Normalization
Normalization is the process of
efficiently organizing data in a database and is used for eliminating
redundant data and ensuring data dependencies make sense (only
storing related data in a table).
Normalization Forms
First Normal Form (1NF)
A database is said to be in First
Normal Form when all entities have a unique identifier or key, and
when every column in every table contains only a single value and
doesn't contain a repeating group or composite field.
e.g
------------------------------
Genre Movies
------------------------------
Action A1, A2, A3
Romance R1, R2
------------------------------
We rearrange it to convert it in First
Normal Form
------------------------------
Genre Movies
------------------------------
Action A1
Action A2
Action A3
Romance R1
Romance R2
------------------------------
Second Normal Form
A database is in Second Normal Form
when it is in First Normal Form plus every non-primary key column in
the table must depend on the entire primary key, not just part of it,
assuming that the primary key is made up of composite columns.
That is, every non primary column
should be fully functionally dependent on primary key column. When a
non primary key column is partially dependent on primary key then it
is known as partial dependency. In 2nd normal form this
partial dependency is removed.
e.g
------------------------------------------------------------------------------
Employee_Name Project_Type
Employee_ID Project_ID
------------------------------------------------------------------------------
We rearrange it to convert it in Second
Normal Form
table 1:
------------------------------------------
Employee_Name Employee_ID
-----------------------------------------
table 2:
----------------------------------
Project_ID Project_Type
---------------------------------
Third Normal Form
A database is in Third Normal Form when
it is in Second Normal Form and each column that isn't part of the
primary key doesn't depend on another column that isn't part of the
primary key. This is known as Transitive Dependency,
which is a situation where a non-key column of a table is dependent
on another non-key column.
e.g
------------------------------------------------------------------------------------
Student_ID Student_Name
Course_Name Course_Duration
------------------------------------------------------------------------------------
>table 1
------------------------------------------------------------
Student_ID Student_Name Course_Id
------------------------------------------------------------
>table 2
------------------------------------------------------------
Course_Id Course_Name Course_Duration
------------------------------------------------------------
-K Himaanshu Shukla...
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