With regards to our products relation example, the combination : (A composite key)įor our example, the list of super keys is shown below. 0 A super key is the set of one or more attribute that allow us to identify uniquely entity in an entity set. It provides a unique identifier for records, ensures data integrity, and optimizes database performance.
Simply put, this step will require that you identify all candidate keys and all composite keys from the list you made in step 1, and eliminate the ones that do not fall under this category. The Super Key in DBMS is a crucial aspect of database management. A bad FD happens when we have an attribute or set of attributes that functionally determine some but not all. This requirement simply entails that there cannot be the same attribute value for distinct tuples. Informally, we say a super key FD is a good FD. Next, from the list above, remove all combinations that are not in compliance with the super key requirement. List all sets of possible attributes combinations from the table, as shown below: It means a candidate key is obtained from a super key only. Thus, a super key is the superset of a key known as a Candidate key (discussed in the next section). The word super denotes the superiority of a key. Using the products relation above, we can perform the steps below to get the super keys of the relation. We can define a super key as a set of those keys that identify a row or a tuple uniquely.
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