Can someone explain 2nd and 3rd normal forms? I have been through some literature. But I am still unclear.

Also, I am not sure what exactly is meant by functional dependency and transitive dependency. Can someone elaborate on this?

Thanks

There is a sequence to know the concepts in regard to 2nf and 3nf and that is as follows

1. Functinal dependecy(FD)
2. Full and partial functional dependency
3. Prime and Non-prime attributes
4. 2NF
5. Transitive dependency
6. 3NF

FD:Suppose there are 2 sets of attribute X and Y of a relation R and Y is said to be functionally dependent on X or functionally determines Y iff
t1[X]=t2[X] then t1[Y] must be equal to t2[Y].where t1 and t2 are two different tuples or rows of R.Now let me illustrate it through an example.
Consider there is a table with the following attributes
Designation Pay_scale Nameand
Designation->Pay_scale
here the arrow mark denotes that Designation functionally determines Pay_scale
We can say Designation is X attribute and Pay_scale is Y attribute.Now let me put some values into it
Designation Pay_scale Name
Lecturer 8000.00 Akshaya
Professor 20000.00 M.Prasad
Asst_prof 16000.00 N.patra
Lecturer 8000.00 Soma
Asst_prof 16000.00 M.Dash

Here in the above table u can see the values of Designation in (row1 and row4) and (row3 and row5) are same and so is the values of Pay_scale in the corressponding rows.But same is not true with Name attribute.This is all because Designation->Pay_scale

Full and Partial functional dependency:

A functional dependency X->Y is a full functional dependecy ,if removal of any attribute A from X means that the dependency doesn't hold any more that means (X-{A}) doesn't functionally determines Y.

Now consider the a table with following attributes and given FDs
SSN,PNUMBER,HOURS,ENAME,PNAME,PLOCATION
and
SSN->ENAME
PNUMBER->PNAME,PLOCATION
SSN,PNUMBER->HOURS

and SSN,PNUMBER combinely forms primary key for the table.

Here I would like to tell you primary key can determine all other attributes of a given table
Now in the above table even if you remove PNUMBER from Primary key,ENAME can be easily determined by SSN because SSN->ENAME(given) dependencies.And if SSN is removed From Primary key then also PNAME,PLOCATION can be easily determined by PNUMBER.This table doesn't satisfy the concept of full functional dependecy.
2NF:
Defn:A relation scheme R is in 2NF if every nonprime attribute A in R is fully functionally dependent on the primary key of R.
Now What is non prime attribute?
The attribute which is not a part of any candidate key.
Refer to the aforementioned table.All other attribute except SSN,PNUMBER
are non prime attributesSo this table is not in 2NF
If you break the above the above table into three different tables as follows then the problem would automatically solved

• SSN,PNUMBER,HOURS (SSN,PNUMBER is the primary key for this relation)
• SSN,ENAME(SSN is the primary key for this relation)
• PNUMBER,PNAME,PLOCATION(PNUMBER is the primary key for this relation)

Today I cannot explain you transitive dependecy and 3NF as I have got some other works in my hand.