##### Determine the highest normal form for the foll...

Determine the highest normal form for the following instance.

STUDENT | COURSE | INSTRUCTOR |
---|---|---|

Narayan | Database | Mark |

Smith | Database | Navethe |

Smith | Operating Systems | Ammar |

Smith | TOC | Schulman |

Wallace | Database | Mark |

Wallace | Operating Systems | Ahamad |

Wong | Database | Omiecinsky |

Zelaya | Database | Navathe |

(A) 1NF | |

(B) 2NF | |

(C) 3NF | |

(D) BCNF |

Hint:

First start with finding out the functional dependencies with the given snapshot of relation.

How is this in 3nf, plz explain? instructor-> course is a fd and there seems no other fd

i try here if we carefully see that the dependency : 1. student course -------> Instructor

2. Instructor--------> course

here candidate key : {student course} and prime attribute: {student, course}

so we find highest so start with BCNF : 1. follow

2. not follow

then comes to 3NF : 1. follow

2. follow

hence highest normal form is 3NF.

The two FDs in this instance are

{STUDENT, COURSE} → INSTRUCTOR,

INSTRUCTOR → COURSE

So, candidate keys are {STUDENT, COURSE} and {STUDENT, INSTRUCTOR}.

Therefore, all are prime attributes.

Now, as all the values are atomic, the instance is in 1NF.

2NF rule is that all non-prime attributes should be fully-functionally depend on each of the candidate keys.

As there are no non-prime attribute, the instance is in 2NF.

3NF rule is for each functional dependency left hand side should be a super-key and if not right hand side should be a prime attribute.

As all are prime attributes, so 3NF rule is also satisfied.

BCNF rule is for each functional dependency left hand side should be a super-key, which is not the case for FD: INSTRUCTOR → COURSE

Therefore, the instance is not in BCNF.

So, the highest normal form for the instance is 3NF.

Ma'am, is it correct to assume the functional dependencies like this? Because later there might be entries which violate these FDs. So looking at an instance we can't be sure which FDs hold, but we can only be sure which FDs do not hold.

from Navathe: