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  • How do I select differing rows in two MySQL tables with the same structure?

    - by chiborg
    I have two tables, A and B, that have the same structure (about 30+ fields). Is there a short, elegant way to join these tables and only select rows where one or more columns differ? I could certainly write some script that creates the query with all the column names but maybe there is an SQL-only solution. To put it another way: Is there a short substitute to this: SELECT * FROM table_a a JOIN table_b b ON a.pkey=b.pkey WHERE a.col1 != b.col2 OR a.col2 != b.col2 OR a.col3 != b.col3 # .. repeat for 30 columns

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  • How to correctly stop thread which is using Control.Invoke

    - by codymanix
    I tried the following (pseudocode) but I always get a deadlock when Iam trying to stop my thread. The problem is that Join() waits for the thread to complete and a pending Invoke() operation is also waiting to complete. How can I solve this? Thread workerThread = new Thread(BackupThreadRunner); volatile bool cancel; // this is the thread worker routine void BackupThreadRunner() { while (!cancel) { DoStuff(); ReportProgress(); } } // main thread void ReportProgress() { if (InvokeRequired) { Invoke(ReportProgress); } UpdateStatusBarAndStuff(); } // main thread void DoCancel() { cancel=true; workerThread.Join(); }

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  • Should I use integer primary IDs?

    - by arthurprs
    For example, I always generate an auto-increment field for the users table, but I also specify a UNIQUE index on their usernames. There are situations that I first need to get the userId for a given username and then execute the desired query, or use a JOIN in the desired query. It's 2 trips to the database or a JOIN vs. a varchar index. Should I use integer primary IDs? Is there a real performance benefit on INT over small VARCHAR indexes?

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  • How do I replace values within a data frame with a string in R?

    - by Arturito
    short version: How do I replace values within a data frame with a string found within another data frame? longer version: I'm a biologist working with many species of bees. I have a data set with many thousands of bees. Each row has a unique bee ID # along with all the relevant info about that specimen (data of capture, GPS location, etc). The species information for each bee has not been entered because it takes a long time to ID them. When IDing, I end up with boxes of hundred of bees, all of the same species. I enter these into a separate data frame. I am trying to write code that will update the original data file with species information (family, genus, species, sex, etc) as I ID the bees. Currently, in the original data file, the species info is blank and is interpreted as NA within R. I want to have R find all unique bee ID #'s and fill in the species info, but I am having trouble figuring out how to replace the NA values with a string (e.g. "Andrenidae") Here is a simple example of what I am trying to do: rawData<-data.frame(beeID=c(1:20),family=rep(NA,20)) speciesInfo<-data.frame(beeID=seq(1,20,3),family=rep("Andrenidae",7)) rawData[rawData$beeID == 4,"family"] <- speciesInfo[speciesInfo$beeID == 4,"family"] So, I am replacing things as I want, but with a number rather than the family name (a string). What I would eventually like to do is write a little loop to add in all the species info, e.g.: for (i in speciesInfo$beeID){ rawData[rawData$beeID == i,"family"] <- speciesInfo[speciesInfo$beeID == i,"family"] } Thanks in advance for any advice! Cheers, Zak EDIT: I just noticed that the first two methods below add a new column each time, which would cause problems if I needed to add species info multiple times (which I typically do). For example: rawData<-data.frame(beeID=c(1:20),family=rep(NA,20)) Andrenidae<-data.frame(beeID=seq(1,20,3),family=rep("Andrenidae",7)) Halictidae<-data.frame(beeID=seq(1,20,3)+1,family=rep("Halictidae",7)) # using join library(plyr) rawData <- join(rawData, Andrenidae, by = "beeID", type = "left") rawData <- join(rawData, Halictidae, by = "beeID", type = "left") # using merge rawData <- merge(x=rawData,y=Andrenidae,by='beeID',all.x=T,all.y=F) rawData <- merge(x=rawData,y=Halictidae,by='beeID',all.x=T,all.y=F) Is there a way to either collapse the columns so that I have one, unified data frame? Or a way to update the rawData rather than adding a new column each time? Thanks in advance!

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  • python list directory , subdirectory and files

    - by thomytheyon
    Hi Alls, I'm trying to make a script to list all directory, subdirectory, and files in a given directory. I tried this : import sys,os root="/home/patate/directory/" path=os.path.join(root,"targetdirectory") for r,d,f in os.walk(path): for file in f: print os.path.join(root,file) Unfortunatly it doesn't work properly, i get all the files, but not them complete path. like : if the dir struct would be : /home/patate/directory/targetdirectory/123/456/789/file.txt It would print: /home/patate/directory/targetdirectory/file.txt What i need is the first result, any help would be greatly appreciated ! Thanks

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  • Select data from three different tables with null data

    - by user3678972
    I am new in Sql. My question is how to get data from three different tables with null values. I have tried a query as below: SELECT * FROM [USER] JOIN [Location] ON ([Location].UserId = [USER].Id) JOIN [ParentChild] ON ([ParentChild].UserId = [USER].Id) WHERE ParentId=7 which I find from this link. Its working fine but, it not fetches all and each data associated with the ParentId Something like it only fetches data which are available in all tables, but also omits some data which not available in Location tables but it comes under the given ParentId. For example: UserId ParentId 1 7 8 7 For userId 8, there is data available in Location table,so it fetches all data. But there is no data for userId 1 available in Location table, so the query didn't work for this. But I want all and every data. If there is no data for userId then it can return only null columns. Is it possible ?? hope everyone can understand my problem.

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  • Sql combine 2 rows to one

    - by Yan
    Hi , i have this table Testers employee name ------------ Sam Korch dan mano i want to combine tow rows to one, it will be "Sam Korch,Dan Mano" i have this query select @theString = COALESCE(@theString + ',', '') + EmployeeName from Testers join vw_EKDIR on Testers.TesterGlobalId = vw_EKDIR.GlobalID where TestId = 31 it working but i dont want to do select i want the result will be in @thestring so i try to do this query set @theString = ( select @theString = COALESCE(@theString + ',', '') + EmployeeName from Testers join vw_EKDIR on Testers.TesterGlobalId = vw_EKDIR.GlobalID where TestId = 31 ) it is not working ... i want @thestring will be the result. any idaes ? thanks

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  • Decoupling into DAL and BLL - my concerns.

    - by novice_man
    Hi, In many posts concerning this topic I come across very simple examples that do not answer my question. Let's say a have a document table and user table. In DAL written in ADO.NET i have a method to retries all documents for some criteria. Now I the UI I have a case where I need to show this list along with the names of the creator. Up to know I have it done with one method in DAL containig JOIN statement. However eveytime I have such a complex method i have to do custom mapping to some object that doesn't mark 1:1 to DB. Should it be put into another layer ? If so then I will have to resing from join query for iteration through results and querying each document author. . . which doen't make sense... (performance) what is the best approach for such scenarios ?

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  • Invalid SQL Query

    - by svovaf
    I have the next query that in my opinion is a valid one, but I keep getting error telling me that there is a proble on "WHERE em.p4 = ue.p3" - Unknown column 'ue.p3' in 'where clause'. This is the query: SELECT DISTINCT ue.p3 FROM table1 AS ue INNER JOIN table2 AS e ON ue.p3 = e.p3 WHERE EXISTS( SELECT 1 FROM ( SELECT (COUNT(*) >= 1) AS MinMutual FROM table4 AS smm WHERE smm.p1 IN ( SELECT sem.p3 FROM table3 AS sem INNER JOIN table2 AS em ON sem.p3 = em.p3 WHERE em.p4 = ue.p3 AND sem.type = 'friends' AND em.p2 = 'normal' ) AND smm.p5 IN ( 15000,15151 ) ) AS Mutual WHERE Mutual.MinMutual = TRUE) LIMIT 11 If I execute the sub-query which is inside the EXISTS function, everything is O.K. PLEASE HELP!

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  • Rails/mysql SUM distinct records - optimization

    - by pepernik
    Hey. How would you optimize this SQL SELECT SUM(tmp.cost) FROM ( SELECT DISTINCT clients.id as client, countries.credits_cost AS cost FROM countries INNER JOIN clients ON clients.country_id = countries.id INNER JOIN clients_groups ON clients_groups.client_id=clients.id WHERE clients_groups.group_id IN (1,2,3,4,5,6,7,8,9) GROUP BY clients.id ) AS tmp; I'm using this example as part of my Ruby on Rails project. Note that my nested SQL (tmp) can have more then 10 milion records. You can split that in more SQLs if the performance is better. Should I add any indexes to make it quicker (i have it on IDs)?

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  • Logical python question - handeling directories and files in them

    - by Konstantin
    Hello! I'm using this function to extract files from .zip archive and store it on the server: def unzip_file_into_dir(file, dir): import sys, zipfile, os, os.path os.makedirs(dir, 0777) zfobj = zipfile.ZipFile(file) for name in zfobj.namelist(): if name.endswith('/'): os.mkdir(os.path.join(dir, name)) else: outfile = open(os.path.join(dir, name), 'wb') outfile.write(zfobj.read(name)) outfile.close() And the usage: unzip_file_into_dir('/var/zips/somearchive.zip', '/var/www/extracted_zip') somearchive.zip have this structure: somearchive.zip 1.jpeg 2.jpeg another.jpeg or, somethimes, this one: somearchive.zip somedir/ 1.jpeg 2.jpeg another.jpeg Question is: how do I modify my function, so that my extracted_zip catalog would always contain just images, not images in another subdirectory, even if images are stored in somedir inside an archive.

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  • Mysql query - problem with order by

    - by Sergio
    I'm using two tables for selecting messages between users. Table "messages" for recording the messages and table "members" for checking users data (are they activ or deleted). This query working fine. What I need to do is list the received messsages order by last received. I tried to do with "ORDER BY messages.id DESC" at the end of this query but it didn't work. All messages are listed from first received. This is the mysql join table query that I'm using: sql = "select distinct messages.fromid, messages.readed, messages.fromid, messages.toid, members.id as pid From messages Inner Join members on members.id = messages.fromid Where messages.toid = ".$mid." AND members.status = 7 AND messages.kreaded !='1' AND messages.subject != 'readed' GROUP BY fromid" Is there any way to do this?

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  • What are some useful SQL statements that should be known by all developers who may touch the Back en

    - by Jian Lin
    What are some useful SQL statements that should be known by all developers who may touch the Back end side of the project? (Update: just like in algorithm, we know there are sorting problems, shuffling problems, and we know some solutions to them. This question is aiming at the same thing). For example, ones I can think of are: Get a list of Employees and their boss. Or one with the employee's salary greater than the boss. (Self-join) Get a list of the most popular Classes registered by students, from the greatest number to the smallest. (Count, group by, order by) Get a list of Classes that are not registered by any students. (Outer join and check whether the match is NULL, or by Get from Classes table, all ClassIDs which are NOT IN (a subquery to get all ClassIDs from the Registrations table)) Are there some SQL statements that should be under the sleeve of all developers that might touch back end data?

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  • Hibernate Criteria: Return different entity type than rooted entity?

    - by Gilean
    I have entities similar to: ProductLine: id, name ProductLineContents: content_id, product_line_id Content: id, text, updated_time What I'd like to do is: for each product line, get the latest content (so if theres two content entries associated to one product line, the latest updated_time is rturned, and if one content item is associated to two product lines, it is returned twice). Something similar to: select content.* from productline inner join productlinecontents inner join content; However I can't seem to figure out how to have Hibernate Criteria return a different entity than the original one it was created with. So if I wanted to start the criteria at the product line with createCriteria(ProductLine.class) along with the proper joins, then it only returns ProductLine objects, but I need Content objects. What's the best way to accomplish this? The actual data model is much more complex and can't be modified

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  • Difference in select for update of ... in Oracle Database 10g and 11g

    - by sax
    Hi, I found out that Oracle Database 10g and 11g treat the following PL/SQL block differently (I am using scott schema for convenience): DECLARE v_ename bonus.ename%TYPE; BEGIN SELECT b.ename INTO v_ename FROM bonus b JOIN emp e ON b.ename = e.ename JOIN dept d ON d.deptno = e.deptno WHERE b.ename = 'Scott' FOR UPDATE OF b.ename; END; / While in 10g (10.2) this code ends successfully (well NO_DATA_FOUND exception is raised but that is expected), in 11g (11.2) it raises exception "column ambiguously defined". And that is definitely not expected. It seems like it does not take into account table alias because I found out that when I change the column in FOR UPDATE OF e.empno (also does not work) to e.mgr (which is unique) it starts working. So is this some error in 11g? Any thoughts?

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  • Use LINQ to count the number of combinations existing in two lists

    - by Ben McCormack
    I'm trying to create a LINQ query (or queries) that count the total number of occurences of a combinations of items in one list that exist in a different list. For example, take the following lists: CartItems DiscountItems ========= ============= AAA AAA AAA BBB AAA BBB BBB CCC CCC DDD The result of the query operation should be 2 since I can find two combinations of AAA and BBB (from DiscountItems) within the contents of CartItems. My thinking in approaching the query is to join the lists together to shorten CartItems to only include items from DiscountItems. The solution would be to find the CartItem in the resulting query that occurs the least amount of times, thus indicating how many combinations of items exist in CartItems. How can this be done? Here's the query I already have, but it's not working. query results in an enumeration with 100 items, far more than I expected. Dim query = From cartItem In Cart.CartItems Group Join discountItem In DiscountGroup.DiscountItems On cartItem.SKU Equals discountItem.SKU Into Group Select SKU = cartItem.SKU, CartItems = Group Return query.Min(Function(x) x.CartItems.Sum(Function(y) y.Quantity))

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  • SQL Server Error: maximum number of prefixes. The maximum is 3.

    - by Ian Boyd
    Trying to run a cross-server update: UPDATE cmslive.CMSFintrac.dbo.lsipos SET PostHistorySequencenNmber = ( SELECT TransactionNumber FROM Transactions WHERE Transactions.TransactionDate = cmslive.CMSFintrac.dbo.lsipos.TransactionDate) Gives the error: Server: Msg 117, Level 15, State 2, Line 5 The number name 'cmslive.CMSFintrac.dbo.lsipos' contains more than the maximum number of prefixes. The maximum is 3. What gives? Note: Rearranging the query into a less readable join form: UPDATE cmslive.CMSFintrac.dbo.lsipos SET PostHistorySequenceNumber = B.TransactionNumber FROM cmslive.CMSFintrac.dbo.lsipos A INNER JOIN Transactions B ON A.TransactionDate = B.TransactionDate does not give an error.

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  • Convert executed SQL result to a list of Model object

    - by huynq9
    I'm wondering that is it possible to convert the executed query result to a list of models. I'm using Ruby with ActiveRecord and need to execute custom SQL query to join two or many tables. The code looks like below: connection = ActiveRecord::Base.connection sql = "select T1.f1, T2.f2 from T1 left join T2 on T1.id = T2.id" @result = connection.execute(sql) In Ruby code, I defined a models to manage the executed SQL result: class Model property :f1, :f2 end Is there any way to convert @result to list of Model object? so I can deal with each item in the list as following @result.each do |item| puts item.f1 puts item.f2 end

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  • Subquery Doctrine Couldn't find class

    - by yosesita
    I'm trying to create a query like this one : $q = Doctrine_Query::create() -select('p.nombre') -addSelect('(select count(*) from alojamiento a left join localidad l on a.localidad_id=l.id where p.id=l.provincia_id and a.activo=true)') -from('provincia p'); but it fails : error 500, couldn't find class a. And : $q = Doctrine_Query::create() -select('nombre') -addSelect('(select count(*) from alojamiento left join localidad on alojamiento.localidad_id=localidad.id where provincia.id=localidad.provincia_id and alojamiento.activo=true)') -from('provincia'); leads to : SQLSTATE[42S22]: Column not found: 1054 Unknown column 'a.localidad_id' in 'on clause'. Any help would be greatly appreciated !

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  • Comparing date in access database

    - by Simon
    How can i compare the day in the access database to a given day in c#? The date column in the database is an general date(day/month/year) try { database = new OleDbConnection(connectionString); database.Open(); date = DateTime.Now.ToShortDateString(); string queryString = "SELECT user_name,zivila.naziv " + "FROM (users LEFT JOIN obroki_save ON obroki_save.ID_uporabnika=users.ID)" + " LEFT JOIN zivila ON zivila.ID=obroki_save.ID_zivila " + " WHERE users.ID= " + a.ToString() + " AND obroki_save.datum=# " + date; loadDataGrid(queryString); } catch (Exception ex) { MessageBox.Show(ex.Message); return; }

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  • acts-as-taggable-on: find tags with name LIKE, sort by tag_counts?

    - by James
    Hi I'm using the rails plugin acts-as-taggable-onand I'm trying to find the top 5 most used tags whose names match and partially match a given query. When I do User.skill_counts.order('count DESC').limit(5).where('name LIKE ?', params[:query]) This return the following error: ActiveRecord::StatementInvalid: SQLite3::SQLException: ambiguous column name: name: SELECT tags.*, COUNT(*) AS count FROM "tags" INNER JOIN users ON users.id = taggings.taggable_id LEFT OUTER JOIN taggings ON tags.id = taggings.tag_id AND taggings.context = 'skills' WHERE (taggings.taggable_type = 'User') AND (taggings.taggable_id IN(SELECT users.id FROM "users")) AND (name LIKE 'asd') GROUP BY tags.id, tags.name HAVING COUNT(*) > 0 ORDER BY count DESC LIMIT 5 But when I do User.skill_counts.first.name this returns "alliteration" I'd appreciate any help on this matter.

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  • Slow query with unexpected scan

    - by zerkms
    Hello I have this query: SELECT * FROM SAMPLE SAMPLE INNER JOIN TEST TEST ON SAMPLE.SAMPLE_NUMBER = TEST.SAMPLE_NUMBER INNER JOIN RESULT RESULT ON TEST.TEST_NUMBER = RESULT . TEST_NUMBER WHERE SAMPLED_DATE BETWEEN '2010-03-17 09:00' AND '2010-03-17 12:00' the biggest table here is RESULT, contains 11.1M records. The left 2 tables about 1M. this query works slowly (more than 10 minutes) and returns about 800 records. executing plan shows clustered index scan over all 11M records. RESULT.TEST_NUMBER is a clustered primary key. if I change 2010-03-17 09:00 to 2010-03-17 10:00 - i get about 40 records. it executes for 300ms. and plan shows clustered index seek if i replace * in SELECT clause to RESULT.TEST_NUMBER (covered with index) - then all become fast in first case too. this points to hdd io issues, but doesn't clarifies changing plan. so, any ideas?

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  • retrieve columns from sqlite3

    - by John Smith
    I have two tables in sqlite: CREATE TABLE fruit ('fid' integer, 'name' text); CREATE TABLE basket ('fid1' integer, 'fid2' integer, 'c1' integer, 'c2' integer); basket is supposed to have count c1 of fruit fid1 and c2 of fruit fid2 I created a view fruitbasket; create view fruitbasket as select * from basket inner join fruit a on a.fid=basket.fid1 inner join fruit b on b.fid=basket.fid2; it works (almost) as expected. When I type pragma table_info(fruitbasket); I get the following output 0|fid1|integer|0||0 1|fid2|integer|0||0 2|c1|integer|0||0 3|c2|integer|0||0 4|fid|integer|0||0 5|name|text|0||0 6|fid:1|integer|0||0 7|name:1|text|0||0 The problem is that I cannot seem to SELECT name:1. How can I do it other than going back and re-aliasing the columns?

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  • What are some useful SQL statements / usage patterns that should be known by all developers who may

    - by Jian Lin
    What are some useful SQL statements that should be known by all developers who may touch the Back end side of the project? (Update: just like in algorithm, we know there are sorting problems, shuffling problems, and we know some solutions to them. This question is aiming at the same thing). For example, ones I can think of are: Get a list of Employees and their boss. Or one with the employee's salary greater than the boss. (Self-join) Get a list of the most popular Classes registered by students, from the greatest number to the smallest. (Count, group by, order by) Get a list of Classes that are not registered by any students. (Outer join and check whether the match is NULL, or by Get from Classes table, all ClassIDs which are NOT IN (a subquery to get all ClassIDs from the Registrations table)) Are there some SQL statements that should be under the sleeve of all developers that might touch back end data?

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  • How can I push a string from one client connected to a WCF service to another connected as well?

    - by Sergio Tapia
    Here's what I have so far: IService: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.ServiceModel; namespace ServiceLibrary { [ServiceContract(SessionMode = SessionMode.Allowed, CallbackContract = typeof(IServiceCallback))] public interface IService { [OperationContract(IsOneWay = false, IsInitiating = true, IsTerminating = false)] void Join(string userName); } interface IServiceCallback { [OperationContract(IsOneWay = true)] void UserJoined(string senderName); } } Service: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.ServiceModel; namespace ServiceLibrary { [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)] public class Service:IService { IServiceCallback callback = null; public void Join(string userName) { callback = OperationContext.Current.GetCallbackChannel<IServiceCallback>(); } } } Just a simple string passed from one client to another.

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