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• Do entity collections and object sets implement IQueryable<T>?

  - by Chevex

  I am using Entity Framework for the first time and noticed that the entities object returns entity collections. DBEntities db = new DBEntities(); db.Users; //Users is an ObjectSet<User> User user = db.Users.Where(x => x.Username == "test").First(); //Is this getting executed in the SQL or in memory? user.Posts; //Posts is an EntityCollection<Post> Post post = user.Posts.Where(x => x.PostID == "123").First(); //Is this getting executed in the SQL or in memory? Do both ObjectSet and EntityCollection implement IQueryable? I am hoping they do so that I know the queries are getting executed at the data source and not in memory. EDIT: So apparently EntityCollection does not while ObjectSet does. Does that mean I would be better off using this code? DBEntities db = new DBEntities(); User user = db.Users.Where(x => x.Username == "test").First(); //Is this getting executed in the SQL or in memory? Post post = db.Posts.Where(x => (x.PostID == "123")&&(x.Username == user.Username)).First(); // Querying the object set instead of the entity collection. Also, what is the difference between ObjectSet and EntityCollection? Shouldn't they be the same? Thanks in advance!

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• Unable to save data in database manually and get latest auto increment id, cakePHP

  - by shabby

  I have checked this question as well and this one as well. I am trying to implement the model described in this question. What I want to do is, on the add function of message controller, create a record in thread table(this table only has 1 field which is primary key and auto increment), then take its id and insert it in the message table along with the user id which i already have, and then save it in message_read_state and thread_participant table. This is what I am trying to do in Thread Model: function saveThreadAndGetId(){ //$data= array('Thread' => array()); $data= array('id' => ' '); //Debugger::dump(print_r($data)); $this->save($data); debug('id: '.$this->id); $threadId = $this->getInsertID(); debug($threadId); $threadId = $this->getLastInsertId(); debug($threadId); die(); return $threadId; } $data= array('id' => ' '); This line from the above function adds a row in the thread table, but i am unable to retrieve the id. Is there any way I can get the id, or am I saving it wrongly? Initially I was doing the query thing in the message controller: $this->Thread->query('INSERT INTO threads VALUES();'); but then i found out that lastId function doesnt work on manual queries so i reverted.

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• EF/LINQ: Where() against a property of a subtype

  - by ladenedge

  I have a set of POCOs, all of which implement the following simple interface: interface IIdObject { int Id { get; set; } } A subset of these POCOs implement this additional interface: interface IDeletableObject : IIdObject { bool IsDeleted { get; set; } } I have a repository hierarchy that looks something like this: IRepository<T <: BasicRepository<T <: ValidatingRepository<T (where T is IIdObject) I'm trying to add a FilteringRepository to the hierarchy such that all of the POCOs that implement IDeletableObject have a Where(p => p.IsDeleted == false) filter applied before any other queries take place. My goal is to avoid duplicating the hierarchy solely for IDeletableObjects. My first attempt looked like this: public override IQueryable<T> Query() { return base.Query().Where(t => ((IDeletableObject)t).IsDeleted == false); } This works well with LINQ to Objects, but when I switch to an EF backend I get: "LINQ to Entities only supports casting Entity Data Model primitive types." I went on to try some fancier parameterized solutions, but they ultimately failed because I couldn't make T covariant in the following case for some reason I don't quite understand: interface IQueryFilter<out T> // error { Expression<Func<T, bool>> GetFilter(); } I'd be happy to go into more detail on my more complicated solutions if it would help, but I think I'll stop here for now in hope that someone might have an idea for me to try. Thanks very much in advance!

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• Creating a Mysql view to SELECT coloumns from different tables

  - by user330429

  I need help in constructing a VIEW on 4 tables. The view should contain coloumns: ER.ID, ER.EMPID, ER.CUSTID, ER.STATUS, ER.DATEREPORTED, ER.REPORT, EB.NAME, CR.CUSTNAME, CR.LOCID, CL.LOCNAME, DI.DEPTNAME ALIASES EMP_REPORT ER , EMP_BIO EB, CUST_RECORD CR, CUST_LOC CL, DEPT_ID DI THE DATA MODELS ARE: describe EMP_REPORT; +--------------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | empid | int(11) | NO | | NULL | | | custid | int(11) | NO | | NULL | | | status | varchar(32) | NO | | NULL | | | datereported | bigint(20) | NO | | NULL | | | report | text | YES | | NULL | | +--------------+-------------+------+-----+---------+----------------+ describe EMP_BIO; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | empid | int(11) | NO | PRI | NULL | | | name | varchar(56) | NO | | NULL | | | sex | char(1) | NO | | NULL | | | deptid | int(11) | NO | | NULL | | | email | varchar(32) | NO | | NULL | | | mobile | bigint(20) | YES | | NULL | | | gtlk | varchar(32) | YES | | NULL | | | skype | varchar(32) | YES | | NULL | | | cvid | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ describe CUST_RECORD; +----------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+--------------+------+-----+---------+----------------+ | custid | int(11) | NO | PRI | NULL | auto_increment | | custname | varchar(32) | NO | | NULL | | | address | varchar(255) | YES | | NULL | | | contactp | varchar(32) | YES | | NULL | | | mobile | bigint(20) | YES | | NULL | | | locid | int(11) | NO | | NULL | | | remarks | text | YES | | NULL | | | date | int(11) | YES | | NULL | | | addedby | int(11) | YES | | NULL | | +----------+--------------+------+-----+---------+----------------+ describe CUST_LOC; +---------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------+-------------+------+-----+---------+-------+ | locid | int(11) | NO | PRI | 0 | | | locname | varchar(32) | NO | | NULL | | +---------+-------------+------+-----+---------+-------+ describe DEPT_ID; +----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------+-------------+------+-----+---------+-------+ | deptid | int(11) | NO | | NULL | | | deptname | varchar(32) | YES | | NULL | | +----------+-------------+------+-----+---------+-------+ The table EMP_REPORT contains reports submitted by employees, all the coloumns in it needs to be fetched. The empid in this table should be used to fetch corresponding name in EMP_BIO (employee biodata) table. The custid in EMP_REPORT should be used to fetch corresponding locid in CUST_RECORD(customer record) which is used to fetch locname in CUST_LOC(customer location) table. The empid in EMP_REPORT is used to fetch corresponding deptid in EMP_BIO table which is then used to fetch corresponding deptname from DEPT_ID(department id) table. I tried constructing view using union of different select queries, but dint get proper results. Please help me. Thanks in advance. PS: sorry for my poor english

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• django dynamically deduce SITE_ID according to the domain

  - by dcrodjer

  I am trying to develop a site which will render multiple customized sites according to the domain name (subdomain to be more precise). My all the domain names are redirected to the So for each site there will be a corresponding model which defines how the site should look (SITE - SITE_SETTINGS) What will be the best way to utilize the django sites framework to get the SITE_ID of the current site from the domain name instead of hard-coding it in the settings files (django sites documentation) and run database queries, render the views accordingly? If using multiple settings file is my only option can this (wsgi script handle domain name) be done? Update So finally, following lukes answer, what I will do is define a custom middleware which makes the views available with the important vars required according to the domain. And as far as sitemaps and comments is concerned, I will have to customize sitemaps app and a custom sites model on which the other models of sites will be based. And since the comments system is based on the hard-coded sitemap ID I can use it just as is on the models (models will already be filtered according to the site based on my sites framework) though the permalink feature will have to be customized. So a lot of customization. Please suggest if I am going wrong anywhere in this because I have to ensure that the features of the project are optimized. Thanks!

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• Numerical calculations in Prolog

  - by user8472

  While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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• Searching Natural Language Sentence Structure

  - by Cerin

  What's the best way to store and search a database of natural language sentence structure trees? Using OpenNLP's English Treebank Parser, I can get fairly reliable sentence structure parsings for arbitrary sentences. What I'd like to do is create a tool that can extract all the doc strings from my source code, generate these trees for all sentences in the doc strings, store these trees and their associated function name in a database, and then allow a user to search the database using natural language queries. So, given the sentence "This uploads files to a remote machine." for the function upload_files(), I'd have the tree: (TOP (S (NP (DT This)) (VP (VBZ uploads) (NP (NNS files)) (PP (TO to) (NP (DT a) (JJ remote) (NN machine)))) (. .))) If someone entered the query "How can I upload files?", equating to the tree: (TOP (SBARQ (WHADVP (WRB How)) (SQ (MD can) (NP (PRP I)) (VP (VB upload) (NP (NNS files)))) (. ?))) how would I store and query these trees in a SQL database? I've written a simple proof-of-concept script that can perform this search using a mix of regular expressions and network graph parsing, but I'm not sure how I'd implement this in a scalable way. And yes, I realize my example would be trivial to retrieve using a simple keyword search. The idea I'm trying to test is how I might take advantage of grammatical structure, so I can weed-out entries with similar keywords, but a different sentence structure. For example, with the above query, I wouldn't want to retrieve the entry associated with the sentence "Checks a remote machine to find a user that uploads files." which has similar keywords, but is obviously describing a completely different behavior.

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• SQL connection to database repeating

  - by user175084

  ok now i am using the SQL database to get the values from different tables... so i make the connection and get the values like this: DataTable dt = new DataTable(); SqlConnection connection = new SqlConnection(); connection.ConnectionString = ConfigurationManager.ConnectionStrings["XYZConnectionString"].ConnectionString; connection.Open(); SqlCommand sqlCmd = new SqlCommand("SELECT * FROM Machines", connection); SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd); sqlCmd.Parameters.AddWithValue("@node", node); sqlDa.Fill(dt); connection.Close(); so this is one query on the page and i am calling many other queries on the page. So do i need to open and close the connection everytime...??? also if not this portion is common in all: DataTable dt = new DataTable(); SqlConnection connection = new SqlConnection(); connection.ConnectionString = ConfigurationManager.ConnectionStrings["XYZConnectionString"].ConnectionString; connection.Open(); can i like put it in one function and call it instead.. the code would look cleaner... i tried doing that but i get errors like: Connection does not exist in the current context. any suggestions??? thanks

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• Performance of Multiple Joins

  - by geeko

  Greetings Overflowers, I need to query against objects with many/complex spacial conditions. In relational databases that is translated to many joins (possibly 10+). I'm new to this business and wondering whether to go with MS SQL Server 2008 R2 or Oracle 11g or document-based solutions such as RavenDB or simply go with some spacial database (GIS)... Any thoughts ? Regards UPDATE: Thank you all for your answers. Would anybody opt for document/spatial databases ? My database would consist of tens of millions to few billion records. Mostly read-only. Almost no updates unless in case of mistakes in input. Overnight inserts and not that frequent. The join tables are predicted beforehand but the number of self joins (tables joining themselves multiple times) is not. Small pages of results from such queries are going to be viewed on an highly interactive website so response time is critical. Any predictions on how this can perform on MS SQL Server 2008 R2 or Oracle 11g ? I'm also concerned about boosting performance by adding more servers, which one scales better ? How about PostgresQL ?

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• WCF data services (OData), query with inheritance limitation?

  - by Mathieu Hétu

  Project: WCF Data service using internally EF4 CTP5 Code-First approach. I configured entities with inheritance (TPH). See previous question on this topic: Previous question about multiple entities- same table The mapping works well, and unit test over EF4 confirms that queries runs smoothly. My entities looks like this: ContactBase (abstract) Customer (inherits from ContactBase), this entity has also several Navigation properties toward other entities Resource (inherits from ContactBase) I have configured a discriminator, so both Customer and Resource map to the same table. Again, everythings works fine on the Ef4 point of view (unit tests all greens!) However, when exposing this DBContext over WCF Data services, I get: - CustomerBases sets exposed (Customers and Resources sets seems hidden, is it by design?) - When I query over Odata on Customers, I get this error: Navigation Properties are not supported on derived entity types. Entity Set 'ContactBases' has a instance of type 'CodeFirstNamespace.Customer', which is an derived entity type and has navigation properties. Please remove all the navigation properties from type 'CodeFirstNamespace.Customer'. Stacktrace: at System.Data.Services.Serializers.SyndicationSerializer.WriteObjectProperties(IExpandedResult expanded, Object customObject, ResourceType resourceType, Uri absoluteUri, String relativeUri, SyndicationItem item, DictionaryContent content, EpmSourcePathSegment currentSourceRoot) at System.Data.Services.Serializers.SyndicationSerializer.WriteEntryElement(IExpandedResult expanded, Object element, ResourceType expectedType, Uri absoluteUri, String relativeUri, SyndicationItem target) at System.Data.Services.Serializers.SyndicationSerializer.<DeferredFeedItems>d__b.MoveNext() at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteItems(XmlWriter writer, IEnumerable`1 items, Uri feedBaseUri) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeedTo(XmlWriter writer, SyndicationFeed feed, Boolean isSourceFeed) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeed(XmlWriter writer) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteTo(XmlWriter writer) at System.Data.Services.Serializers.SyndicationSerializer.WriteTopLevelElements(IExpandedResult expanded, IEnumerator elements, Boolean hasMoved) at System.Data.Services.Serializers.Serializer.WriteRequest(IEnumerator queryResults, Boolean hasMoved) at System.Data.Services.ResponseBodyWriter.Write(Stream stream) Seems like a limitation of WCF Data services... is it? Not much documentation can be found on the web about WCF Data services (OData) and inheritance specifications. How can I overpass this exception? I need these navigation properties on derived entities, and inheritance seems the only way to provide mapping of 2 entites on the same table with Ef4 CTP5... Any thoughts?

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• Is this possible: JPA/Hibernate query with list property in result ?

  - by Kdeveloper

  In hibernate I want to run this JPQL / HQL query: select new org.test.userDTO( u.id, u.name, u.securityRoles) FROM User u WHERE u.name = :name userDTO class: public class UserDTO { private Integer id; private String name; private List<SecurityRole> securityRoles; public UserDTO(Integer id, String name, List<SecurityRole> securityRoles) { this.id = id; this.name = name; this.securityRoles = securityRoles; } ...getters and setters... } User Entity: @Entity public class User { @id private Integer id; private String name; @ManyToMany @JoinTable(name = "user_has_role", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = {@JoinColumn(name = "security_role_id") } ) private List<SecurityRole> securityRoles; ...getters and setters... } But when Hibernate 3.5 (JPA 2) starts I get this error: org.hibernate.hql.ast.QuerySyntaxException: Unable to locate appropriate constructor on class [org.test.UserDTO] [SELECT NEW org.test.UserDTO (u.id, u.name, u.securityRoles) FROM nl.test.User u WHERE u.name = :name ] Is a select that includes a list as a result not possible? Should I just create 2 seperate queries?

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• What technologies/tools do people use to implement live websites ?

  - by MadSeb

  Hi, I have the following situation: -I have a server A hooked up to a piece of hardware that sends values and information out of every second. Programs on the server machine can read these values. This server A is in a very remote location so Internet connection is very slow and not reliable but the connection does exist. Let's say it's a weather station in the Arctic. -Users from the home location want to monitorize the weather values somehow. Well, the users can use a remote desktop connection the server A but that would be too too slow. My idea is somehow to have a website on a web server (let's call the webserver - B and B is in a home location ) and make the server A connect to the server B and somehow send values and the web application reads the values and displays them....... but how to do such a system ?? I know I can use MySQL and have the server A connect to a SQL server on server B and send INSERT queries and have the web application running on server B constantly read from the SQL server but I think that would be way way too slow and I think there has to be a better solution. Any ideas ? BTW. The users should be able to send information to the weather station from the website as well ( so an ADMIN user should be allowed to shut down the weather station from the website or whatever) Best regards, MadSeb

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• What's the SQL function for timestamp manipulation?

  - by Eric Leroy

  I'm new to SQL and the time functions are different than mySQL so I'm having a terrible time finding a good site reference with USEFUL timestamp queries. I'm not able to locate the correct way of doing this query in SQL: Id Timestamp ----------------------------------- 1145744 2012-10-10 18:15:11.500 1145743 2012-10-10 18:15:11.313 1145742 2012-10-10 18:15:11.313 1145741 2012-10-10 18:15:11.253 1145740 2012-10-10 18:15:11.190 1145739 2012-10-10 18:15:11.190 1145738 2012-10-10 18:15:11.127 1145737 2012-10-10 18:15:11.067 1145736 2012-10-10 18:15:11.063 1145735 2012-10-10 18:15:10.940 1145734 2012-10-10 18:15:10.817 SELECT * from table WHERE Timestamp ... RANGE I need the range of 2 timestamps so I can select rows by the following parameters: second range minute range hour range day range week range month range year range Is there one function to put in 2 timestamps and get the range? or is this a mix of functions I need? Any good site references would be greatly appriceated. MSDN site isn't helping me isolate the proper way of doing this. I've been searching for about an hour trying to get the last day from 1:30PM to 1:30PM today.

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• customer.name joining transactions.name vs. customer.id [serial] joining transactions.id [integer]

  - by Frank Computer

  INFORMIX-SQL 7.32 Pawnshop Application: one-to-many relationship where each customer (master) can have many transactions (detail). customer( id serial, pk_name char(30), {PATERNAL-NAME MATERNAL-NAME, FIRST-NAME MIDDLE-NAME} [...] ); unique index on id; unique cluster index on name; transaction( fk_name char(30), ticket_number serial, [...] ); dups cluster index on fk_name; unique index on ticket_number; Several people have told me this is not the correct way to join master to detail. They said I should always join customer.id[serial] to transactions.id[integer]. When a customer pawns merchandise, clerk queries the master using wildcards on name. The query usually returns several customers, clerk scrolls until locating the right name, enters a 'D' to change to detail transactions table, all transactions are automatically queried, then clerk enters an 'A' to add a new transaction. The problem with using customer.id joining transaction.id is that although the customer table is maintained in sorted name order, clustering the transaction table by fk_id groups the transactions by fk_id, but they are not in the same order as the customer name, so when clerk is scrolling through customer names in the master, the system has to jump allover the place to locate the clustered transactions belonging to each customer. As each new customer is added, the next id is assigned to that customer, but new customers dont show up in alphabetical order. I experimented using id joins and confirmed the decrease in performance. How can I use id joins instead of name joins and still preserve the clustered transaction order by name if transactions has no name column?

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• PHP OOP: Avoid Singleton/Static Methods in Domain Model Pattern

  - by sunwukung

  I understand the importance of Dependency Injection and its role in Unit testing, which is why the following issue is giving me pause: One area where I struggle not to use the Singleton is the Identity Map/Unit of Work pattern (Which keeps tabs on Domain Object state). //Not actual code, but it should demonstrate the point class Monitor{//singleton construction omitted for brevity static $members = array();//keeps record of all objects static $dirty = array();//keeps record of all modified objects static $clean = array();//keeps record of all clean objects } class Mapper{//queries database, maps values to object fields public function find($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; } $values = $this->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); Monitor::new[$id]=$Object return $Object; } $User = $UserMapper->find(1);//domain object is registered in Id Map $User->changePropertyX();//object is marked "dirty" in UoW // at this point, I can save by passing the Domain Object back to the Mapper $UserMapper->save($User);//object is marked clean in UoW //but a nicer API would be something like this $User->save(); //but if I want to do this - it has to make a call to the mapper/db somehow $User->getBlogPosts(); //or else have to generate specific collection/object graphing methods in the mapper $UserPosts = $UserMapper->getBlogPosts(); $User->setPosts($UserPosts); Any advice on how you might handle this situation? I would be loathe to pass/generate instances of the mapper/database access into the Domain Object itself to satisfy DI - At the same time, avoiding that results in lots of calls within the Domain Object to external static methods. Although I guess if I want "save" to be part of its behaviour then a facility to do so is required in its construction. Perhaps it's a problem with responsibility, the Domain Object shouldn't be burdened with saving. It's just quite a neat feature from the Active Record pattern - it would be nice to implement it in some way.

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• Combining two-part SQL query into one query

  - by user332523

  Hello, I have a SQL query that I'm currently solving by doing two queries. I am wondering if there is a way to do it in a single query that makes it more efficient. Consider two tables: Transaction_Entries table and Transactions, each one defined below: Transactions - id - reference_number (varchar) Transaction_Entries - id - account_id - transaction_id (references Transactions table) Notes: There are multiple transaction entries per transaction. Some transactions are related, and will have the same reference_number string. To get all transaction entries for Account X, then I would do SELECT E.*, T.reference_number FROM Transaction_Entries E JOIN Transactions T ON (E.transaction_id=T.id) where E.account_id = X The next part is the hard part. I want to find all related transactions, regardless of the account id. First I make a list of all the unique reference numbers I found in the previous result set. Then for each one, I can query all the transactions that have that reference number. Assume that I hold all the rows from the previous query in PreviousResultSet UniqueReferenceNumbers = GetUniqueReferenceNumbers(PreviousResultSet) // in Java foreach R in UniqueReferenceNumbers // in Java SELECT * FROM Transaction_Entries where transaction_id IN (SELECT * FROM Transactions WHERE reference_number=R Any suggestions how I can put this into a single efficient query?

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• PHP/MySQL time zone migration

  - by El Yobo

  I have an application that currently stores timestamps in MySQL DATETIME and TIMESTAMP values. However, the application needs to be able to accept data from users in multiple time zones and show the timestamps in the time zone of other users. As such, this is how I plan to amend the application; I would appreciate any suggestions to improve the approach. Database modifications All TIMESTAMPs will be converted to DATETIME values; this is to ensure consistency in approach and to avoid having MySQL try to do clever things and convert time zones (I want to keep the conversion in PHP, as it involves less modification to the application, and will be more portable when I eventually manage to escape from MySQL). All DATETIME values will be adjusted to convert them to UTC time (currently all in Australian EST) Query modifications All usage of NOW() to be replaced with UTC_TIMESTAMP() in queries, triggers, functions, etc. Application modifications The application must store the time zone and preferred date format (e.g. US vs the rest of the world) All timestamps will be converted according to the user settings before being displayed All input timestamps will be converted to UTC according to the user settings before being input Additional notes Converting formats will be done at the application level for several main reasons The approach to converting time zones varies from DB to DB, so handing it there will be non-portable (and I really hope to be migrating away from MySQL some time in the not-to-distant future). MySQL TIMESTAMPs have limited ranges to the permitted dates (~1970 to ~2038) MySQL TIMESTAMPs have other undesirable attributes, including bizarre auto-update behaviour (if not carefully disabled) and sensitivity to the server zone settings (and I suspect I might screw these up when I migrate to Amazon later in the year). Is there anything that I'm missing here, or does anyone have better suggestions for the approach?

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• How can I get a iterable resultset from the database using pdo, instead of a large array?

  - by Tchalvak

  I'm using PDO inside a database abstraction library function query. I'm using fetchAll(), which if you have a lot of results, can get memory intensive, so I want to provide an argument to toggle between a fetchAll associative array and a pdo result set that can be iterated over with foreach and requires less memory (somehow). I remember hearing about this, and I searched the PDO docs, but I couldn't find any useful way to do that. Does anyone know how to get an iterable resultset back from PDO instead of just a flat array? And am I right that using an iterable resultset will be easier on memory? I'm using Postgresql, if it matters in this case. . . . The current query function is as follows, just for clarity. /** * Running bound queries on the database. * * Use: query('select all from players limit :count', array('count'=>10)); * Or: query('select all from players limit :count', array('count'=>array(10, PDO::PARAM_INT))); **/ function query($sql_query, $bindings=array()){ DatabaseConnection::getInstance(); $statement = DatabaseConnection::$pdo->prepare($sql_query); foreach($bindings as $binding => $value){ if(is_array($value)){ $statement->bindParam($binding, $value[0], $value[1]); } else { $statement->bindValue($binding, $value); } } $statement->execute(); // TODO: Return an iterable resultset here, and allow switching between array and iterable resultset. return $statement->fetchAll(PDO::FETCH_ASSOC); }

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• Problem in DataBinding an Enum using dictionary approach to a combobox in WPF.

  - by Ashish Ashu

  I have a Dictionary which is binded to a combobox. I have used dictionary to provide spaces in enum. public enum Option {Enter_Value, Select_Value}; Dictionary<Option,string> Options; <ComboBox x:Name="optionComboBox" SelectionChanged="optionComboBox_SelectionChanged" SelectedValuePath="Key" DisplayMemberPath="Value" SelectedItem="{Binding Path = SelectedOption}" ItemsSource="{Binding Path = Options}" /> This works fine. My queries: 1. I am not able to set the initial value to a combo box. In above XAML snippet the line SelectedItem="{Binding Path = SelectedOption}" is not working. I have declared SelectOption in my viewmodel. This is of type string and I have intialized this string value in my view model as below: SelectedOption = Options[Options.Enter_Value].ToString(); 2. The combobox is binded to datadictionary which have two options first is "Enter_value" and second is "Select_value" which is actually Option enum. Based on the Option enum value I want to perform different action. For example if option is equal to option.Enter_value then Combo box becomes editable and user can enter the numeric value in it. if option is equal to option.Select_value value then the value comes from the database and the combo box becomes read only and shows the fetched value from the database. Please Help!!

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• Mysql query in drupal database - groupwise maximum with duplicate data

  - by nselikoff

  I'm working on a mysql query in a Drupal database that pulls together users and two different cck content types. I know people ask for help with groupwise maximum queries all the time... I've done my best but I need help. This is what I have so far: # the artists SELECT users.uid, users.name AS username, n1.title AS artist_name FROM users LEFT JOIN users_roles ur ON users.uid=ur.uid INNER JOIN role r ON ur.rid=r.rid AND r.name='artist' LEFT JOIN node n1 ON n1.uid = users.uid AND n1.type = 'submission' WHERE users.status = 1 ORDER BY users.name; This gives me data that looks like: uid username artist_name 1 foo Joe the Plumber 2 bar Jane Doe 3 baz The Tooth Fairy Also, I've got this query: # artwork SELECT n.nid, n.uid, a.field_order_value FROM node n LEFT JOIN content_type_artwork a ON n.nid = a.nid WHERE n.type = 'artwork' ORDER BY n.uid, a.field_order_value; Which gives me data like this: nid uid field_order_value 1 1 1 2 1 3 3 1 2 4 2 NULL 5 3 1 6 3 1 Additional relevant info: nid is the primary key for an Artwork every Artist has one or more Artworks valid data for field_order_value is NULL, 1, 2, 3, or 4 field_order_value is not necessarily unique per Artist - an Artist could have 4 Artworks all with field_order_value = 1. What I want is the row with the minimum field_order_value from my second query joined with the artist information from the first query. In cases where the field_order_value is not valuable information (either because the Artist has used duplicate values among their Artworks or left that field NULL), I would like the row with the minimum nid from the second query.

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• Incrementing value by one over a lot of rows

  - by Andy Gee

  Edit: I think the answer to my question lies in the ability to set user defined variables in MySQL through PHP - the answer by Multifarious has pointed me in this direction Currently I have a script to cycle over 10M records, it's very slow and it goes like this: I first get a block of 1000 results in an array similar to this: $matches[] = array('quality_rank'=>46732, 'db_id'=>5532); $matches[] = array('quality_rank'=>12324, 'db_id'=>1234); $matches[] = array('quality_rank'=>45235, 'db_id'=>8345); $matches[] = array('quality_rank'=>75543, 'db_id'=>2562); I then cycle through them one by one and update the record $mult = count($matches)*2; foreach($matches as $m) { $rank++; $score = (($m[quality_rank] + $rank)/($mult))*100; $s = "UPDATE `packages_sorted` SET `price_rank` = '".$rank."', `deal_score` = '".$score."' WHERE `db_id` = '".$m[db_id]."' LIMIT 1"; } It seems like this is a very slow way of doing it but I can't find another way to increment the field price_rank by one each time. Can anyone suggest a better method. Note: Although I wouldn't usually store this kind of value in a database I really do need on this occasion for comparison search queries later on in the project. Any help would be kindly appreciated :)

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• MySQL LIMIT 1 but query 15 rows?

  - by Ian

  Basically what I'm trying to do is compare the ID's of rows against 15 results in MySQL, eliminating all but 1 (using NOT IN) and then pull that result. Now normally this would be fine by itself, however the order of the 15 rows I'm doing the SQL query for are constantly changing based on a ranking, so there is a possibility that between the time the ranking updates, and the ajax request (which I submit the ID's for NOT IN) more than just one ID has changed, which would of course bring back more than one row which I do not want. So in short, is there a way in which I can query 15 rows, but only return one? Without having to run two separate queries. Any help is appreciated, thank you. EXAMPLE: Say I have 7 items in my database, and I'm displaying 5 on the page to the user. These are what are being displayed to the user: Apple Orange Kiwi Banana Grape But in the database I also have Peach Blackberry Now what I want to do is if the user deletes an item from their list, it will add another item (based on a ranking they have) Now the issue is, in order to know what they have on their list at the moment I send the remaining items to the database (say they deleted Kiwi, I would send Apple, Orange, Banana, and Grape) So now I select the highest ranked 5 items from are remaining six items, make sure they are not the ones already displayed on the page, and then add the new one to list (either Peach or Blackberry) All good and well, except that if both peach and blackberry now outrank grape, then I will be returning two results instead of just one. Because it would've searched... Apple Orange Banana Peach Blackberry and excluded... Apple Orange Banana Grape Which leaves us with both Peach and Blackberry, instead of just Peach or Blackberry

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• NHibernate + Fluent long startup time

  - by PaRa

  Hi all, am new to NHibernate. When performing below test took 11.2 seconds (debug mode) i am seeing this large startup time in all my tests (basically creating the first session takes a tone of time) setup = Windows 2003 SP2 / Oracle10gR2 latest CPU / ODP.net 2.111.7.20 / FNH 1.0.0.636 / NHibernate 2.1.2.4000 / NUnit 2.5.2.9222 / VS2008 SP1 using System; using System.Collections; using System.Data; using System.Globalization; using System.IO; using System.Text; using System.Data; using NUnit.Framework; using System.Collections.Generic; using System.Data.Common; using NHibernate; using log4net.Config; using System.Configuration; using FluentNHibernate; [Test()] public void GetEmailById() { Email result; using (EmailRepository repository = new EmailRepository()) { results = repository.GetById(1111); } Assert.IsTrue(results != null); } public class EmailRepository : RepositoryBase { public EmailRepository():base() { } } In my RepositoryBase public T GetById(object id) { using (var session = sessionFactory.OpenSession()) using (var transaction = session.BeginTransaction()) { try { T returnVal = session.Get(id); transaction.Commit(); return returnVal; } catch (HibernateException ex) { // Logging here transaction.Rollback(); return null; } } } The query time is very small. The resulting entity is really small. Subsequent queries are fine. Its seems to be getting the first session started. Has anyone else seen something similar?

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• SQL query for an access database needed

  - by masfenix

  Hey guys, first off all sorry, i can't login using my yahoo provider. anyways I have this problem. Let me explain it to you, and then I'll show you a picture. I have a access db table. It has 'report id', 'recpient id', and 'recipient name' and 'report req'. What the table "means" is that do the user using that report still require it or can we decommission it. Here is how the data looks like (blocked out company userids and usernames): *check the link below, I cant post pictures cuz yahoo open id provider isnt working. So basically I need to have 3 select queries: 1) Select all the reports where for each report, ALL the users have said no to 'reportreq'. In plain English, i want a listing of all the reports that we have to decommission because no user wants it. 2) Select all the reports where the report is required, and the batchprintcopy is more then 0. This way we can see which report needs to be printed and save paper instead of printing all the reports. 3)A listing of all the reports where the reportreq field is empty. I think i can figure this one out myself. This is using Access/VBA and the data will be exported to an excel spreadsheet. I just a simple query if it exists, OR an alogorithm to do it quickly. I just tried making a "matrix" and it took about 2 hours to populate. https://docs.google.com/uc?id=0B2EMqbpeBpQkMTIyMzA5ZjMtMGQ3Zi00NzRmLWEyMDAtODcxYWM0ZTFmMDFk&hl=en_US

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• build SQL query string using user input

  - by user175084

  i have to make a string by using the values which the user selects on the webpage suppose i need to display files for multiple machines with differnt search criteria.. i currently use this code: DataTable dt = new DataTable(); SqlConnection connection = new SqlConnection(); connection.ConnectionString = ConfigurationManager.ConnectionStrings["DBConnectionString"].ConnectionString; connection.Open(); SqlCommand sqlCmd = new SqlCommand("SELECT FileID FROM Files WHERE MachineID=@machineID and date= @date", connection); SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd); sqlCmd.Parameters.AddWithValue("@machineID", machineID); sqlCmd.Parameters.AddWithValue("@date", date); sqlDa.Fill(dt); now this is fixed query where the user just has one machine and just selects one date... i want to make a query in which the user has multiple search options like type or size if he wants depending on what he selects also if he can select multiple machines.. SELECT FileID FROM Files WHERE (MachineID=@machineID1 or MachineID = @machineID2...) and (date= @date and size=@size and type=@type... ) all of this happens in runtime... other wise i have to create a for loop to put multiple machines one by one... and have multiple queries depending on the case the user selected... this is quiet interesting and i could use some help... thanks

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