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• MySQL dual license behavior

  - by jromero

  Hi SO, I'm running a commercial(closed source) Web App development for the first time. Initially I considered MySQL the most feasible option for a DB, until I get quite confused about its dual license behavior. If I want a commercial application do I still can use the GPL version of MySQL or I must get a license? The same question in a different way: If I use MySQL's GPL version does that force me to license the whole app under GPL? Either case I would go with PostgreSQL, I just want to make really really sure about this. Even in SO I've seen related("duplicates") questions but never a clear answer... All other tools I'm gonna use to code the project are licensed under BSD or MIT. Just in case, the role of MySQL in the project is merely as relational DB to store persistent data and query it. I'd really appreciate if someone can clarify this for me. Regards, thanks in advanced.

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• Should I use Perl or PHP or something else for this project?

  - by Clinton

  I'm about to embark on a project that will need to: Process XML Heavy text parsing of non-xml documents Insertion of data from xml and non-xml documents into a relational DB. Present processed data to user from db using webpages. The website will be subject to short periods of very heavy loads to pages (300+ visitors a minute for several minutes), but most of the time will be idle (a dozen or so visitors a minute). The ability to cache or scale to load will be very nice. I have a very strong background in Java and web services, but I do not want to use Java for this project as I'd like to diversify my skill set. Which language would you recommend and what are some pros and cons that you might recognize from your own experiences?

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• What is the most efficient way to store a mapping "key -> event stream"?

  - by jkff

  Suppose there are ~10,000's of keys, where each key corresponds to a stream of events. I'd like to support the following operations: push(key, timestamp, event) - pushes event to the event queue for key, marked with the given timestamp. It is guaranteed that event timestamps for a particular key are pushed in sorted or almost sorted order. tail(key, timestamp) - get all events for key since the given timestamp. Usually the timestamp requests for a given key are almost monotonically increasing, almost synchronously with pushes for the same key. This stuff has to be persistent (although it is not absolutely necessary to persist pushes immediately and to keep tails with pushes strictly in sync), so I'm going to use some kind of database. What is the optimal kind of database structure for this task? Would it be better to use a relational database, a key-value storage, or something else?

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• What format do I use to store a relatively small amount of user data

  - by wcm

  I am writing a small program for our local high school (pro bono). The program has an interface allows the user to enter school holidays. This is a simple stand alone Windows app. What format should I use to store the data? A big relational data is obviously overkill. My initial plan was to store the data in an XML file. Co-workers have been suggesting that I use JSON files, Access Databases, SQL Lite, and SQL Server Express. There was even a suggestion of old school INI files.

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• Java: JPA classes, refactoring from Date to DateTime

  - by bguiz

  With a table created using this SQL Create Table X ( ID varchar(4) Not Null, XDATE date ); and an entity class defined like so @Entity @Table(name = "X") public class X implements Serializable { @Id @Basic(optional = false) @Column(name = "ID", nullable = false, length = 4) private String id; @Column(name = "XDATE") @Temporal(TemporalType.DATE) private Date xDate; //java.util.Date ... } With the above, I can use JPA to achieve object relational mapping. However, the xDate attribute can only store dates, e.g. dd/MM/yyyy. How do I refactor the above to store a full date object using just one field, i.e. dd/MM/yyyy HH24:mm?

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• Strategy in storing ad-hoc numbers/constants?

  - by Jiho Han

  I have a need to store a number of ad-hoc figures and constants for calculation. These numbers change periodically but they are different type of values. One might be a balance, a money amount, another might be an interest rate, and yet another might be a ratio of some kind. These numbers are then used in a calculation that involve other more structured figures. I'm not certain what the best way to store these in a relational DB is - that's the choice of storage for the app. One way, I've done before, is to create a very generic table that stores the values as text. I might store the data type along with it but the consumer knows what type it is so, in situations I didn't even need to store the data type. This kind of works fine but I am not very fond of the solution. Should I break down each of the numbers into specific categories and create tables that way? For example, create Rates table, and Balances table, etc.?

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• Are there any e-commerce websites that use NoSQL databases

  - by Saif Bechan

  I have read a lot lately about 'NoSQL' databases such as CouchDB, MongoDB etc. Most of the websites I have seen using this are mainly text based websites such as The New York Times and Source forge. I was wondering if you could apply this to websites where payment is a huge issue. I am thinking of the following issues: How well can you secure the data Do these system provide an easy backup/restore machanism How are transactions handled commit/rollback I have read the following articles that cover some aspects: Can I do transactions and locks in CouchDB? Pros/Cons of document based database vs relational database In these posts the aspect of transactions if covered. However the questions of security and backups is not covered. Can someone shed some light on this subject? And if possible, does anyone know of some e-commerce websites that have successfully implemented the document based database.

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• What JavaScript framework to choose? JQuery+JQueryUI, Dojo or ExtJS?

  - by Ivan

  I am choosing a JavaScript Framework to master and use extensively in all my future projects (mostly working with relational DATA, web services via AJAX and implementing complex rich client UIs). Now I am choosing between JQuery+JQueryUI, Dojo and ExtJS. What should I choose? 1st priority is power and functionality, 2nd priority is beauty and maintainability of code and ease of use, 3rd priority is flexibility and modularity, 4th priority is speed and size. IE compatibility hardly matters, I'd like it to be modern, legacy-free and standard-conformant.

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• What goes between SQL Server and Client?

  - by worlds-apart89

  This question is an updated version of a previous question I have asked on here. I am new to client-server model with SQL Server as the relational database. I have read that public access to SQL Server is not secure. If direct access to the database is not a good practice, then what kind of layer should be placed between the server and the client? Note that I have a desktop application that will serve as the client and a remote SQL Server database that will provide data to the client. The client will input their username and password in order to see their data. I have heard of terms like VPN, ISA, TMG, Terminal Services, proxy server, and so on. I need a fast and secure n-tier architecture. P.S. I have heard of web services in front of the database. Can I use WCF to retrieve, update, insert data? Would it be a good approach in terms of security and performance?

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• What's a better choice for SQL-backed number crunching - Ruby 1.9, Python 2, Python 3, or PHP 5.3?

  - by Ivan

  Crterias of 'better': fast im math and simple (little of fields, many records) db transactions, convenient to develop/read/extend, flexible, connectible. The task is to use a common web development scripting language to process and calculate long time series and multidimensional surfaces (mostly selectint/inserting sets of floats and dong maths with rhem). The choice is Ruby 1.9, Python 2, Python 3, PHP 5.3, Perl 5.12, JavaScript (node.js). All the data is to be stored in a relational database (due to its heavily multidimensional nature), all the communication with outer world is to be done by means of web services.

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• PHP or C# script to parse CSV table values to fill in one-to-many table

  - by Yaaqov

  I'm looking for an example of how to split-out comma-delimited data in a field of one table, and fill in a second table with those individual elements, in order to make a one-to-many relational database schema. This is probably really simple, but let me give an example: I'll start with everything in one table, Widgets, which has a "state" field to contain states that have that widget: Table: WIDGET =============================== | id | unit | states | =============================== |1 | abc | AL,AK,CA | ------------------------------- |2 | lmn | VA,NC,SC,GA,FL | ------------------------------- |3 | xyz | KY | =============================== Now, what I'd like to create via code is a second table to be joined to WIDGET called *Widget_ST* that has widget id, widget state id, and widget state name fields, for example Table: WIDGET_ST ============================== | w_id | w_st_id | w_st_name | ------------------------------ |1 | 1 | AL | |1 | 2 | AK | |1 | 3 | CA | |2 | 1 | VA | |2 | 2 | NC | |2 | 1 | SC | |2 | 2 | GA | |2 | 1 | FL | |3 | 1 | KY | ============================== I am learning C# and PHP, so responses in either language would be great. Thanks.

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• Efficient persistent storage for simple id to table of values map for java

  - by wds

  I need to store some data that follows the simple pattern of mapping an "id" to a full table (with multiple rows) of several columns (i.e. some integer values [u, v, w]). The size of one of these tables would be a couple of KB. Basically what I need is to store a persistent cache of some intermediary results. This could quite easily be implemented as simple sql, but there's a couple of problems, namely I need to compress the size of this structure on disk as much as possible. (because of amount of values I'm storing) Also, it's not transactional, I just need to write once and simply read the contents of the entire table, so a relational DB isn't actually a very good fit. I was wondering if anyone had any good suggestions? For some reason I can't seem to come up with something decent atm. Especially something with an API in java would be nice.

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• The conceptual process of populating related tables in a database (MySql) from a CSV file

  - by user322772

  I'm new to relational databases and all the material I've read covered primary and foreign keys, normal forms, and joins but left out to populate the database once it's created. How do you import a CSV file so the fields match their related table? Say you were tying to build a beer database and had a CSV file with each line as a record. Header: brewer, beer_name, country, city, state, beer_category, beer_type, alcohol_content Record 1: Anheuser-Busch, Budweiser, United States, St. Louis, Mo, Pale lager, Regular, 5.0% Record 2: Anheuser-Busch, Bud Light, United States, St. Louis, Mo, Pale lager Light, 4.2% Record 3: Miller Brewing Company, Miller Lite, United States, Milwaukee, WI, Pale lager, Light, 4.2% You can create a "Brewer" table and a "Beer" table. When importing how does you connect the primary keys between the tables?

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• Remove a certain value from string which keeps on changing

  - by user2971375

  I m trying to make a utility to generate a Insert script of sql tables along with relational table. I got all the values in c#. Now I want to remove the one column name and its value from the script.most probably the identity column. Eg. The string I have (which keeps on changing with table name and varies) INSERT Core.Customers ([customerId],[customername],[customeradress],[ordernumber]) Values(123,N'Rahul',N'244 LIZ MORN',2334) NOW I know I have to remove CustomerId. (sometimes need to be replaces with @somevariable) Please give me an efficient way how to retrieve customerId value and Deleting column name and value . Conditions: insert script length and columns names keep changing. Method should return the deleted value. At some point of time customer id can be same as order id. In that case my string.remove method fails.

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• What to read as a good intro and quickstart to aspect-oriented programming and metaprogramming?

  - by Ivan

  As I've found myself repeating myself a lot, writing very similar queries and classes for different entities (despite of doing strong object and relational normalisation), etc, I've came to an Idea that I could and should automate the most of this and write an engine which will compile simple declarative models I specify into all the code limiting my job to describe the task and and finally just customise the result as needed. As far as I know this is about metaprogramming and aspect-oriented programming. How do I get acquainted with modern tools available quickly so that I don't invent one more bicycle developing my own?

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• Entity framework and database logic.

  - by Xavier Devian

  Hi all, i have a question that's being around for several years. As all you know entity framework is an ORM tool that tries to model the database to an object oriented access model. All the samples I've seen are quering directly to the database tables. So, which is the role of the views in the database now?. The views were used to model the database in a more friendly way, that is, several physical tables, one logic table. This was great for example in hidding the complex relational model on stored procedures as queryng the views inside them was much easier than reproducing the query joins over and over on each stored procedure. So the question is, why is entity framework so good if stored procedures can not take benefit of it?

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• What mail storage should I choose for our web application; IMAP, key-valud store, rdbms, ...

  - by tvrtko

  I have to store e-mail messages for use with our application. I have "metadata" for all messages inside a relational database, but I don't feel comfortable keeping message content (gigabytes and terabytes of email data) inside a database. I'm currently using IMAP as a storage, but I have my doubts if I choose correctly. First of all there is a problem of uidvalidity and how to keep a permanent reference to message inside IMAP. Second, I'm not sure if this is the most robust solution in terms of backup/restore strategies, corruption of store, replication ... Positive side is that I can query IMAP using the headers because the data is mostly indexed. I don't know if key-value stores are a better approach (Casandra, Tokyo cabinet, redis). How they handle storing 1KB and 50MB of data. How they prevent corruption and when corruption or device failure happens how can I repair the store.

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• Pros and cons of sorting data in DB?

  - by Roman

  Let's assume I have a table with field of type VARCHAR. And I need to get data from that table sorted alphabetically by that field. What is the best way (for performance): add sort by field to the SQL-query or sort the data when it's already fetched? I'm using Java (with Hibernate), but I can't tell anything about DB engine. It could be any popular relational database (like MySQL or MS Sql Server or Oracle or HSQL DB or any other). The amount of records in table can vary greatly but let's assume there are 5k records.

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• Can I expose MySQL data using PHP and OData?

  - by user359796

  As I understand it, OData is just a standardized way to expose relational data RESTfully. If I've got a PHP application, it should be able to process those RESTful requests and manipulate a MySQL database based on the request data and then return an ATOM feed. First, are the preceeding statements correct? Second, does a PHP library to do this already exist or would I have to create my own? If I have completely misunderstood these technologies and my question doesn't make sense, please feel free to let me know.

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• Making OR/M loosely coupled and abstracted away from other layers.

  - by Genuine

  Hi all. In an n-tier architecture, the best place to put an object-relational mapping (OR/M) code is in the data access layer. For example, database queries and updates can be delegated to a tool like NHibernate. Yet, I'd like to keep all references to NHibernate within the data access layer and abstract dependencies away from the layers below or above it. That way, I can swap or plug in another OR/M tool (e.g. Entity Framework) or some approach (e.g. plain vanilla stored procedure calls, mock objects) without causing compile-time errors or a major overhaul of the entire application. Testability is an added bonus. Could someone please suggest a wrapper (i.e. an interface or base class) or approach that would keep OR/M loosely coupled and contained in 1 layer? Or point me to resources that would help? Thanks.

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• Windows Phone7 Development: Selecting target SDK(OS) version

  - by JibW

  I am a bit confusing in selecting the target version in Windows phone7 Application development. In my Windows phone7 app I need to use a light weight relational DB Which didn't introduce with version 7.0 but SQL CE with 7.1 version. The problem is if I select the target version as 7.1, then the devices which came up with windows phone7 OS 7.0 will not be able to install this. But I heard that all the devices that came with windows phone7 OS version 7.0 is upgradable for windows OS version 7.1 for free. If this is the case then if I select the development SDK version as 7.1, then will all the windows phone7 devices be able to install this? Like to know which will be the best Target version in this case to select, before I start developing. Any guidance/ Idea is highly appreciated. Thanks...

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• Has anyone used an object database with a large amount of data?

  - by Jon Kruger

  Object databases like MongoDB and db4o are getting lots of pub lately. Everyone that plays with them seems to love it. I'm guessing that they are dealing with about 640K of data in their sample apps. Has anyone tried to use an object database with a large amount of data (say, 50GB or more)? Are you able to still execute complex queries against it (like from a search screen)? How does it compare to your usual relational database of choice? I'm just curious. I want to take the object database plunge, but I need to know if it'll work on something more than a sample app.

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• What are some "mental steps" a developer must take to begin moving from SQL to NO-SQL (CouchDB, Fath

  - by Byron Sommardahl

  I have my mind firmly wrapped around relational databases and how to code efficiently against them. Most of my experience is with MySQL and SQL. I like many of the things I'm hearing about document-based databases, especially when someone in a recent podcast mentioned huge performance benefits. So, if I'm going to go down that road, what are some of the mental steps I must take to shift from SQL to NO-SQL? If it makes any difference in your answer, I'm a C# developer primarily (today, anyhow). I'm used to ORM's like EF and Linq to SQL. Before ORMs, I rolled my own objects with generics and datareaders. Maybe that matters, maybe it doesn't. Here are some more specific: How do I need to think about joins? How will I query without a SELECT statement? What happens to my existing stored objects when I add a property in my code? (feel free to add questions of your own here)

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• SaaS Multi-tenancy Applications: How is data import/export/backup being implemented?

  - by Mark Redman

  How are applications providing import / export (or backups) of data in SaaS based multi-tenancy applications, particularly single database designs? Imports: Keeping things simple I think basic imports are useful, ie CSV to a spec (or a way of providing a mapping between CSV columns and fields in the database. Exports: In single database designs I have seen XML exports and HTML (basic sitse generated) exports of data? I would assume that XML is a better option? How does one cater for relational data? Would you reference various things within XML and provide documentation of the relationships or let users figurethis out? Are vendors providing an export/backup that can be imported back in/restored? Your comments appreciated.

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• Zip Code to City/State and vice-versa in a database?

  - by Simucal

  I'm new to SQL and relational databases and I have what I would imagine is a common problem. I'm making a website and when each user submits a post they have to provide a location in either a zip code or a City/State. What is the best practice for handling this? Do I simply create a Zip Code and City and State table and query against them or are there ready made solutions for handling this? I'm using SQL Server 2005 if it makes a difference. I need to be able to retrieve a zip code given a city/state or I need to be able to spit out the city state given a zip code.

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