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• varchar comparison in SQL Server

  - by Ram

  I am looking for some SQL varchar comparison function like C# string.compare (we can ignore case for now, should return zero when the character expression are same and a non zero expression when they are different) Basically I have some alphanumeric column in one table which needs to be verified in another table. I cannot do select A.col1 - B.col1 from (query) as "-" operator cannot be applied on character expressions I cannot cast my expression as int (and then do a difference/subtraction) as it fails select cast ('ASXT000R' as int) Conversion failed when converting varchar 'ASXT000R' to int Soundex would not do it as soundex is same for 2 similar strings Difference would not do it as select difference('abc','ABC') = 4 (as per msdn, difference is the difference in the soundex of 2 character expressions and difference =4 implies least different) Is there any other way of doing it ?

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• Representing Sparse Data in PostgreSQL

  - by Chris S

  What's the best way to represent a sparse data matrix in PostgreSQL? The two obvious methods I see are: Store data in a single a table with a separate column for every conceivable feature (potentially millions), but with a default value of NULL for unused features. This is conceptually very simple, but I know that with most RDMS implementations, that this is typically very inefficient, since the NULL values ususually takes up some space. However, I read an article (can't find its link unfortunately) that claimed PG doesn't take up data for NULL values, making it better suited for storing sparse data. Create separate "row" and "column" tables, as well as an intermediate table to link them and store the value for the column at that row. I believe this is the more traditional RDMS solution, but there's more complexity and overhead associated with it. I also found PostgreDynamic, which claims to better support sparse data, but I don't want to switch my entire database server to a PG fork just for this feature. Are there any other solutions? Which one should I use?

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• MySQL Select problems

  - by John Nuñez

  Table #1: qa_returns_items Table #2: qa_returns_residues I have a long time trying to get this Result: item_code - item_quantity 2 - 1 3 - 2 IF qa_returns_items.item_code = qa_returns_residues.item_code AND status_code = 11 THEN item_quantity = qa_returns_items.item_quantity - qa_returns_residues.item_quantity ELSEIF qa_returns_items.item_code = qa_returns_residues.item_code AND status_code = 12 THEN item_quantity = qa_returns_items.item_quantity + qa_returns_residues.item_quantity ELSE show diferendes END IF I tried this Query: select SubQueryAlias.item_code, total_ecuation, SubQueryAlias.item_unitprice, SubQueryAlias.item_unitprice * total_ecuation as item_subtotal, item_discount, (SubQueryAlias.item_unitprice * total_ecuation) - item_discount as item_total from ( select ri.item_code , case status_code when 11 then ri.item_quantity - rr.item_quantity when 12 then ri.item_quantity + rr.item_quantity end as total_ecuation , rr.item_unitprice , rr.item_quantity , rr.item_discount * rr.item_quantity as item_discount from qa_returns_residues rr left join qa_returns_items ri on ri.item_code = rr.item_code WHERE ri.returnlog_code = 1 ) as SubQueryAlias where total_ecuation > 0 GROUP BY (item_code); The query returns this result: item_code - item_quantity 1 - 2 2 - 2

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• ASP.NET membership spaces in username

  - by SaphuA

  Hi, We just came across a weird bug in our application that uses the asp.net membership. The administrator had created some users with spaces behind their name: 'My Username ' In the Users table this is saved normally, so without the spaces: 'My Username' The user can also login using the name without the spaces: 'My Username' When we use User.Identity.Name in our applicatie the result is the username WITH the spaces: 'My Username '. Where do these spaces come from? They aren't stored in the Users table so where does he get this from?! Thanks!

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• How can i query for null values in entity framework?

  - by AZ

  I want to execute a query like this var result = from entry in table where entry.something == null select entry; and get an IS NULL generated. Edited: After the first two answers i feel the need to clarify that I'm using Entity Framework and not Linq to SQL. The object.Equals() method does not seem to work in EF. Edit no.2: The above query works as intended. It correctly generates IS NULL. My production code however was var value = null; var result = from entry in table where entry.something == value select entry; and the generated SQL was something = @p; @p = NULL. It seems that EF correctly translates the constant expression but if a variable is involved it treats it just like a normal comparison. Makes sense actually. I'll close this question

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• validating creation by post_id and ip_address - Ruby on Rails

  - by bgadoci

  I have created a blog application using Ruby on Rails which includes the ability to vote on posts. A user can click vote and a record is created in the vote table. I am now trying to limit that same person from voting for a post multiple times. class Post has_many :votes end class Vote belongs_to :post end When a vote record is created I am using the VotesController to pass the :post_id and using a hidden field in the view to pass the ip_address (both to the vote table). I am wondering if there is a way to add a validation to the Vote Model that searches to see if a post_id has an ip_address that matches the person requesting to vote. I have tried simply using the validates_uniqueness_of :ip_address but that restricts the user from voting on any post. I just want to restrict the user from voting on a particular post that they have already voted on. Is there a way to do this through validation?

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• Bind a users role to dropdown?

  - by Dynde

  Hi... I'm trying to bind a selected user's role to a dropdown-list. The purpose of this is to be able to change said user's role. I'm attempting this inside a formview hooked up to a linqdatasource which contains a row from the aspnet_User table. The dropdown list is hooked up to a linqdatasource of all the roles in the aspnet_Roles table (with DataValueField="RoleID", DataTextField="RoleName"). I figured it would be possible with something like: SelectedValue='<%# Bind("aspnet_UsersInRole[0].aspnet_Role.RoleID") %>' But this throws a parser exception, about the bind call not being correctly formatted. The roles are there, they show up when I remove the "SelectedValue" Can anyone point me in the right direction?

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• Finding gaps (missing records) in database records using SQL

  - by Tony_Henrich

  I have a table with records for every consecutive hour. Each hour has some value. I want a T-SQL query to retrieve the missing records (missing hours, the gaps). So for the DDL below, I should get a record for missing hour 04/01/2010 02:00 AM (assuming date range is between the first and last record). Using SQL Server 2005. Prefer a set based query. DDL: CREATE TABLE [Readings]( [StartDate] [datetime] NOT NULL, [SomeValue] [int] NOT NULL ) INSERT INTO [Readings]([StartDate], [SomeValue]) SELECT '20100401 00:00:00.000', 2 UNION ALL SELECT '20100401 01:00:00.000', 3 UNION ALL SELECT '20100401 03:00:00.000', 45

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• Putting update logic in your migrations

  - by Daniel Abrahamsson

  A couple of times I've been in the situation where I've wanted to refactor the design of some model and have ended up putting update logic in migrations. However, as far as I've understood, this is not good practice (especially since you are encouraged to use your schema file for deployment, and not your migrations). How do you deal with these kind of problems? To clearify what I mean, say I have a User model. Since I thought there would only be two kinds of users, namely a "normal" user and an administrator, I chose to use a simple boolean field telling whether the user was an adminstrator or not. However, after I while I figured I needed some third kind of user, perhaps a moderator or something similar. In this case I add a UserType model (and the corresponding migration), and a second migration for removing the "admin" flag from the user table. And here comes the problem. In the "add_user_type_to_users" migration I have to map the admin flag value to a user type. Additionally, in order to do this, the user types have to exist, meaning I can not use the seeds file, but rather create the user types in the migration (also considered bad practice). Here comes some fictional code representing the situation: class CreateUserTypes < ActiveRecord::Migration def self.up create_table :user_types do |t| t.string :name, :nil => false, :unique => true end #Create basic types (can not put in seed, because of future migration dependency) UserType.create!(:name => "BASIC") UserType.create!(:name => "MODERATOR") UserType.create!(:name => "ADMINISTRATOR") end def self.down drop_table :user_types end end class AddTypeIdToUsers < ActiveRecord::Migration def self.up add_column :users, :type_id, :integer #Determine type via the admin flag basic = UserType.find_by_name("BASIC") admin = UserType.find_by_name("ADMINISTRATOR") User.all.each {|u| u.update_attribute(:type_id, (u.admin?) ? admin.id : basic.id)} #Remove the admin flag remove_column :users, :admin #Add foreign key execute "alter table users add constraint fk_user_type_id foreign key (type_id) references user_types (id)" end def self.down #Re-add the admin flag add_column :users, :admin, :boolean, :default => false #Reset the admin flag (this is the problematic update code) admin = UserType.find_by_name("ADMINISTRATOR") execute "update users set admin=true where type_id=#{admin.id}" #Remove foreign key constraint execute "alter table users drop foreign key fk_user_type_id" #Drop the type_id column remove_column :users, :type_id end end As you can see there are two problematic parts. First the row creation part in the first model, which is necessary if I would like to run all migrations in a row, then the "update" part in the second migration that maps the "admin" column to the "type_id" column. Any advice?

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• Why index_merge is not used here?

  - by user198729

  Setup: mysql> create table t(a integer unsigned,b integer unsigned); mysql> insert into t(a,b) values (1,2),(1,3),(2,4); mysql> create index i_t_a on t(a); mysql> create index i_t_b on t(b); mysql> explain select * from t where a=1 or b=4; +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | t | ALL | i_t_a,i_t_b | NULL | NULL | NULL | 3 | Using where | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ Is there something I'm missing?

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• SQL Join Problem

  - by Harley

  Table one contains ID|Name 1 Mary 2 John Table two contains ID|Color 1 Red 1 Blue 2 Green 2 Blue 2 Black I want to end up with is ID|Name|Red|Blue|Green|Black 1 Mary    Y      Y 2 John            Y        Y       Y Thanks for and help.

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• How to prevent column b containing the same value as any column a in Oracle?

  - by Janek Bogucki

  What is a good way to prevent a table with 2 columns, a and b, from having any record where column b is equal to any value in column a? This would be used for a table of corrections like this, MR -> Mr Prf. -> Prof. MRs -> Mrs I can see how it could be done with a trigger and a subquery assuming no concurrent activity but a more declarative approach would be preferable. This is an example of what should be prevented, Wing Commdr. -> Wing Cdr. Wing Cdr. -> Wing Commander Ideally the solution would work with concurrent inserts and updates.

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• How to define one-to-many connection between a same model through another model

  - by Mekajiki

  I want to define one-to-many relationship as follows; User has one introducer User has many newcomers(who is introduced by the user) Use "Introduction" model instead of adding a column to users table. My table and model definition is as follows; DB Scheme: create_table "introductions", force: true do |t| t.integer "introducer_id" t.integer "newcomer_id" t.datetime "created_at" t.datetime "updated_at" User model: class User < ActiveRecord::Base has_many :introductions, foreign_key: :introducer_id has_many :newcomers, through: :introductions, source: :newcomer belongs_to :introduction, foreign_key: :newcomer_id belongs_to :introducer end Introduction model: class Introduction < ActiveRecord::Base belongs_to :introducer, class_name: 'User' belongs_to :newcomer, class_name: 'User' end This works fine: user1.newcomers.push user2 but, user2.introducer # => nil How can I define belongs_to relationship correctly?

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• How to merge two tables based on common column and sort the results by date

  - by techiepark

  Hello friends, I have two mysql tables and i want to merge the results of these two tables based on the common column rev_id. The merged results should be sorted by the date of two tables. Please help me. CREATE TABLE `reply` ( `id` int(3) NOT NULL auto_increment, `name` varchar(25) NOT NULL default '', `member_id` varchar(45) NOT NULL, `rev_id` int(3) NOT NULL default '0', `description` text, `post_date` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP, `flag` char(2) NOT NULL default 'N', PRIMARY KEY (`id`), KEY `member_id` (`member_id`) ) ENGINE=MyISAM; CREATE TABLE `comment` ( `com_id` int(8) NOT NULL auto_increment, `rev_id` int(5) NOT NULL default '0', `member_id` varchar(50) NOT NULL, `comm_desc` text NOT NULL, `date_created` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP, PRIMARY KEY (`com_id`), KEY `member_id` (`member_id`) ) ENGINE=MyISAM;

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• Linq to sql Error "Data at the root level is invalid " for nullable xml column

  - by Mukesh

  I have Created a table like CREATE TABLE [dbo].[tab1]( [Id] [int] NOT NULL, [Name] [varchar](100) NOT NULL, [Meta] [xml] NULL, CONSTRAINT [PK_tab1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] When I am doing linq to sql query to fetch a data it throw an error "data at the root level is invalid linq". In further investigation I come to know that the meta column is null in that case. In real it is nullable Do I have to remove the nullable and set some blank root node as default or there is some another way to get rid of the error. My linq Query which throws error var obj1= (from obj in dbContext.tab1s where obj.id== 123 select obj).FirstOrDefault<Tab1>();

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• DataBinding a DropDownList in ASP.NET MVC 2

  - by Daniel Coffman

  I'm extremely frustrated trying to switch to MVC after a couple years of webforms development. Here's my extremely simple problem that I can't manage to solve: I have a list of States in a table called StateProvince. I have a DropDownList. I want the DropDownList to display all of the States in the StateProvince table and post the selected state back on HTTP PUT. This is what I'm doing: <%: Html.DropDownListFor(model = model.StateProvinceId, new SelectList(Model.StateProvinces, "StateProvinceId", "Name") )% I'm getting an Object reference not set to an instance of an object. Why? How can I make this work? Keep it simple, I know nothing about MVC.

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• find rows that fall between a day and time of the week in sql server

  - by Corgalore

  I have a table of rows in MS SQL that contain a start and end day of the week, hour, and time. I need a T-SQL query that can pull rows from that table where GETDATE matches the day of week and time of those rows. Specifically, I need the query to work if a row has a day/time that starts on one day of the week and ends on the next day. Here's the structure I'm working with: _start_day_of_week (int) = 5_start_hour (int) = 15_start_minute (int) = 30 _end_day_of_week (int) = 6_end_hour (int) = 2 _end_minute (int) = 30 _title (string) = 'My Sample Row' _id (int) = 1 How would I retrieve this row given the current DATETIME?

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• Connect sortable lists together and update SQL using jQuery UI

  - by rebellion

  I'm using jQuery UI's sortable lists to sort items in a todo list, and the reordering of the lists works like a charm. I have several UL lists for each todo category, i.e. Design, Development, etc. I want to be able to move an item from one category to another, and jQuery UI's sortable lists plugin allows me to do this with the connectWith option parameter. But I can't seem to find how to update the database as well. The todo database table has a field for a reference to the category which is laying in it's own table. This is the current code: $('.sortable').sortable({ axis: 'y', opacity: .5, cancel: '.no-tasks', connectWith: '.sortable', update: function(){ $.ajax({ type: 'POST', url: basepath + 'task/sort_list', data: $(this).sortable('serialize') }); } }); Do I need to add another value to the AJAX's data parameter, or do the sortable plugin this for me in the serialize function?

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• VARCHAR does not work as expected in Apache Derby

  - by Tom Brito

  I'm having this same problem: How can I truncate a VARCHAR to the table field length AUTOMATICALLY in Derby using SQL? To be specific: CREATE TABLE A ( B VARCHAR(2) ); INSERT INTO A B VALUES ('1234'); would throw a SQLException: A truncation error was encountered trying to shrink VARCHAR '123' to length 2. that is already answered: No. You should chop it off after checking the meta-data. Or if you don't wanna check the meta-data everytime, then you must keep both your code and database in sync. But thats not a big deal, its a usual practice in validators. but my doubt is: isn't VARCHAR suppose to variate its size to fit the data? What's wrong with apache derby's VARCHAR?

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• Need a mysql query to extract data from mm-forms

  - by Kirill

  http://cl.ly/201a11b430bf60ef9e97 is what the rows look like, after I clean them up a bit: SELECT fk_form_joiner_id,form_key,value FROM wp_contactform_submit_data WHERE form_key!='page_post_id' AND form_key!='captcha-802' AND form_key!='page_post_title' AND form_key!='user_ID' What I need is a query where it would transform this into a structure like: id | First-name | Surname-name | your-email | dob | address-1 | address-2 | county | postcode | phone ------------------------------------------------------------------------------------------------------- 88 | jack | Somethin | [email protected] | dob | (etc) I think I know a way to do this through php, but I think there must be a way to do it as a mysql query. Ultimately, I need to export this (into a csv), but if you could give me a query that would output this into a mysql table (or at least a workable select query, that I could then turn into an insert query loop, to create a table), I'd do it form there. Thank you.

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• Enforcing a query in MySql to use a specific index

  - by Hossein

  Hi, I have large table. consisting of only 3 columns (id(INT),bookmarkID(INT),tagID(INT)).I have two BTREE indexes one for each bookmarkID and tagID columns.This table has about 21 Million records. I am trying to run this query: SELECT bookmarkID,COUNT(bookmarkID) AS count FROM bookmark_tag_map GROUP BY tagID,bookmarkID HAVING tagID IN (-----"tagIDList"-----) AND count >= N which takes ages to return the results.I read somewhere that if make an index in which it has tagID,bookmarkID together, i will get a much faster result. I created the index after some time. Tried the query again, but it seems that this query is not using the new index that I have made.I ran EXPLAIN and saw that it is actually true. My question now is that how I can enforce a query to use a specific index? also comments on other ways to make the query faster are welcome. Thanks

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• Select from multiple tables, remove duplicates

  - by staze

  I have two tables in a SQLite DB, and both have the following fields: idnumber, firstname, middlename, lastname, email, login One table has all of these populated, the other doesn't have the idnumber, or middle name populated. I'd LIKE to be able to do something like: select idnumber, firstname, middlename, lastname, email, login from users1,users2 group by login; But I get an "ambiguous" error. Doing something like: select idnumber, firstname, middlename, lastname, email, login from users1 union select idnumber, firstname, middlename, lastname, email, login from users2; LOOKS like it works, but I see duplicates. my understanding is that union shouldn't allow duplicates, but maybe they're not real duplicates since the second user table doesn't have all the fields populated (e.g. "20, bob, alan, smith, [email protected], bob" is not the same as "NULL, bob, NULL, smith, [email protected], bob"). Any ideas? What am I missing? All I want to do is dedupe based on "login". Thanks!

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• MySQL and Collation

  - by user294787

  I have a table with a column using utf8_unicode_ci character set. This table stores Japanese data and my problem is that using this character set, I'm not able to store the same word written in katakana and hiragana because it's considered to be the same word. For example ??? and ???, which mean I, me. I know that I can change the character set to utf8_general_ci to resolve this problem but is it possible to bypass this limitation ? I mean, keep utf8_unicode_ci character set and make those two words be inserted? Is it possible to make this work using CONVERT or CAST operators? Thanks.

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• Why is my iPhone SDK 3.2 iPad code showing a white screen?

  - by Anthony Glyadchenko

  I'm trying to get a UISplitViewController working with an iPad app. I have the table view controller linked up under the Master pane and a plain UIView under the Detail view. I also have [window addSubview:splitView.view]; in my code. For some reason I just get a white screen even though the table view controller code is properly coded and linked under my nib. Any help would be great! Thanks! Here's where you can find the code: http://drop.io/s28bu4t/asset/mydevice-hd-zip

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• MySQL top count({column}) with a limit

  - by Josh K

  I have a table with an ip address column. I would like to find the top five addresses which are listed. Right now I'm planning it out the following: Select all distinct ip addresses Loop through them all saying count(id) where IP='{ip}' and storing the count List the top five counts. Downsides include what if I have 500 ip addresses. That's 500 queries I have to run to figure out what are the top five. I'd like to build a query like so select ip from table where 1 order by count({distinct ip}) asc limit 5

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