1. Third normal form is a principle in database normalization. It builds on the principles of first and second normal form. A table, or relation, is considered to be in third normal form if it satisfies the following conditions:
1. It is already in first and second normal form. This includes requirements such as having atomic values, unique column names, rows being unique, no partial dependencies, and splitting tables into separate tables if there happens to be partial dependencies.
2. There are no transitive functional dependencies. This means no non-key attribute depends on another non-key attribute.
There are so many reasons why third normal form is important. For one, it reduces data redundancy. If you have attributes depending on non-key attributes, updating rows in your data can become very redundant as it means replicating data over and over again. It is, essentially, less functional. The database design becomes simplified when 3NF is kept and databases can be well-structured. The query performance improves as well when 3NF is kept. Overall, it has so many benefits and creates more reliable database systems.
2. A view is like a table but it's not a table. A view takes a selection of data but, unless indexed, it's not stored into the actual database. It is a "virtual table" whose contents are defined by a query. It is similar to a table in the way that both are database objects, as well as the fact that views can be used AS tables, even if they are virtual/logical tables that don't exist in an exact location. Some ways that tables and views are different are that, like said above, views are not stored while tables are, tables are used to store the data whereas views are used to extract data, tables execute a fast result whereas views generate a slow result, and lastly it is not an easy task to replace a table directly whereas it's easier to replace a view and recreate it whenever.
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