# Resolving ambiguous columns during a join **URL:** \ **Category:** Rails\ **Created:** [December 29, 2005, 9:05pm UTC](https://www.ruby-forum.com/t/resolving-ambiguous-columns-during-a-join/54714 "2005-12-29T21:05:43Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Duane](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b4bc9f/32.png) [@Duane](https://www.ruby-forum.com/u/Duane)\ **Post date:** [December 29, 2005, 9:05pm UTC](https://www.ruby-forum.com/t/resolving-ambiguous-columns-during-a-join/54714/1 "2005-12-29T21:05:43Z")
I am working with an existing schema and thus limited in how much I can bend my existing column names. I have a table Users, and a table ForumUsers, for which I have a “has\_one” relationship - a user has\_one forumuser. When I look at my user records I wish to include some information from forumuser: @users = User.find :all, :include =\> :forum\_user, :order =\> “email” … However, both these tables have a “status” column, and I end up getting ambiguous column reference errors. Could someone please tell me how and where I can either tell forumuser not to load up its status field at all (I don’t need it for this case), or else rename it to resolve the conflict? The error occurs at the “:include =\> :forum\_user” reference, so perhaps is there something I can specify there that says “only include attributes x,y,z from forum\_user”? Thank you! ---
**Author:** ![Duane](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/b4bc9f/32.png) [@Duane](https://www.ruby-forum.com/u/Duane)\ **Post date:** [December 30, 2005, 12:45am UTC](https://www.ruby-forum.com/t/resolving-ambiguous-columns-during-a-join/54714/2 "2005-12-30T00:45:47Z")
Duane wrote: > I am working with an existing schema and thus limited in how much I can > bend my existing column names. I have a table Users, and a table > ForumUsers, for which I have a “has\_one” relationship - a user has\_one > forumuser. When I look at my user records I wish to include some > information from forumuser: > > @users = User.find :all, :include =\> :forum\_user, :order =\> “email” … > > However, both these tables have a “status” column, and I end up getting > ambiguous column reference errors. > > Could someone please tell me how and where I can either tell forumuser > not to load up its status field at all (I don’t need it for this case), > or else rename it to resolve the conflict? The error occurs at the > “:include =\> :forum\_user” reference, so perhaps is there something I can > specify there that says “only include attributes x,y,z from forum\_user”? > > Thank you! Duane, here is an example. * * * My test schema - schema.rb # This file is autogenerated. Instead of editing this file, please use the # migrations feature of ActiveRecord to incrementally modify your database, and # then regenerate this schema definition. ActiveRecord::Schema.define() do create\_table “forum\_users”, :force =\> true do |t| t.column “name”, :string, :limit =\> 50 t.column “status”, :boolean, :default =\> false t.column “user\_id”, :integer, :default =\> 0, :null =\> false end create\_table “users”, :force =\> true do |t| t.column “name”, :string, :limit =\> 50 t.column “status”, :boolean, :default =\> false end ## end In my test, the user has a status of 0 and the forum user has a status of 1. > > u = User.find(1) > > =\> #\“0”, “name”=\>“Damon”, > > “id”=\>“1”}\> > > u.forum\_user > > =\> #\“1”, “name”=\>“DC > > Scales”, “id”=\>“1”, “user\_id”=\>“1”}\> > > – > > User Load (0.001579) SELECT \* FROM users WHERE (users.id = 1) LIMIT > > 1 > > User Columns (0.034679) SHOW FIELDS FROM users > > ForumUser Load (0.001829) SELECT \* FROM forum\_users WHERE > > (forum\_users.user\_id = 1) LIMIT 1 * * * > > users = users = User.find(:all, :include =\> :forum\_user) > > =\> [#\“0”, “name”=\>“Damon”, > > “id”=\>“1”}, @forum\_user=#\ > @attributes={“status”=\>“1”, “name”=\>“DC Scales”, “id”=\>“1”, > > “user\_id”=\>“1”}\>\>] > > – User Columns (0.004300) SHOW FIELDS FROM users ForumUser Columns (0.003337) SHOW FIELDS FROM forum\_users User Load Including Associations (0.027452) SELECT forum\_users.`id` AS t1\_r0, forum\_users.`name` AS t1\_r1, users.`id` AS t0\_r0, forum\_users.`status` AS t1\_r2, users.`name` AS t0\_r1, forum\_users.`user_id` AS t1\_r3, users.`status` AS t0\_r2 FROM users LEFT OUTER JOIN forum\_users ON forum\_users.user\_id = users.id – > > u = users[0] > > =\> #\“0”, “name”=\>“Damon”, > > “id”=\>“1”}, @forum\_user=#\ > @attributes={“status”=\>“1”, “name”=\>“DC Scales”, “id”=\>“1”, > > “user\_id”=\>“1”}\>\> > > u.forum\_user.status > > =\> true > > u.status > > =\> false So there can be no ambiguity if you are accessing the object directly. Problem solved. However, if you are for some reason being forced to use find\_by\_sql, you’ll want to use “AS” in your SQL to refer to it by another name. For example, users = User.find\_by\_sql(“select u.name, u.status, u.status as userstatus, fu.name, fu.status,fu.status as forumstatus from users u, forum\_users fu where fu.user\_id = u.id”) =\> [#\“1”, “name”=\>“DC Scales”, “userstatus”=\>“0”, “forumstatus”=\>“1”}\>] > > u = users[0] > > =\> #\“1”, “name”=\>“DC Scales”, > > “userstatus”=\>“0”, “forumstatus”=\>“1”}\> > > puts u.userstatus, u.status, u.forumstatus > > 0 > > true > > 1 You can see that the status field in our result has been clobbered by the forum user’s status. However, we’ve got access to the user status with our “u.userstatus” reference. Interesting that the u.status gets converted to a boolean but our aliased fields are unchanged ( “0” and “1” ). HTH, -damon > **[Damon Clinkscales](https://damonc.onuniverse.com/)** > > Damon Clinkscales