Database Reference
In-Depth Information
Figure 6.
a. The SELECT clause of Sub-Fuzzy query Template is assigned the list of R's attributes that
appears in the SELECT clause or join predicates of the Global Fuzzy query, including those
which appear in the
aggregate
functions.
b. Selection and join predicates using R's attributes in the Global Fuzzy query are propagated
to Sub-Fuzzy query Template.
c. The FROM clause of Sub-Fuzzy query Template is assigned R.
2. For the inter-global relation
join
predicates in the WHERE clause of Global Fuzzy query, the
projec-
tions
are retained in WHERE clause of Global Fuzzy query Residue. The clause WITH SOURCE
CONTEXT is also retained, however, processed at last.
3. The values of α and β in the HAVING clause of the global fuzzy query are assigned to the having
clause of all the sub-queries.
Example:
Consider here again a similar fuzzy query as in above Example but with
anyDB
option
attached to WHERE clause. Thus, a new global fuzzy query Qb has been formulated which is decom-
posed as shown in Figure 6.
It can be shown that the join predicate
T Name EQ T HoD
1
. .
a
can't be evaluated before the two
Global FTS-relations Dept and
Emp
are derived. Nevertheless, the selection predicate
2
