Ruby on rails 4 Rails和Postgresql迁移更改列类型
我需要在rails中不时更改列类型。我无法更改列类型。它显示此错误Ruby on rails 4 Rails和Postgresql迁移更改列类型,ruby-on-rails-4,postgresql-9.4,Ruby On Rails 4,Postgresql 9.4,我需要在rails中不时更改列类型。我无法更改列类型。它显示此错误 "rake aborted! StandardError: An error has occurred, this and all later migrations canceled: PG::DatatypeMismatch: ERROR: column "fun_from" cannot be cast automatically to type timestamp without time zone HINT: Sp
"rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:
PG::DatatypeMismatch: ERROR: column "fun_from" cannot be cast automatically to type timestamp without time zone
HINT: Specify a USING expression to perform the conversion.
: ALTER TABLE "general_infos" ALTER COLUMN "fun_from" TYPE timestamp/home/PCA/db/migrate/20150730102811_change_data_type_in_general_infos.rb:3:in `change'
ActiveRecord::StatementInvalid: PG::DatatypeMismatch: ERROR: column "fun_from" cannot be cast automatically to type timestamp without time zone
HINT: Specify a USING expression to perform the conversion.
: ALTER TABLE "general_infos" ALTER COLUMN "fun_from" TYPE timestamp
/home/PCA/db/migrate/20150730102811_change_data_type_in_general_infos.rb:3:in `change'
PG::DatatypeMismatch: ERROR: column "fun_from" cannot be cast automatically to type timestamp without time zone
HINT: Specify a USING expression to perform the conversion.
/home/PCA/db/migrate/20150730102811_change_data_type_in_general_infos.rb:3:in `change'"
下面是我尝试过的格式
change_column(:table_name, :column_name, :datetime )
并尝试了以下格式
change_column :table_name, :column_name, 'datetime USING CAST(column_name AS datetime)'
psql版本-9.4.4&任何人都可以给我解决方案。请将错误消息的格式设置为:(1)它们不是粗体的,(2)是代码块,类似于您的后可能副本末尾的两行。Net是指您应该删除现有列并添加datetime列,因为没有合理的方法从times生成datetime。我不会删除该列。如果我删除了该列并删除了其值,请将错误消息的格式设置为:(1)它们不是粗体的,(2)是代码块,类似于您的后可能副本末尾的两行。Net是指您应该删除现有列并添加datetime列,因为没有合理的方法从times生成datetimes。如果我删除了该列并删除了其值,我不会删除该列。