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• SQL SERVER – SQL Server Performance: Indexing Basics – SQL in Sixty Seconds #006 – Video

  - by pinaldave

  A DBA’s role is critical, because a production environment has to run 24×7, hence maintenance, trouble shooting, and quick resolutions are the need of the hour.  The first baby step into any performance tuning exercise in SQL Server involves creating, analyzing, and maintaining indexes. Though we have learnt indexing concepts from our college days, indexing implementation inside SQL Server can vary.  Understanding this behavior and designing our applications appropriately will make sure the application is performed to its highest potential. Vinod Kumar and myself we often thought about this and realized that practical understanding of the indexes is very important. One can not master every single aspects of the index. However there are some minimum expertise one should gain if performance is one of the concern. More on Indexes: SQL Index SQL Performance I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Here is the interview of Vinod Kumar by myself. 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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• SQL SERVER – Copy Column Headers from Resultset – SQL in Sixty Seconds #026 – Video

  - by pinaldave

  SQL Server Management Studio returns results in Grid View, Text View and to the file. When we copy results from Grid View to Excel there is a common complaint that the column  header displayed in resultset is not copied to the Excel. I often spend time in performance tuning databases and I run many DMV’s in SSMS to get a quick view of the server. In my case it is almost certain that I need all the time column headers when I copy my data to excel or any other place. SQL Server Management Studio have two different ways to do this. Method 1: Ad-hoc When result is rendered you can right click on the resultset and click on Copy Header. This will copy the headers along with the resultset. Additionally, you can use the shortcut key CTRL+SHIFT+C for coping column headers along with the resultset. Method 2: Option Setting at SSMS level This is SSMS level settings and I kept this option always selected as I often need the column headers when I select the resultset. Go Tools >> Options >> Query Results >> SQL Server >> Results to Grid >> Check the Box “Include column header when copying or saving the results.” Both of the methods are discussed in following SQL in Sixty Seconds Video. Here is the code used in the video. Related Tips in SQL in Sixty Seconds: Copy Column Headers in Query Analyzers in Result Set Getting Columns Headers without Result Data – SET FMTONLY ON If we like your idea we promise to share with you educational material. 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 Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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• 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 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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• 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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• 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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• 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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• Co-worker renamed all of my queries

  - by anon

  I don't know if I should be very irritated or what. I single handedly built over 300 queries for a large database, and developed a naming convention so I could find them later. No one else in my office even knows how to build a query, but I came in yesterday to find that all of them had been renamed. I am now having a very hard time finding things, and I am trying to figure out what to do. I spoke with the person responsible, and she just downplayed the whole thing. She said she renamed them so she can find them more easily. Unfortunately, I am the only one who knows how to build, edit, and maintain them, and the only reason she needed to find them was to test the queries. The new naming convention doesn't make sense at all, and I feel like we have taken a backwards step in the development process. What I'm trying to figure out is: 1) Am I overreacting? 2) What is the best way to handle this? I hate to mention this to my boss, but after speaking with my co-worker yesterday, I can already tell she feels like she did nothing wrong.

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• OTN???DB???????????????·Oracle ACE????????????????!

  - by OTN-J Master

  ??????????? ???????????????????????????????????????? ????????????????????????”??????”??????????????????????????????????????????????????????????????????????????????????????(1)?????????????????(????????)?(2)?????????????????????(???????)????????????2??????????????????????????????????????????????????? ???????????????????????????????????????????????????????????????????????????? ????Oracle DBA & Developer Day??????????????????????????????????????????????????????????????????????????????????????????????OTN?????????????????? 2012???????????????????????????????? ?????????????? (??????) ?23????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? >> ??????????????????! DBA??? (??????) ?12? ???????????????????????(1)????2?????????????????????????????????????????????????????????????????????????????????????1???????1?????????????????????????????????????????1?????????????????????????????????????????????????????????????????????????????????????????????????????????????????I/O???????????????????????????????????????????????>> ????? ????????Oracle Database?SQL?? (Oracle ACE ?? ???) (??????) ~Oracle SQL???????????????? ~ SQL??????????????????????Oracle SQL??????????????????????????????SQL???????????????? SQL?????????????????????????SQL????????????????????? ?8? Pivot?UnPivot?1? Pivot?UnPivot?? (Pivot?UnPivot??/select???Pivot?UnPivot?????)?2? Pivot???? (Pivot????/Pivot????/Pivot??Pivot???????/Pivot??????)?3? UnPivot???? (UnPivot????/UnPivot????/UnPivot??UnPivot???????/UnPivot??????) >> ?????

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• Records not being saved to core data sqlite file

  - by esd100

  I'm a complete newbie when it comes to iOS programming and much less Core Data. It's rather non-intuitive for me, as I really came into my own with programming with MATLAB, which I guess is more of a 'scripting' language. At any rate, my problem is that I had no idea what I had to do to create a database for my application. So I read a little bit and thought I had to create a SQL database of my stuff and then import it. Long story short, I created a SQLite db and I want to use the work I have already done to import stuff into my CoreData database. I tried exporting to comma-delimited files and xml files and reading those in, but I didn't like it and it seemed like an extra step that I shouldn't need to do. So, I imported the SQLite database into my resources and added the sqlite framework. I have my core data model setup and it is setting up the SQLite database for the model correctly in the background. When I run through my program to add objects to my entities, it seems to work and I can even fetch results afterward. However, when I inspect the Core Data Database SQLite file, no records have been saved. How is it possible for it to fetch results but not save them to the database? - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ //load in the path for resources NSString *paths = [[NSBundle mainBundle] resourcePath]; NSString *databaseName = @"histology.sqlite"; NSString *databasePath = [paths stringByAppendingPathComponent:databaseName]; [self createDatabase:databasePath ]; NSError *error; if ([[self managedObjectContext] save:&error]) { NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]); } // Test listing all CELLS from the store NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entityMO = [NSEntityDescription entityForName:@"CELL" inManagedObjectContext:[self managedObjectContext]]; [fetchRequest setEntity:entityMO]; NSArray *fetchedObjects = [[self managedObjectContext] executeFetchRequest:fetchRequest error:&error]; for (CELL *cellName in fetchedObjects) { //NSLog(@"cellName: %@", cellName); } -(void) createDatabase:databasePath { NSLog(@"The createDatabase function was entered."); NSLog(@"The databasePath is %@ ",[databasePath description]); // Setup the database object sqlite3 *histoDatabase; // Open the database from filessytem if(sqlite3_open([databasePath UTF8String], &histoDatabase) == SQLITE_OK) { NSLog(@"The database was opened"); // Setup the SQL Statement and compile it for faster access const char *sqlStatement = "SELECT * FROM CELL"; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(histoDatabase, sqlStatement, -1, &compiledStatement, NULL) != SQLITE_OK) { NSAssert1(0, @"Error while creating add statement. '%s'", sqlite3_errmsg(histoDatabase)); } if(sqlite3_prepare_v2(histoDatabase, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { // Loop through the results and add them to cell MO array while(sqlite3_step(compiledStatement) == SQLITE_ROW) { CELL *cellMO = [NSEntityDescription insertNewObjectForEntityForName:@"CELL" inManagedObjectContext:[self managedObjectContext]]; if (sqlite3_column_type(compiledStatement, 0) != SQLITE_NULL) { cellMO.cellName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)]; } else { cellMO.cellName = @"undefined"; } if (sqlite3_column_type(compiledStatement, 1) != SQLITE_NULL) { cellMO.cellDescription = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)]; } else { cellMO.cellDescription = @"undefined"; } NSLog(@"The contents of NSString *cellName = %@",[cellMO.cellName description]); } } // Release the compiled statement from memory sqlite3_finalize(compiledStatement); } sqlite3_close(histoDatabase); } I have a feeling that it has something to do with the timing of opening/closing both of the databases? Attached I have some SQL debugging output to the terminal 2012-05-28 16:03:39.556 MedPix[34751:fb03] The createDatabase function was entered. 2012-05-28 16:03:39.557 MedPix[34751:fb03] The databasePath is /Users/jack/Library/Application Support/iPhone Simulator/5.1/Applications/A6B2A79D-BA93-4E24-9291-5B7948A3CDF4/MedPix.app/histology.sqlite 2012-05-28 16:03:39.559 MedPix[34751:fb03] The database was opened 2012-05-28 16:03:39.560 MedPix[34751:fb03] The database was prepared 2012-05-28 16:03:39.575 MedPix[34751:fb03] CoreData: annotation: Connecting to sqlite database file at "/Users/jack/Library/Application Support/iPhone Simulator/5.1/Applications/A6B2A79D-BA93-4E24-9291-5B7948A3CDF4/Documents/MedPix.sqlite" 2012-05-28 16:03:39.576 MedPix[34751:fb03] CoreData: annotation: creating schema. 2012-05-28 16:03:39.577 MedPix[34751:fb03] CoreData: sql: pragma page_size=4096 2012-05-28 16:03:39.578 MedPix[34751:fb03] CoreData: sql: pragma auto_vacuum=2 2012-05-28 16:03:39.630 MedPix[34751:fb03] CoreData: sql: BEGIN EXCLUSIVE 2012-05-28 16:03:39.631 MedPix[34751:fb03] CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA' 2012-05-28 16:03:39.632 MedPix[34751:fb03] CoreData: sql: CREATE TABLE ZCELL ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZCELLDESCRIPTION VARCHAR, ZCELLNAME VARCHAR ) ... 2012-05-28 16:03:39.669 MedPix[34751:fb03] CoreData: annotation: Creating primary key table. 2012-05-28 16:03:39.671 MedPix[34751:fb03] CoreData: sql: CREATE TABLE Z_PRIMARYKEY (Z_ENT INTEGER PRIMARY KEY, Z_NAME VARCHAR, Z_SUPER INTEGER, Z_MAX INTEGER) 2012-05-28 16:03:39.672 MedPix[34751:fb03] CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(1, 'CELL', 0, 0) ... 2012-05-28 16:03:39.701 MedPix[34751:fb03] CoreData: sql: CREATE TABLE Z_METADATA (Z_VERSION INTEGER PRIMARY KEY, Z_UUID VARCHAR(255), Z_PLIST BLOB) 2012-05-28 16:03:39.702 MedPix[34751:fb03] CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA' 2012-05-28 16:03:39.703 MedPix[34751:fb03] CoreData: sql: DELETE FROM Z_METADATA WHERE Z_VERSION = ? 2012-05-28 16:03:39.704 MedPix[34751:fb03] CoreData: sql: INSERT INTO Z_METADATA (Z_VERSION, Z_UUID, Z_PLIST) VALUES (?, ?, ?) 2012-05-28 16:03:39.705 MedPix[34751:fb03] CoreData: sql: COMMIT 2012-05-28 16:03:39.710 MedPix[34751:fb03] CoreData: sql: pragma cache_size=200 2012-05-28 16:03:39.711 MedPix[34751:fb03] CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA 2012-05-28 16:03:39.712 MedPix[34751:fb03] The contents of NSString *cellName = Beta Cell 2012-05-28 16:03:39.712 MedPix[34751:fb03] The contents of NSString *cellName = Gastric Chief Cell ... 2012-05-28 16:03:39.714 MedPix[34751:fb03] The database was prepared 2012-05-28 16:03:39.764 MedPix[34751:fb03] The createDatabase function has finished. Now fetching. 2012-05-28 16:03:39.765 MedPix[34751:fb03] CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZCELLDESCRIPTION, t0.ZCELLNAME FROM ZCELL t0 2012-05-28 16:03:39.766 MedPix[34751:fb03] CoreData: annotation: sql connection fetch time: 0.0008s 2012-05-28 16:03:39.767 MedPix[34751:fb03] CoreData: annotation: total fetch execution time: 0.0016s for 0 rows. 2012-05-28 16:03:39.768 MedPix[34751:fb03] cellName: <CELL: 0x6bbc120> (entity: CELL; id: 0x6bbc160 <x-coredata:///CELL/t57D10DDD-74E2-474F-97EE-E3BD0FF684DA34> ; data: { cellDescription = "S cells are cells which release secretin, found in the jejunum and duodenum. They are stimulated by a drop in pH to 4 or below in the small intestine's lumen. The released secretin will increase the s"; cellName = "S Cell"; organs = ( ); specimens = ( ); systems = ( ); tissues = ( ); }) ... Sections were cut short to abbreviate. But note that the fetch results contain information, but it says that total fetch execution was for "0" rows? How can that be? Any help will be greatly appreciated, especially detailed explanations. :) Thanks.

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