Decomposing into 2NF I'm currently studying normalization. I know how to normalize the data for given unnormalized list. 

But I found this question in our past papers. I don't know how to answer to it. 

Q. Decompose R{a,b,c,d,e,f} into 2NF using following functional dependencies. 

a -&gt; b,c,d,e,f 
b,c -&gt; a,d,e,f 
b -&gt; f 
d -&gt; e 


Please can anyone tell me how to do this? I went through some earlier questions,
but still have doubts.

For this my answer is:

      R0 = a - &gt; b,c
      R1 = b,c - &gt; a,d,e
      R2 = b - &gt; f
Keep the simple dependencies as is:

b -&gt; f
d -&gt; e


Remove the dependent columns from the other dependencies.

a -&gt; b,c,d 
b,c -&gt; a,d 


At this point you have two candidate keys a and b,c.  As we already have a dependency on b.  I would keep the b,c dependency and drop the dependency on a.  It would appear that b,c defines a weak entity (or repeating group) related to b.  I would consider creating a unique key on a.