Schema rb not updating
Rails maps Oracle data types to Ruby logical types like :string, :decimal, :text and so on. In your RAILS_ROOT run: Open the db/migrate/001_sample_script and you'll see the class definition already laid out for you.For a complete reference on those types and allowable options for each (like :precision) see Active Record:: Connection Adapters:: Table Definition#column. All that's left is to fill in the method definitions!You could choose to try to roll back the changes by retracing your steps, but it's very error prone. If your schema generation scripts were written for a specific database like My SQL and later in the development process you decide to move to Oracle, you'll have to rewrite the SQL in its entirety.The Migration library takes the burden of having to remember the details of each database vendor's implementation off your shoulders. To get the most out of this article you'll want to have at least a rudimentary understanding of the way Rails works.Even with a single set of database files rolling out your changes is problematic at best.And if you need to roll the change back, it's likely that the only way to do it is to drop all the tables, restore to a known good version of your schema, and reload the data from a backup.While it gets the job done, it's entirely inflexible.
What most developers end up settling on is some sort of combination of ongoing database creation scripts and data load scripts written in pure SQL.
Be very careful with that; unless you've tested your migration extensively you could seriously damage your production database!
Now you're going to walk through the use of Rails' Migrations in an example (contrived) application called Discographr.
Rake is a pure ruby implementation analogous to Unix/Linux "make" utility and is another very useful tool for managing a project.
Tasks are defined and run through Rake as rake That command will run all the Migrations it finds under db/migrate until it's at the highest version number.