H. Mannila and K.-J. R#ih#. Design of Relational Databases. AddisonWesley Publishing Company, Wokingham, UK, 1992.  Home/Search   Document Not in Database   Summary   Related Articles

....can be found using the above algorithm. Several choices of the specialization relation are possible, and the number of iterations in the outermost loop of the algorithm depends on that choice. Example 7 Consider the discovery of all inclusion dependencies that hold in a given database instance [17, 21, 24]. Given a database schema R, an inclusion dependency over R is an expression R[X] S[Y ] where R and S are relation schemas of R, and X and Y are equal length sequences of attributes of R and S, respectively, that do not contain duplicates. Suppose r is a database over R, and let r and s be ....

....dependency is an expression X B, where X R and B 2 R. Such a dependency is true in the relation r, if for all pairs of rows t; u 2 r we have: if t and u have the same value for all attributes in X, they have the same value for B. For various algorithms for nding such dependencies, see [3, 24, 25, 26, 32]. Functional dependencies with a xed right hand side B can be found using the levelwise algorithm by considering the set of sentences fX j X Rg; and the selection predicate q: q(r; X) is true if and only if X B holds in r. The specialization relation is then the reverse of set inclusion: ....

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H. Mannila and K.-J. R#ih#. Design of Relational Databases. AddisonWesley Publishing Company, Wokingham, UK, 1992.

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