BCS 260 Lecture Notes - Lecture 5: Candidate Key, Functional Dependency, Foreign Key
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A functional dependency occurs when a candidate key determines all the other attributes in a relation. In other words, all the attributes in a relation is functionally dependent on the candidate key. A dependency is shown with the determinant on the left and then an arrow showing the attribute(s) that depend on it, as shown below. Learn to apply a process for normalizing relations. Steps in the normalization process are as follows: identify all the candidate keys of the relation, identify all the functional dependencies in the relation, examine the determinants of the functional dependencies. If any determinant is not a candidate key, the relation is not well formed. Every determinate (lhs) must be a candidate key. Any relation that is not well formed should be broken into two or more relations that are well formed (we"ve seen this breaking down our spreadsheet line items) A relation is in first normal form (1 n f) if it:
