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  • ActiveRecord find all parents that have associated children

    - by brad
    I don't know why I can't figure this out, I think it should be fairly simple. I have two models (see below). I'm trying to come up with a named scope for SupplierCategory that would find all SupplierCategory(s) (including :suppliers) who's associated Supplier(s) are not empty. I tried a straight up join, named_scope :with_suppliers, :joins => :suppliers which gives me only categories with suppliers, but it gives me each category listed separately, so if a category has 2 suppliers, i get the category twice in the returned array: Currently I'm using: named_scope :with_suppliers, :include => :suppliers and then in my view I'm using: <%= render :partial => 'category', :collection => @categories.find_all{|c| !c.suppliers.empty? } %> Not exactly eloquent but illustrates what I'm trying to achieve. Class Definitions class SupplierCategory < AR has_many :suppliers, :order => "name" end class Supplier < AR belongs_to :supplier end

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  • Is an index required for columns in ON clause?

    - by newbie
    Do I have to create an index on columns referenced in Joins? E.g. SELECT * FROM left_table INNER JOIN right_table ON left_table.foo = right_table.bar WHERE ... Should I create indexes on left_table(foo), right_table(bar), or both? I noticed different results when I used EXPLAIN (Postgresql) with and without indexes and switching around the order of the comparison (right_table.bar = left_table.foo) I know for sure that indexes are used for the left of the WHERE clause but I am wondering whether I need indexes for columns listed in ON clauses.

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  • SQL to get rows (not groups) that match an aggregate

    - by xulochavez
    Given table USER (name, city, age), what's the best way to get the user details of oldest user per city? I have seen the following example SQL used in Oracle which I think it works select name, city, age from USER, (select city as maxCity, max(age) as maxAge from USER group by city) where city=maxCity and age=maxAge So in essence: use a nested query to select the grouping key and aggregate for it, then use it as another table in the main query and join with the grouping key and the aggregate value for each key. Is this the standard SQL way of doing it? Is it any quicker than using a temporary table, or is in fact using a temporary table interanlly anyway?

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  • Performance problem on a query.

    - by yapiskan
    Hi, I have a performance problem on a query. First table is a Customer table which has millions records in it. Customer table has a column of email address and some other information about customer. Second table is a CommunicationInfo table which contains just Email addresses. And What I want in here is; how many times the email address in CommunicationInfo table repeats in Customers table. What could be the the most performer query. The basic query that I can explain this situation is; Select ci.Email, count(*) from Customer c left join CommunicationInfo ci on c.Email1 = ci.Email or c.Email2 = ci.Email Group by ci.Email But sure, it takes about 5, 6 minutes in execution. Thanks in Advance.

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  • Include only the latest/newest associated record with active record?

    - by railsnewbie
    is it possible to load only the latest associated record of an associated table? an example: class author attr_accessible :first_name, :last_name, :birthday has_many :books end class book attr_accessible :pages, :date of publication, :title belongs_to :author end Is there a way to generate a scope to load only the newest released book the author wrote? Or the book with the most pages? I know, that I could include or join all books. But I don't know if its possible to load only a specific book for each author. So that I could do a query like this: Author.authors_and_their_newest_book So that I could get these results first_name_author_1, last_name_author_1, birthday_author_1, pages_book_3, date of publication_book_3, title_book_3 first_name_author_2, last_name_author_2, birthday_author_2, pages_book_5, date of publication_book_5, title_book_5 first_name_author_3, last_name_author_3, birthday_author_3, pages_book_9, date of publication_book_9, title_book_9 ...

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  • How to $.extend 2 objects by adding numerical values together from keys with the same name?

    - by muudless
    I currently have 2 obj and using the jquery extend function, however it's overriding value from keys with the same name. How can I add the values together instead? obj1 = {"orange":2,"apple":1, "grape":1} obj2 = {"orange":5,"apple":1, "banana":1} mergedObj = $.extend({}, obj1, obj2); var printObj = typeof JSON != "undefined" ? JSON.stringify : function(obj) { var arr = []; $.each(obj, function(key, val) { var next = key + ": "; next += $.isPlainObject(val) ? printObj(val) : val; arr.push( next ); }); return "{ " + arr.join(", ") + " }"; }; console.log('all together: '+printObj(mergedObj) ); And I get obj1 = {"orange":5,"apple":1, "grape":1, "banana":1} What I need is obj1 = {"orange":7,"apple":2, "grape":1, "banana":1}

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  • How to make a staging table in ms sql 2005?

    - by chobo2
    Hi I heard about doing staging tables and I am wondering how you actually do it. I want to do a sqlbulk copy into a staging table. Then then update the real table. I heard in mssql 2008 that you can use something called merge but I am using ms sql 2005 so I heard I have to use a update inner join? I am not sure how that would look like(I am guessing best way would be to write it in SP). Also the staging table needs to be able to handle concurrent updates. I was thinking of putting another column in the staged as GUID so that way I know which records belong to which group and when it is time to delete the records from the staged table I can just use that. So can anyone show me any examples or tutorials on how to do it? Also how fast is this way? Say if your updating 50,000 records how long would that take(a guesstimate is fine)

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  • Outer select column value in joined subquery?

    - by Michael DePetrillo
    Is it possible to use a column value from an outer select within a joined subquery? SELECT table1.id, table2.cnt FROM table1 LEFT JOIN (SELECT COUNT(*) as `cnt` FROM table2 where table2.lt > table1.lt and table2.rt < table1.rt) as table2 ON 1; This results in "Unknown column 'table1.lt' in 'where clause'". Here is the db dump. CREATE TABLE IF NOT EXISTS `table1` ( `id` int(1) NOT NULL, `lt` int(1) NOT NULL, `rt` int(4) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS `table2` ( `id` int(1) NOT NULL, `lt` int(1) NOT NULL, `rt` int(4) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1; INSERT INTO `table1` (`id`, `lt`, `rt`) VALUES (1, 1, 4); INSERT INTO `table2` (`id`, `lt`, `rt`) VALUES (2, 2, 3);

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  • Stringly typed values table in sql, is there a better way to do this? (we're using MSSQL)

    - by Jason Hernandez
    We have have a table layout with property names in one table, and values in a second table, and items in a third. (Yes, we're re-implementing tables in SQL.) We join all three to get a value of a property for a specific item. Unfortunately the values can have multiple data types double, varchar, bit, etc. Currently the consensus is to stringly type all the values and store the type name in the column next to the value. tblValues DataTypeName nvarchar Is there a better, cleaner way to do this?

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  • SQL Server 15MM rows, simple COUNT query. 15+ seconds?

    - by john
    We took over a website from another company after a client decided to switch. We have a table that grows by about 25k records a day, and is currently at 15MM records. The table looks something like: id (PK, int, not null) member_id (int, not null) another_id (int, not null) date (datetime, not null) SELECT COUNT(id) FROM tbl can take up to 15 seconds. A simple inner join on 'another_id' takes over 30 seconds. I can't imagine why this is taking so long. Any advice? SQL Server 2005 Express

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  • Best Book for a new Database Developer

    - by John
    We have just had a graduate join the team with the end aim of assisting out our very busy DBA. He has only a basic SQL knowledge from his degree so we are looking for a really good getting started book preferably based on MS SQL server. Purchase Update: Thanks to the replies we have now purchased Head First SQL to review what he already knows and Beginning SQL Server 2005 Programming to enhance these skills. Further down the page you can see my full review of the books for our needs. However still feel free to post more books as others may find them useful!

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  • Index outof range? Automatica generate field .How to manipulate GridView2.Columns as BoundField;

    - by mike
    Index outof range?GridView2.Columns[6] as BoundField I use Automatica generate field . How to manipulate GridView2.Columns as BoundField with auto-generate feather? JobPostDataContext db = new JobPostDataContext(); var query = from j in db.JobLists join u in db.UserLists on j.UserID equals u.UserID where j.JobTitle.Contains(this.TextBox1.Text) select new { j.JobID, j.JobTitle, j.Summary, j.Details, j.CompanyName, j.CompanyEmail, j.DatePosted, j.UserID, u.City, u.State, u.Country }; GridView2.DataSource = query; GridView2.DataBind(); BoundField DatePosted = GridView2.Columns[6] as BoundField; DatePosted.DataFormatString = "{0:MMM,dd yy}";

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  • Multiple &(AND) fails in query

    - by N e w B e e
    here is my query $sql = 'SELECT * FROM Orders INNER JOIN [Order Details] ON Orders.OrderNumber = [Order Details].OrderNumber WHERE Orders.CartID =2 AND [Order Details].Option10 Is Null AND [Order Details].Status="Shipped"'; this queries when entered in MS_Access sql view, returns the correct results, but when I copy and paste the same query in my php script, it fails and gives the error Too few parameters, expected 1... although data is there, query is working in access... Please note if I omitted on AND condition, it works eg if I removed shipped conidtion or is null condition, it works then too.. any hint? whats wrong with it?? any help?thanks

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  • How do I deal with drupal hook_views_tables?

    - by wamp
    For the title field,I want to return node.title,but what I tried is not working: return array('og' => array('name' => 'og', 'join' => array('left' => array('table' => 'node', 'field' => 'nid' ), 'right' => array('field' => 'nid' ), ), 'fields' => array( 'title' => array('name' => t('OG: Group: Group name'), 'table' => 'node', 'handler' => 'og_handler_field_title', 'help' => t('show group name.'), 'sortable' => true, 'sort_handler' => 'views_og_query_ogname', 'notafield' => false, ),

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  • how to interact vb.net with flash chat room?

    - by elca
    I'm making a vb.net application which interacts with a flash chat room. I was capturing http traffic with live HTTP header in Firefox but it is not HTTP traffic. How can I implement it so that it can interact with a flash chat room? For example in this site. When people enter here they are required to enter a nickname to chat with other people. So what I exactly want know is, when enter this site I want to input my nickname into this flash chat window and click 'Join' button within VB.NET How can i implement this program with vb.net? Any clues or any samples will be much appreciated! Thank you!

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  • What is the best practise for relational database tables in mysql?

    - by George
    Hi, I know, there is a lot of info on mysql out there. But I was not really able to find an answer to this specific and actually simple question: Let's say I have two tables: USERS (with many fields, e.g. name, street, email, etc.) and GROUPS (also with many fields) The relation is (I guess?) 1:n, that is ONE user can be a member of MANY groups. What I dis, is create another table, named USERS_GROUPS_REL. This table has only two fields: us_id (unique key of table USERS) and gr_id (unique key of table GROUPS) In PHP I do a query with join. Is this "best practice" or is there a better way? Thankful for any hint!

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  • Approach to Selecting top item matching a criteria

    - by jkelley
    I have a SQL problem that I've come up against routinely, and normally just solved w/ a nested query. I'm hoping someone can suggest a more elegant solution. It often happens that I need to select a result set for a user, conditioned upon it being the most recent, or the most sizeable or whatever. For example: Their complete list of pages created, but I only want the most recent name they applied to a page. It so happens that the database contains many entries for each page, and only the most recent one is desired. I've been using a nested select like: SELECT pg.customName, pg.id FROM ( select id, max(createdAt) as mostRecent from pages where userId = @UserId GROUP BY id ) as MostRecentPages JOIN pages pg ON pg.id = MostRecentPages.id AND pg.createdAt = MostRecentPages.mostRecent Is there a better syntax to perform this selection?

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  • PHP SQL, SELECT corresponding data from 3 tables at once?

    - by user346325
    I have 3 tables, 'u' 'd' 's' 'u' has userid divid 'd' has divid divname 's' has sname primaryuserid secondaryuserid Now what I'd like to do is display a table with rows of the following format userid, divname, sname Plus figure out a way to decipher whether userid is a primary or secondary for this sname table. I'm able to show userid and divname using a left join, but I don't know how I would add a third table? To make it trickier, there can be more than 1 snames for each userid, up to ~20. Is there a way to display 0-20 snames depending on the userid, seperated with commas?

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  • Why am I getting a MySQL error?

    - by John Hoffman
    Here is my query. Its intention is allow access to properties of the animals that constitute a match of two animals. The match table contains columns for animal1ID and animal2ID to store which animals constitute the match. SELECT id, (SELECT * FROM animals WHERE animals.id=matches.animal1ID) AS animal1, (SELECT * FROM users WHERE animals.id=matches.animalID) AS animal2 FROM matches WHERE id=5 However, MySQl returns this error: Operand should contain 1 column(s). Why? Is there an alternative way to do this, perhaps with a JOIN statement?

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  • strange behavior of <> to filter null values

    - by Kerezo
    Hi experts: I have a table Called tblAlarm and it has some records like this: I have another table for determine what user see what message: Now I want to write a query to show Messages that user has not seen if message didinot expired.(for example it's year between BeginYear and EndYear and so on ...). I write this query: SELECT * FROM tblAlarms LEFT OUTER JOIN tblUsersAlarms tua ON tblAlarms.Id=tua.MessageID WHERE @CurrentYear BETWEEN tblAlarms.BeginYear AND tblAlarms.EndYear AND @CurrentMonth BETWEEN tblAlarms.BeginMonth AND tblAlarms.EndMonth AND @CurrentDay BETWEEN tblAlarms.BeginDay AND tblAlarms.EndDay AND (@CurrentHour * 60 + @CurrentMinute) BETWEEN tblAlarms.BeginHour*60 + tblAlarms.BeginMinute AND tblAlarms.EndHour*60 + tblAlarms.EndMinute --AND (tua.UserID <> 128 AND tua.UserID IS NULL) and it returns : but if I unComment last line it does not return any record.How I can determine what messages that users has not been seen? thanks

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  • PHP MySQL query string

    - by user1174762
    I am newer to PHP and MySQL and I am having trouble understanding join. I think, for me, the problem lies with actually understanding the logic of the query. What I am trying to do Is select all of the status updates from a table named "post", but only ones from users I am "following", and then display them In order by date. So, I have two databases which are set up like so: posts |post_id|user_id|post_body|date_upload| | 1 | 4 | hey. | 01/2/2012 | follows |relation_id|user_id|followee_id| | 1 | 4 | 2 | Could someone please explain how I should syntactically and Logically set this up? Thank you!

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  • MySQL: Select remaining rows

    - by Bjork24
    I've searched everywhere for this, but I can't seem to find a solution. Perhaps I'm using the wrong terms. Either way, I'm turning to good ol' trusty S.O. to help my find the answer. I have two tables, we'll call them 'tools' and 'installs' tools = id, name, version installs = id, tool_id, user_id The 'tools' table records available tools, which are then installed by a user and recorded in the 'installs' table. Selecting the installed tools are simple enough: SELECT tools.name FROM tools LEFT JOIN installs ON tools.id = installs.tool_id WHERE user_id = 99 ; How do I select the remaining tools -- the ones that have yet to be installed by user #99? I'm sorry if this is painfully obvious, but I just can't seem to figure it out! Thanks for the help!

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  • Why isn't INT more efficient than UNIQUEIDENTIFIER (according to the execution plan)?

    - by ck
    I have a parent table and child table where the columns that join them together are the UNIQUEIDENTIFIER type. The child table has a clustered index on the column that joins it to the parent table (its PK, which is also clustered). I have created a copy of both of these tables but changed the relationship columns to be INTs instead, have rebuilt the indexes so that they are essentially the same structure and can be queried in the same way. When I query for a known 20 records from the parent table, pulling in all the related records from the child tables, I get identical query costs across both, i.e. 50/50 cost for the batches. If this is true, then my giant project to change all of the tables like this appears to be pointless, other than speeding up inserts. Can anyone provide any light on the situation? EDIT: The question is not about which is more efficient, but why is the query execution plan showing both queries as having the same cost?

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  • Selecting only the entries that have a distinct combination of values?

    - by Theodore E O'Neal
    I have a table, links1, that has the columns headers CardID and AbilityID, that looks like this: CardID | AbilityID 1001 | 1 1001 | 2 1001 | 3 1002 | 2 1002 | 3 1002 | 4 1003 | 3 1003 | 4 1003 | 5 What I want is to be able to return all the CardID that that have two specific AbilityID. For example: If I choose 1 and 2, it returns 1001. If I choose 3 and 4, it returns 1002 and 1003. Is it possible to do this with only one table, or will I need to create an identical table and do an INNER JOIN on those?

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