I am confuse about fully qualified name can anyone explain?

Answer 1

fully qualified means prefixing a "columnname" with "tablename." to avoid confusion.

e.g. if two tables Customers & Vendors both have a field called city below is an example how a fully qualified query will look like.

select Customers.city, Vendors.city from Customers C, Vendors V Where C.CityId = V.CityId;

hope this helps.