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Hi all, hope this is the right forum. Please feel free to move it otherwise:
I am confused on whether functional dependence can be determined uniquely by the particulars of a given table, or if it is determined in a more general sense
So I have my relational table. Let A,B be attributes , i.e., different fields. My working definition of B being functionally-dependent on A is that each value of A is associated with exactly one value of B. Now, A may
functionally determine B in a specific table, but not in all tables. So which definition do we use, the one
associated to the specific table, or the more general one?
Specific case:
Now I have in my table the fields OH (On Hand), and the field WN (Warehouse Name) , and in my table, OH determines WN:. In this particular table, there is only one repeated value for OH , the value 8 , specifically, and it happens to be the case that both values 8 are associated with the same warehouse name. In this sense, OH functionally determines WN, since knowing the value of OH uniquely-determines the 'value' WN. But it is absurd to believe this can be generalized: clearly there may be cases where there are the same number of products in two-or-more databases. So, can I then conclude that OH functionally determines WN or not?
Thanks.
I am confused on whether functional dependence can be determined uniquely by the particulars of a given table, or if it is determined in a more general sense
So I have my relational table. Let A,B be attributes , i.e., different fields. My working definition of B being functionally-dependent on A is that each value of A is associated with exactly one value of B. Now, A may
functionally determine B in a specific table, but not in all tables. So which definition do we use, the one
associated to the specific table, or the more general one?
Specific case:
Now I have in my table the fields OH (On Hand), and the field WN (Warehouse Name) , and in my table, OH determines WN:. In this particular table, there is only one repeated value for OH , the value 8 , specifically, and it happens to be the case that both values 8 are associated with the same warehouse name. In this sense, OH functionally determines WN, since knowing the value of OH uniquely-determines the 'value' WN. But it is absurd to believe this can be generalized: clearly there may be cases where there are the same number of products in two-or-more databases. So, can I then conclude that OH functionally determines WN or not?
Thanks.