Field type and data type

Hi,I want to check somethings,
From my understanding ,data type is follow your database's table column type,
If your metabase'table set Field type be No File type,then system will use "data type",
But other type system use "Field type" instead of "data type",
Example: "Field type" set Category,but data type is Float. Then when I use this column,system identify column is Category rather than Float.
Have I got that right?

Can Field type default on No File type or specific type?

Hi @summer02905
Have a look here: