Hi there again 
I'm creating my mysql tables using migrations and I have noticed that the t.timestamps line creates two columns named 'created_at' and 'updated_at' as datetime type but they allow null values.
How can I say to rails I want that these two columns are not null (:null=>default doesn't work).
Regards
You can specify that a column allows NULL or not like this:
:null => true
:null => false
The docs for TaleDefinition#column should be useful. That’s the method that’s called when you use, e.g., add_column in a migration.
http://www.railsbrain.com/api/edge/doc/index.html?a=M001499&name=TableDefinition#column
Regards,
Craig