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  • GROUP BY as a way to pick the first row from a group of similar rows, is this correct, is there any

    - by FipS
    I have a table which stores test results like this: user | score | time -----+-------+------ aaa | 90% | 10:30 bbb | 50% | 9:15 *** aaa | 85% | 10:15 aaa | 90% | 11:00 *** ... What I need is to get the top 10 users: user | score | time -----+-------+------ aaa | 90% | 11:00 bbb | 50% | 9:15 ... I've come up with the following SELECT: SELECT * FROM (SELECT user, score, time FROM tests_score ORDER BY user, score DESC, time DESC) t1 GROUP BY user ORDER BY score DESC, time LIMIT 10 It works fine but I'm not quite sure if my use of ORDER BY is the right way to pick the first row of each group of sorted records. Is there any better practice to achieve the same result? (I use MySQL 5)

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  • date comparisons in Rails

    - by aressidi
    Hi there, I'm having trouble with a date comparison in a named scope. I'm trying to determine if an event is current based on its start and end date. Here's the named scope I'm using which kind of works, though not for events that have the same start and end date. named_scope :date_current, :conditions => ["Date(start_date) <= ? AND Date(end_date) >= ?", Time.now, Time.now] This returns the following record, though it should return two records, not one... >> Event.date_current => [#<Event id: 2161, start_date: "2010-02-15 00:00:00", end_date: "2010-02-21 00:00:00", ...] What it's not returning is this as well >> Event.find(:last) => #<Event id: 2671, start_date: "2010-02-16 00:00:00", end_date: "2010-02-16 00:00:00", ...> The server time seems to be in UTC and I presume that the entries are being stored in the DB in UTC. Any ideas as to what I'm doing wrong or what to try? Thanks!

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  • Speeding up inner-joins and subqueries while restricting row size and table membership

    - by hiffy
    I'm developing an rss feed reader that uses a bayesian filter to filter out boring blog posts. The Stream table is meant to act as a FIFO buffer from which the webapp will consume 'entries'. I use it to store the temporary relationship between entries, users and bayesian filter classifications. After a user marks an entry as read, it will be added to the metadata table (so that a user isn't presented with material they have already read), and deleted from the stream table. Every three minutes, a background process will repopulate the Stream table with new entries (i.e. whenever the daemon adds new entries after the checks the rss feeds for updates). Problem: The query I came up with is hella slow. More importantly, the Stream table only needs to hold one hundred unread entries at a time; it'll reduce duplication, make processing faster and give me some flexibility with how I display the entries. The query (takes about 9 seconds on 3600 items with no indexes): insert into stream(entry_id, user_id) select entries.id, subscriptions_users.user_id from entries inner join subscriptions_users on subscriptions_users.subscription_id = entries.subscription_id where subscriptions_users.user_id = 1 and entries.id not in (select entry_id from metadata where metadata.user_id = 1) and entries.id not in (select entry_id from stream where user_id = 1); The query explained: insert into stream all of the entries from a user's subscription list (subscriptions_users) that the user has not read (i.e. do not exist in metadata) and which do not already exist in the stream. Attempted solution: adding limit 100 to the end speeds up the query considerably, but upon repeated executions will keep on adding a different set of 100 entries that do not already exist in the table (with each successful query taking longer and longer). This is close but not quite what I wanted to do. Does anyone have any advice (nosql?) or know a more efficient way of composing the query?

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  • Optimum size of transaction in Postgres?

    - by Joe
    I'm running a process that does a lot of updates ( 100,000) to a table. I have the choice between putting all the updates in a single transaction or committing transactions every 1000 or so. Ignore for the moment the case where a transaction fails and is aborted. I'm interested in the best size of transaction for memory and speed efficiency.

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  • CakePHP. How can i make a model test in a table with another primary key?

    - by Marcelo
    I have this table CREATE TABLE myexamples.problems ( id INT, name VARCHAR(45) NULL , pk_id INT AUTO_INCREMENT PRIMARY KEY ); But when I try test a model in cakephp, it fails because the table has two autoincrement attributes. The following query CREATE TABLE `test_suite_problems` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(45) DEFAULT NULL, `pk_id` int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (`pk_id`) ) DEFAULT CHARSET=latin1, COLLATE=latin1_swedish_ci, ENGINE=InnoDB; raise this error: "1075: Incorrect table definition; there can be only one auto column and it must be defined as a key" I have in the model class <?php class Problem extends AppModel { var $name = 'Problem'; var $displayField = 'name'; var $primaryKey='problems'; } ?> But I don't know how to make the field ID not having an autoincrement attribute, and I can't change the table structure.

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  • Compare and find differences in two tables in Oracle

    - by Ruslan
    Hi! i have 2 tables: account: ID, ACC, AE_CCY, DRCR_IND, AMOUNT, MODULE flex: ID, ACC, AE_CCY, DRCR_IND, AMOUNT, MODULE I want to show differences comparing only by: AE_CCY, DRCR_IND, AMOUNT, MODULE and ACC by first 4 characters Example: ID ACC AE_CCY DRCR_IND AMOUNT MODULE -- --------- ------ -------- ------ ------ 1 734647674 USD D 100 OP and in flex: ID ACC AE_CCY DRCR_IND AMOUNT MODULE -- --------- ------ -------- ------ ------ 1 734647654 USD D 100 OP 2 734665474 USD D 100 OP 9 734611111 USD D 100 OP ID's 2 and 9 should be shown as differences. If I use FULL JOIN I'll get no differences as substr(account.ACC,1,4) = substr(flex.ACC,1,4) are equal and others are equal and MINUS doesn't work because ID's different. Thanks.

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  • MYSQL Convert rows to columns performance problem

    - by Tarski
    I am doing a query that converts rows to columns similar to this post but have encountered a performance problem. Here is the query:- SELECT Info.Customer, Answers.Answer, Answers.AnswerDescription, Details.Code1, Details.Code2, Details.Code3 FROM Info LEFT OUTER JOIN Answers ON Info.AnswerID = Answers.AnswerID LEFT OUTER JOIN (SELECT ReferenceNo, MAX(CASE DetailsIndicator WHEN 'cde1' THEN DetailsCode ELSE NULL END ) Code1, MAX(CASE DetailsIndicator WHEN 'cde2' THEN DetailsCode ELSE NULL END ) Code2, MAX(CASE DetailsIndicator WHEN 'cde3' THEN DetailsCode ELSE NULL END ) Code3 FROM DetailsData GROUP BY ReferenceNo) Details ON Info.ReferenceNo = Details.ReferenceNo There are less than 300 rows returned, but the Details table is about 180 thousand rows. The query takes 45 seconds to run and needs to take only a few seconds. When I type show processlist; into MYSQL it is hanging on "Sending Data". Any thoughts as to what the performance problem might be?

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  • How can I alter a temp table?

    - by William
    I need to create a temp table, than add a new int NOT NULL AUTO_INCREMENT field to it so I can use the new field as a row number. Whats wrong with my query? SELECT post, newid FROM ((SELECT post`test_posts`) temp ALTER TABLE temp ADD COLUMN newid int NOT NULL AUTO_INCREMENT)

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  • Setting property of objects in datacontext

    - by ryudice
    Hi, all my entities have a common property which specifies the company they belong to, I would like to set this property in a method in my datacontext but I do not want to use the partial methods for each of the entity types that the datacontext provides, is there a method that receives any entity that is inserted throught the datacontext so that I can hook to it or override it and set the property using reflection? thanks.

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  • oracle plsql select pivot without dynamic sql to group by

    - by kayhan yüksel
    To whom it may respond to, We would like to use SELECT function with PIVOT option at a 11g r2 Oracle DBMS. Our query is like : "select * from (SELECT o.ship_to_customer_no, ol.item_no,ol.amount FROM t_order o, t_order_line ol WHERE o.NO = ol.order_no and ol.item_no in (select distinct(item_no) from t_order_line)) pivot --xml ( SUM(amount) FOR item_no IN ( select distinct(item_no) as item_no_ from t_order_line));" As can be seen, XML is commented out, if run as PIVOT XML it gives the correct output in XML format, but we are required to get the data as unformatted pivot data, but this sentence throws error : ORA-00936: missing expression Any resolutions or ideas would be welcomed, Best Regards -------------if we can get the result of this to sys_refcursor using execute immediate it will be solved ------------------------ the procedure : PROCEDURE pr_test2 (deneme OUT sys_refcursor) IS v_sql NVARCHAR2 (4000) := ''; TYPE v_items IS TABLE OF NVARCHAR2 (30); v_pivot_items NVARCHAR2 (4000) := ''; BEGIN FOR i IN (SELECT DISTINCT (item_no) AS items FROM t_order_line) LOOP v_pivot_items := ',''' || i.items || '''' || v_pivot_items; END LOOP; v_pivot_items := LTRIM (v_pivot_items, ','); v_sql := 'begin select * from (SELECT o.ship_to_customer_no, ol.item_no,ol.amount FROM t_order o, t_order_line ol WHERE o.NO = ol.order_no and OL.ITEM_NO in (select distinct(item_no) from t_order_line)) pivot --xml ( SUM(amount) FOR item_no IN (' || v_pivot_items || '));end;'; open DENEME for select v_sql from dual; Kayhan YÜKSEL

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  • Updating Excel Cell with Non-Numeric Data in C#

    - by kbo206
    I have a query that is ExcelQuery = "Update [Sheet1$] set CITIZEN_ID = #" + value + " where CITIZEN_ID = " + value; As you can see, I'm essentially just appending a "#" onto the CITIZEN_ID field. value is a int/numeric value. So if I had "256" in the CITIZEN_ID column it would be converted to "#256" When I execute this I get an OleDbException Syntax error in date in query expression so I surrounded part of the query in single quotes like this, ExcelQuery = "Update [Sheet1$] set CITIZEN_ID = '#" + value + "' where CITIZEN_ID = " + value; With that I get yet another OleDbException this time with, Data type mismatch in criteria expression. I'm guessing for some reason the CITIZEN_ID fields don't want to take anything besides a plain number. Is there any way I can remedy this to get that pound symbol in? Thanks!

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  • Complex SQL query, one to many relationship

    - by Ethan
    Hey SO, I have a query such that I need to get A specific dog All comments relating to that dog The user who posted each comment All links to images of the dog the user who posted each link I've tried a several things, and can't figure out quite how to work it. Here's what I have (condensed so you don't have to wade through it all): SELECT s.dog_id, s.name, c.comment, c.date_added AS comment_date_added, u.username AS comment_username, u.user_id AS comment_user_id, l.link AS link, l.date_added AS link_date_added, u2.username AS link_username, u2.user_id AS link_user_id FROM dogs AS d LEFT JOIN comments AS c ON c.dog_id = d.dog_id LEFT JOIN users AS u ON c.user_id = u.user_id LEFT JOIN links AS l ON l.dog_id = d.dog_id LEFT JOIN users AS u2 ON l.user_id = u2.user_id WHERE d.dog_id = '1' It's sorta close to working, but it'll only return me the first comment, and the first link all as one big array with all the info i requested. The are multiple comments and links per dog, so I need it to give me all the comments and all the links. Ideally it'd return an object with dog_id, name, comments(an array of the comments), links(an array of the links) and then comments would have a bunch of comments, date_added, username, and user_id and links would have a bunch of links with link, date_added, username and user_id. It's got to work even if there are no links or comments. I learned the basics of mySQL somewhat recently, but this is pretty far over my head. Any help would be wonderful. Thanks!

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  • SSIS - Multiple Configurations

    - by Mick Walker
    I have inherited a SSIS project. I have never worked with SSIS before, and the one thing that seems strange to me, is that there is no way to manage multiple configurations. For each SSIS package we have 3 delpoyment environments, DEV, UAT and PRODUCTION. At the moment I am having to edit the configuration for every package we deploy manually for each change (and there are a lot of packages). Does anyone know of a more graceful way to handle these configuration changes?

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  • have we limitation in submit some query in c# to oracle

    - by rima
    Can I send this query from my C# connection to my oracle connection? "Select Object_name,status from object_name where object_type='function';" or "Select Object_name,status from object_name where object_type='Procedure';" or because as I remember, I have this problem when I write a program to connect to Access with java,those days I try to submit some query to get all table name. regard.

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  • Select Statements in Jobs

    - by Andrew Vogel
    I have inherited a few jobs and I am trying to understand why select statements would be in their steps. I would think that select statements would be pointless in an automated job that displays nothing for an end user.

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  • Repository vs Data Access

    - by vdh_ant
    Hi guys In the context of the n-tier application, is there a difference between what you would consider your data access classes to be and your repositories? I tend to think yes but I just wanted to see what other thought. My thinking is that the job of the repository is just to contain and execute the raw query itself, where as the data access class would create the context, execute the repository (passing in the context), handle mapping the data model to the domain model and return the result back up... What do you guys think? Also do you see any of this changing in a Linq to XML scenario (assuming that you change the context for the relevant XDocument)? Cheers Anthony

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  • Which Oracle table uses a sequence?

    - by Jaú
    Having a sequence, I need to find out which table.column gets its values. As far as I know, Oracle doesn't keep track of this relationship. So, looking up for the sequence in source code would be the only way. Is that right? Anyone knows of some way to find out this sequence-table relationship?

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  • Table names, and loop to describe

    - by Greg
    Working in Oracle 10g. Easy way to list all tables names (select table_name from dba_tables where owner = 'me') But now that I have the table names, is there an easy way to loop through them and do a 'describe' on each one in sequence?

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  • Receiving a NullPointerException when calling a cursor in Android

    - by LordSnoutimus
    I am creating an application which tracks the users location using GPS, stores the longitude and latitude in a database using a content provider then output the first long and lat to a mapview. I am able to create the cursor using this line of code: Cursor c = getContentResolver().query(GPSContentProvider.CONTENT_URI, null, null, null, null); startManagingCursor(c); However, when I make a call to move to the first row in the database or even try to close the cursor using c.close(); I receive a NullPointerException.

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  • rails: date type and GetDate

    - by cbrulak
    This is a follow up to this question: http://stackoverflow.com/questions/2930256/unique-responses-rails-gem I'm going to create an index based on the user id, url and a date type. I want date type (not datetime type) because I want the day, the 24 hour day to be part of the index to avoid duplication of page views counts on the same day. In other words: A view only counts once in a day by a visitor. I also want the default value of that column (viewdate) to be the function GETDATE(). This is what I have in my migration: execute "ALTER TABLEpage_viewsADD COLUMN viewdate datetime DEFAULTGETDATE()`" But the value viewdate is always empty. What am I missing? (as an aside, any other suggestions for accomplishing this goal?)

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  • Replication - syncronizing most of the data some of the time

    - by uncle brad
    I have some data that isn't properly "partitioned" (for lack of a better word). All inserts, processing and reporting happen on the same table. The bulk of the processing happens not long after the insert and not long after that it becomes immutable (we're talking days). I could do all inserts and processing on a new table that I replicate to the old table. When I detect that the data has become immutable I would delete the data from the new table, but I would edit the delete replication stored procedure so that the delete did not replicate. How bad an idea is this? It seems attractive at the moment (I haven't slept on it yet) because it might mitigate a performance problem with only very small changes to the application. It also seems like it might be a good way to shoot myself in the foot.

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  • How to get distinct values from a column with all its corresponding values in another column

    - by Vishnu
    I know the question is bit confusing. Please read below. I have a table table_categories (id INT(11), cname VARCHAR(25),survey_id INT(11)) I want to retrieve the values for the column cname without duplication, that is distinct values but with all the values in the other column. id cname survey_id -- -------- --------- 1 Trader 2 2 Beginner 2 25 Human 1 26 Human 2 From the above example I want to retrieve distinct cnames with all the values of the survey_id. I don't want to use any programming language. Is there any way by using a single query. Please give me a solution in MySQL.

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  • ora-00939 error in reporting services, SSRS

    - by san
    Hi, I have an SSRS report , Oracle is my backend and am using this following query for dataset of my second parameter. select distinct X from v_stf_sec_user_staffing_center usc where usc.center_group_id in ( select distinct center_group_id from V_T_STAFFING_CENTER_GROUP scg where INSTR(','||REPLACE(:PI_REGION_LIST,' ')||',', ','||scg.group_abbreviation||',') 0) and usc.nt_user_name=:PI_NT_USER_NAME Here PI_REGION_LIST is a multivalued parameter of string type. and PI_NT_USER_NAME is a default string valued parameter this query works fine when i try to execute in manulally in the Data tab , also in the Oracle tool. But when i run the report in SSRS and select more than 3 values for the parameter PI_REGION_LIST the report throws an error on this dataset, ora-00939 error,too many arguments for function. I am not able to figure out the error here. Please help me with an idea. Thanks in advance, Suni.

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  • How to model parent to child pair in MySQL (SQL)

    - by mikeschuld
    I have a data model that includes element types Stage, Actor, and Form. Logically, Stages can be assigned pairs of ( Form <--- Actor ) which can be duplicated many times (i.e. same person and same form added to the same stage at a later date/time). Right now I am modeling this with these tables: Stage Form Actor Form_Actor _______________ |Id | |FormId | --> Id in Form |ActorId | --> Id in Actor Stage_FormActor __________________ |Id | |StageId | --> Id in Stage |FormActorId | --> Id in Form_Actor I am using CodeSmith to generate the data layer for this setup and none of the templates really know how to handle this type of relationship correctly when generating classes. Ideally, the ORM would have Stage.FormActors where FormActor would be the pair Form, Actor. Is this the correct way to model these relationships. I have tried using all three Ids in one table as well Stage_Form_Actor ______________ |Id | |StageId | --> Id in Stage |FormId | --> Id in Form |ActorId | --> Id in Actor This doesn't really get generated very well either. Ideas?

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