database - Decomposing a relation into 3NF, how do separate the relation? -


given relation, r = abcde

and set of fd's:

ab > c de > c b  > d

i'm able find candidate key abe (correct?)

i need decompose relation r 3nf.

what don't understand is, measure decompose? figure take candidate key , fd's in consideration, specific process? i've looked @ has been dense me apply small problem.

abe candidate key.

start tests 1nf, , show existing relation r satisfies 1nf. when find normal form r not satisfy, fix it.

for example, in testing 2nf, see fd ab->c partial key dependency. (abe candidate key; c dependent on part of key.) use projection remove c r.

  • r { abe cd} started with. after removing c projection have
  • r1 { abe d}, and
  • r2 { ab c}

repeat until tables in 5nf. (r1 not in 2nf; r2 in 5nf.)


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