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• SQL SERVER – Table Variables and Transactions – SQL in Sixty Seconds #007 – Video

  - by pinaldave

  Today’s SQL in Sixty Seconds video is inspired from my presentation at TechEd India 2012 on Misconception and Resolution. Quite often I have seen people getting confused with certain behavior of the T-SQL. They expect SQL to behave certain way and SQL Server behave differently. This kind of issue often creates confusion and frustration. Sometime I have seen them also confusing it with bug and submitting the bug, where reality is totally different. Similar concept which are going to see today. I have seen quite commonly developer assuming that table various will be rolled back when transaction is rolled back. This sixty seconds video describes that table various are not rolled back when transactions are rolled back. More on Errors: Difference Temp Table and Table Variable – Effect of Transaction Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT Debate – Table Variables vs Temporary Tables – Quiz – Puzzle – 13 of 31 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Video

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• Learning advanced java skills

  - by moe

  I've been programming in java for a while and I really like the language, I've mostly just done game programming, but I want to get a feel for some of the more commonly used api's and frameworks and just get a generally more well-rounded grasp of the language and the common libraries in the current job market. From what I found things like spring, hibernate, and GWT are pretty in demand right now. I looked at some tutorials online and they weren't hard to follow but I really felt like I had no context for what I was learning - I had no idea how any of it would be use in a real work environment. I know nothing can rival the benefit I'd get from actual work experience but that's not an option for me right now, I need another way to learn these technologies in a way where I'll at least feel comfortable working with them and know what I'm doing beyond just understanding what code does what. I checked out a few books but they were all really old(like pre-2006, am I right to assume those books would be kind of out of date today?) or required experience with libraries that I didn't have and can't get. I hate getting stuck looking for the best resource to learn something instead of spending my time actually learning. All I really want is someone to point me to a resource(website or ebook) that is aimed at already experienced java developers and will not only teach me some interesting useful java technology(anything that is useful, I dont know much outside of graphics libraries and game related things so I was thinking some database or web programming api's) but also give me a good perspective of it and leave me feeling confident that I could actually use what I learned on a practical application. If my post makes you think I'm not yet experienced to be learning these things, which I doubted earlier today but am now starting to question, then what do you think is the next step for me? I just want to get better at java. Thanks everyone

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• SQL SERVER – Contest – Summary of 5 Day and Additional Information

  - by pinaldave

    I am overwhelmed with the response of our contest ran earlier this week. Every day we are giving away USD 198 worth give aways to readers in USA and India. If you have not participated so far, I encourage you to participate today itself. Here are links to our 5 day contest. The winner of the contest will be announced on August 20th. Query Hint – Contest Win Joes 2 Pros Combo (USD 198) – Day 1 of 5 Identity Fields – Contest Win Joes 2 Pros Combo (USD 198) – Day 2 of 5 Clustered Index and Primary Key – Contest Win Joes 2 Pros Combo (USD 198) – Day 3 of 5 Expanding Views – Contest Win Joes 2 Pros Combo (USD 198) – Day 4 of 5 Understanding XML – Contest Win Joes 2 Pros Combo (USD 198) – Day 5 of 5 Here are a few important notes related to the contest. A few people asked me what should they do as they have forgotten to mention their country in the response. Please resubmit with correct data, we will only consider latest entry from one person. What if you are not from the USA or India? Participate in the Bonus Quiz. Leave a comment for each of the questions above with your favorite article and you may be eligible for winning something cool. What if I am winner of two contests out of 5 contests? Well, in that case, we will send you one set of Combo Kit and Amazon Gift Card of USD 100 for another contest which you won. Can I exchange my kit with other stuff? No, if you do not want kit, give it to someone who needs it. Btw, I strongly suggest that you participate in the Bonus Quiz. There is something cool for everyone! Reference: Pinal Dave (http://blog.sqlauthority.com)         Filed under: Database, DBA, Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• WordPress page title repeated in SOME pages

  - by cmykrgbb

  I have created a Wordpress site and titles were working just fine. Then, some time and plugins installed later, I noticed that in SOME pages I get the title repeated 2 times. Example of wrong page title: Contact - NAME | NAME Example of normal title: Our Services | NAME Now, if I go to General Settings and change title it will change both, no improvement. SEO by Yoast has the option to reset page titles, but that just removes all titles leaving the current URL as page title, so no good either. Here is the code I originally had: <title><?php wp_title(''); ?><?php if(wp_title('', false)) { echo ' | '; } ?><?php bloginfo('name'); ?></title> Here is the code I am using now: <title><?php wp_title('|'); ?></title> To sum up, I think somewhere in the database there's a wp_title repeated: once using '-' as separator, another one (the current one) using '|'. Any help will be most appreciated, thanks!

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• Proper Data Structure for Commentable Comments

  - by Wesley

  Been struggling with this on an architectural level. I have an object which can be commented on, let's call it a Post. Every post has a unique ID. Now I want to comment on that Post, and I can use ID as a foreign key, and each PostComment has an ItemID field which correlates to the Post. Since each Post has a unique ID, it is very easy to assign "Top Level" comments. When I comment on a comment however, I feel like I now need a PostCommentComment, which attaches to the ID of the PostComment. Since ID's are assigned sequentially, I can no longer simply use ItemID to differentiate where in the tree the comment is assigned. I.E. both a Post and a Post Comment might have an ID of '5', so my foreign key relationship is invalid. This seems like it could go on infinitely, with PostCommentCommentComment's etc... What's the best way to solve this? Should I have a field in the comment called "IsPostComment" or something of the like to know which collection to attach the ID to? This strikes me as the best solution I've seen so far, but now I feel like I need to make recursive DataBase calls which start to get expensive. Meaning, I get a Post and get all PostComments where ItemID == Post.ID && where IsPostComment == true Then I take that as a collection, gather all the ID's of the PostComments, and do another search where ItemID == PostComment[all].ID && where IsPostComment == false, then repeat infinitely. This means I make a call for every layer, and if I'm calling 100 Posts, I might make 1000 DB calls to get 10 layers of comments each. What is the right way to do this?

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• GIS-based data visualization and maintenance tool

  - by Dave Jarvis

  Background Looking to leverage an existing GIS system for exploring organizational data. Architecture The following figure represents a high-level overview of the system's desired features: The most basic usage would be as follows: The user visits a web site. The system presents a map (having regions, cities, and buildings). The user drills-down on the map to a particular building. The system provides a basic CRUD interface. The user can view and modify information about personnel (e.g., their assigned teams), equipment (e.g., network appliances), applications, and the building itself (e.g., contact and phone numbers). Ideally, all the components should be open-source (or otherwise free). Problem This must be a small project that needs a quick (but functional) prototype, mostly to confirm whether or not such a system would be useful in the long term. Questions What software components would you use to quickly develop a working prototype? What open-source solutions already exist, if any? Ideas Here is what I am thinking: PostGIS - Define the regions, cities, and sites Google Maps - Display an interactive, clickable map geoJSON - Protocol between PostGIS and Google Maps Seam - CRUD interface Custom Development For example, this would entail: Installation and configuration Configure SSH for remote logins Subversion (or git) PostgreSQL PostGIS Java Tomcat Seam JasperReports Enter GIS information into PostGIS Aggregate data sources into PostgreSQL database Develop starting page for map interface Develop clickable Google Maps interface Develop summary reports Develop CRUD interface using Seam for data maintenance Surely something like this already exists? Thank you!

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• How should I architect my Model and Data Access layer objects in my website?

  - by Robin Winslow

  I've been tasked with designing Data layer for a website at work, and I am very interested in architecture of code for the best flexibility, maintainability and readability. I am generally acutely aware of the value in completely separating out my actual Models from the Data Access layer, so that the Models are completely naive when it comes to Data Access. And in this case it's particularly useful to do this as the Models may be built from the Database or may be built from a Soap web service. So it seems to me to make sense to have Factories in my data access layer which create Model objects. So here's what I have so far (in my made-up pseudocode): class DataAccess.ProductsFromXml extends DataAccess.ProductFactory {} class DataAccess.ProductsFromDatabase extends DataAccess.ProductFactory {} These then get used in the controller in a fashion similar to the following: var xmlProductCreator = DataAccess.ProductsFromXml(xmlDataProvider); var databaseProductCreator = DataAccess.ProductsFromXml(xmlDataProvider); // Returns array of Product model objects var XmlProducts = databaseProductCreator.Products(); // Returns array of Product model objects var DbProducts = xmlProductCreator.Products(); So my question is, is this a good structure for my Data Access layer? Is it a good idea to use a Factory for building my Model objects from the data? Do you think I've misunderstood something? And are there any general patterns I should read up on for how to write my data access objects to create my Model objects?

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• Tracking state of a one time event on a big website

  - by Mattis

  Assume a website with 250 million active users. I add a new feature to the website. Once a user visits I want to use a short tutorial to teach them how to use said feature. I only want them to complete the tutorial once (or actively click it away). What is the smart way to code the verification check for this? How do I track the progress in the database? Having a separate table with like NewTutorial_completed = 1 for user_id = 21312315 would just snowball. It also feels intuitively bad to check for every one-time event for every user on every page view. While writing the question I got one idea, to have a separate event log that is checked periodically for any new action the user need to see or perform. I push events to this log and once they are completed they are removed from the log. No need to store NewTutorial_completed = 1-type variables this way. I am sure this is a common problem. I would appreciate any input on what best practice is.

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• Organising data access for dependency injection

  - by IanAWP

  In our company we have a relatively long history of database backed applications, but have only just begun experimenting with dependency injection. I am looking for advice about how to convert our existing data access pattern into one more suited for dependency injection. Some specific questions: Do you create one access object per table (Given that a table represents an entity collection)? One interface per table? All of these would need the low level Data Access object to be injected, right? What about if there are dozens of tables, wouldn't that make the composition root into a nightmare? Would you instead have a single interface that defines things like GetCustomer(), GetOrder(), etc? If I took the example of EntityFramework, then I would have one Container that exposes an object for each table, but that container doesn't conform to any interface itself, so doesn't seem like it's compatible with DI. What we do now, in case it helps: The way we normally manage data access is through a generic data layer which exposes CRUD/Transaction capabilities and has provider specific subclasses which handle the creation of IDbConnection, IDbCommand, etc. Actual table access uses Table classes that perform the CRUD operations associated with a particular table and accept/return domain objects that the rest of the system deals with. These table classes expose only static methods, and utilise a static DataAccess singleton instantiated from a config file.

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• ORA-600 Troubleshooting

  - by [email protected]

  Have you observed an ORA-0600 or ORA-07445 reported in your alert log? The ORA-600 error is the generic internal error number for Oracle program exceptions. It indicates that a process has encountered a low-level, unexpected condition. The ORA-600 error statement includes a list of arguments in square brackets: ORA 600 "internal error code, arguments: [%s], [%s],[%s], [%s], [%s]" The first argument is the internal message number or character string. This argument and the database version number are critical in identifying the root cause and the potential impact to your system.  The remaining arguments in the ORA-600 error text are used to supply further information (e.g. values of internal variables etc).   Looking for the best way to diagnose? There is an ORA-600 Troubleshooter Tool available in My Oracle Support.  This tool will lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or you can pull out the first 10 or 15 stack pointers from the associated trace file to match up against known bugs. Note 153788.1 ORA-600/ORA-7445 TroubleshooterNote 1082674.1 A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video] Also, take a quick look at the Master Note for Diagnosing ORA-600 ( MasterNoteORA600.docx) for some tips on diagnosing.

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• Creating a layer of abstraction over the ORM layer

  - by Daok

  I believe that if you have your repositories use an ORM that it's already enough abstracted from the database. However, where I am working now, someone believe that we should have a layer that abstract the ORM in case that we would like to change the ORM later. Is it really necessary or it's simply a lot of over head to create a layer that will work on many ORM? Edit Just to give more detail: We have POCO class and Entity Class that are mapped with AutoMapper. Entity class are used by the Repository layer. The repository layer then use the additional layer of abstraction to communicate with Entity Framework. The business layer has in no way a direct access to Entity Framework. Even without the additional layer of abstraction over the ORM, this one need to use the service layer that user the repository layer. In both case, the business layer is totally separated from the ORM. The main argument is to be able to change ORM in the future. Since it's really localized inside the Repository layer, to me, it's already well separated and I do not see why an additional layer of abstraction is required to have a "quality" code.

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• Compute the AES-encryption key given the plaintext and its ciphertext?

  - by Null Pointers etc.

  I'm tasked with creating database tables in Oracle which contain encrypted strings (i.e., the columns are RAW). The strings are encrypted by the application (using AES, 128-bit key) and stored in Oracle, then later retrieved from Oracle and decrypted (i.e., Oracle itself never sees the unencrypted strings). I've come across this one column that will be one of two strings. I'm worried that someone will notice and presumably figure out what those two values to figure out the AES key. For example, if someone sees that the column is either Ciphertext #1 or #2: Ciphertext #1: BF,4F,8B,FE, 60,D8,33,56, 1B,F2,35,72, 49,20,DE,C6. Ciphertext #2: BC,E8,54,BD, F4,B3,36,3B, DD,70,76,45, 29,28,50,07. and knows the corresponding Plaintexts: Plaintext #1 ("Detroit"): 44,00,65,00, 74,00,72,00, 6F,00,69,00, 74,00,00,00. Plaintext #2 ("Chicago"): 43,00,68,00, 69,00,63,00, 61,00,67,00, 6F,00,00,00. can he deduce that the encryption key is "Buffalo"? 42,00,75,00, 66,00,66,00, 61,00,6C,00, 6F,00,00,00. I'm thinking that there should be only one 128-bit key that could convert Plaintext #1 to Ciphertext #1. Does this mean I should go to a 192-bit or 256-bit key instead, or find some other solution? (As an aside, here are two other ciphertexts for the same plaintexts but with a different key.) Ciphertext #1 A ("Detroit"): E4,28,29,E3, 6E,C2,64,FA, A1,F4,F4,96, FC,18,4A,C5. Ciphertext #2 A ("Chicago"): EA,87,30,F0, AC,44,5D,ED, FD,EB,A8,79, 83,59,53,B7.

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• Real-time stock market application

  - by Sam

  I'm an amateur programmer. I'd like to develop a software application (like Tradestation), to analyse real-time market data. Please teach me if the following approach is correct, ie the procedures, knowledge or software needed etc: Use a DB to read the real-time feed from data provider: what should be the right DB to use? I know it should be a time serious one. Can I use SQL, Mysql, or others? What database can receive real-time data feed? Do I need to configure the DB to do this? If the real-time data is in ASCII form, how can it be converted to those that can be read by the DB and my application? Should I have to write codes or just use some add-ins? What kind of add-in are needed? How should I code the program to retrieve the changing data from the DB so that the analysis software screen data can also change asynchronously? (like the RTD in excel) Which aspects of programming do I need to learn to develop the above? Are there web resources/ books I can refer to for more information?

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• Engineered Systems: Oracle schlägt drei Fliegen mit einer Klappe

  - by A&C Redaktion

  Die News aus dem Partnergeschäft von Oracle sorgen für Schlagzeilen im Magazin ChannelPartner. Über den neuen Fokus auf Engineered Systems und die SMB Appliances heißt es dort, so könne Oracle „drei Fliegen mit einer Klappe schlagen“: Erstens wird früheren Sun Hardware-Resellern der Einstieg ins Software-Geschäft erleichtert, zweitens bieten die Appliances neue Möglichkeiten für den Mittelstand und drittens bekräftigt die Strategie das zweistufige Channel-Modell. Dazu Silvia Kaske, Senior Director Channel Sales & Alliances Oracle Deutschland: "Wir stärken weltweit den Channel, weil das SMB-Geschäft zunehmend anzieht." Neben der durchaus positiven Wertung der Channel-Strategie bietet der Artikel einen anschaulichen Überblich darüber, was Engineered Systems eigentlich sind. Außerdem werden die Einsatzmöglichkeiten (Big Data, Mobile Computing, Cloud etc.) und Angebote von Oracle in diesem Bereich dargestellt und diskutiert. Das Highlight hierbei ist – wen wundert’s – die Oracle Database Appliance. Mit dem Portfolio wächst natürlich auch die Zahl der Spezialisierungen. Logisch, findet Silvia Kaske: "Endkunden erwarten keine Generalisten, sondern Spezialisten. Nur mit einem klaren Fokus wird der Partner erfolgreich sein". Hier geht’s zum vollständigen CP-Artikel unter dem Titel „Oracle lockt Channel mit SMB-Appliances“.

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• Methodologies for Managing Users and Access?

  - by MadBurn

  This is something I'm having a hard time getting my head around. I think I might be making it more complicated than it is. What I'm trying to do is develop a method to store users in a database with varying levels of access, throughout different applications. I know this has been done before, but I don't know where to find how they did it. Here is an example of what I need to accomplish: UserA - Access to App1, App3, App4 & can add new users to App3, but not 4 or 1. UserB - Access to App2 only with ReadOnly access. UserC - Access to App1 & App4 and is able to access Admin settings of both apps. In the past I've just used user groups. However, I'm reaching a phase where I need a bit more control over each individual user's access to certain parts of the different applications. I wish this were as cut and dry as being able to give a user a role and let each role inherit from the last. Now, this is what I need to accomplish. But, I don't know any methods of doing this. I could easily just design something that works, but I know this has been done and I know this has been studied and I know this problem has been solved by much better minds than my own. This is for a web application and using sql server 2008. I don't need to store passwords (LDAP) and the information I need to store is actually very limited. Basically just username and access.

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• Storing User-uploaded Images

  - by Nyxynyx

  What is the usual practice for handling user uploaded photos and storing them on the database and server? For a user profile image: After receiving the image file from user, rename file to <image_id>_<username> Move image to /images/userprofile Add img filename to a table users containing their profile details like first_name, last_name, age, gender, birthday For a image for a review done by user: After receiving the image file from user, rename file to <image_id>_<review_id> Move image to /images/reviews Add img filename to a table reviews containing their profile details like review_id, review_content, user_id, score. Question 1: How should I go about storing the image filenames if the user can upload multiple photos for a particular review? Serialize? Question 2: Or have another table review_images with columns review_id, image_id, image_filename just for tracking images? Will doing a JOIN when retriving the image_filename from this table slow down performance noticeably? Question 3: Should all the images be stored in a single folder? Will there be a problem when we have 100K photos in the same folder? Is there a more efficient way to go about doing this?

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• Is there a canonical source supporting "all-surrogates"?

  - by user61852

  Background The "all-PK-must-be-surrogates" approach is not present in Codd's Relational Model or any SQL Standard (ANSI, ISO or other). Canonical books seems to elude this restrictions too. Oracle's own data dictionary scheme uses natural keys in some tables and surrogate keys in other tables. I mention this because these people must know a thing or two about RDBMS design. PPDM (Professional Petroleum Data Management Association) recommend the same canonical books do: Use surrogate keys as primary keys when: There are no natural or business keys Natural or business keys are bad ( change often ) The value of natural or business key is not known at the time of inserting record Multicolumn natural keys ( usually several FK ) exceed three columns, which makes joins too verbose. Also I have not found canonical source that says natural keys need to be immutable. All I find is that they need to be very estable, i.e need to be changed only in very rare ocassions, if ever. I mention PPDM because these people must know a thing or two about RDBMS design too. The origins of the "all-surrogates" approach seems to come from recommendations from some ORM frameworks. It's true that the approach allows for rapid database modeling by not having to do much business analysis, but at the expense of maintainability and readability of the SQL code. Much prevision is made for something that may or may not happen in the future ( the natural PK changed so we will have to use the RDBMS cascade update funtionality ) at the expense of day-to-day task like having to join more tables in every query and having to write code for importing data between databases, an otherwise very strightfoward procedure (due to the need to avoid PK colisions and having to create stage/equivalence tables beforehand ). Other argument is that indexes based on integers are faster, but that has to be supported with benchmarks. Obviously, long, varying varchars are not good for PK. But indexes based on short, fix-length varchar are almost as fast as integers. The questions - Is there any canonical source that supports the "all-PK-must-be-surrogates" approach ? - Has Codd's relational model been superceded by a newer relational model ?

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• Is there any way to send a column value from outer query to inner sub query? [closed]

  - by chetan

  'Discussions' table schema title description desid replyto upvote downvote views browser used a1 none 1 1 12 - bad topic b2 a1 2 3 14 sql database a3 none 4 5 34 - crome b4 a3 3 4 12 The above table has two types of content types Main Topics and Comments. Unique content identifier 'desid' used to identify that its a main topic or a comment. 'desid' starts with 'a' for Main Topic and for comment 'desid' starts with 'b'. For comment 'replyto' is the 'desid' of main topic to which this comment is associated. I like to find out the list of the top main topics that are arranged on the basis of (upvote+downvote+visits+number of comments to it) addition. The following query gives top topics list in order of (upvote+downvote+visits) select * with highest number of upvote+downvote+views by query "select * from [DB_user1212].[dbo].[discussions] where desid like 'a%' order by (upvote+downvote+visited) desc For (comments+upvote+downvote+views ) I tried select * from [DB_user1212].[dbo].[discussions] where desid like 'a%' order by ((select count(*) from [DB_user1212].[dbo].[discussions] where replyto = desid )+upvote+downvote+visited) desc but it didn't work because its not possible to send desid from outer query to inner subquery. How to solve this? Please note that I want solution in query language only.

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• Parameterized Django models

  - by mgibsonbr

  In principle, a single Django application can be reused in two or more projects, providing functionality relevent to both. That implies that the same database structure (tables and relations) will be re-created identically in different databases, and most times this is not a problem (assuming the projects/databases are unrelated - for instance when someone downloads a complete app to use in their own projects). Sometimes, however, the models must be "tweaked" a little to better fit the problem needs. This can be accomplished by forking the app, but I wondered if there wouldn't be a better option in cases where the app designer can anticipate the most common customizations. For instance, if I have a model that could relate to another as one-to-one or one-to-many, I could specify the unique property as a parameter, that can be specified in the project's settings: class This(models.Model): other = models.ForeignKey(Other, unique=settings.OTHER_TO_THIS) Or if a model can relate to many others, I could create an intermediate table for each of them (thus enforcing referential integrity) instead of using generic fks: for related in settings.MODELS_RELATED_TO_OTHER: model_name = '%s_Other' % related globals()[model_name] = type(model_name, (models.Model,) { me:models.ForeignKey(find_model_class(related)), other:models.ForeignKey(Other), # Some other properties all intersection tables must have }) Etc. Let me stress out that I'm not proposing to change the models at runtime nor anything like that; once the parameters were defined and syncdb called for the first time, those parameters are not to be changed again (unless you're doing a schema migration). Is this a good design? Are there better ways to accomplish the same thing, or maybe drawbacks I coulnd't anticipate? This technique is meant to be used sparingly (only on apps meant to be reused in wildly different contexts, and only when a specific need of customization can be detected while the app model is being designed).

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• Algorithm for rating books: Relative perception

  - by suneet

  So I am developing this application for rating books (think like IMDB for books) using relational database. Problem statement : Let's say book "A" deserves 8.5 in absolute sense. In case if A is the best book I have ever seen, I'll most probably rate it 9.5 whereas for someone else, it might be just an average book, so he/they will rate it less (say around 8). Let's assume 4 such guys rate it 8. If there are 10 guys who are like me (who haven't ever read great literature) and they all rate it 9.5-10. This will effectively make it's cumulative rating greater than 9 (9.5*10 + 8*4) / 14 = 9.1 whereas we needed the result to be 8.5 ... How can I take care of(normalize) this bias due to incorrect perception of individuals. MyProposedSolution : Here's one of the ways how I think it could be solved. We can have a variable Lit_coefficient which tells us how much knowledge a user has about literature. If I rate "A"(the book) 9.5 and person "X" rates it 8, then he must have read books much better than "A" and thus his Lit_coefficient should be higher. And then we can normalize the ratings according to the Lit_coefficient of user. Could there be a better algorithm/solution for the same?

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• How to Structure a Trinary state in DB and Application

  - by ABMagil

  How should I structure, in the DB especially, but also in the application, a trinary state? For instance, I have user feedback records which need to be reviewed before they are presented to the general public. This means a feedback reviewer must see the unreviewed feedback, then approve or reject them. I can think of a couple ways to represent this: Two boolean flags: Seen/Unseen and Approved/Rejected. This is the simplest and probably the smallest database solution (presumably boolean fields are simple bits). The downside is that there are really only three states I care about (unseen/approved/rejected) and this creates four states, including one I don't care about (a record which is seen but not approved or rejected is essentially unseen). String column in the DB with constants/enum in application. Using Rating::APPROVED_STATE within the application and letting it equal whatever it wants in the DB. This is a larger column in the db and I'm concerned about doing string comparisons whenever I need these records. Perhaps mitigatable with an index? Single boolean column, but allow nulls. A true is approved, a false is rejected. A null is unseen. Not sure the pros/cons of this solution. What are the rules I should use to guide my choice? I'm already thinking in terms of DB size and the cost of finding records based on state, as well as the readability of code the ends up using this structure.

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• Is this a ridiculous way to structure a DB schema, or am I completely missing something?

  - by Jim

  I have done a fair bit of work with relational databases, and think I understand the basic concepts of good schema design pretty well. I recently was tasked with taking over a project where the DB was designed by a highly-paid consultant. Please let me know if my gut intinct - "WTF??!?" - is warranted, or is this guy such a genius that he's operating out of my realm? DB in question is an in-house app used to enter requests from employees. Just looking at a small section of it, you have information on the users, and information on the request being made. I would design this like so: User table: UserID (primary Key, indexed, no dupes) FirstName LastName Department Request table RequestID (primary Key, indexed, no dupes) <...> various data fields containing request details UserID -- foreign key associated with User table Simple, right? Consultant designed it like this (with sample data): UsersTable UserID FirstName LastName 234 John Doe 516 Jane Doe 123 Foo Bar DepartmentsTable DepartmentID Name 1 Sales 2 HR 3 IT UserDepartmentTable UserDepartmentID UserID Department 1 234 2 2 516 2 3 123 1 RequestTable RequestID UserID <...> 1 516 blah 2 516 blah 3 234 blah The entire database is constructed like this, with every piece of data encapsulated in its own table, with numeric IDs linking everything together. Apparently the consultant had read about OLAP and wanted the 'speed of integer lookups' He also has a large number of stored procedures to cross reference all of these tables. Is this valid design for a small to mid-sized SQL DB? Thanks for comments/answers...

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• CMS and Databases vs. DIY

  - by hozza

  I have been programming for many years now, primarily in PHP and the like and would consider myself an intermediate programmer. Some of my online projects have now gone global and very widely used, i am now in deep thought about scalability etc. All of my systems so far are written in PHP, no known database structure such as MySQL etc. Instead our databases use an 'operating system style' method of storing information, files and folders if you will. We also do not use any outside/third-party software or CMS, so far this has work out extremely well. Most people, when they hear about the way we do things, criticize and say that is an idiotic idea but normally after seeing our systems in more dept are converted to our way of doing things. Is it really that bad to not use a standard databasing systems and only using the one (slightly heavier than others) language of PHP? How well on the face of it will this kind of setup scale? N.B. Our systems include things such as account and user management, documentation development and task/project managing.

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• Where ORMs blur the lines between code and data, how do you decide what logic should be a stored procedure, and what should be coded?

  - by PhonicUK

  Take the following pseudocode: CreateInvoiceAndCalculate(ItemsAndQuantities, DispatchAddress, User); And say CreateInvoice does the following: Create a new entry in an Invoices table belonging to the specified User to be sent to the given DispatchAddress. Create a new entry in an InvoiceItems table for each of the items in ItemsAndQuantities, storing the Item, the Quantity, and the cost of the item as of now (by looking it up from an Items table) Calculate the total amount of the invoice (ex shipping and taxes) and store it in the new Invoice row. At a glace you wouldn't be able to tell if this was a method in my applications code, or a stored procedure in the database that is being exposed as a function by the ORM. And to some extent it doesn't really matter. Now technically none of this is business logic. You're not making any decisions - just performing a calculation and creating records. However some may argue that because you are performing a calculation that affects the business (the total amount to be invoiced) that this isn't something that should be done in a stored procedure and instead should be in code. So for this specific example - why would it be more appropriate to do one or the other? And where do you draw the line? Or does it even particular matter as long as it's sufficiently well documented?

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• DB Object passing between classes singleton, static or other?

  - by Stephen

  So I'm designing a reporting system at work it's my first project written OOP and I'm stuck on the design choice for the DB class. Obviously I only want to create one instance of the DB class per-session/user and then pass it to each of the classes that need it. What I don't know it what's best practice for implementing this. Currently I have code like the following:- class db { private $user = 'USER'; private $pass = 'PASS'; private $tables = array( 'user','report', 'etc...'); function __construct(){ //SET UP CONNECTION AND TABLES } }; class report{ function __construct ($params = array(), $db, $user) { //Error checking/handling trimed //$db is the database object we created $this->db = $db; //$this->user is the user object for the logged in user $this->user = $user; $this->reportCreate(); } public function setPermission($permissionId = 1) { //Note the $this->db is this the best practise solution? $this->db->permission->find($permissionId) //Note the $this->user is this the best practise solution? $this->user->checkPermission(1) $data=array(); $this->db->reportpermission->insert($data) } };//end report I've been reading about using static classes and have just come across Singletons (though these appear to be passé already?) so what's current best practice for doing this?

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