hash join - Page 54 - Developer IT

PHP / MySQL - How to retrieve 2 separate sets of objects?

- by Dan

Hi, I have a set of models which correspond to tables in my database. I have been retrieving them easily enough, for example. $result = $mysqli->query('SOME SQL'); $post = $result->fetch_object; What would be the best approach for performing a join and also returning the related objects? For example, each post is created by a user, so for each row returned in the joined statement, both a page and user object should be returned. Any advice appreciated. Thanks.

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Ruby on Rails Join Table Associations

- by Eef

Hey, I have a Ruby on Rails application setup like so: User Model has_and_belongs_to_many :roles Role Model has_many :transactions has_and_belongs_to_many :users Transaction Model belongs_to :role This means that a join table is used called roles_users and it also means that a user can only see the transactions that have been assigned to them through roles, usage example: user = User.find(1) transactions = user.roles.first.transactions This will return the transactions which are associated with the first role assigned to the user. If a user has 2 roles assigned to them, at the moment to get the transactions associated with the second role I would do: transactions = user.roles.last.transactions I am basically trying to figure out a way to setup an association so I can grab the user's transactions via something like this based on the roles defined in the association between the user and roles: user = User.find(1) transactions = user.transactions I am not sure if this is possible? I hope you understand what I am trying to do.

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subscript for a join (\bowtie) operation in LyX/LaTeX

- by Amir Rachum

I'm using LyX to write some Relational Algebra queries. I'm using the \bowtie symbol for the join operation but when I try to put a text in subscript directly under the symbol, I get the following error: ...a_{\t{pId}}\t{person}\right)\bowtie\limits {\t{pId}{1}=\t{pId}_{2}... I'm ignoring this misplaced \limits or \nolimits command. Anyone knows how to do what I want? Preferably in LyX, but ERT code snippets will also be appreciated. Thanks! Edit: \t is a macro for \text.

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LINQ Join 2 List<T>s

- by David Murdoch

Preface: I don't understand what this does: o => o.ID, i => i.ID, (o, id) => o So go easy on me. :-) I have 2 lists that I need to join together: // contains ALL contacts for a customer. // Each item has a unique ID. // There are no duplicates. ContactCollection list1 = myCustomer.GetContacts(); // contains the customer contacts (in list1) relevant to a REPORT // the items in this list may have properties that differ from those in list1. /*****/// e.g.: /*****/ bool SelectedForNotification; /*****/// may be different. ContactCollection list2 = myReport.GetContacts(); I need to create a third ContactCollection that contains all of the contacts in list1 but with the properties of the items in list2, if they are there (list3.Count == list1.Count). I feel as though I'm not making any sense. So, please ask questions in the comments and I'll try to clarify.

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joining two sets in LINQ

- by user343209

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Need help joining tables...

- by yuudachi

I am a MySQL newbie, so sorry if this is a dumb question.. These are my tables. student table: SID (primary) student_name advisor (foreign key to faculty.facultyID) requested_advisor (foreign key to faculty.facultyID) faculty table: facultyID (primary key) advisor_name I want to query a table that shows everything in the student table, but I want advisor and requested_advisor to show up as names, not the ID numbers. so like it displays like this on the webpage: Student Name: Jane Smith SID: 860123456 Current Advisor: John Smith Requested advisor: James Smith not like this Student Name: Jane Smith SID: 860123456 Current Advisor: 1 Requested advisor: 2 SELECT student.student_name, SID, student_email, faculty.advisor_name FROM student INNER JOIN faculty ON student.advisor = faculty.facultyID; this comes out close, but I don't know how to get the requested_advisor to show up as a name.

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has_many :through when join table doesn't contain FK to both tables

- by seth.vargo

I have a structure that isn't really a has_many :through example, but I'd like it to behave like one: # user.rb belongs_to :blog has_many :posts # post.rb belongs_to :user # blog.rb has_many :users has_many :posts, :through => :users # this obviously doesn't work becase # both FKs aren't in the blogs table I want to get ALL posts for a blog in an array. I'm aware that I can do this with Ruby using each or getting fancy with collect, but I'd like to let SQL do the work. Can someone explain how I can set up my models in a way that lets me call @blog.posts using SQL, not Ruby? Edit: I know in SQL I can write something like: SELECT * FROM posts WHERE posts.user_id IN ( SELECT users.id FROM users WHERE users.blog_id = 7 ) which obviously shows two queries are needed. I don't think this is possible with a join, but I'm not totally sure. It's obvious that a subquery is needed, but how do I get rails to build that subquery with ARel instead of having to return and use Ruby to loop and collect and such?

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How can I make an SQL statement that finds unassociated records?

- by William Calleja

I have two tables as follows: tblCountry (countryID, countryCode) tblProjectCountry(ProjectID, countryID) The tblCountry table is a list of all countries with their codes and the tblProjectCountry table associates certain countries with certain projects. I need an SQL statement that gives me a list of the countries with their country code that do NOT have an associated record in the tblProjectCountry table. so far I got to here: SELECT tblCountry.countryID, tblCountry.countryCode FROM tblProjectCountry INNER JOIN tblCountry ON tblProjectCountry.countryID = tblCountry.countryID WHERE (SELECT COUNT(ProjectID) FROM tblProjectCountry WHERE (ProjectID = 1) AND (countryID = tblCountry.countryID)) = 0 The above statement parses as correct but doesn't give the exact result I'm looking for. Can anyone help?

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please help me in this query

- by testkhan

I have three tables (user, friends, posts) and two users (user1 and user2). When user1 adds user2 as friend then user1 can see the posts of user2 just like on Facebook. But only the posts after the date when user1 added user2 as friend. My query is like this: $sql = mysql_query("SELECT * FROM posts p JOIN friends f ON p.currentuserid = f.friendid AND p.time >= f.friend_since OR p.currentuserid='user1id' WHERE f.myid='user1id' ORDER BY p.postid DESC LIMIT 20"); it is working all the way fine but with a little problem.....!! it displays user2, user3 (all the users as friends of user1) posts for single time but shows user1 posts multiple.......i.e user2. hi user1. userssfsfsfsfsdf user1. userssfsfsfsfsdf user3. dddddddd user1. sdfsdsdfsdsfsf user1. sdfsdsdfsdsfsf but i in database it is single entry/post why it is happening........!! How can I fix it?

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MySQL - getting SUM of MAX results from 2 tables

- by SODA

Hi, Here's my problem: I have 2 identical tables (past month data, current month data) - data_2010_03, data_2010_04: Content_type (VARCHAR), content_id (INT), month_count (INT), pubDate (DATETIME) Data in month_count is updated hourly, so for each combination of content_type and content_id we insert new row, where value of month_count is incrementally updated. Now I try something like this: SELECT MAX(t1.month_count) AS max_1, MAX(t2.month_count) AS max_2, SUM(max_1 + max_2) AS result, t1.content_type, t1.content_id FROM data_2010_03 AS t1 JOIN data_2010_04 AS t2 ON t1.content_type = t2.content_type AND t1.content_id = t2.content_id WHERE t2.pubDate < '2010-04-08' AND t1.content_type = 'video' GROUP BY t1.content_id ORDER BY result desc, max_1 desc, max_2 desc LIMIT 0,10 I get an error "Unknown column 'max_1' in 'field list'. Please help.

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SQL: join within same table with different 'where' clause

- by Pmarcoen

Ok, so the problem I'm facing is this, I have a table with 3 columns : ID, Key and Value. ID | Key | Value ================ 1 | 1 | ab 1 | 2 | cd 1 | 3 | ef 2 | 1 | gh 2 | 2 | ij 2 | 3 | kl Now I want to select the value of Keys 1 & 3 for all IDs, the return should be like this ID | 1 | 2 ================ 1 | ab | ef 2 | gh | kl So per ID 1 row containing the Values for Keys 1 & 3. I tried using 'join' but since I need to use multiple where clauses I can't figure out how to get this to work ..

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Can't enumerate LinQ results with left join

- by nvtthang

var itemSet = from item in da.GetList<Models.account>() join file in objFileStorageList on item.account_id equals file.parent_id into objFile from fileItem in objFile.DefaultIfEmpty() where item.company != null && item.company.company_id == 123 orderby item.updatedDate descending select new { Id = item.account_id, RefNo = item.refNo, StartDate = item.StartDate , EndDate = item.EndDate , Comment = item.comment, FileStorageID = fileItem != null ? fileItem.fileStorage_id : -1, Identification = fileItem != null ? fileItem.identifier : null, fileName = fileItem != null ? fileItem.file_nm : null }; It raises error message when I try to enumerate through collection result from Linq query above. LINQ to Entities does not recognize the method 'System.Collections.Generic.IEnumerable1[SCEFramework.Models.fileStorage] DefaultIfEmpty[fileStorage](System.Collections.Generic.IEnumerable1[SCEFramework.Models.fileStorage])' method, and this method cannot be translated into a store expression foreach (var item in itemSet) { string itemRef= item.RefNo; } Please suggest me any solutions. Thanks in advance.

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Select the first row in a join of two tables in one statement

- by Oscar Cabrero

hi i need to select only the first row from a query that joins tables A and B, on table B exist multiple records with same name. there are not identifiers in any of the two tables. i cannt change the scheme either because i do not own the DB TABLE A NAME TABLE B NAME DATA1 DATA2 Select Distinct A.NAME,B.DATA1,B.DATA2 From A Inner Join B on A.NAME = B.NAME this gives me NAME DATA1 DATA2 sameName 1 2 sameName 1 3 otherName 5 7 otherName 8 9 but i need to retrieve only one row per name NAME DATA1 DATA2 sameName 1 2 otherName 5 7 i was able to do this by adding the result into a temp table with a identity column and the select the Min Id per name. the problem here is that i require to do this in one single statement. this is a DB2 database thanks

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IS NULL doesn't work as expected in SQL Server 2000 with no Service Pack on it

- by user306825

The following batch executed on different instances of SQL Server 2000 illustrates the problem. select @@version create table a (a int) create table b (b int) insert into a(a) values (1) insert into a(a) values (2) insert into a(a) values (3) insert into b(b) values (1) insert into b(b) values (2) select * from a left outer join (select 1 as test, b from b) as j on j.b = a.a where j.test IS NULL drop table a drop table b Output 1: Microsoft SQL Server 2000 - 8.00.194 (Intel X86) Aug 6 2000 00:57:48 Copyright (c) 1988-2000 Microsoft Corporation Developer Edition on Windows NT 6.1 (Build 7600: ) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) a test b ----------- ----------- ----------- (0 row(s) affected) Output 2: Microsoft SQL Server 2000 - 8.00.2039 (Intel X86) May 3 2005 23:18:38 Copyright (c) 1988-2003 Microsoft Corporation Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 2) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) a test b ----------- ----------- ----------- 3 NULL NULL (1 row(s) affected) If someone encounters the same problem - make sure you have the SP installed!

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mysql left outer join

- by tirso

hi to all I have two tables employee and timecard, employee table has fields employee_id,firstname,middlename,lastname and timecard table has fields employee_id,time-in,time-out,tc_date_transaction. I want to select all employee records which have the same employee_id with timecard and date is equal with the current date. If there are no records equal with the current date then return also the records of employee even without time-in,timeout and tc_date_transaction. I have query like this SELECT * FROM employee LEFT OUTER JOIN timecard ON employee.employee_id = timecard.employee_id WHERE tc_date_transaction = "17/06/2010"; result should like this: employee_id,firstname, middlename, lastname,time-in,time-out,tc_date_transaction 1,john,t,cruz,08:00,05:00,17/06/2010 2,mary,j,von,null,null,null any help would greatly appreciated Thanks in advance

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An analog of String.Join(string, string[]) for IEnumerable<T>

- by abatishchev

class String contains very useful method - String.Join(string, string[]). It creates a string from an array, separating each element of array with a symbol given. But general - it doesn't add a separator after the last element! I uses it for ASP.NET coding for separating with "<br />" or Environment.NewLine. So I want to add an empty row after each row in asp:Table. What method of IEnumerable<TableRow> can I use for the same functionality?

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MySQL cross table regular expression match

- by Josef Sábl

I have a web application and I am working on engine that analyzes referals. Now I have table with pageviews along with referes that looks something like this: pv_id referer ------------------------------------------------------------ 5531854534 http://www.google.com/search?ie=UTF-8... 8161876343 http://google.cn/search?search=human+rights 8468434831 http://search.yahoo.com/search;_... The second table contains sources definitions like: source regex ------------------------------------------------------------ Google ^https?:\/\/[^\/]*google\.([a-z]{2,4})(\/.*|)$ Yahoo ^https?:\/\/[^\/]*yahoo\.com(\/.*|)$ What I want is third table created by joinin these two: pv_id source ------------------------------------------------------------ 5531854534 Google 8161876343 Google 8468434831 Yahoo How to join these tables with regular expression?

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Rails way for querying join table in has_and_belongs_to_many

- by Michelle

I have a user model and a role model with a has_and_belongs_to_many reliationship. The join table is roles_users (two columns - the PK of the user and the role) and has no corresponding model. I want to have a method that returns all users with a given role. In SQL that'd be something like SELECT u.id FROM role.r, roles_users ru WHERE r.role_id = #{role.id} AND r.role_id = ru.role_id I see that Rails' activerecord has a find_by_sql method, but it's only expecting one results to be returned. What is the "Rails Way" to give me a list of users with a given role e.g. def self.find_users_with_role(role) users = [] users << # Some ActiveRecord magic or custom code here..? end

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IS NULL doesn't work as expected in MSSQL 2000 with no Service Pack on it

- by user306825

The following batch executed on different instances of mssql 2000 illustrates the problem. select @@version create table a (a int) create table b (b int) insert into a(a) values (1) insert into a(a) values (2) insert into a(a) values (3) insert into b(b) values (1) insert into b(b) values (2) select * from a left outer join (select 1 as test, b from b) as j on j.b = a.a where j.test IS NULL drop table a drop table b Output 1: Microsoft SQL Server 2000 - 8.00.194 (Intel X86) Aug 6 2000 00:57:48 Copyright (c) 1988-2000 Microsoft Corporation Developer Edition on Windows NT 6.1 (Build 7600: ) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) a test b (0 row(s) affected) Output 2: Microsoft SQL Server 2000 - 8.00.2039 (Intel X86) May 3 2005 23:18:38 Copyright (c) 1988-2003 Microsoft Corporation Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 2) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) (1 row(s) affected) a test b 3 NULL NULL (1 row(s) affected) If someone encounters the same problem - make sure you have the SP installed!

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An analog of String.Join(string, string[]) for List<T> or other generic enumerable

- by abatishchev

class String contains very useful method - String.Join(string, string[]). It creates a string from an array, separating each element of array with a symbol given. But general - it doesn't add a separator after the last element! I uses it for ASP.NET coding for separating with "<br />" or Environment.NewLine. So I want to add an empty row after each row in asp:Table. What method of IEnumerable<TableRow> can I use for the same functionality?

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Issue with Java join() method.

- by gmunk

First of all here are some code snippets: http://pastebin.com/9ZCwekXs http://pastebin.com/TtLLXPYP I'm trying to animate some images. The thing is that I want the main thread to wait for the animation thread to finish and then to continue. I searched around, read a little bit and decided to use the join() method. It perfectly waits for the thread to finish but I doesn't animate correctly. The repaint() method gets called 2 times instead of nine. I think maybe the problem is because I used singletons. Here is the singleton implementation. http://pastebin.com/bA3qLZJE

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querying databases on same server with linq

- by geoff swartz

In normal sql I could do joins on tables in different databases as long as they were on the same server (or linked servers). In linq I can't figure out how to do that. Is this possible? For example, if I have a database called db1 and another called db2. db1 has a table called people and db2 has a table called address I could do something like... select a.addressline1, p.firstname from db1.dbo.people p inner join db2.dbo.address a on p.peopleid = a.peopleid Is this possible with linq? Thanks.

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displaying values from join query array

- by THOmas

I have used a join query for retrieving value from two tables one is blogquestion and userdetails I wrote this query $this->questions = Doctrine_Query::create() ->select('b.question_id,b.user_id,b.question_title,b.question_tags,b.created_at,u.id,u.name') ->from('BlogQuestion b') ->leftJoin('b.UserDetails u') ->execute(); In the template iam displaying the result using a foreach <?php foreach($questions as $quest):?> echo $quest->getQuestionTitle() echo $quest->getQuestionTags() echo $quest->getName() <?php endforeach?> title is getting from the blogquestion table and name is in usredetails table iam getting the eerror Unknown record property / related component "name" on "BlogQuestion"

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MySQL Query, limit output display according/only to associated ID!

- by Jess

So here's my situation. I have a books table and authors table. An author can have many books... In my authors page view, the user (logged in) can click an author in a tabled row and be directed to a page displaying the author's books (collected like this URI format: viewauthorbooks.php?author_id=23), very straight forward... However, in my query, I need to display the books for the author only, and not all books stored in the books table (as i currently have!) As I am a complete novice, I used the most simple query of: SELECT * FROM tasks_tb :)....this returns the books for me, but returns every single value (book) in the database, and not ones associated with the selected author. And when I click a different author the same books are displayed for them...I think everyone gets what I'm trying to achieve, I just don't know how to perform the query. I'm guessing that I need to start using more advanced query clauses like INNER JOIN etc. Anyone care to help me out :)

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Fill data gaps - UNION, PARTITION BY, or JOIN?

- by Dave Jarvis

Problem There are data gaps that need to be filled. Would like to avoid UNION or PARTITION BY if possible. Query Statement The select statement reads as follows: SELECT count( r.incident_id ) AS incident_tally, r.severity_cd, r.incident_typ_cd FROM report_vw r GROUP BY r.severity_cd, r.incident_typ_cd ORDER BY r.severity_cd, r.incident_typ_cd Data Sources The severity codes and incident type codes are from: severity_vw incident_type_vw The columns are: incident_tally severity_cd incident_typ_cd Actual Result Data 36 0 ENVIRONMENT 1 1 DISASTER 27 1 ENVIRONMENT 4 2 SAFETY 1 3 SAFETY Required Result Data 36 0 ENVIRONMENT 0 0 DISASTER 0 0 SAFETY 27 1 ENVIRONMENT 0 1 DISASTER 0 1 SAFETY 0 2 ENVIRONMENT 0 2 DISASTER 4 2 SAFETY 0 3 ENVIRONMENT 0 3 DISASTER 1 3 SAFETY Question How would you use UNION, PARTITION BY, or LEFT JOIN to fill in the zero counts?

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Search found 8547 results on 342 pages for 'hash join'.

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- by Dan

- by Eef

- by Amir Rachum

- by David Murdoch

- by user343209

- by yuudachi

- by seth.vargo

- by William Calleja

- by testkhan

- by SODA

- by Pmarcoen

- by nvtthang

- by Oscar Cabrero

- by user306825

- by tirso

- by abatishchev

- by Josef Sábl

- by Michelle

- by user306825

- by abatishchev

- by gmunk

- by geoff swartz

- by THOmas

- by Jess

- by Dave Jarvis

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