A table is in 3NF when it is in 2NF and contains no transitive dependencies. Given that defintion of 3NF,the Boyce-codd normal from (BCNF) is merely a special 3nF case in which all determinant keys are candidate keys. when a table has only a single candidate key, a 3NF table is automatically in BCNF.
A table that is not in 3NF may be split into new tables until all of the tables meet the 3NF requirments.
Normalization is an imposttant part-but only a part-of the desing process. As entities and attributes are defined during the ER modeling process,subject each entity (set) to normalization checks and form new entity (set) as required.Incorporate the normalized entities into the ERD and continue the iterative ER process until all entities and thir attributes are defined and all equivalent tables are in 3NFThe larger the number of tables, the more additional 1/0 operations and processing logic required to join them.