$rake db:migrate An error has occurred, this and a

问题:

I am new to RoR and I keep getting this error message:

$ rake db:migrate
==  CreateUsers: migrating ====================================================
-- create_table(:users)
rake aborted!
An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: table "users" already exists: CREATE TABLE "users" ("id"
INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255), "email" varchar
(255), "created_at" datetime, "updated_at" datetime)

Tasks: TOP => db:migrate
(See full trace by running task with --trace)

I've been searching for a solution for 3 days, but I cannot seem to find anything that works for me.

Thank you in advance for your help :) PS - I am running off Windows.

回答1:

table "users" already exists seems to be the problem. Have you tried to manually remove the table from your database with some SQLITE admin tool?

Or you can include a remove table in your migration script (should be called create_users.rb inside your db/migrate folder). Inside def up insert drop_table :users :

      def up
         drop_table :users

         create_table :users do |t|
         t.string :name
         #...

         t.timestamps
      end

Oh and I remember from my RoR time that the table name "Users" can cause problems later on. Might be this is related.

回答2:

Not sure if you are following Michael Hartl's tutorial on RoR.

But someone has said there's a problem in the steps of the tutorial http://archive.railsforum.com/viewtopic.php?id=44944

rake db:drop:all <---------- will wipe everything then run rake db:migrate again should fix the problem.

Good Luck

回答3:

Because the table already exists, you need to delete/remove it before executing the migration.

Easy, GUI way to do this is with the SQLite Database Browser (http://sourceforge.net/projects/sqlitebrowser/).

Click the button with the Table-X icon. Choose User Table click Delete.

Then run rake db:migrate

Bada boom bada bing

回答4:

I had a similar problem, then i did => rake db:drop => rake db:create => rake db:migrate

worked perfectly.