are encrypted. This is simple when it's just couple of columns (send an email to all devs/document) but that quickly gets out of hand ... So, what is the best practice for doing application level encryption into a database that doesn't support encryption? In particular, what is a good design to solve the above two bullet points? If you had specific schema additions would love it if you could give details ("Have a NVARCHAR(max) column to store the cipher metadata as JSON" or a SQL script/commands). If someone would like to recommend a library, I'd be happy to stay away from "DIY" too. Before going too deep - I assume there isn't any way I can add encryption support to Azure by creating a stored procedure, right?

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• Why should I use document based database instead of relational database?

  - by Bartosz Blimke

  Why should I use document based database like CouchDB instead of using relational database. Are there any typical kinds of applications or domains where the document based database is more suitable than the relational database?

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• Connect two database from 2 different host

  - by Maggie

  Hi, currently I have two websites: 1. A website connected to mySQL database in host A. 2. A website connected to Ms. Access database in Host B. Is there anyway if I update the database in Host B, the database in Host A can be updated automatically? Thank you. Really appreciate your help.

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• Improvements to Joshua Bloch's Builder Design Pattern?

  - by Jason Fotinatos

  Back in 2007, I read an article about Joshua Blochs take on the "builder pattern" and how it could be modified to improve the overuse of constructors and setters, especially when an object has a large number of properties, most of which are optional. A brief summary of this design pattern is articled here [http://rwhansen.blogspot.com/2007/07/theres-builder-pattern-that-joshua.html]. I liked the idea, and have been using it since. The problem with it, while it is very clean and nice to use from the client perspective, implementing it can be a pain in the bum! There are so many different places in the object where a single property is reference, and thus creating the object, and adding a new property takes a lot of time. So...I had an idea. First, an example object in Joshua Bloch's style: Josh Bloch Style: public class OptionsJoshBlochStyle { private final String option1; private final int option2; // ...other options here <<<< public String getOption1() { return option1; } public int getOption2() { return option2; } public static class Builder { private String option1; private int option2; // other options here <<<<< public Builder option1(String option1) { this.option1 = option1; return this; } public Builder option2(int option2) { this.option2 = option2; return this; } public OptionsJoshBlochStyle build() { return new OptionsJoshBlochStyle(this); } } private OptionsJoshBlochStyle(Builder builder) { this.option1 = builder.option1; this.option2 = builder.option2; // other options here <<<<<< } public static void main(String[] args) { OptionsJoshBlochStyle optionsVariation1 = new OptionsJoshBlochStyle.Builder().option1("firefox").option2(1).build(); OptionsJoshBlochStyle optionsVariation2 = new OptionsJoshBlochStyle.Builder().option1("chrome").option2(2).build(); } } Now my "improved" version: public class Options { // note that these are not final private String option1; private int option2; // ...other options here public String getOption1() { return option1; } public int getOption2() { return option2; } public static class Builder { private final Options options = new Options(); public Builder option1(String option1) { this.options.option1 = option1; return this; } public Builder option2(int option2) { this.options.option2 = option2; return this; } public Options build() { return options; } } private Options() { } public static void main(String[] args) { Options optionsVariation1 = new Options.Builder().option1("firefox").option2(1).build(); Options optionsVariation2 = new Options.Builder().option1("chrome").option2(2).build(); } } As you can see in my "improved version", there are 2 less places in which we need to add code about any addition properties (or options, in this case)! The only negative that I can see is that the instance variables of the outer class are not able to be final. But, the class is still immutable without this. Is there really any downside to this improvement in maintainability? There has to be a reason which he repeated the properties within the nested class that I'm not seeing?

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• Need advice on framework design: how to make extending easy

  - by beginner_

  I'm creating a framework/library for a rather specific use-case (data type). It uses diverse spring components, including spring-data. The library has a set of entity classes properly set up and according service and dao layers. The main work or main benefit of the framework lies in the dao and service layer. Developers using the framework should be able to extend my entity classes to add additional fields they require. Therefore I made dao and service layer generic so it can be used by such extended entity classes. I now face an issue in the IO part of the framework. It must be able to import the according "special data type" into the database. In this part I need to create a new entity instance and hence need the actual class used. My current solution is to configure in spring a bean of the actual class used. The problem with this is that an application using the framework could only use 1 implementation of the entity (the original one from me or exactly 1 subclass but not 2 different classes of the same hierarchy. I'm looking for suggestions / desgins for solving this issue. Any ideas?

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• Android From Local DB (DAO) to Server sync (JSON) - Design issue

  - by Taiko

  I sync data between my local DB and a Server. I'm looking for the cleanest way to modelise all of this. I have a com.something.db package That contains a Data Helper and couple of DAO classes that represents objects stored in the db (I didn't write that part) com.something.db --public DataHelper --public Employee @DatabaseField e.g. "name" will be an actual column name in the DB -name @DatabaseField -salary etc... (all in all 50 fields) I have a com.something.sync package That contains all the implementation detail on how to send data to the server. It boils down to a ConnectionManager that is fed by different classes that implements a 'Request' interface com.something.sync --public interface ConnectionManager --package ConnectionManagerImpl --public interface Request --package LoginRequest --package GetEmployeesRequest My issue is, at some point in the sync process, I have to JSONise and de-JSONise my data (E.g. the Employee class). But I really don't feel like having the same Employee class be responsible for both his JSONisation and his actual representation inside the local database. It really doesn't feel right, because I carefully decoupled the rest, I am only stuck on this JSON thing. What should I do ? Should I write 3 Employee classes ? EmployeeDB @DatabaseField e.g. "name" will be an actual column name in the DB -name @DatabaseField -salary -etc... 50 fields EmployeeInterface -getName -getSalary -etc... 50 fields EmployeeJSON -JSON_KEY_NAME = "name" The JSON key happens to be the same as the table name, but it isn't requirement -name -JSON_KEY_SALARY = "salary" -salary -etc... 50 fields It feels like a lot of duplicates. Is there a common pattern I can use there ?

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• design an extendible and pluggable business logic flow handler in php

  - by Broncha

  I am working on a project where I need to allow a pluggable way to inject business processes in the normal data flow. eg There is an ordering system. The standard flow of the application is A consumer orders an item. Pays for it and card is authorized. Admin captures the payment. Order is marked as complete and item is shipped. But this process may vary (extra steps in between) for different clients. Say a client would need to validate the location of the consumer before he is presented with a credit card form, OR his policies might require some other processes in between. I am thinking of using State Pattern for processing orders, saving the current state of the order in database, and initializing the state of order from the saved state. I would also need some mechanism, where a small plugin would be able to inject business specific states in the state machine. Am I thinking the right way? Are there already implemented patterns for this kind of situation? I am working with Codeigniter and basically this would mean for me, to redirect to proper controller according to the current state of the order. Like, if the state of the order is unconfirmed then redirect the user to details page and then change the state to pending. If some client would need to do some validation, then register an intermediate state between unconfirmed and pending Please suggest.

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• What are good NoSQL and non-relational database solutions for audit/logging database

  - by Juha Syrjälä

  What would be suitable database for following? I am especially interested about your experiences with non-relational NoSQL systems. Are they any good for this kind of usage, which system you have used and would recommend, or should I go with normal relational database (DB2)? I need to gather audit trail/logging type information from bunch of sources to a centralized server where I could generate reports efficiently and examine what is happening in the system. Typically a audit/logging event would consist always of some mandatory fields, for example globally unique id (some how generated by program that generated this event) timestamp event type (i.e. user logged in, error happened etc) some information about source (server1, server2) Additionally the event could contain 0-N key-value pairs, where value might be up to few kilobytes of text. It must run on Linux server It should work with high amount of data (100GB for example) it should support some kind of efficient full text search It should allow concurrent reading and writing It should be flexible to add new event types and add/remove key-value pairs to new events. Flexible=no changes should be required to database schema, application generating the events can just add new event types/new fields as needed. it should be efficient to make queries against database. For reporting and exploring what happened. For example: How many events with type=X occurred in some time period. Get all events where field A has value Y. Get all events with type X and field A has value 1 and field B is not 2 and event occurred in last 24h

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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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• 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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• Database Design for a double entry accounting system

  - by Khou

  Should journal entries be recorded in a database design? In the real world it makes sense to keep a daily entry book, then later transfer the daily entry book into double entry accounts. but in the computerized version, doing this produces duplicate records and that doesn't quite make sense? ???? What i mean is 1) user enter details , it gets recorded (this would be called the journalbook in real life) 2) the software does all the double entry accounting then references the journalbook and splits up the transaction into the double entry accounting system.

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• Domain driven design: Manager and service

  - by ryudice

  I'm creating some business logic in the application but I'm not sure how or where to encapsulate it, I've used the repository pattern for data access, I've seen some projects that use DDD that have some classes with the "Service" suffix and the "manager" suffix, what are each of this clases suppose to take care of in DDD?

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• Database design in blogging systems

  - by Peter

  As a learning exercise I'm trying to put myself a blogging system. The goal is to code something that will let me create multiple blogs, like blogger.com or wordpress.com, but much simplified. I would like to ask you, what do you think is best database design for this type of script. Is it better to have one big table, containing posts from all blogs of all users (like friendfeed) or would it be better to create separate table for each blog's posts? Big thanks in advance for your help, Peter.

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• mysql, sqlite database source code

  - by Yang

  hi guys, i know implementing database is a huge topic, but i want to have a basic understanding of how database systems works (e.g. memory management, binary tree, transaction, sql parsing, multi-threading, partitions, etc) by investigating the source code of the database, since there are a few already proven very robust open source databases like mysql, sqlite and so on. however, the code are very complicated and i have no clue where to start. also i find that the old school database textbooks are only explaining the theory, not the implementation details. Can anyone suggest how should i get started and is there any books that emphasis on the technology and techniques of building dbms used in modern database industry? Thank in advance!

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• Oracle vocabulary, what is the mysql/SQL Server equivalent of a database

  - by jeph perro

  Hi, I need some help with vocabulary, I don't use Oracle that often but I am familiar with MySQL and SQL Server. I have an application I need to upgrade and migrate, and part of the procedure to do that involves exporting to an XML file, allowing the installer to create new database tables, then import to the new database tables from the XML file. In Oracle, my database connection specifies a username, password, and an SID. Let's call the SID, "COMPANY-APPS". This SID contains tables belonging to several applications, each of which connects with a different user ( "WIKIUSER", "BUGUSER", "TIMETRACKERUSER" ). My question is: Can I re-use the same user to create the new tables ( with the same names ). In MySQL or SQL Server, I would create a new database and grant my user privileges to create tables in it. OR, do I need to create a new database user for my upgraded tables?

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