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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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  • 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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  • make db connection persistent throught zend framework

    - by kamikaze_pilot
    I'm using zend framework. currently everytime I need to use the db I go ahead and connect to the DB: function connect(){ $connParams = array("host" => $host, "port" => $port, "username" => $username, "password" => $password, "dbname" => $dbname); $db = new Zend_Db_Adapter_Pdo_Mysql($connParams); return $db } so I would just call the connect() function everytime I need to use the db My question is...suppose I want to reuse $db everywhere in my site and only connect once in the very initial stage of the site load and then close the connection right before the site gets sent to the user, what would be the best practice to accomplish this? Which file in Zend should I save $db in, what method should I use to save it (global variable?), and which file should I do the connection closing in?

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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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  • Using a variable derived from a drop-down list as the column name in a select statement ... Access DB

    - by user1459698
    I'm working with the world's worst DB that was already here so don't blame me for that. So, here's what I have so far ... module = txtModule.value presstype = txtPressType.value SQL_query = "SELECT * FROM tbl_spareparts WHERE '"& module &"' <> '""' AND '"& module &"' = '"& presstype &"' AND Manufacturer = '"& txtsrch.value &"' ORDER BY SAP_Part_No" Set rsData = conn.Execute(SQL_query) This brings up the following SQL statement: SELECT * FROM tbl_spareparts WHERE 'Banyan_Module' <> '"' AND 'Banyan_Module' = 'PB' AND Manufacturer = 'Tester' ORDER BY SAP_Part_No Is there any way I can use the module variable as a column name - obviously the ''s around the column name are causing an error. This is really bothering me. BTW, I'm writing this in VBScript inside a .HTA application page as it has to run locally on tech PCs. Thanks. R.

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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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  • 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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  • MySQL query problem

    - by Luke
    Ok, I have the following problem. I have two InnoDB tables: 'places' and 'events'. One place can have many events, but event can be created without entering place. In this case event's foreign key is NULL. Simplified structure of the tables looks as follows: CREATE TABLE IF NOT EXISTS `events` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, `places_id` int(9) unsigned DEFAULT NULL, PRIMARY KEY (`id`), KEY `fk_events_places` (`places_id`), ) ENGINE=InnoDB; ALTER TABLE `events` ADD CONSTRAINT `events_ibfk_1` FOREIGN KEY (`places_id`) REFERENCES `places` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS `places` ( `id` int(9) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`id`), ) ENGINE=InnoDB; Question is, how to construct query which contains name of the event and name of the corresponding place (or no value, in case there is no place assigned?). I am able to do it with two queries, but then I am visibly separating events which have place assigned from the ones that are without place. Help really appreciated.

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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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  • 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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  • Hibernate Auto-Increment not working

    - by dharga
    I have a column in my DB that is set with Identity(1,1) and I can't get hibernate annotations to work for it. I get errors when I try to create a new record. In my entity I have the following. @GeneratedValue(strategy=GenerationType.IDENTITY, generator="native") @Column(name="SeqNo", unique=true, nullable=false) BigDecimal seqNo; But when I try to add a new record I get the following error. Cannot insert explicit value for identity column in table 'MemberSelectedOptions' when IDENTITY_INSERT is set to OFF. I don't want to set IDENTIY_INSERT to ON because I want the identity column in the db to manage the values. The SQL that is run is the following; where you can clearly see the insert. insert into dbo.MemberSelectedOptions (OptionStatusCd, EffectiveDate, TermDate, SelectionStatusDate, SysLstUpdtUserId, SysLstTrxDtm, SourceApplication, GroupId, MemberId, OptionId, SeqNo) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) What am I missing?

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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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  • Virtual directories as DB queries

    I have a site, e.g. site.com I would like users to be able to access it in their locale at site.com/somecity This is similar to craigslist, but they do it with subdomains e.g. sfbay.craigslist.org Using Apache HTTP server. MySql for DB. If you can provide a brief explanation and perhaps links to more thorough discussions, I would be quite interested in learning. I'm developing a web-app and wonder if I should focus some time to read up on Apache, or should I focus more of my time on server-side programming. Thanks!

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  • How to query range of data in DB2 with highest performance?

    - by Fuangwith S.
    Usually, I need to retrieve data from a table in some range; for example, a separate page for each search result. In MySQL I use LIMIT keyword but in DB2 I don't know. Now I use this query for retrieve range of data. SELECT * FROM( SELECT SMALLINT(RANK() OVER(ORDER BY NAME DESC)) AS RUNNING_NO , DATA_KEY_VALUE , SHOW_PRIORITY FROM EMPLOYEE WHERE NAME LIKE 'DEL%' ORDER BY NAME DESC FETCH FIRST 20 ROWS ONLY ) AS TMP ORDER BY TMP.RUNNING_NO ASC FETCH FIRST 10 ROWS ONLY but I know it's bad style. So, how to query for highest performance?

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  • SQL clone record with a unique index

    - by Milhous
    Is there a clean way of cloning a record in SQL that has an index(auto increment). I want to clone all the fields except the index. I currently have to enumerate every field, and use that in an insert select, and I would rather not explicitly list all of the fields, as they may change over time.

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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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  • Fastest way to store/retrieve a dictionary - SQL, text file...?

    - by AP257
    Hi all, This is a really really super dumb question, so I apologise, but I'd be grateful for some advice. I've got a text file of words and word frequencies. It's very large - theoretically we're talking millions of rows. I just want to retrieve values from the file, and do it as quickly and efficiently as possible (for a web app, in Django). My question is: what is the best way to store and retrieve the values? Should import them into SQL? Or keep the file and use grep? Or put them into a JSON dictionary...? Or some other way? Sorry for the dumb question, would be very grateful for advice!

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  • How to find the entity with the greatest primary key?

    - by simpatico
    I've an entity LearningUnit that has an int primary key. Actually, it has nothing more. Entity Concept has the following relationship with it: @ManyToOne @Size(min=1,max=7) private LearningUnit learningUnit; In a constructor of Concept I need to retrieve the LearningUnit with the greatest primary key. If no LearningUnit exists yet I instantiate one. I then set this.learningUnit to the retrieved/instantied. Finally, I call the empty constructor of Concept in a try-catch block, to have the entitymanager do the cardinality check. If an exception is thrown (I expect one in the case that already another 7 Concepts are referring to the same LearningUnit. In that case, I case instantiate a new LearningUnit with a new greater primary key. Please, also point out, if any, clear pitfalls in my outlined algorithm above.

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  • Can't create a MySQL query that generates 4 rows for each row in the table it references.

    - by UkraineTrain
    I need to create a MySQL query that generates 4 rows for each row in the table it references. I need some of the information in those rows to repeat and some to be different. In the table each row stands for one day. I need to break the day up in 6 hour increments, hence the four rows for each entry. I need to create one column which for each day will have '12AM', '6AM', '12PM', and '6PM' values and another column will have the corresponding numeric values calculated for those entries. Thanks a lot in advance and I will really appreciate any help on this.

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  • How should I migrate DDL changes from one environment to the next?

    - by Rl
    I make DDL changes using SQL Developer's GUI. Problem is, I need to apply those same changes to the test environment. I'm wondering how others handle this issue. Currently I'm having to manually write ALTER statements to bring the test environment into alignment with the development environment, but this is prone to error (doing the same thing twice). In cases where there's no important data in the test environment I usually just blow everything away, export the DDL scripts from dev and run them from scratch in test. I know there are triggers that can store each DDL change, but this is a heavily shared environment and I would like to avoid that if possible. Maybe I should just write the DDL stuff manually rather than using the GUI?

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  • Mysql- "FLUSH TABLES WITH READ LOCK" started automatically

    - by ming yeow
    I would like to understand how this happened. I was running a query that would take a long time, but should not lock up any table. However, my dbs were practically down - it seems like it was being locked up by "FLUSH TABLES WITH READ LOCK" 03:21:31 select type_id, count(*) from guid_target_infos group by type_id 02:38:11 select type_id, count(*) from guid_infos group by type_id 02:24:29 FLUSH TABLES WITH READ LOCK But i did not start this command. can someone tell me why it was started automatically?

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