Sometimes it makes sense to store the value of a query in a variable within MySQL. You might do this if you're avoiding ActiveRecord because you're in a data migration. Here's how: execute %{SELECT (@setuid_id:=id) FROM roles WHERE title = 'setuid'};
execute %{SELECT (@admin_id:=id) FROM roles WHERE title = 'admin'};Similarly, sometimes it's helpful to use the results of a query in order to insert several rows at the same time. MySQL has INSERT...SELECT syntax that can be used like this: execute %{
INSERT INTO roles_users (role_id, user_id)
SELECT @setuid_id, user_id
FROM roles_users
WHERE role_id = @admin_id
}The above query finds all the admins and gives them the setuid role as well.
If you're a Python coder coding in Ruby, don't forget that ["a", "b", "c"] is more simply written %w(a b c).
You probably know that you can lookup rows via ActiveRecord finder methods like Role.find_b…