Re: Creating indexes on views/BCNF
Date: Wed, 16 Jan 2008 12:06:02 -0800 (PST)
On Jan 14, 5:38 pm, aehc..._at_ntu.edu.sg wrote:
> Is there a commercial RDBMS that allows one to create indices on
> I'm asking this partly because of BCNF.
> A typical BCNF problem is (where -> is a FD)
> A, B->C
> C -> B
> which becomes the following relations
> R_1 [_A_, _C_]
> R_2 [_C_, B]
> where _X_ denotes an attribute in the primary key
> R [_A_,_C_,B] is not in 2NF
> But there's an additional constraint where the equijoin of R_1 and
> on C would have the candidate key A,B.
> Is there a way to express this last constraint (i.e., a candidate key
> on a view) in an implementation system?
> Cecil Chua
Please forgive the self-promotion, but my article here: http://www.sqlservercentral.com/articles/Data+Modeling/61529/ is the 4th in a series of 5 articles on db design. It shows, specifically, how to implementa a multi-relvar constraint using an indexed view on MS SQL Server. I think there exists an analogous facility in Oracle, but I'm not sure about other DBMSs (such as MySQL).
TroyK Received on Wed Jan 16 2008 - 21:06:02 CET