Search Results

Search found 7116 results on 285 pages for 'nested queries'.

Page 197/285 | < Previous Page | 193 194 195 196 197 198 199 200 201 202 203 204  | Next Page >

• Programming languages & proof of concepts

  - by Mike

  There are plenty of programming languages out there, as you all may know. I am primarily looking for a list of programming languages WITH some very neat proof of concepts. I would really like to learn a new language, but whenever I dive into something new and popular, it isn't what I expected. Any tutorial out there will give you code, small examples, but won't show you the true power of the language. I am looking for examples that run entirely on the language that it is exemplifying. For example, If I said C#, I could possibly show you a complete C# app with backend queries, reports, tables, all with a nice interface. It would be completely reliant on the language that is provided, so no supporting languages. I understand that most languages are integrated with other languages in order to provide a richer application. Any links, charts, websites that may reflect this request is appreciated.

  Read the article

• Complicated conditional SQL query

  - by DevAno1

  I'm not even sure if it's possible but I need it for my Access database. So I have following db structure : Now I need to perform a query that takes category_id from my product and do the magic : - let's say product belongs to console (category_id is in table Console) - from console_types take type_id, where category_id == category_id - but if product belongs to console_game (category_id is in table console_game) - from console_game take game_cat_id, where category_id == category_id I'm not sure if mysql is capable of such thing. If not I'm really f&%ranked up. Maybe there is a way to split this into 2,3 separate queries ?

  Read the article

• java jdbc connection to mysql problem

  - by fatnjazzy

  Hi, I am trying to connect to mysql from java web application in eclipse. Connection con = null; try { //DriverManager.registerDriver(new com.mysql.jdbc.Driver()); Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://localhost/db_name","root" ,""); if(!con.isClosed()) System.out.println("Successfully connected to " + "MySQL server using TCP/IP..."); } catch(Exception e) { System.err.println("Exception: " + e.getMessage()); } finally { try { if(con != null) con.close(); } catch(SQLException e) { System.out.println(e.toString()); } } I am always getting the Exception: com.mysql.jdbc.Driver I have downloaded this jar http://forums.mysql.com/read.php?39,218287,220327 import it to the "java build path/lib" the mysql version is 5.1.3 under. running: mysql 5.1.3 (db is up and running queries form PHP) windows XP java jee Thanks

  Read the article

• Group by date range on weeks/months interval

  - by khelll

  I'm using MySQL and I have the following table: | clicks | int | | day | date | I want to be able to generate reports like this, where periods are done in the last 4 weeks: | period | clicks | | 1/7 - 7/5 | 1000 | | 25/6 - 31/7 | .... | | 18/6 - 24/6 | .... | | 12/6 - 18/6 | .... | or in the last 3 months: | period | clicks | | July | .... | | June | .... | | April | .... | Any ideas how to make select queries that can generate the equivalent date range and clicks count?

  Read the article

• Help with grasping (INNER?) JOIN

  - by Greenie

  I'm having trouble building a query. I can do what I want in 3 different queries. SELECT id FROM table1 WHERE url LIKE '%/$downloadfile' put that in $url_id SELECT item_id FROM table2 WHERE rel_id = '$url_id'" put that in $item_id SELECT rel_id FROM table2 WHERE rel_id = '$item_id' AND field_id = '42'" put that in $user_id But from reading examples on joins and inner joins I think there's a more elegant way. I cant wrap my brain around writing a better query (but would like to) I can describe how it should go: table1 fields: id, url table2 fields item_id, rel_id, field_id I know the last part of table1.url (LIKE '%/$filename') with that I select table1.id. table1.id is equal to one entry in table2.rel_id. So get that and select the table2.item_id. In table2 there is another entry which has the same table2.item_id and it will have a table2.field_id = '42' And finally the value I need is the table2.rel_id where the table2.field_id was 42. I will fetch that value and put it in $user_id Can this be done with one query using joins/inner joins?

  Read the article

• pipelined function

  - by user289429

  Can someone provide an example of how to use parallel table function in oracle pl/sql. We need to run massive queries for 15 years and combine the result. SELECT * FROM Table(TableFunction(cursor(SELECT * FROM year_table))) ...is what we want effectively. The innermost select will give all the years, and the table function will take each year and run massive query and returns a collection. The problem we have is that all years are being fed to one table function itself, we would rather prefer the table function being called in parallel for each of the year. We tried all sort of partitioning by hash and range and it didn't help. Also, can we drop the keyword PIPELINED from the function declaration? because we are not performing any transformation and just need the aggregate of the resultset.

  Read the article

• How to flush data in php and disconnect user but keep the script alive

  - by Rodrigo

  This is a trick question, while developing a php+ajax application i felt into some long queries, nothing wrong with them, but they could be done in background. I know that there's a way to just send a reply to user while throwing the real processing to another process by exec(), however it dosen't feels right for me, this might generate exploits and it's not pratical on making it compatible with virtual servers and cross platform. PHP offers the ob_* functions although they help on flushing the cache, but the user will keep connected until the script is running. I'm wondering if there's an alternate to exec to keep a script running after sending data to user and closing connection/thread with apache, or a less "dirty" way to have processing data sent to another script.

  Read the article

• Compare range of ip addresses with start and end ip address in MySQL

  - by Maarten

  I have a MySQL table where I store IP ranges. It is setup in the way that I have the start address stored as a long, and the end address (and an id and some other data). Now I have users adding ranges by inputting a start and end ip address, and I would like to check if the new range is not already (partially) in the database. I know I can do a between query, but that doesn't seem to work with 2 different columns, and I also cannot figure out how to pass a range to compare it. Doing it in a loop in PHP is a possibility, but would with a range of e.g. 132.0.0.0-199.0.0.0 be quite a big amount of queries..

  Read the article

• Instrumenting Database Access

  - by Whisk

  Jeff mentioned in one of the podcasts that one of the things he always does is put in instrumentation for database calls, so that he can tell what queries are causing slowness etc. This is something I've measured in the past using SQL Profiler, but I'm interested in what strategies other people have used to include this as part of the application. Is it simply a case of including a timer across each database call and logging the result, or is there a 'neater' way of doing it? Maybe there's a framework that does this for you already, or is there a flag I could enable in e.g. Linq-to-SQL that would provide similar functionality. I mainly use c# but would also be interested in seeing methods from different languages, and I'd be more interested in a 'code' way of doing this over a db platform method like SQL Profiler.

  Read the article

• Is it OK to allow users to query an OLTP SQL Server database with excel?

  - by user169867

  I have a SQL Server 2005 database used by several applications. Some users wish to query the database directly from excel. I can understand this, because it is a useful tool for adhoc queries and then getting the data in a format that's easily transmitted and manipulated by other users. My question is: Does Excel (say 2003/2007) do its querying in a way that won't cause concurency issues? Or is it done in such a way that a seperate datawarehouse database needs to be made to handle this scenario? Thanks for any advise.

  Read the article

• HBase as web app backend

  - by NathanD

  Can anyone advise if it is a good idea to have HBase as primary data source for web-based application? My primary concern is HBase's response time to queries. Is it possible to have sub-second response? edit: more details about the app itself. Amount of data: ~500GB of text data, expect to reach 1TB soon Number of concurrent users using the app: up to 50 The app will be used to present reports about data stored in HBase, like how many times keyword "X" occured in last 24h. For ~80% of requests from that app I will know the exact key, 20% will be scans (I'm looking into HBase schema design related topics to make it run fast)

  Read the article

• Help Forming An SQL Query That Selects The Max Difference Of Two Fields

  - by Frank

  I'm trying to select a record with the most effective votes. Each record has an id, the number of upvotes (int) and the number of downvotes (int) in a MySQL database. I know basic update, select, insert queries but I'm unsure of how to form a query that looks something like: SELECT * FROM topics WHERE MAX(topic.upvotes - topic.downvotes). Please excuse my made up SQL. The tutorials on SQL I find on the internet cover very basic stuff. Does anyone recommend a good book on this subject?

  Read the article

• OOP App Architecture: Which layer does a lazy loader sit in?

  - by JW

  I am planning the implemention an Inheritance Mapper pattern for an application component http://martinfowler.com/eaaCatalog/inheritanceMappers.html One feature it needs to have is for a domain object to reference a large list of aggreageted items (10,000 other domain objects) So I need some kind of lazy loading collection to be passed out of the aggregate root domain object to other domain objects. To keep my (php) model scripts organised i am storing them in two folders: MyComponent\ controllers\ models\ domain\ <- domain objects, DDD repository, DDD factory daccess\ <- PoEAA data mappers, SQL queries etc views\ But now I am racking my brains wondering where my lazy loading collection sits. Any suggestions / justifications for putting it in one place over another another? DDD = Domain Driven Design Patterns, Eric Evans - book PoEAA = Patterns of Application Architecture Patterns, Martin Fowler - book

  Read the article

• Building html tables from query data... faster?

  - by Andrew Heath

  With my limited experience/knowledge I am using the following structure to generate HTML tables on the fly from MySQL queries: $c = 0; $t = count($results); $table = '<table>'; while ($c < $t) { $table .= "<tr><td>$results[0]</td><td>$results[1]</td> (etc etc) </tr>"; ++$c; } $table .= '</table>'; this works, obviously. But for tables with 300+ rows there is a noticeable delay in pageload while the script builds the table. Currently the maximum results list is only about 1,100 rows, and the wait isn't long, but there's clearly a wait. Are there other methods for outputting an HTML table that are faster than my WHILE loop? (PHP only please...)

  Read the article

• How to estimate memory need by XPathDocument for a specific xml file

  - by bill seacham

  Is there any way to estimate the memory requirement for creating an XpathDocument instance based on the file size of the xml? XpathDocument xdoc = new XpathDocument(xmlfile); Is there any way to programmatically stop the process of creating the XpathDocument if memory drops to a very low level? Since it loads the entire xml into memory, it would be nice to know ahead of time if the xml is too big. What I have found is that when I create a new XpathDocument with a big xml file, an outofmemory exception is never fired, but that the process slows to a crawl, only 5 Mb of memory remains a available and the Task Manager reports it is not responding. This happened with a 266 Mb xml file when there was 584 Mb of ram. I was able to load a 150 Mb file with no problems in 18. After loading the xml, I want to do xpath queries using an XpathNavigator and an XpathNodeIterator. I am using .net 2.0, xp sp3.

  Read the article

• Aggregate functions in ANSI SQL

  - by morpheous

  I want to use multiple aggregate functions in a query. All the examples i have seem on aggregate functions however, are trivial. Typically, they are of the form: SELECT field1,agg_func1, agg_func2 GROUP BY SOME_COLUMNS HAVING agg_func1 OP SOME_SCALAR Where: OP: is a boolean operator (e.g. <, = etc) SOME_SCALAR: is a scalar (i.e. a constant number) What I want to know is if it is possible to write (IN ANSI SQL) queries like: SELECT field1,agg_func1, agg_func2, agg_func3 GROUP BY SOME_COLUMNS HAVING (agg_func1 OP1 agg_func2) OP2 (agg_func2 OP3 agg_func3) Where: OP[N] are boolean operators or ANSI SQL clause operators like 'BETWEEN', 'LIKE', 'IN' etc. Also, assuming this is possible (I have not seen any documentation saying otherwise) are there any efficiency/performance considerations (i.e. penalties) when the HAVING clause consists of a boolean expression combining the output of the aggregate functions - instead of the normal comparison of the output of the aggregate with a constant number (e.g. min('salary') 100 ) - which is often used in the most banal examples involving aggregate functions?

  Read the article

• Mysql - multiple values and between

  - by realshadow

  Hey, I need to select 10 products and display them. Each product has 3 different prices. The select to get the prices looks like this: SELECT * FROM products_loans WHERE CODE IN('10X15/12', '10X15/Q10-10', '10X15/Q20-10') AND 550 BETWEEN PRICE_FROM AND PRICE_TO; Where 550 is the base price. Now this select returns 3 rows, but I want to modify it so it will return 30 results. I dont like the idea to execute 10 queries at once. I know I can easily achieve that with "OR", but I would like to ask if there is some other more elegant way to this. The select "should" look like this: SELECT * FROM products_loans WHERE KOD IN('10X15/12', '10X15/Q10-10', '10X15/Q20-10') AND (550, 325, 780) BETWEEN CENA_OD AND CENA_DO; Note that there is no "price" column or anything in the table which I could use to do a JOIN and I cant modify the table.

  Read the article

• Adding a MongoDB collection to Netbeans

  - by Saif Bechan

  In Netbeans I have an option to add my mysql databases to netbeans. This way I can easily browse and so small queries. Now I am working on a MongoDB project, and I want to know if it is possible to use the same functionality. I see that on the website of mongo there is a list of drivers, and I see that you can add drivers in netbeans. I do not know if the same thing, or if this can be used. I have tried google, but no luck. Anyone have an idea?

  Read the article

• lambda expression for a query on two tables that returns records from one table

  - by peetee

  I have two tables TableA (articles) int id int Type string name and TableB (compatibles) int linked_ID int tableA_ID TableA records: id=1, Type=0, name="ArticleA" id=2, Type=1, name="ArticleB" id=3, Type=2, name="ArticleC" id=4, Type=1, name="ArticleD" TableB records: linked_ID= 1, tableA_ID=2 linked_ID= 1, tableA_ID=3 linked_ID= 1, tableA_ID=4 TableB has a list of arcicels that are compatible to a certain article. I am quite new to queries (didn't need them in my projects yet). But as C# and WPF allow some pretty cool automation with Binding I would like to add a binding that returns the following: Give me all articles that are of Type 1 and compatible to my selected article (id=1). The simple part of it works well (articles has a list of all articles): private ObservableCollection<Article> _articles = new ObservableCollection<Article>(); [fill it with the available articles] and then: comboBoxArticles.ItemsSource = _articles.AsBindable().Where( c => c.Typ == 0 ); How can I extend the Where clause to query another table? Thanks a lot in advance.

  Read the article

• HQL updates and domain objects

  - by CaptainAwesomePants

  I have what may be a pretty elementary Hibernate question. Do HQL (and/or Criteria) update queries cause updates to live domain objects? And do they automatically flush now-invalid domain objects from the first-level cache? Example: Player playerReference1 = session.get(Player.class,1); session.createQuery("update players set gold = 100").executeUpdate(); //Question #1 -- does playerReference1.getGold() now return 100? Player playerReference2 = session.get(Player.class,1); //Question #2 -- does playerReference2.getGold() return 100, or is it the same exact object? Should I make a practice of evicting all objects that are affected by an HQL update if there's a chance some code will need it later?

  Read the article

• Duplicate an AppEngine Query object to create variations of a filter without affecting the base quer

  - by Steve Mayne

  In my AppEngine project I have a need to use a certain filter as a base then apply various different extra filters to the end, retrieving the different result sets separately. e.g.: base_query = MyModel.all().filter('mainfilter', 123) Then I need to use the results of various sub queries separately: subquery1 = basequery.filter('subfilter1', 'xyz') #Do something with subquery1 results here subquery2 = basequery.filter('subfilter2', 'abc') #Do something with subquery2 results here Unfortunately 'filter()' affects the state of the basequery Query instance, rather than just returning a modified version. Is there any way to duplicate the Query object and use it as a base? Is there perhaps a standard Python way of duping an object that could be used? The extra filters are actually applied by the results of different forms dynamically within a wizard, and they use the 'running total' of the query in their branch to assess whether to ask further questions. Obviously I could pass around a rudimentary stack of filter criteria, but I'd rather use the Query itself if possible, as it adds simplicity and elegance to the solution.

  Read the article

• Why does SQLAlchemy with psycopg2 use_native_unicode have poor performance?

  - by Bob Dover

  I'm having a difficult time figuring out why a simple SELECT query is taking such a long time with sqlalchemy using raw SQL (I'm getting 14600 rows/sec, but when running the same query through psycopg2 without sqlalchemy, I'm getting 38421 rows/sec). After some poking around, I realized that toggling sqlalchemy's use_native_unicode parameter in the create_engine call actually makes a huge difference. This query takes 0.5secs to retrieve 7300 rows: from sqlalchemy import create_engine engine = create_engine("postgresql+psycopg2://localhost...", use_native_unicode=True) r = engine.execute("SELECT * FROM logtable") fetched_results = r.fetchall() This query takes 0.19secs to retrieve the same 7300 rows: engine = create_engine("postgresql+psycopg2://localhost...", use_native_unicode=False) r = engine.execute("SELECT * FROM logtable") fetched_results = r.fetchall() The only difference between the 2 queries is use_native_unicode. But sqlalchemy's own docs state that it is better to keep use_native_unicode=True (http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html). Does anyone know why use_native_unicode is making such a big performance difference? And what are the ramifications of turning off use_native_unicode?

  Read the article

• Embedded MongoDB when running integration tests

  - by seanhodges

  My question is a variation of this one. Since my Java Web-app project requires a lot of read filters/queries and interfaces with tools like GridFS, I'm struggling to think of a sensible way to simulate MongoDB in the way the above solution suggests. Therefore, I'm considering running an embedded instance of MongoDB alongside my integration tests. I'd like it to start up automatically (either for each test or the whole suite), flush the database for every test, and shut down at the end. These tests might be run on development machines as well as the CI server, so my solution will also need to be portable. Can anyone with more knowledge on MongoDB help me get idea of the feasibility of this approach, and/or perhaps suggest any reading material that might help me get started? I'm also open to other suggestions people might have on how I could approach this problem...

  Read the article

• LINQ to Entity, joining on NOT IN tables

  - by SlackerCoder

  My brain seems to be mush right now! I am using LINQ to Entity, and I need to get some data from one table that does NOT exist in another table. For example: I need the groupID, groupname and groupnumber from TABLE A where they do not exist in TABLE B. The groupID will exist in TABLE B, along with other relevant information. The tables do not have any relationship. In SQL it would be quite simply (there is a more elegant and efficient solution, but I want to paint a picture of what I need) SELECT GroupID, GroupName, GroupNumber, FROM TableA WHERE GroupID NOT IN (SELECT GroupID FROM TableB) Is there an easy/elegant way to do this? Right now I have a bunch of queries hitting the db, then comparing, etc. It's pretty messy. Thanks.

  Read the article

• ASP.NET Thread Safety in aspx.cs code behind file

  - by Tim Michalski

  I am thinking of adding a DataContext as a member variable to my aspx.cs code-behind class for executing LinqToSql queries. Is this thread safe? I am not sure if a new instance of this code-behind class is created for each HTTP request, or if the instance is shared amongst all request threads? My fear is that I will get 10 simultaneous concurrent http requests that will be using the same database session. public partial class MyPage : System.Web.UI.Page { private DataContext myDB = new DataContext(); protected void MyAction_Click(object sender, EventArgs e) { myDB.DoWork(); } }

  Read the article

< Previous Page | 193 194 195 196 197 198 199 200 201 202 203 204  | Next Page >