chaitra murthy

 Profile Answers by chaitra murthy 

• Feb 16th, 2009

 

1st Normalization specifies  if and only if all the attributes of the relation R are atomic in nature.
Ex: First (Empno, Prjno, Prjname, Noof Hours, Empname)
Empno: Employee number
Prjno: Project number
Prjname: Project name
NoofHours: Specifies that Employee has worked on each project
Empname: Employee name.
In the above ex, Imagine that employee has worked on mroe than one project. So you will have multiple values for prjno,prjname and Noofhours filelds. This will put in separate row for each column. So table is reduced to 1st Normal form.

2nd Normalization specifies that  table should be in
>1st normal form
>Every Non key column is fully dependent upon the primary key.
>Partial dependency should be eliminated.
So now you will have 3 tables:-
first_1(empno,prjno,noofhours) [Every Non key column is fully dependent upon the primary key]                            
first_2(empno,empname) [Partial dependency should be eliminated]
first_3(prjno,prjname) [Partial dependency should be eliminated]

Hope its clear.

anushandilya123

 Profile Answers by anushandilya123 

• May 8th, 2009

 

For a relation to be in 1st NF the relation should contain atomic attributes
only that is they must be single-valued. If its not so break the composite
attribute into its parts and for multivalued duplicate the tuple with all its
multiple values.
For a relation to be in 2nd NF full functional dependency should exist rather
than partial dependency.