Normalization

Table 1
  • Suppose we need to add a record for new member but he has not rented any movie yet. Then we would not be able to insert the data into the table if MOVIES RENTED column doesn’t allow null value. This is known as insert anamoly.
  • Suppose we have to create a large table with huge data in row and column, then there will be high chance of repeated data in some part of the table.
Types of Normal forms

First Normal Form (1NF)

  • Each table column should contain a single value.
  • Each record needs to be unique.
Table 2

Second Normal Form (2NF)

  • The table must be in 1NF
  • Single Column Primary Key. In other words, all non-key attributes are fully functional dependent on the primary key.
Table 3
Table 4

Third Normal Form (3NF)

  • The table must be in 2NF
  • The table should not contain any transitive functional dependency.
  • It is used to reduce the data duplication. It is also used to achieve the data integrity.
Table 5
Table 6
Table 7

Boyce-Codd Normal Form (BCNF)

  • BCNF is the advance version of 3NF. It is stricter than 3NF.
  • A table is in BCNF if every functional dependency X → Y, X is the super key of the table.
  • For BCNF, the table should be in 3NF, and for every FD, LHS is super key.

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