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• rails summing column values of rows with similar attributes

  - by butterywombat

  Hi all, I have a Sites table that has columns name, and time. The name does not have to be unique. So for example I may have the entries 'hi.com, 5', 'hi.com, 10', 'bye.com, 4'. I would like to sum up all the unique sites so that i get 'hi.com, 15' and 'bye.com, 4' for plotting purposes. How can I do that? (For some reference I was looking at http://railscasts.com/episodes/223-charts but I couldn't get the following (translated to my table) to work def self.total_on(date) where("date(purchased_at) = ?", date).sum(:total_price) end nor do I really understand the syntax of the 'where("date(purchased_at) = ?", date)' part. Thanks for helping a rails newbie!

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• Rails: Modeling an optional relation in ActiveRecord

  - by Hassinus

  I would like to map a relation between two Rails models, where one side can be optionnal. Let's me be more precise... I have two models: Profile that stores user profile information (name, age,...) and User model that stores user access to the application (email, password,...). To give you more information, User model is handled by Devise gem for signup/signin. Here is the scenario of my app: 1/ When a user register, a new row is created in User table and there is an equivalent in Profile table. This leads to the following script: class User < ActiveRecord::Base belongs_to :profile end 2/ A user can create it's profile without registering (kind of public profile with public information), so a row in Profile doesn't have necessarily a User row equivalent (here is the optional relation, the 0..1 relation in UML). Question: What is the corresponding script to put in class Profile < AR::Base to map optionally with User? Thanks in advance.

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• Complicated Order By Clause?

  - by Todd

  Hi. I need to do what to me is an advanced sort. I have this two tables: Table: Fruit fruitid | received | basketid 1 20100310 2 2 20091205 3 3 20100220 1 4 20091129 2 Table: Basket id | name 1 Big Discounts 2 Premium Fruit 3 Standard Produce I'm not even sure I can plainly state how I want to sort (which is probably a big part of the reason I can't seem to write code to do it, lol). I do a join query and need to sort so everything is organized by basketid. The basketid that has the oldest fruit.received date comes first, then the other rows with the same basketid by date asc, then the basketid with the next earliest fruit.received date followed by the other rows with the same basketid, and so on. So the output would look like this: Fruitid | Received | Basket 4 20091129 Premuim Fruit 1 20100310 Premuim Fruit 2 20091205 Standard Produce 3 20100220 Big Discounts Any ideas how to accomplish this in a single execution?

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• How do I select from a stored procedure in Sybase?

  - by Nick Fortescue

  My DBA has constructed me a stored procedure in a Sybase database, for which I don't have the definition. If I run it, it returns a resultset with a set of columns and values. I would like to SELECT further to reduce the rows in the result set. Is this possible? From this question it seems like I could insert the results into a temporary table, but I'm not sure I've got permissions to do this. Is there any way I can SELECT certain rows, or if not, can someone give me example code for simulating with a temporary table?

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• Counting values in data frame subject to conditions

  - by unixsnob

  I have been searching around and I cannot figure out how to sumarise the data I have in my data frame (subject to some ranges). I know that it can be done when applying some combination of daaply/taaply or table but I haven't been able to get the exact result I was expecting. Basically I want to turn this: part_no val1 val2 val3 2 1 2 3 45.3 2 1 3 4 -12.3 3 1 3 4 99.3 3 1 5 2 -3.2 3 1 4 3 -55.3 Into this: part_no val3_between0_50 val3_bw50_100 val3_bw-50_0 val3_bw-100_-50 2 1 0 0 1 0 3 0 1 0 1 1 This is dummy data, I got a lot more rows, but the idea is the same. I just want to count the number of values for a participant that meet certain condition. If anyone could explain it sort of step by step, I would really appreciate it. I saw lots of different little posts around, but none do exactly this and my attempts only got me half way there. Like using table, etc. Thanks!

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• MySQL Returns wrong values on SELECT statement

  - by Andrew K

  All, I'm wondering if this is a MySQL bug, but since I've seen others playing with larger numbers than this, I'm thinking I'm doing something wrong here. Here is my table structure for the table I'm querying: mysql describe ipspace6\G ************* 1. row ************* Field: id Type: decimal(39,0) unsigned Null: NO Key: Default: NULL Extra: ************* 2. row ************* Field: addr Type: decimal(39,0) unsigned Null: NO Key: PRI Default: 0 Extra: ************* 3. row ************* Field: netmask Type: decimal(39,0) unsigned Null: NO Key: Default: 0 Extra: ************* 4. row ************* Field: subnet Type: int(4) Null: NO Key: Default: NULL Extra: Now, I run a simple SELECT statement against the "id" column: mysql SELECT id FROM ipspace6 WHERE id='50552019118453823914642686339427860480'; +----------------------------------------+ | id | +----------------------------------------+ | 50552019118453823730175245602332344320 | | 50552019118453823730175245602332344320 | | 50552019118453823914642686339427860480 | | 50552019118453823914642686339427860480 | +----------------------------------------+ ...What the heck is going on here? Two of these results are valid, and two definitely are not. It's not like I'm doing some super-complex nested query or anything, this is simple stuff, and it's driving me insane. Help, anyone?

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• Are Triggers Based On Queries Atomic?

  - by David

  I have a table that has a Sequence number. This sequence number will change and referencing the auto number will not work. I fear that the values of the trigger will collide. If two transactions read at the same time. I have ran simulated tests on 3 connections @ ~1 million records each and no collisions. CREATE TABLE `aut` ( `au_id` int(10) NOT NULL AUTO_INCREMENT, `au_control` int(10) DEFAULT NULL, `au_name` varchar(50) DEFAULT NULL, `did` int(10) DEFAULT NULL, PRIMARY KEY (`au_id`), KEY `Did` (`did`) ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1 TRIGGER `binc_control` BEFORE INSERT ON `aut` FOR EACH ROW BEGIN SET NEW.AU_CONTROL = (SELECT COUNT(*)+1 FROM aut WHERE did = NEW.did); END;

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• Create "INSERT" statements from mySQL database in Java

  - by girdus

  Does anyone know of any good libraries or scripts out there which will allow me to point to any mySQL table and automatically get a list of all the INSERT statements for the data in the table? DdlUtils allows me to create an XML file from a database model but I would like to have it in INSERT statements format and preferably the ability to choose a couple of tables instead of dumping the entire database. Thanks. EDIT: I need it to be a Java API because I want to programatically call it from my Java method.

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• How to fast rendering UITableView

  - by pubudu

  In my program has two view controller. first one has one button.and second one has tableview with custom cell. in this cell has 5 textviews. when i click button of first tableview.it shows second view controller. Its is very slow rendering table view with 5 , 6 rows.it is working well with simulator.but it is very slow with actual i pad. when i click the button i have to wait 2,3 second with button pressed status.and after it view the second view controller it also very slow rendering.i can see it render rows. [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; this one also i used.when i comment this table from my second view.it navigate first view controller to second view controller very fast. how can i solve this issue?

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• What will happen if I change the type of a column from int to year?

  - by MachinationX

  I have a table in MySQL 4.0 which currently has a year field as a smallint(6) type. What will happen if I convert it directly to a Year type with a query like the following: ALTER TABLE t MODIFY y YEAR(4) NOT NULL DEFAULT CURRENT_TIMESTAMP; When the current members of column y have values like 2010? I assume that because the year type is technically values from 1-255, values above that will be truncated or broken. So if MySQL isn't smart enough to realize that 2010(int) = 110(year), what would be the simplest query or queries to convert the values? Thanks for your help!

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• Help with MySQL and CASE WHEN with a range of values

  - by kickdaddy

  I have an accounts table and a records table where accounts have multiple records. I would like to break down the account totals by "count of records" range. i.e. show the breakdown of Count of Records | Count 0-25 | 100 25 - 50 | 122 50 - 100 | 300 etc. I am using the following query, but I can't get it to group by "grp" which is what I want, any help on the best way to modify query? Thanks! SELECT count(*) as ct, CASE WHEN COUNT(*) < 25 THEN '1-25' WHEN COUNT(*) >= 25 < 50 THEN '25-50' WHEN COUNT(*) >= 50 < 100 THEN '50-100' WHEN COUNT(*) >= 100 < 250 THEN '100-250' WHEN COUNT(*) >= 250 < 500 THEN '250-500' WHEN COUNT(*) >= 500 < 1000 THEN '500-1000' ELSE '1000+' END AS grp FROM records r,accounts a WHERE r.account_id=a.id ORDER BY ct

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• SQL Server Update Trigger, Get fields before and after updated

  - by shmandor

  i need example of SQL Server Update Trigger, Get fields before and after updated to execute sql statments in another table

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• effective counter for unique number of visits in PHP & MySQL

  - by Adnan

  Hello, I am creating a counter for unique number of visits on a post, so what I have until now is a table for storing data like this; cvp_post_id | cvp_ip | cvp_user_id In cases a registered user visits a post, for the first time a record is inserted with cpv_post_id and cvp_user_id, so for his next visit I query the table and if the record is available I do not count him as a new visitor. In cases of an anonymous user the same happens but now the cvp_ip and cpv_post_id are used. My concerns is that I do a query every time anyone visits a post for checking if there has been a visit, what would be a more effective way for doing this?

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• Very basic database theory.

  - by John R

  I have a set of tables to show the relationship between organziations and supporters below. Although I have done some basic mySQL querries, I know very little about database 'design'. I plan to querry the database for: -a list of contributors to a specific organization... or, -a list of organizations that a specific suporter supports. The database tables for organiations and contributors may have other columns in the future and recieve a lesser amount of querries based on that information. A | X A | Y A | Z B | X B | Y C | X C | Z How should the tables be set up? I assume that there should be a third table, but there is still redundent information in the third table. Is there a better way of setting up the tables? +----+-------+ +-------------+----------+ +----+-------+ | id | org | | org | contr | | id | contr.| +----+-------+ +-------------+----------+ +----+-------+ | 1 | A | | 1 | 1 | | 1 | X | | 2 | B | | 1 | 2 | | 2 | Y | | 3 | C | | 1 | 3 | | 3 | Z | +----+-------+ | 2 | 1 | +----+-------+ | 2 | 2 | | 3 | 1 | | 3 | 3 | +-------------+----------+

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• Set to null a parent record so that children are removed: howto?

  - by EugeneP

  How to delete a child row (on delete cascade ?) when setting a null value on a parent? Here's the db design. table A [id, b_id_1, b_id_2] table B [id, other fields...] b_id_1 and b_id_2 can be NULL if any of them is null, it means NO B records for corresponding FK (there are 2 of them) so (b_id_1,b_id_2) can be (null,null), (100, null), (null, 100_or_any_other_number) etc How in one SQL query both set b_id_1 or b_id_2 to null and delete all rows from B that have this id? What FK design should be applied to the 2 tables? what foreign keys should be added? A - B (FK_1: A.b_id_1 references B.id, FK_2: A.b_id_2 references B.id) and also B-A (FK_3: B.id references A.b_id_1, FK_4: B.id references A.b_id_2) ? But again, setting an A's b_id_1 or A's b_id_2 to null - will it remove any of B's records? I don't think so. So how to do that?

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• Clone a 'link' in SWT

  - by Steve

  I have a table of information that includes a username, an ip address, and a timestamp. What I wanted to do was to have the ip address contained within a link object that when the link is clicked it utilizes bgp.he.net to get information about the host/IP address. I have tried creating threads to resolve the IP addresses but it is often a large amount of IP addresses and I read that InetAddress#getByName isn't non-blocking, so I figured having links that go to this site is the next best thing. Question is: Is it possible to have links for each of my IP addresses in the table without creating a new link object for each row? I don't know how bad that would be on memory usage which is why I'm inquiring about cloning an instance of an IP and having the link open bgp.he.net/link.getText()

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• Tree data structure in php

  - by Piyush

  in my application user starts a new tree or get added under a child-user and keep on adding users in branches in such a way- >there are 10 level of tree type structure. >root node contain 1 user and each node(user) can have max 5 child-user in this way tree will be like level 0 = 1 user , level 1 = 5 user, level 2 = 25 user , level 3 = 125 user and so on. I created one MySQL table having columns like- User_id , level, super_id, child1_id, child2_id, child3_id, child4_id, child5_id my question is How can I get all child-user(child to child also) of a particular user at any level do I need to add some more columns in my table??

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• How do I ensure data consistency in this concurrent situation?

  - by MalcomTucker

  The problem is this: I have multiple competing threads (100+) that need to access one database table Each thread will pass a String name - where that name exists in the table, the database should return the id for the row, where the name doesn't already exist, the name should be inserted and the id returned. There can only ever be one instance of name in the database - ie. name must be unique How do I ensure that thread one doesn't insert name1 at the same time as thread two also tries to insert name1? In other words, how do I guarantee the uniqueness of name in a concurrent environment? This also needs to be as efficient as possible - this has the potential to be a serious bottleneck. I am using MySQL and Java. Thanks

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• Use parameters with CTL

  - by Hal

  Hi. I am using a CTL file to load data stored in a file to a specific table in my Oracle database. Currently, I launch the loader file using the following command line: sqlldr user/pwd@db data=my_data_file control=my_loader.ctl I would like to know if it is possible to use specify parameters to be retrieved in the CTL file. Also, is it possible to retrieve the name of the data file used by the CTL to fill the table ?I also would like to insert it for each row. I currently have to call a procedure to update previously inserted records. Any help would be appreciated !

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• IN r, how to combine the summary together

  - by alex

  say i have 5 summary for 5 sets of data. how can i get those number out or combine the summary in to 1 rather than 5 V1 V2 V3 V4 Min. : 670.2 Min. : 682.3 Min. : 690.7 Min. : 637.6 1st Qu.: 739.9 1st Qu.: 737.2 1st Qu.: 707.7 1st Qu.: 690.7 Median : 838.6 Median : 798.6 Median : 748.3 Median : 748.3 Mean : 886.7 Mean : 871.0 Mean : 869.6 Mean : 865.4 3rd Qu.:1076.8 3rd Qu.:1027.6 3rd Qu.:1070.0 3rd Qu.: 960.8 Max. :1107.8 Max. :1109.3 Max. :1131.3 Max. :1289.6 V5 Min. : 637.6 1st Qu.: 690.7 Median : 748.3 Mean : 924.3 3rd Qu.: 960.8 Max. :1584.3 how can i have 1 table looks like v1 v2 v3 v4 v5 Min. : 1st Qu.: Median : Mean : 3rd Qu.: Max. : or how to save those number as vector so i can use matrix to generate a table

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• Ruby on Rail - Format for fetching and displaying Dymanic drop down

  - by Ruby

  Hi, I have 3 tables : Student , Subject and Score Every student can add 3 Subjects (Physics, Mathematics and Chemistry) marks. The combination of (student_id + subject_id) is added to Score table. i.e., capturing that sudent '1' has added 'Mathematics' marks with the actual score (say 0-100 range) student id : subjectid Score 1 Mathematics 95 The Add page of Score has a "subject" drop down. which is displayed from "subject" table. When the student wants to add the 2nd subject marks, in the add page, he should not be displayed the previoys added subject in the drop down. Can any1 tell me how to do this?

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• Split string on first two colons

  - by Mark Miller

  I would like to split a column of strings on the first two colons, but not on any subsequent colons: my.data <- read.table(text=' my.string some.data 12:34:56:78 -100 87:65:43:21 -200 a4:b6:c8888 -300 11:bb:ccccc -400 uu:vv:ww:xx -500', header = TRUE) desired.result <- read.table(text=' my.string1 my.string2 my.string3 some.data 12 34 56:78 -100 87 65 43:21 -200 a4 b6 c8888 -300 11 bb ccccc -400 uu vv ww:xx -500', header = TRUE) I have searched extensively and the following question is the closest to my current dilemma: Split on first comma in string Thank you for any suggestions. I prefer to use base R.

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• Is there a way to split the results of a select query into two equal halfs?

  - by Matthias

  I'd like to have a query returning two ResultSets each of which holding exactly half of all records matching a certain criteria. I tried using TOP 50 PERCENT in conjunction with an Order By but if the number of records in the table is odd, one record will show up in both resultsets. Example: I've got a simple table with TheID (PK) and TheValue fields (varchar(10)) and 5 records. Skip the where clause for now. SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID asc results in the selected id's 1,2,3 SELECT TOP 50 PERCENT * FROM TheTable ORDER BY TheID desc results in the selected id's 3,4,5 3 is a dup. In real life of course the queries are fairly complicated with a ton of where clauses and subqueries.

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• SQL SELECT using in() but excluding others.

  - by Pickledegg

  I have a table called 'countries' linked to another table 'networks' with a many to many relationship: countries countries_networks networks +-------------+----------+ +-------------+----------+ +-------------+---------------+ | Field | Type | | Field | Type | | Field | Type | +-------------+----------+ +-------------+----------+ +-------------+---------------+ | id | int(11) | | id | int(11) | | id | int(11) | | countryName | char(35) | | country_id | int(11) | | name | varchar(100) | +-------------+----------+ | network_id | int(11) | | description | varchar(255) | To retrieve all countries that have a network_id of 6 & 7, I just do the following: ( I could go further to use the networks.name but I know the countries_networks.network_id so i just use those to reduce SQL.) SELECT DISTINCT countryName FROM countries AS Country INNER JOIN countries_networks AS n ON Country.id = n.country_id WHERE n.network_id IN (6,7) This is fine, but I then want to retrieve the countries with a network_id of JUST 8, and no others. I'ver tried the following but its still returning networks with 6 & 7 in. Is it something to do with my JOIN? SELECT DISTINCT countryName FROM countries AS Country INNER JOIN countries_networks AS n ON Country.id = n.country_id WHERE n.network_id IN (8) AND n.network_id not IN(6,7) Thanks.

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• Problem using mysql joins

  - by mariomario

  I'm fairly new to mysql and I have no idea if I'm heading in the right direction but I'm having trouble with a mysql query. I basically have a table of users id name ---- -------- 1 user1 2 user2 3 user3 4 user4 as well as a table of user attributes id userid attribute ---- ----- ------ 1 1 5 2 1 6 3 2 5 4 3 4 I want to be able to select users that have both the attribute 5 and the attribute 6, so in this case I want to return id name ---- -------- 1 user1 I tried using a join like this. SELECT u.id, u.name FROM users u LEFT JOIN attributes a ON (a.userid = u.id) WHERE a.attribute = 5 AND a.attribute = 6 But obviously that won't work, what is the best way of doing this?

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