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• Can I combine values from multiple rows in another table into multiple columns of one row using SQL?

  - by Jordi

  I have two tables: T1: | M_ID | P_ID1 | P_ID2 | rest of T1 columns | | 0 | 0 | 1 | ... | | 1 | 2 | 3 | ... | T2: | P_ID | Type | A | B | | 0 | 1 | a | e | | 1 | 2 | b | f | | 2 | 1 | c | g | | 3 | 2 | d | h | Now, I want to have a query that selects this: | M_ID | P_1a | P_1b | P_2a | P_2b | rest of T1 columns | | 0 | a | e | b | f | ... | | 1 | c | g | c | h | ... | So, in words: I want to select all columns from T1, but I want to replace P_ID1 with the columns from T2, where the P_ID is equal to P_ID1, and the type is 1, and basically the same for P_ID2. I can obviously get the information I need with multiple queries, but I was wondering if there is a way that I can do this with one query. Any ideas? I'm currently using SQL Server 2008r2, but I'd also be interested in solutions for other database software. Thanks for the help!

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• Expression Tree : C#

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally when our LINQ to SQL query compiler translates it to parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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• codeigniter: how to redirect after login to current controller (php_self in regular php)

  - by krike

  Well it's not really a problem but I check if the user exist and log them in and redirect to site/members_area, but I don't want to send the user to a specific page but i want to reload the current controller. So if I login in index/home I would like to be redirected at index/home, how should I proceed? in regular php I would put in the action to redirect to current page <?php echo $_SERVER['PHP_SELF']; ?> This is the code in the framework function validate_credentials() { $this->load->model('membership_model'); $query = $this->membership_model->validate(); if($query) // if the user's credentials validated... { $data = array( 'username' => $this->input->post('username'), 'is_logged_in' => true ); $this->session->set_userdata($data); redirect('site/members_area'); //<-- this line here should be dynamic } else // incorrect username or password { $this->index(); } }

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• IQueryable and lazy loading

  - by Nelson

  I'm having a hard time determining the best way to handle this... With Entity Framework (and L2S), LINQ queries return IQueryable. I have read various opinions on whether the DAL/BLL should return IQueryable, IEnumerable or IList. Assuming we go with IList, then the query is run immediately and that control is not passed on to the next layer. This makes it easier to unit test, etc. You lose the ability to refine the query at higher levels, but you could simply create another method that allows you to refine the query and still return IList. And there are many more pros/cons. So far so good. Now comes Entity Framework and lazy loading. I am using POCO objects with proxies in .NET 4/VS 2010. In the presentation layer I do: foreach (Order order in bll.GetOrders()) { foreach (OrderLine orderLine in order.OrderLines) { // Do something } } In this case, GetOrders() returns IList so it executes immediately before returning to the PL. But in the next foreach, you have lazy loading which executes multiple SQL queries as it gets all the OrderLines. So basically, the PL is running SQL queries "on demand" in the wrong layer. Is there any sensible way to avoid this? I could turn lazy loading off, but then what's the point of having this "feature" that everyone was complaining EF1 didn't have? And I'll admit it is very useful in many scenarios. So I see several options: Somehow remove all associations in the entities and add methods to return them. This goes against the default EF behavior/code generation and makes it harder to do some composite (multiple entity) LINQ queries. It seems like a step backwards. I vote no. If we have lazy loading anyway which makes it hard to unit test, then go all the way and return IQueryable. You'll have more control farther up the layers. I still don't think this is a good option because IQueryable ties you to L2S, L2E, or your own full implementation of IQueryable. Lazy loading may run queries "on demand", but doesn't tie you to any specific interface. I vote no. Turn off lazy loading. You'll have to handle your associations manually. This could be with eager loading's .Include(). I vote yes in some specific cases. Keep IList and lazy loading. I vote yes in many cases, only due to the troubles with the others. Any other options or suggestions? I haven't found an option that really convinces me.

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• How to calculate change in ANSI SQL

  - by morpheous

  I have a table that contains sales data. The data is stored in a table that looks like this: CREATE table sales_data ( sales_time timestamp , sales_amt double ) I need to write parameterized queries that will allow me to do the following: Return the change in sales_amt between times t2 and t1, where t2 and t1 are separated by a time interval (integer) of N. This query will allow for querying for weekly changes in sales (for example). Return the change in change of sales_amt between times t2 and t1, and time t3 and t4. Thats is to calculate the value (val(t2)-val(t1)) - (val(t4)-val(t3)). where t2 and t1 are separated by the same time interval (interval N) as the interval between t4 and t3. This query will allow for querying for changes in weekly changes in sales (for example).

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• ASP.NET Website no Response while Processing Long Process

  - by Ammar

  Dear Programmers, When my Application face a long-time process, i.e fetch a query (SELECT a, b, c FROM d) This query needs 10 seconds to be completed in the MSSQL Management Studio, but when the ASP.NET application try to fetch it, it refuse to return any response to any other requests made on that Server. I am hosting my Application on VPS Server with good specifications, and I am giving this example the (SELECT a, b, c FROM d) just to tell you the issue, it can be any process, maybe processing a movie, or even fetching some data through external API that is experiencing some slow-down,or whatever. Any help or suggestions would be highly appreciated.

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• Get a list of documents from Mongo DB

  - by Andrei Neagu

  Hello, I want to do something like this: List<int> fff = new List<int>(); fff.Add(1); fff.Add(2); fff.Add(5); Mongo m = new Mongo(); m.Connect(); var dataBase = m.GetDatabase("database"); var collection = dataBase.GetCollection("coll"); IMongoQuery queryable = collection.AsQueryable(); MongoQueryProvider prov = new MongoQueryProvider(collection); var query = new MongoQuery(prov); var ffppp = from p221 in query where fff.Contains((int)p221["oid"]) select p221; This throws this error : The method 'Contains' could not be converted into a constant. I saw that mongo has an operator $in. Does any one know how can I use it from c#? (http://www.mongodb.org/display/DOCS/Advanced+Queries) Thanks

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• CONTAINSTABLE with wildcard works different in SQLServer 2005 and SQLServer 2008?

  - by musuk

  I have two same databases one on SQLServer 2005 and one on SqlServer 2008, it have same SQL_Latin1_General_CP1_CI_AS Collation, and full text search catalogs have the same settings. These two databases contains table with same data, NTEXT string: "...kræve en forklaring fra miljøminister Connie Hedegaard.." My problem is: CONTAINSTABLE on SQLServer 2008 finds nothing if query is: select * from ContainsTable(SearchIndex_7, Content, '"miljø*"') ct but SQLServer 2005 works perfectly and finds necessary record. SQLServer 2008 finds necessary record if query is: select * from ContainsTable(SearchIndex_7, Content, '"milj*"') ct or select * from ContainsTable(SearchIndex_7, Content, '"miljøminister"') What can be reason for so strange behavior?

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• How to figure the read/write ratio in Sql Server?

  - by Bill Paetzke

  How can I query the read/write ratio in Sql Server 2005? Are there any caveats I should be aware of? Perhaps it can be found in a DMV query, a standard report, a custom report (i.e the Performance Dashboard), or examining a Sql Profiler trace. I'm not sure exactly. Why do I care? I'm taking time to improve the performance of my web app's data layer. It deals with millions of records and thousands of users. One of the points I'm examining is database concurrency. Sql Server uses pessimistic concurrency by default--good for a write-heavy app. If my app is read-heavy, I might switch it to optimistic concurrency (isolation level: read uncommitted snapshot) like Jeff Atwood did with StackOverflow.

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• What types of programming contest problems are there?

  - by Alex

  Basically, I want to make a great reference for use with programming contests that would have all of the algorithms that I can put together that I would need during a contest as well as sample useage for the code. I'm planning on making this into a sort of book that I could print off and take with me to competitions. I would like to do this rather than simply bringing other books (such as Algorithms books) because I think that I will learn a lot more by going over all of the algorithms myself as well as I would know exactly what I have in the book, making it more efficient to have and use. So, I've been doing research to determine what types of programming problems and algorithms are common on contests, and the only thing I can really find is this (which I have seen referenced a few times): Hal Burch conducted an analysis over spring break of 1999 and made an amazing discovery: there are only 16 types of programming contest problems! Furthermore, the top several comprise almost 80% of the problems seen at the IOI. Here they are: Dynamic Programming Greedy Complete Search Flood Fill Shortest Path Recursive Search Techniques Minimum Spanning Tree Knapsack Computational Geometry Network Flow Eulerian Path Two-Dimensional Convex Hull BigNums Heuristic Search Approximate Search Ad Hoc Problems The most challenging problems are Combination Problems which involve a loop (combinations, subsets, etc.) around one of the above algorithms - or even a loop of one algorithm with another inside it. These seem extraordinarily tricky to get right, even though conceptually they are ``obvious''. Now that's good and all, but that study was conducted in 1999, which was 13 years ago! One thing I know is that there are no BigNums problems any more (as Java has a BigInteger class, they have stopped making those problems). So, I'm wondering if anyone knows of any more recent studies of the types of problems that may be seen in a programming contest? Or what the most helpful algorithms on contests would be?

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• ASP.Net Layered app - Share Entity Data Model amongst layers

  - by Chris Klepeis

  How can I share the auto-generated entity data model (generated object classes) amongst all layers of my C# web app whilst only granting query access in the data layer? This uses the typical 3 layer approach: data, business, presentation. My data layer returns an IEnumerable<T> to my business layer, but I cannot return type T to the presentation layer because I do not want the presentation layer to know of the existence of the data layer - which is where the entity framework auto-generated my classes. It was recommended to have a seperate layer with just the data model, but I'm unsure how to seperate the data model from the query functionality the entity framework provides.

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• nth smallest number among two databases of size n each using divide and conquer

  - by urfriend

  we have two databases of size n containing numbers without repeats. So, in total we have 2n elements. They can be accessed through a query to one database at a time. The query is such that you give it a k and it returns kth smallest entry in that database. we need to find nth smallest entry among all the 2n elements in O(logn) queries. the idea is to use divide and conquer but i need some help thinking through this. thanks!

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• Unable to execute fetch(PDO::FETCH_ASSOC) and not updating csv file.

  - by Rachel

  // First, prepare the statement, using placeholders $query = "SELECT * FROM tableName"; $stmt = $this->connection->prepare($query); // Execute the statement $stmt->execute(); var_dump($stmt->fetch(PDO::FETCH_ASSOC)); while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) { echo "Hi"; // Export every row to a file fputcsv($data, $row); } Is this correct way to do and if yes than why do I get false value for var_dump and than it does not go into while loop and does not write into csv file. Any suggestions ?

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• not returning anything from postgresql function?

  - by netllama

  Is it possible for a PostgreSQL plpgsql function to not return anything? I've created a function, and I don't need it to return anything at all, as it performs a complex SQL query, and inserts the results of that query into another table (SELECT INTO ....). Thus, I have no need or interest in having the function return any output or value. Unfortunately, when I try to omit the RETURN clause of the function declaration, I can't create the function. Is it possible for a PostgreSQL plpgsql function to not return anything?

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• Enumerable Contains Enumerable

  - by Tim

  For a method I have the following parameter IEnumerable<string> tags and with to query a list of objects, let's call them Post, that contains a property IEnumerable<string> Tags { get; set; }. My question is: How do I use linq to query for objects that contains all the tags from the tags parameter? private List<Post> posts = new List<Post>(); public IEnumerable<Post> GetPostsWithTags(IEnumerable<string> tags) { return ???; }

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• Google app engine and paging

  - by klausbyskov

  How would one go about writing a query that selects items 2000-2010 out of a collection of 10000 objects in the data store. I know that it can be done like this in GQL: select * from MyObject limit 10 offset 2000 According to the documentation, when using an offset the engine will still fetch all the rows, only not return them, thus making the query perform in a way that corresponds linearly with the value of offset. Is there any better way? Such as using a pseudo ROWNUM column like one could do in other types of data stores.

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• retrieve contact's nickname

  - by TomTasche

  Hello, I want to get the nickname of a contact from addressbook. I start with his phone number, query it and want the nickname (aka alias) as a result. Cursor cur = context.getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.NUMBER + " = " + incomingNumber, null, null); if (cur.moveToFirst()) { Log.e("saymyname", cur.getString(cur.getColumnIndex(ContactsContract.CommonDataKinds.Nickname.NAME))); Log.e("saymyname", cur.getString(cur.getColumnIndex(ContactsContract.CommonDataKinds.Nickname.LABEL))); } Output of the logs is the incomingNumber (first Log.e() ) and null (second Log.e() ), but I want to get the contact's nickname! Thanks Tom

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• Fatal error: Function name must be a string in.. PHP error

  - by Jonesy

  Hi I have a class called User and a method called insertUser(). function insertUser($first_name, $last_name, $user_name, $password, $email_address, $group_house_id) { $first_name = mysql_real_escape_string($first_name); $last_name = mysql_real_escape_string($last_name); $user_name = mysql_real_escape_string($user_name); $password = mysql_real_escape_string($password); $email_address = mysql_real_escape_string($email_address); $query = "INSERT INTO Users (FirstName,LastName,UserName,Password,EmailAddress, GroupHouseID) VALUES ('$first_name','$last_name','$user_name','$password','$email_address','$group_house_id')"; $mysql_query($query); } And I call it like this: $newUser = new User(); $newUser->insertUser($first_name, $last_name, $user_name, $email, $password, $group_house_id); When I run the code I get this error: Fatal error: Function name must be a string in /Library/WebServer/Documents/ORIOnline/includes/class_lib.php on line 33 Anyone know what I am doing wronly? Also, this is my first attempt at OO PHP. Cheers, Jonesy

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• Rails relation select

  - by Dimitar Vouldjeff

  Hi, I have the following models: class User < ActiveRecord::Base has_many :results, :dependent => :destroy has_many :participants, :dependent => :destroy has_many :courses, :through => :participants end class Course < ActiveRecord::Base has_many :tests, :dependent => :destroy has_many :participants, :dependent => :destroy has_many :users, :through => :participants end class Result < ActiveRecord::Base belongs_to :test belongs_to :user end class Test < ActiveRecord::Base belongs_to :course has_many :results, :dependent => :destroy end The Idea is that a user has_and_belongs_to_many courses, the course has_many tests, and every test has_and_belongs_to_many users (results). So what is the best query to select every Result from a single Course (not test), and also the query to select every Result from a single Course, but from one user. Thanks!

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• problem in counting children category

  - by moustafa

  I have this table: fourn_category (id , sub) I am using this code to count: function CountSub($id){ $root = array($id); $query = mysql_query("SELECT id FROM fourn_category WHERE sub = '$id'"); while( $row = mysql_fetch_array( $query, MYSQL_ASSOC ) ){ array_push($root,$row['id']); CountSub($row['id']); } return implode(",",$root); } It returns the category id as 1,2,3,4,5 to using it to count the sub by IN() But the problem is that it counts this: category 1 category 2 category 3 category 4 category 5 Category 1 has 1 child not 4. Why? How can I get all children's trees?

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• Pear MDB2 class and raiserror exceptions in SQL Server

  - by drholzmichl

  Hi, in SQL Server it's possible to raise an error with raiserror(). I want to use a severity, which doesn't interrupt the connection. This error is raised in a stored procedure. In SQL Management Studio all is fine and I get my error code when executing this SP. But when trying to execute this SP via MDB2 in PHP5 this doesn't work. All I get is an empty array. MDB2 object is created via (including needed options): $db =& MDB2::connect($dsn); $db->setFetchMode(MDB2_FETCHMODE_ASSOC); $db->setOption('portability',MDB2_PORTABILITY_ALL ^ MDB2_PORTABILITY_EMPTY_TO_NULL); The following works (I get a PEAR error): $db->query("RAISERROR('test',11,0);"); But when calling a stored procedure which raises this error via $db->query("EXEC sp_raise_error"); there is not output. What's wrong?

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• NHibernate Overcoming NotSupportedException

  - by Jordan Wallwork

  Does anyone know of any way to overcome NotSupportedException? I have a method against a User: public virtual bool IsAbove(User otherUser) { return HeirarchyString.StartsWith(otherUser.HeirarchyString); } And I want to do: _session.Query<User>.Where(x => loggedInUser.IsAbove(x)); But this throws a NotSupportedException. The real pain though is that using _session.Query<User>.Where(x => loggedInUser.HeirarchyString.StartsWith(x.HeirarchyString)); works absolutely fine. I don't like this as a solution, however, because it means that if I change how the IsAbove method works, I have to remember all the places where I have duplicated the code whenever I want to update it

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• Equivalent of mysql_insert_id() for Postgresql ? [closed]

  - by xRobot

  Possible Duplicate: mysql_insert_id alternative for postgresql Is there a Postgresql equivalent of mysql_insert_id() to get the ID generated in the last query ??

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• SQl rows to columns conversion

  - by Thihara

  Hi, I have a table ClassAttendance and I'm using MSSQL 2005 studentID--attendanceDate---------------------------------------status 1004--------2010-03-17--------------------------------------------------0 1005--------2010-03-17--------------------------------------------------1 1006--------2010-03-17--------------------------------------------------0 1007--------2010-03-17--------------------------------------------------0 1004--------2010-03-19--------------------------------------------------0 1005--------2010-03-19--------------------------------------------------1 1006--------2010-03-19--------------------------------------------------0 1007--------2010-03-19--------------------------------------------------0 1004--------2010-03-20--------------------------------------------------1 as you can see studentID is a foreign Key for a table called StudentData and attendedDate has an unknown number of rows. Can i get the output like below by using a query? I need the dates in one month to be columns and the value of the date columns will be values in the status column. The number of date records per studentID is the same its the number of dates in the attendanceDate filed that is unknown. studentID---------2010-03-17--------2010-03-19------2010-03-20 1004-----------------------------0----------------------0--------------------1 etc. This is for a creating a report so I need to do it in a query. Please help if you can.

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• How can I compare my PHPASS-hashed stored password to my incoming POST data?

  - by Ygam

  Here's a better example, just a simple checking..stored value in database has password: fafa (hashed with phpass in registration) and username: fafa; i am using the phpass password hashing framework public function demoHash($data) //$data is the post data named password { $hash =new PasswordHash(8, false); $query = ORM::factory('user'); $result = $query ->select('username, password') ->where('username', 'fafa') ->find(); $hashed = $hash->HashPassword($data); $check = $hash->CheckPassword($hashed, $result->password); echo $result->username . "<br/>"; echo $result->password . "<br/>"; return $check; } check is returning false

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