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• What is a good architecture for a Lift-JPA application?

  - by egervari

  I was wondering what is the best practice for a JPA model in Lift? I noticed that in the jpa demo application, there is just a Model object that is like a super object that does everything. I don't think this can be the most scalable approach, no? Is it is wise to still do the DAO pattern in Lift? For example, there's some code that looks a tad bloated and could be simplified across all model objects: Model.remove(Model.getReference(classOf[Author], someId)) Could be: AuthorDao.remove(someId) I'd appreciate any tips for setting up something that will work with the way Lift wants to work and is also easy to organize and maintain. Preferably from someone who has actually used JPA on a medium to large Lift site rather than just postulating what Spring does (we know how to do that) ;) The first phase of development will be around 30-40 tables, and will eventually get to over 100... we need a scalable, neat approach.

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• Dealing with schema upgrades while using Hibernate

  - by nehagp

  I'm using Hibernate as the ORM for my application. I would like to know if there is a good solution to dealing with schema upgrades in my application when these upgrades are done by someone else. For example, I have a set of hbm.xml files and corresponding java classes generated using Hibernate tools. Now in production, everything works fine until the db schema is upgraded (tables/columns may be dropped/added). I do not (my app doesn't) have access to do that so how do I deal with this using Hibernate? Thanks!

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• Copy new records from datatable and identify changes in old records

  - by Betite

  Assume there are two tables: Remote_table and My_table. Remote_table has 6 columns: **PROJECT JOB_TYPE MONTH YEAR** HOURS IS_DELETED 134393 70 1 2013 30 0 134393 70 2 2013 50 0 134393 70 3 2013 80 0 134393 70 10 2012 10 0 134393 70 11 2012 0 0 134393 70 12 2012 15 0 My_table is a copy of remote_table. I tried to copy only the new records from the remote_table by this query: SELECT * FROM [remote_DB].[LudanProjectManager].[dbo].Remote_table EXCEPT SELECT * FROM My_table It works OK but I get a duplicate primary key exception when changes have been made on the remote_table on the hours column. Can anyone think of a way to copy only the new records from remote_table and if changes has been made on old records, to identify them and update the my_table to correspond?

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• How to strore Java Date to Mysql datetime...?

  - by user275843

  can any body tell me how can i store Java Date to Mysql datetime...? when i am trying to do so...only date is stored and time remain 00:00:00 in mysql date stores like this... 2009-09-22 00:00:00 i want not only date but also time...like 2009-09-22 08:08:11 please help me.... EDIT---- i am using JPA(Hibernate) with spring mydomain classes uses java.util.Date but i have created tables using handwritten queries... this is my create statement CREATE TABLE ContactUs (id BIGINT auto_increment, userName VARCHAR(30), email VARCHAR(50), subject VARCHAR(100), message VARCHAR(1024), messageType VARCHAR(15), contactUsTime datetime, primary key(id))TYPE=InnoDB;

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• Copy Data from One SQL Server Table to Other in Same Database Without Specifying Columns

  - by Scott

  In SQL Server there is the ability to INSERT all of the data from one table into another using the following statement: INSERT INTO TABLE1 SELECT * FROM TABLE2 When running this on a table with an identity column, even though we have run the command SET IDENTITY_INSERT TABLE1 ON, we get the error: An explicit value for the identity column in table can only be specified when a column list is used and IDENTITY_INSERT is ON This implies that we would have to list off all of the columns within the INSERT in order for this to work properly. In the situation that we are in, we do not have access to the column names, only the list of the tables we need to copy over. Is there any way to get around this limitation?

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• Symfony 1.4: Deleting a sfGuardUser

  - by Tom

  Hi, I'm having some trouble with the following... I have a sfGuardUser table set up normally, and it has a one-to-one relationship with a Profile table, which contains some additional user info. When a user wants to delete themselves from the site, I'd like to retain their info in the Profile table for various purposes BUT delete the sfGuardUser in order to keep that table cleaner/shorter (not just set it to inactive). I was under the impression that I could set the FK in the Profile table to NULL and then delete the sfGuardUser, but it seems the FK-constraint fails. Indeed, it seems I can't delete either and the queries fail: If I try to delete the sfGuardUser, the Profile table will have an invalid FK If I try to delete a Profile, the sfGuardUser will have an invalid FK Other than leaving outdated sfGuardUsers and Profiles in these tables, or having to use a cascaded delete to get rid of both, can anyone tell me if there's any other way around this? Thank you.

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• Best approach to creating a database driven Java website?

  - by Craig Whitley

  I'm fairly new to programming and new to java, but I'd like to jump in the deep end with a little database driven website project. I've read quite a lot about requirements in the 'real world' requesting experience with Spring and Hibernate, so I have those installed on netbeans and a project created (if I hit run I get the default spring page). Now I just need a little guidance as to where to start designing my app (please tell me if I'm getting in a bit too over my head for a beginner!). Should I start off with my classes? - create all my classes as they map to my database tables and decide which attributes and methods each will require? Can anyone suggest any good books for maybe.. making a java based website from scratch (i.e. from design right through to deployment) that might be useful for a beginner? Any help appreciated thanks.

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• Tips for improving performance of DB that is above size 40 GB (Sql Server 2005) and growing monthly

  - by HotTester

  The current DB or our project has crossed over 40 GB this month and on an average it is growing monthly by around 3 GB. Now all the tables are best normalized and proper indexing has been used. But still as the size is growing it is taking more time to fire even basic queries like 'select count(1) from table'. So can u share some more points that will help in this front. Database is Sql Server 2005. Further if we implement Partitioning wouldn't it create a overhead ? Thanks in advance.

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• How to achieve "merge" of two data sets with Insert SQL statemen (Oracle DBMS)t?

  - by Roman Kagan

  Hi: What would be the insert SQL statement to merge data from two tables. For example I have events_source_1 table (columns: event_type_id, event_date) and events_source_2 table (same columns) and events_target table (columns: event_type_id, past_event_date nullalbe, future_event_date nullable). Events_source_1 has past events, Events_source_2 has future events and resultant events_target would contain past and future events in the same row for same event_type_id. If there is no past_events but future_events then past_event_date won't be set and only future_event_date will be and the opposite is true too. Thanks a lot in advance for helping me resolving this problem.

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• What are the repercussions of not checking existing data when adding a foreign key?

  - by scottm

  I've inherited a database that doesn't exactly strive for data integrity. I am trying to add some foreign keys to change that, but there is data in some tables that doesn't fit the constraints. Most likely, the data won't be used again so I want to know what problems I might face by leaving it there. The other option I see is to move it into some kind of table without referential constraints, just for historical purposes. So, what are the repercussions of not checking existing data? If I create a foreign key constraint on a table and don't check existing data, will all new data inserted into the table be enforced?

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• MySQL Join Comma Separated Field

  - by neeraj

  I have two tables. First Table is a batch table that contain comma separated student id in field "batch" batch -------------- id batch -------------- 1 1,2 2 3,4 Second Table is marks marks ---------------------- id studentid subject marks 1 1 English 50 2 2 English 40 3 3 English 70 4 1 Math 65 5 4 English 66 6 5 English 75 7 2 Math 55 How we can find those students of first batch id =1 who have scored more than 45 marks in English without using sub query. Problem i found to get this done using a single query is that we can not use IN as an association operator in JOIN statement What changes are required in below query to make it work? SELECT * FROM batch INNER JOIN marks ON marks.studentid IN(batch.batch) where batch.id = 1

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• Use content of fieldnames in query..

  - by rokdd

  Hi, i have three mysql tables: Table 456 id | binder | property1 1 | b | hello 2 | b | goodbye 3 | a | bonjour Table binder id | binder | tableid1 | tableid2 1 | a | 23 | 456 2 | b | 21 | 456 3 | c | 45 | 42 Table 21 id | property1 | data.. 1 | goodbye | data about goodbye.. 2 | ciao | data about ciao.. So first i want to select in binder the binder i need to get the tablesname where data is stored. So i need to select table by a fieldname in this case the fieldname is tableid1 and would have the content 21 so that i have to look in 21. AND it should be property 1 from table 456 and table 21 the same... i am using php and already tried with union and subquerys but it seems that i am to silly to prepare such query!

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• Multiple user database design

  - by dieguitoweb

  I have to develop a basic social network for an academic purpose; but I need some tips for the users management.. The users are subdivided into 3 groups with different privilege: admins,analysts and standards users. For every user should be stored into the database the following information: name,lastname,e-mail,age,password. I'm not quite sure how I should design the database between theese two solutions: 1)one table called 'users' with the 'role' attribute that explain what a user can do and what can't do, and the permissions are managed via php 2)every application user is a database user created with the query 'CREATE ROLE' (It's a postgres database) and he has permissions on some tables granted with the 'GRANT' statement You should take into account that the project is for a database exam.. thanks

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• How do I reload a Roo project without clearing the database?

  - by Omniwombat

  I've been learning how to build projects using Roo and am making good progress. I have the nucleus of a project which correctly displays my defined entities and allows me to create, edit, and delete the representative objects. I am using mysql at the database and I see that objects entered using the UI correctly appear in the mysql database. Per the Roo instructions, I am starting the webapp using "mvn tomcat:run". Unfortunately, I've discovered that whenever I restart Tomcat using Maven, it clears all of the existing objects out of the database. I'm left with empty tables. It seems to do this as the final step just prior to Tomcat stating that the server has started. I know this is just me being a n00b, but searches haven't been very helpful, none of the project's XML files seem relevant,

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• basic database design table on rails

  - by runcode

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

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• How do I do a semijoin using SQLAlchemy?

  - by Jason Baker

  http://en.wikipedia.org/wiki/Relational_algebra#Semijoin Let's say that I have two tables: A and B. I want to make a query that would work similarly to the following SQL statement using the SQLAlchemy orm: SELECT A.* FROM A, B WHERE A.id = B.id AND B.type = 'some type'; The thing is that I'm trying to separate out A and B's logic into different places. So I'd like to make two queries that I can define in separate places: one where A uses B as a subquery, but only returns rows from A. I'm sure this is fairly easy to do, but an example would be nice if someone could show me.

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• Full stack framework for Java

  - by Jonathan Barbero

  Hello everyone, I'm looking for a full stack framework (from persistency to view generation (CRUD)) for Java. I don't have experience with Rails style frameworks, like Grails, but I worked a lot with Hibernate, Struts, Spring ... I prefer a framework that let you naturally modify the business domain design with the less effort ( i.e. writing the sql querys to modify the tables and constrains, change the view pages, etc ... ). I was looking a bit about this topic, I saw Naked Objects for example but its development has stopped. So, I want to hear about your experience. Thanks in advance.

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• Master data validation in service layer

  - by rakesh-nitj

  User enters the data in the forms by choosing values from the master data drop downs in web layer. Data is populated in the dropdowns based on some logic from the master data tables and we know for sure that its a valid master data as far as web layer is concern. Now my question is, should be check the validity of the master data in service layer again because we want to use service layer for mulitple interfaces (Web User Interface, Web Services, Unit Test Cases etc.) or we should validate the master data in respective interfaces only.

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• Returning multiple datasets from a stored proc in VB

  - by Ryan Stephens

  I have an encrypted SQL Server stored proc that I run with (or the vb .net equivalent code of): declare @p4 nvarchar(100) set @p4=NULL declare @p5 bigint set @p5=NULL exec AA_PAY_BACS_EXPORT_RETRIEVE_S @PS_UserId=N'ADMN', @PS_Department=N'', @PS_PayFrequency=2, @PS_ErrorDescription=@p4 output select @p4, @p5 this returns 2 datasets and the output parameters for the results, the datasets are made up of various table joins etc, one holds the header record and one the detail records. I need to get the 2 datasets into a structure in VB .net (e.g. linq, sqldatareader, typed datasets) so that I can code with them, I don't know what tables any of this comes from and there are alot of them Whooopeee!!! I came close using Linq to SQL and IMultipleResults but got frustrated when I had to recode it every time I made a change to the designer file. My feelings are that there must be a simple way to do this, any ideas?

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• IF/ELSE makes stored procedure not return a result set

  - by Brendan Long

  I have a stored procedure that needs to return something from one of two databases: IF @x = 1 SELECT @y FROM Table_A ELSE IF @x = 2 SELECT @y FROM Table_B Either SELECT alone will return what I want, but adding the IF/ELSE makes it stop returning anything. I tried: IF @x = 1 RETURN SELECT @y FROM Table_A ELSE IF @x = 2 RETURN SELECT @y FROM Table_B But that causes a syntax error. The two options I see are both horrible: Do a UNION and make sure that only one side has any results: SELECT @y FROM Table_A WHERE @x = 1 UNION SELECT @y FROM Table_B WHERE @x = 2 Create a temporary table to store one row in, and create and delete it every time I run this procedure (lots). Neither solution is elegant, and I assume they would both be horrible for performance (unless MS SQL is smart enough not to search the tables when the WHERE class is always false). Is there anything else I can do? Is option 1 not as bad as I think?

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• how to write T-SQL to compare and copy data?

  - by George2

  Hello everyone, I have two SQL Server 2008 Enterprise databases (on two machines), and one of the databases is master database and another database is slave database. I want to transfer update from a table in source database to a table in destination database (two tables are of the same schema, both of them are using a single column as unique primary key). The transfer rule is (in short, the rule is keeping the destination database the same as source database because of the update of the source database), if there is a new row in source database but not in destination database, insert the row in destination database; if a row not exists in source database but exists in destination database, delete the row in destination database; if a row's content (i.e. columns other than primary key columns) changes in source database, update the new content into destination database. thanks in advance, George

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• group_concat on an empty join in MySQL

  - by Yossarian

  Hello, I've got the following problem: I have two tables: (simplified) +--------+ +-----------+ | User | | Role | +--------+ +-----------+ | ID<PK> | | ID <PK> | +--------+ | Name | +-----------+ and M:N relationship between them +-------------+ | User_Role | +-------------+ | User<FK> | | Role<FK> | +-------------+ I need to create a view, which selects me: User, and in one column, all of his Roles (this is done by group_concat). I've tried following: SELECT u.*, group_concat(r.Name separator ',') as Roles FROM User u LEFT JOIN User_Role ur ON ur.User=u.ID LEFT JOIN Role r ON ur.Role=r.ID GROUP BY u.ID; However, this works for an user with some defined roles. Users without role aren't returned. How can I modify the statement, to return me User with empty string in Roles column when User doesn't have any Role? Explanation: I'm passing the SQL data directly to a grid, which then formats itself, and it is easier for me to create slow and complicated view, than to format it in my code. I'm using MySQL

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• Getting started with SQLite (Android)

  - by Tarmon

  Hey Everyone, I have limited SQL background, basically a small amount of manipulation through HTML and mostly with pre-existing databases. What I am trying to do is set up a database that will store time information for bus routes. So basically I have different routes with stops for each route and then a list of times that the bus arrives at each stop. Here is an example of a table of times from their website: Link. I am wondering what would be the best way to layout my database/tables? Also what is the purpose of the _id field in each table? Thanks, Rob! P.S. Sorry if my lack of knowledge on the subject has caused me to post a duplicate question.

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• SSIS - Limiting Concurrent Connections

  - by Bigtoe

  Hi Folks, I am using SSIS to connect to a legecy mainframe database and this allows only 5 concurrent connections at a time. I have a dataflow task with many tables to transfer and it kicks outs because of this limitation. I have split up the Data Flow task into seperate data flows and this is working for the moment, but it is not optiomal as they need to be sequenced and 1 large transfer in a flow is holding up subsequent transfers. Anyone any idea of how to limit the number of connections in a single data flow, I had a look at using the Engine Threads but this did not make any difference. Any help much appericated.

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• Newbie SQL joining question: houses, refrigerators, and apples

  - by Philip Brocoum

  There are three tables in my database: apples, refrigerators, and houses. Each apple belongs to a refrigerator (it has a column that references the refrigerator that it's in), and each refrigerator belongs to a house. The problem is, each apple ALSO belongs to a house. I guess this isn't "normalized" or whatever, but it's the way it is. Obviously, each apple should belong to the house that its refrigerator belongs to. An apple can't be in two different places at once, after all. So, my question is this: what SQL statement will allow me to find all of the "bad apples" that for some reason incorrectly reference a different house than the refrigerator that they are supposedly in. In other words, I need to find the apples that contain contradictory information. I don't know if this is a "join" question or not, but I'm sure there's probably a very straightforward way of figuring this out. I just don't know what it is. Thanks for your help!

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