什么';这是什么;从…起至;在我的mysql表模式中?
我编写了一个简单的rails迁移来设置我的什么';这是什么;从…起至;在我的mysql表模式中?,mysql,ruby-on-rails,migration,Mysql,Ruby On Rails,Migration,我编写了一个简单的rails迁移来设置我的gardens表的name列的默认值: class ChangeColumnDefaultToGarden < ActiveRecord::Migration def up change_column_null :gardens, :name, false change_column_default :gardens, :name, from: nil, to: "" change_column_null :garde
gardens
表的name
列的默认值:
class ChangeColumnDefaultToGarden < ActiveRecord::Migration
def up
change_column_null :gardens, :name, false
change_column_default :gardens, :name, from: nil, to: ""
change_column_null :gardens, :square_feet, false
change_column_null :gardens, :zone, false
end
def down
change_column_null :gardens, :name, true
change_column_default :gardens, :name, from: "", to: nil
change_column_null :gardens, :square_feet, true
change_column_null :gardens, :zone, true
end
end
什么是
:from:
和:to:
?我不熟悉mysql语法。您对正确方法的调用不正确:
def up
change_column_default(:gardens, :name, "")
end
但您可以将change null和default组合成一个调用:
def up
change_column_default(:gardens, :name, "")
end
def up
change_column_null :gardens, :name, false, ""
end
def down
change_column_null :gardens, :name, true
end