Database Reference
In-Depth Information
Box 2.
Fuzzy queries with the syntax:
SELECT <attributes> FROM <tables> WHERE <fuzzy condition>
Queries with fuzzy conditions in partitioning:
SELECT <attributes> FROM <tables> WHERE <condition>
GROUP BY <attributes> HAVING <quantified fuzzy condition>
Updates with fuzzy condition:
UPDATE <table> SET <attribute>= <value> WHERE <fuzzy condition>
Queries with fuzzy subquery at FROM clause:
SELECT <attributes> FROM <fuzzy subquery> AS <alias>
WHERE <fuzzy condition>
Fuzzy Set operations:
(<Q1> INTERSECT/UNION/EXCEPT <Q2>)
where,
At least one of the queries (Q1 or Q2) is a fuzzy subquery.
A <fuzzy condition> is a fuzzy logic expression of the form:
<exp> = <pred>
or
(<fuzzy condition>)
or
NOT <fuzzy condition>
or
<fuzzy condition> <conn> <fuzzy condition>
where
<exp>
is a traditional SQL value expression
<pred>
is a fuzzy predicate term that may be:
an user defined fuzzy predicate identifier <name>
a combination <mod><pred>, being <mod> the name of a user defined
modifier or a built-in modifier ANT/NOT
<conn>
is a fuzzy logic connector that may be:
a built in fuzzy logic operator AND/OR
a <name> identifying an user defined fuzzy connector
A <quantified fuzzy condition> is a fuzzy logic expression of the form:
<quant> ARE <fuzzy condition>
where
<quant>
is a <name> identifying an user defined fuzzy quantifier
The main thing is that the fuzzy catalog is composed of system tables and we can maintain or view
them trough sentences of the standard SQL, with the constraints of the RDBMS and system privileges.
The general algorithm to process a SQLf-DML with a fuzzy term would be:
