Ruby on Rails在评论中添加评论

Question

我在rails中创建了一个注释控制器，但是如果我运行服务器，它将在db migrate中给出错误。

原因：

SQLite3::SQLException: table "comments" already exists
C:/Users/SIBI/Desktop/rails1/hello_world/db/migrate/20190516103017_create_comments.rb:3:in `change'
bin/rails:4:in `require'
bin/rails:4:in `<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)