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  • Fluent nHibernate - How to map a non-key column on a junction table?

    - by The Matt
    Taking an example that is provided on the Fluent nHibernate website, I need to extend it slightly: I need to add a 'Quantity' column to the StoreProduct table. How would I map this using nHibernate? An example mapping is provided for the given scenario above, but I'm not sure how I would get the Quantity column to map to a property on the Product class: public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id); Map(x => x.Name); HasMany(x => x.Employee) .Inverse() .Cascade.All(); HasManyToMany(x => x.Products) .Cascade.All() .Table("StoreProduct"); } }

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  • How to Auto-Increment Non-Primary Key? - SQL Server

    - by user311509
    CREATE TABLE SupplierQuote ( supplierQuoteID int identity (3504,2) CONSTRAINT supquoteid_pk PRIMARY KEY, PONumber int identity (9553,20) NOT NULL . . . CONSTRAINT ponumber_uq UNIQUE(PONumber) ); The above ddl produces an error: Msg 2744, Level 16, State 2, Line 1 Multiple identity columns specified for table 'SupplierQuote'. Only one identity column per table is allowed. How can i solve it? I want PONumber to be auto-incremented.

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  • DB Design - Linking to a parent without circular reference issues

    - by zSysop
    Hi all, I'm having trouble coming up with a solution for the following issue. Lets say i have a db that looks something like the following: Issue Table Id | Details | CreateDate | ClosedDate Issue Notes Table Id | ObjectId | Notes | NoteDate Issue Assignment Table Id | ObjectId | AssignedToId| AssignedDate I'd like allow the linking of an issue to another issue. I thought about adding a column to the Issue table called ParentIssueId and that would allow me the ability to link issues, but i foresee circular references occurring within the issue table if i go through with this implementation. Is there a better way to go about doing this, and if so, how? Thanks

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  • Transaction within transaction

    - by user281521
    Hello, I want to know if open a transaction inside another is safe and encouraged? I have a method: def foo(): session.begin try: stuffs except Exception, e: session.rollback() raise e session.commit() and a method that calls the first one, inside a transaction: def bar(): stuffs try: foo() #<<<< there it is :) stuffs except Exception, e: session.rollback() raise e session.commit() if I get and exception on the foo method, all the operations will be rolled back? and everything else will work just fine? thanks!!

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  • What is the fastest way to get a DataTable into SQL Server?

    - by John Gietzen
    I have a DataTable in memory that I need to dump straight into a SQL Server temp table. After the data has been inserted, I transform it a little bit, and then insert a subset of those records into a permanent table. The most time consuming part of this operation is getting the data into the temp table. Now, I have to use temp tables, because more than one copy of this app is running at once, and I need a layer of isolation until the actual insert into the permanent table happens. What is the fastest way to do a bulk insert from a C# DataTable into a SQL Temp Table? I can't use any 3rd party tools for this, since I am transforming the data in memory. My current method is to create a parameterized SqlCommand: INSERT INTO #table (col1, col2, ... col200) VALUES (@col1, @col2, ... @col200) and then for each row, clear and set the parameters and execute. There has to be a more efficient way. I'm able to read and write the records on disk in a matter of seconds...

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  • How do i get the data from a surveillance camera to a storage i can stream from?

    - by radbyx
    Hi my sisters house was robbed chrismas evening :( I talked with her about making a surveillance system for her. The idea is to have a system that detects intruders and then send a SMS to you while streaming it to a private website. The hard part: How and where do I storage the data from the camera so it's streamable? I think i can manage to do the streaming, website and SMS server, but i need the data (fundamentation). Thanks, any help is much appriciated.

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  • How to undo SQL changes using installer

    - by Sunil Agarwal
    I have installer to install procedures, scripts, views, etc in SQL server 2005/2008. Now I want to add a condition in the installer like if there is any error while installing, I want to undo all the changes done in SQL server. I tried to store the procedures, views, etc which I am changing while installing and reverting them back if I get any error. But am not able to do it the way I want. Can someone guide me if he had done the same thing? To specify I am using WIX installer. Also if someone has tried SMO, it will be of great help.

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  • mysql circular dependency in foreign key constraints

    - by Flavius
    Given the schema: What I need is having every user_identities.belongs_to reference an users.id. At the same time, every users has a primary_identity as shown in the picture. However when I try to add this reference with ON DELETE NO ACTION ON UPDATE NO ACTION, MySQL says #1452 - Cannot add or update a child row: a foreign key constraint fails (yap.#sql-a3b_1bf, CONSTRAINT #sql-a3b_1bf_ibfk_1 FOREIGN KEY (belongs_to) REFERENCES users (id) ON DELETE NO ACTION ON UPDATE NO ACTION) I suspect this is due to the circular dependency, but how could I solve it (and maintain referential integrity)?

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  • about Select statement !

    - by user329820
    hi, I have read that after select we use column-names but I have found a statement that was like this: SELECT 'A' FROM T WHERE A = NULL; would you lease help me? thanks (A is a column- name here?) my DBMS is MySQL

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  • Can't fill a column of NULLs with actual values by making an association to the proper values in the

    - by UkraineTrain
    I have a table with separate columns for months, days and a varchar column for 6 hour increments for each day ('12AM', '6AM', '12PM', '6PM'). There's also a column that's supposed to have calculated numeric values for each of those 6 hour increments. These calculated values come from some reference table. This reference table contains values for each day for several months broken down by hour where each hour has its own column. So, basically, I have to add the values for each 6 hour increment. I have no idea how to associate the correct values in the reference table to those 6 hour increments. I will really appreciate any help on this.

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  • Hosting an Access DB

    - by Mitciv
    Hey, So I'm inexperienced in hosting DB's and I've always had the luxury of someone else getting the db setup. I was going to help a friend out with getting a webpage setup, I've got experience in Asp.Net MVC so I'm going with that. They want to setup a search page to query a db and display the results. My question I have is in getting the DB setup and hosted. They currently just have the Access DB on a local computer. There is basically only one table that would need to be queried for the search. What is the best approach to getting this table/db accessible? They would like to keep the main copy of the db on the local machine, so copying the entire db over to the hosted site would be time consuming, could the lone table needed be solely copied to the host? Should I try to convince them to make changes on the hosted db and just make copies of that for their local machines? Any suggestions are welcome, Again I'm a total noob when it comes to hosting databases. Thanks

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  • Synchronizing MySQL databases

    - by Wasim
    Hi all, I have a maintanance problem synchronizing my MySQL data bases . These are the databases I have : My development DB : Here I make my curret development changes . Staging DB : I need to make all the changes I did in the development on it before using , currently I hold migration scripts for structure and data. Production DB : A production environment . Have to do exacly the same as the staging . My problem , is sync. the structure , and some of the data. This is really a very hard work to maintaine. Is there any technics , tools to do with MySQL . What is replication , is it good for my situation , how to use it . Thanks in advance ...

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  • I have data about deadlocks, but I can't understand why they occur

    - by Alex
    I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL Profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second Linq-to-SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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  • Zend Framework Relations vs. Table Select

    - by rtmilker
    Hey! I just want to know your guys opinion on using join tables within the zend framework. Of course you can use relations by defining a referenceMap and dependentTables and stuff, or using setIntegrityCheck(false) within a db select(). The setIntegrityCheck version seems a little bit dirty to me, but the other version is not very suitable for big querys and joining many tables... I'm a PHP developer for 5 years now and new to the zend framework and just want get a direction for my first project. Thanks!!!

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  • How to handle expired items?

    - by Mark
    My site allows users to post things on the site with an expiry date. Once the item has expired, it will no longer be displayed in the listings. Posts can also be closed, canceled, or completed. I think it would be be nicest just to be able to check for one attribute or status ("is active") rather than having to check for [is not expired, is not completed, is not closed, is not canceled]. Handling the rest of those is easy because I can just have one "status" field which is essentially an enum, but AFAIK, it's impossible to set the status to "expired" as soon as that time occurs. How do people typically handle this?

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  • What does "Select Distinct Null As xxxxx" mean?

    - by Soylent Green
    Background: I am mapping Sybase stored procedure return values to java objects using Spring. For example I map a Sybase datatype of varchar as a String type in Java, and a Sybase datatype of int as an int type in Java, etc. I have come across the following code in one of the stored procedures: SELECT DISTINCT A.Col1 AS val1, A.Col2 AS val2, NULL AS someVal, A.col3 AS val3, ... A.col9 AS val9 FROM #SomeTable A ORDER BY Col2, Col3 I have 2 related questions: What does Null mean in this scenario? I am confused as to what is happening here. I am able to determine the data type of Col1, Col2, etc. of course by looking at the table definition of Table A defined earlier in the stored procedure. Thus I know what datatype I can define in my Java object for val1, val2, etc.. But what about "someVal"? What datatype mapping am I supposed to perform for this Null value? I am fairly inexperienced in SQL. Perhaps the answer is much simpler than I realize.

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  • Multiple has_many's of the same model

    - by Koning Baard
    I have these models: Person has_many :messages_form_person, :foreign_key => :from_user_id, :class_name => :messages has_many :messages_to_person, :foreign_key => :to_user_id, :class_name => :messages Message belongs_to :to_person, :foreign_key => :to_user_id, :class_name => :person belongs_to :from_person, :foreign_key => :to_user_id, :class_name => :person And this view: person#show <% @person.messages_to_person.each do |message| %> <%=h message.title %> <% end %> But I get this error: TypeError in People#show Showing app/views/people/show.html.erb where line #26 raised: can't convert Symbol into String Extracted source (around line #26): 23: <%=h @person.biography %> 24: </p> 25: 26: <% @person.messages_to_person.each do |message| %> 27: 28: <% end %> 29: I basicly want that people can send eachother messages. Can anyone help me? Thanks.

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  • What is the fastest findByName query with hibernate?

    - by Karussell
    I am sure I can improve the performance of the following findByName query of hibernate: public List<User> findByName(String name) { session.createCriteria(User.class).add(Restrictions.eq("name", name)).list(); } In which way should I improve it or even more important: in which ways should I improve it first? I will need the full object with all the collections (layz or not) and deps of this class.

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  • Will MySql caching cause performance problems?

    - by Camran
    I am about to upload my website onto a VPS. It is a classifieds website, where all data is stored in MySql and Solr. I wonder if when using MySql:s cache, the server will slow down? Ie, if somebody makes a search for the first time, and MySql is to cache the query, will the caching make the server slower than if it would not cache anything? After the caching is done I know things will improve in terms of performance... But I would like to know if I should even use the cache or not, what do you think? Thanks

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  • New replicaset resident memory is larger than the existing sets

    - by eded
    From the mongodb tutorial of how to resync a set, I wipe all the files in /data/db and restart the mongod process to resync the data. Everything looks ok, I get the same number of documents as the existing two sets(primary and one secondary). However, when I check the memory on MMS. it shows me my new resynced set/mongod process has a different memory status value than the other two. For existing twos using db.serverStatus.mem shows like the following: "mem" : { "bits" : 64, "resident" : 239, "virtual" : 66348, "supported" : true, "mapped" : 32865, "mappedWithJournal" : 65730 } however, the new resynced set shows like: "mem" : { "bits" : 64, "resident" : 1239, "virtual" : 52447, "supported" : true, "mapped" : 25700, "mappedWithJournal" : 51400 } the resynced resident memory is 6-10 times more than the existing ones. I wouder if it is normal because all data comes in suddenly during the resyncing?? and even virtual and mapped value are different too. Can anyone explain?? thanks

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