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Question. What are different types of normalization

1NF: This type of normalization states that there must not be any duplicates in the tables that we use. In other words, all the tables used must have a primary key defined.

2NF: This type of normalization states that data redundancy can be reduced if attributes those are dependent on one of the keys of a composite primary key are isolated to a separate table. Not only does this reduces data redundancy but also helps in increasing data retention when a delete is done. For example, consider a table that has the following columns: Part Id, State, City, and Country. Here, assume Part Id & Country form the composite primary key. The attributes state & city depend only on the country. 2NF states that if such is the case then split the table into 2 tables. One with Part Id & country as the columns. Other with Country, state & city as the columns. In the 1st table if a delete is made to all the rows with Part Id = ‘X’ then we would lose country related data too. But in the 2nd case this would not happen.

3NF: This type of normalization states that if a dependency exists on certain attributes other than the primary key then the table split depending on the dependency has to be done. Consider the same example above. In the present case consider that Part Id is the only primary key. Now state, city depend only on country & not on Part Id. This table is already in 1NF & 2NF. But to achieve 3NF we would do the same split as above.

Fourth Normal Form
This is also known as Boyce Code Normal Form.In these normal forms or further normal forms data should be be seperated into so many tables and there should not be complexity in the tables



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