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• What's the best way to store sort order in SQL?

  - by Duracell

  The guys at the top want sort order to be customizable in our app. So I have a table that effectively defines the data type. What is the best way to store our sort order. If I just created a new column called 'Order' or something, every time I updated the order of one row I imagine I would have to update the order of every row to ensure posterity. Is there a better way to do it?

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• ASP.NET configure data source is not returning anything?

  - by Greg McNulty

  I'm selecting table data of the current user: SELECT [ConfidenceLevel], [LoveLevel], [HappinessLevel] FROM [UserData] WHERE ([UserProfileID] = @UserProfileID) I have set a control to the unique user ID and it is getting the correct value: HTML: <asp:Label ID="userID" runat="server" Text="Labeluser"></asp:Label> C#: userID.Text = Membership.GetUser().ProviderUserKey.ToString(); I then use it in the where clause using the Configure Data Source window unique ID = control then controlID userID (fills in .text for me) I compile and run but nothing shows up where the table should be. Any suggestions? Here is the code it has created: <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDataSource1"> <Columns> <asp:BoundField DataField="ConfidenceLevel" HeaderText="ConfidenceLevel" SortExpression="ConfidenceLevel" /> <asp:BoundField DataField="LoveLevel" HeaderText="LoveLevel" SortExpression="LoveLevel" /> <asp:BoundField DataField="HappinessLevel" HeaderText="HappinessLevel" SortExpression="HappinessLevel" /> </Columns> </asp:GridView> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionStringToDB %>" SelectCommand="SELECT [ConfidenceLevel], [LoveLevel], [HappinessLevel] FROM [UserData] WHERE ([UserProfileID] = @UserProfileID)"> <SelectParameters> <asp:ControlParameter ControlID="userID" Name="UserProfileID" PropertyName="Text" Type="Object" /> </SelectParameters> </asp:SqlDataSource>

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• Tools to work with App Engine data dumps

  - by Thilo

  Using the bulkloader.py utility you can download all data from your application's Datastore. It is not obvious how the data is stored, however. From the looks of it, you get a SQLite file with all data in binary format in a single table: sqlite> .tables bulkloader_database_signature result sqlite> .schema result CREATE TABLE result ( id BLOB primary key, value BLOB not null, sort_key BLOB); Are there any tools to work with this data?

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• IntegrityError: foreign key violation upon delete

  - by Lukasz Korzybski

  I have Order and Shipment model. Shipment has a foreign key to Order. class Order(...): ... class Shipment() order = m.ForeignKey('Order') ... Now in one of my views I want do delete order object along with all related objects. So I invoke order.delete(). I have Django 1.0.4, PostgreSQL 8.4 and I use transaction middleware, so whole request is enclosed in single transaction. The problem is that upon order.delete() I get: ... File "/usr/local/lib/python2.6/dist-packages/django/db/backends/__init__.py", line 28, in _commit return self.connection.commit() IntegrityError: update or delete on table "main_order" violates foreign key constraint "main_shipment_order_id_fkey" on table "main_shipment" DETAIL: Key (id)=(45) is still referenced from table "main_shipment". I checked in connection.queries that proper queries are executed in proper order. First shipment is deleted, after that django executes delete on order row: {'time': '0.000', 'sql': 'DELETE FROM "main_shipment" WHERE "id" IN (17)'}, {'time': '0.000', 'sql': 'DELETE FROM "main_order" WHERE "id" IN (45)'} Foreign key have ON DELETE NO ACTION (default) and is initially deferred. I don't know why I get foreign key constraint violation. I also tried to register pre_delete signal and manually delete shipment objects before delete on order is called, but it resulted in the same error. I can change ON DELETE behaviour for this key in Postgres but it would be just a hack, I wonder if anyone has a better idea what's going on here. There is also a small detail, my Order model inherits from Cart model, so it actually doesn't have id field but cart_ptr_id and after DELETE on order is executed there is also DELETE on cart, but it seems unrelated? to the shipment-order problem so I simplified it in the example.

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• Are Parameters really enough to prevent Sql injections?

  - by Rune Grimstad

  I've been preaching both to my colleagues and here on SO about the goodness of using parameters in SQL queries, especially in .NET applications. I've even gone so far as to promise them as giving immunity against SQL injection attacks. But I'm starting to wonder if this really is true. Are there any known SQL injection attacks that will be successfull against a parameterized query? Can you for example send a string that causes a buffer overflow on the server? There are of course other considerations to make to ensure that a web application is safe (like sanitizing user input and all that stuff) but now I am thinking of SQL injections. I'm especially interested in attacks against MsSQL 2005 and 2008 since they are my primary databases, but all databases are interesting. Edit: To clarify what I mean by parameters and parameterized queries. By using parameters I mean using "variables" instead of building the sql query in a string. So instead of doing this: SELECT * FROM Table WHERE Name = 'a name' We do this: SELECT * FROM Table WHERE Name = @Name and then set the value of the @Name parameter on the query / command object.

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• Dynamic Typed Table/Model in J2EE?

  - by Viele

  Hi, Usually with J2EE when we create Model, we define the fields and types of fields through XML or annotation before compilation time. Is there a way to change those in runtime? or better, is it possible to create a new Model based on the user's input during the runtime? such that the number of columns and types of fields are dynamic (determined at runtime)? Help is much appreciated. Thank you.

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• SQL query performance optimization (TimesTen)

  - by Sergey Mikhanov

  Hi community, I need some help with TimesTen DB query optimization. I made some measures with Java profiler and found the code section that takes most of the time (this code section executes the SQL query). What is strange that this query becomes expensive only for some specific input data. Here’s the example. We have two tables that we are querying, one represents the objects we want to fetch (T_PROFILEGROUP), another represents the many-to-many link from some other table (T_PROFILECONTEXT_PROFILEGROUPS). We are not querying linked table. These are the queries that I executed with DB profiler running (they are the same except for the ID): Command> select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; < 1169655247309537280 > < 1169655249792565248 > < 1464837997699399681 > 3 rows found. Command> select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; < 1169655247309537280 > 1 row found. This is what I have in the profiler: 12:14:31.147 1 SQL 2L 6C 10825P Preparing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272 12:14:31.147 2 SQL 4L 6C 10825P sbSqlCmdCompile ()(E): (Found already compiled version: refCount:01, bucket:47) cmdType:100, cmdNum:1146695. 12:14:31.147 3 SQL 4L 6C 10825P Opening: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.147 4 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.148 5 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.148 6 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.228 7 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.228 8 SQL 4L 6C 10825P Closing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:35.243 9 SQL 2L 6C 10825P Preparing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928 12:14:35.243 10 SQL 4L 6C 10825P sbSqlCmdCompile ()(E): (Found already compiled version: refCount:01, bucket:44) cmdType:100, cmdNum:1146697. 12:14:35.243 11 SQL 4L 6C 10825P Opening: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; 12:14:35.243 12 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; 12:14:35.243 13 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; 12:14:35.243 14 SQL 4L 6C 10825P Closing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; It’s clear that the first query took almost 100ms, while the second was executed instantly. It’s not about queries precompilation (the first one is precompiled too, as same queries happened earlier). We have DB indices for all columns used here: T_PROFILEGROUP.M_ID, T_PROFILECONTEXT_PROFILEGROUPS.M_ID_OID and T_PROFILECONTEXT_PROFILEGROUPS.M_ID_EID. My questions are: Why querying the same set of tables yields such a different performance for different parameters? Which indices are involved here? Is there any way to improve this simple query and/or the DB to make it faster? UPDATE: to give the feeling of size: Command> select count(*) from T_PROFILEGROUP; < 183840 > 1 row found. Command> select count(*) from T_PROFILECONTEXT_PROFILEGROUPS; < 2279104 > 1 row found.

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• How to read pdb format by javascript?

  - by Ted Wong

  I know that it is a databases in Palm OS, as the development is shift to webOS. Is there any third party javascript library to do the work? or it needs to write manually?

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• How to make a mapped field inherited from a superclass transient in JPA?

  - by Russ Hayward

  I have a legacy schema that cannot be changed. I am using a base class for the common features and it contains an embedded object. There is a field that is normally mapped in the embedded object that needs to be in the persistence id for only one (of many) subclasses. I have made a new id class that includes it but then I get the error that the field is mapped twice. Here is some example code that is much simplified to maintain the sanity of the reader: @MappedSuperclass class BaseClass { @Embedded private Data data; } @Entity class SubClass extends BaseClass { @EmbeddedId private SubClassId id; } @Embeddable class Data { private int location; private String name; } @Embeddable class SubClassId { private int thingy; private int location; } I have tried @AttributeOverride but I can only get it to rename the field. I have tried to set it to updatable = false, insertable = false but this did not seem to work when used in the @AttributeOverride annotation. See answer below for the solution to this issue. I realise I could change the base class but I really do not want to split up the embedded object to separate the shared field as it would make the surrounding code more complex and require some ugly wrapping code. I could also redesign the whole system for this corner case but I would really rather not. I am using Hibernate as my JPA provider.

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• What is the best scala-like persistence framework available right now?

  - by egervari

  What is the best scala-like persistence framework available right now? Hibernate works, but it's not very scala-like. It insists on using annotations, no-arg constructors, doesn't work with anonymous class instances, doesn't work with scala collections, has an outdated string-based query model, etc. I'm looking for something that really fits Scala. Does it exist? Or do I have to make it?

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• PDO update with conditional?

  - by dmontain

  I have a PDO mysql that updates 3 fields. $update = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2, field3=:field3 WHERE key=:key"); But I want field3 to be updated only when $update3 = true; Is this possible to accomplish with a single query? I could do it with 2 queries where I update field1 and field2 then check the boolean and update field3 if needed in a separate query. But hopefully there is a way to accomplish this in 1 query?

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• Where do filesystems like Reiser, NTFS, etc store the file tables?

  - by Mike Curry

  Where do filesystems like Reiser, NTFS, etc store the file tables? We're looking at writing our own filesystem, and wondering if we should use a single file to hold it all using btree's or use something out there. Any advice? This is more a learning exercise than anything. Edit: removed NFS, and replaced with NTFS

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• How to update multiple rows with one single query

  - by xRobot

  I use Postgresql + PHP. Say I have this table: Books ( id, title, year ) and this array of titles in PHP: $titles = array ("bible","kafka","Book of Eli"); now I want update all rows where the title is in the $titles array above. So I need a query like this: UPDATE books SET year = '2001-11-11' WHERE title is in $titles; Is is possible with one single query ? Or do I need to use FOR loop ?

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• Weaknesses of Hibernate

  - by Sinuhe

  I would like to know which are the weak points of Hibernate 3. This is not pretended to be a thread against Hibernate. I think it will be a very useful knowledge for decide if Hibernate is the best option for a project or for estimating its time. A weakness can be: A bug Where JDBC or PLSQL are better Performance issues ... Also, can be useful to know some solutions for that problems, better ORM or techniques, or it will be corrected in Hibernate 4. For example, AFAIK, Hibernate will have a very bad performance updating 10000 rows comparing to JDBC in this query: update A set state=3 where state=2

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• How can I display a manual efficiently in Sharepoint

  - by Matt Palfreman

  My organisiation uses Sharepoint for its 'intranet'. I have been given the task of creating a site for my department. One of the things I need on there is a procedure guide, which is basically a 150 page document, whereby each page is a separate procedure. Is there an efficient way within sharepoint that these procedures can be stored and searchable somehow, rather than dumping a 150 page document on there?

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• Delphi DB Aware visual attractive tag component available?

  - by David

  I need to implement a tag system for video program and before I build something myself, is there an attractive drag-n-drop tag component that will filter a table for me?

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• Is it a good practice to implement aggregate routes in Entity Framework 4?

  - by Kohan

  Having just started working on a new project using Entity Framework 4, I spoke to some of the other team that use NHibernate for advice. They implement aggregate routes on their entities, so instead of adding an order through the orders entity, they would add it through customer.order by having an addOrder method on customer. This is the approach I have taken but I am, alas, running into problems. These are issues that I hope to work out, but it got me thinking ... Is this a good way to work or am I fighting an uphill battle unnecessarily?

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• Complex SQL query... 3 tables and need the most popular in the last 24 hours using timestamps!

  - by Stefan

  Hey guys, I have 3 tables with a column in each which relates to one ID per row. I am looking for an sql statement query which will check all 3 tables for any rows in the last 24 hours (86400 seconds) i have stored timestamps in each tables under column time. After I get this query I will be able to do the next step which is to then check to see how many of the ID's a reoccurring so I can then sort by most popular in the array and limit it to the top 5... Any ideas welcome! :) Thanks in advanced. Stefan

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• do I have both sql 05 and 08 installed?

  - by Blankman

  When in 'sql server configuration manager' I see, under 'sql server services', 2 items that look like sql server's: sql server (sqlexpress) sql server (mssqlserver) Does that mean I have 2 versions installed at the same time? The 'sql server (mssqlserver) is currently stopped).

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• NHibernate - Stream large result sets?

  - by Dan Black

  Hi, I have to read in a large record set, process it, then write it out to a flat file. The large result set comes from a Stored Proc in SQL 2000. I currently have: var results = session.CreateSQLQuery("exec usp_SalesExtract").List(); I would like to be able to read the result set row by row, to reduce the memory foot print Thanks

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• Which key value store is the most promising/stable?

  - by Mike Trpcic

  I'm looking to start using a key/value store for some side projects (mostly as a learning experience), but so many have popped up in the recent past that I've got no idea where to begin. Just listing from memory, I can think of: CouchDB MongoDB Riak Redis Tokyo Cabinet Berkeley DB Cassandra MemcacheDB And I'm sure that there are more out there that have slipped through my search efforts. With all the information out there, it's hard to find solid comparisons between all of the competitors. My criteria and questions are: (Most Important) Which do you recommend, and why? Which one is the fastest? Which one is the most stable? Which one is the easiest to set up and install? Which ones have bindings for Python and/or Ruby? Edit: So far it looks like Redis is the best solution, but that's only because I've gotten one solid response (from ardsrk). I'm looking for more answers like his, because they point me in the direction of useful, quantitative information. Which Key-Value store do you use, and why? Edit 2: If anyone has experience with CouchDB, Riak, or MongoDB, I'd love to hear your experiences with them (and even more so if you can offer a comparative analysis of several of them)

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• SQL Backup files, distinguish partial and full backup files

  - by ccook

  I have scheduled backups running through SQL Agent, with Full Backups nightly, and differential backups hourly. Is there a way to determine which of the backup files is the Full backup, and which is the latest differential? Intuitively, it would seem the largest backup within 24 hours is the full, and the latest smaller backup is the partial. However, this isn't robust. Is there a way to probe the backup file to check the backup type? (Preferably in c#)

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• How to make this sub-sub-query work?

  - by Josh Weissbock

  I am trying to do this in one query. I asked a similar question a few days ago but my personal requirements have changed. I have a game type website where users can attend "classes". There are three tables in my DB. I am using MySQL. I have four tables: hl_classes (int id, int professor, varchar class, text description) hl_classes_lessons (int id, int class_id, varchar lessonTitle, varchar lexiconLink, text lessonData) hl_classes_answers (int id, int lesson_id, int student, text submit_answer, int percent) hl_classes stores all of the classes on the website. The lessons are the individual lessons for each class. A class can have infinite lessons. Each lesson is available in a specific term. hl_classes_terms stores a list of all the terms and the current term has the field active = '1'. When a user submits their answers to a lesson it is stored in hl_classes_answers. A user can only answer each lesson once. Lessons have to be answered sequentially. All users attend all "classes". What I am trying to do is grab the next lesson for each user to do in each class. When the users start they are in term 1. When they complete all 10 lessons in each class they move on to term 2. When they finish lesson 20 for each class they move on to term 3. Let's say we know the term the user is in by the PHP variable $term. So this is my query I am currently trying to massage out but it doesn't work. Specifically because of the hC.id is unknown in the WHERE clause SELECT hC.id, hC.class, (SELECT MIN(output.id) as nextLessonID FROM ( SELECT id, class_id FROM hl_classes_lessons hL WHERE hL.class_id = hC.id ORDER BY hL.id LIMIT $term,10 ) as output WHERE output.id NOT IN (SELECT lesson_id FROM hl_classes_answers WHERE student = $USER_ID)) as nextLessonID FROM hl_classes hC My logic behind this query is first to For each class; select all of the lessons in the term the current user is in. From this sort out the lessons the user has already done and grab the MINIMUM id of the lessons yet to be done. This will be the lesson the user has to do. I hope I have made my question clear enough.

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• Rails: translations for table's column.

  - by Andrew

  In rails application I have two models: Food and Drink. Both food and drink have a name, which has to be stored in two languages. How do I better realize translations for theese tables? First solution I realized was to replace name column with name_en and name_ru. Another solution is to encode with YAML hash like { :en => 'eng', :ru => 'rus' } and store yaml as a name. What would you recommend, assuming content is not static? Maybe there's good article?

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• bidirectional habtm linking

  - by Alexey Poimtsev

  Hi, all. I have application with 2 groups of models - content based (news, questions) and "something" based (devices, applications etc). I need to link all models between groups - for example question may belongs to 3 different things - one application and 2 devices. The same - for news. From other side - i need to see all news articles and questions related to some application or device. Any idea how to develop this in rails? I have only one idea - mixins that will add methods content_id and thing_id to models and join table.

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