Normalization: First Normal Form (1NF) Functional Dependency Second Normal Form (2NF) Third Normal Form (3NF)

1. Database Management System
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2.  First Normal Form (1NF)
 Functional Dependency
 Second Normal Form (2NF)
 Third Normal Form (3NF)
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3. NAMHIN

4. Normalization is a process of organizing the data in database to avoid data
redundancy, insertion anomaly, update anomaly, deletion anomaly and
make it more efficient and error free.
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5. Normalization ensures:
 The database is structured in the best possible way.
 To achieve control over data redundancy.
 To ensure data consistency.
 To ensure tables have a flexible structure.
 To allow data in different tables can be used in complex queries.
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6. NORMALIZA
TION
First normal form(1NF)
Second normal form(2NF)
Third normal form(3NF)
& so on….
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8.  Place all items that appear in the repeating group in a new table
 Designate a primary key for each new table produced.
 Duplicate in the new table the primary key of the table from which the repeating
group was extracted or vice versa.
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9. Book_Company
Author
Publication
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11.  A relation is in 2NF if it is in 1NF, and every non-key attribute is fully
dependent on each candidate key.
 2NF (and 3NF) both involve the concepts of key and non-key attributes.
 A key attribute is any attribute that is part of a key;
 Any attribute that is not a key attribute, is a non-key attribute.
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12. LineNum ProdNum QtyInvNum
InvNum, LineNum ProdNum, Qty
InvDate
Since there is a determinant that is not a
candidate key, InvLine is not BCNF
InvLine is not 2NF since there is a partial
dependency of InvDate on InvNum
InvDateInvNum
Qty is the only non-key attribute, and it is
dependent on InvNum
InvLine is only in 1NF
There are two candidate keys.
Consider this InvLine table (in 1NF)
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13. SECOND NORMAL FORM
LineNum ProdNum QtyInvNum InvDate
InvLine
The above relation has redundancies: the invoice date is
repeated on each invoice line.
We can improve the database by decomposing the relation
into two relations:
LineNum ProdNum QtyInvNum
InvDateInvNum
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14. Is the following relation in 2NF.
inv_no line_no prod_no prod_desc qty
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16.  A relation is in 3NF if the relation is in 1NF and all determinants of non-
key attributes are candidate keys.
 A relation in 3NF will not have any transitive dependencies.
 of non-key attribute on a candidate key through another non-key
attribute.
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17. EmpName, DeptNum, and DeptName are non-key attributes.
DeptNum determines DeptName, a non-key attribute, and
DeptNum is not a candidate key.
EmpNum EmpName DeptNum DeptName
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18. EmpNum EmpName DeptNum DeptName
We correct the situation by decomposing the original relation
into two 3NF relations. Note the decomposition is lossless.
EmpNum EmpName DeptNum DeptNameDeptNum
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20. We say an attribute, B, has a functional dependency on another attribute, A,
if for any two records, which have the same value for A, then the values for
B in these two records must be the same.
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21. A full functional dependency is a state of database
normalization that equates to the normalization standard of
Second Normal Form (2NF). In brief, this means that it
meets the requirements of First Normal Form (1NF), and
all non-key attributes are fully functionally dependent on
the primary key.
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22. A partial dependency exists when an attribute B is
functionally dependent on an attribute A, and A is a
component of a multipart candidate key.
InvNum LineNum Qty InvDate
Candidate keys: {InvNum, LineNum} InvDate is
partially dependent on {InvNum, LineNum} as
InvNum is a determinant of InvDate and InvNum is
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23. Consider attributes A, B, and C, and where
A  B and B  C.
Functional dependencies are transitive, which means that we also
have the functional dependency A  C
We say that C is transitively dependent on A through B.
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24. EmpNum EmpEmail DeptNum DeptNname
EmpNum EmpEmail DeptNum DeptNname
DeptName is transitively dependent on EmpNum via DeptNum
EmpNum  DeptName
EmpNum  DeptNum
DeptNum  DeptName
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