Database Reference
In-Depth Information
fs
Definition: FTS intersection
( )
(
)
µ
( .
t A t A
,
. )
≥ ∧
α µ
( . ) max
t A
=
µ
( . ),
t A
µ
(
t A
. )
fs sameDB
EQ
R
T
T
R R
(
)
1
1
T
= ∩
R
S
=
t A
.
,
µ
(
t
. ), .
A t s
β
( .
t s
= ≠ ∗ ∧
t
)
µ
( .
t A t A
,
. )
≥ ∧
α µ
( . ) max
t A
=
α β
,
1
T
R
EQ
S
T
1
1
(
) ≥ ∧
µ
( . ),
t A
µ
( .
t A
)
β
( .
t s
= ≠ ∗
t
)
T
S
S
S
1
fs anyDB
f
f
f
f
f
f
T
= ∩
R
S
=
( .
t A
,
µ
( . ),
t A smerge
(
π
(
σ
(
R
S
)))) .
t A
((
π
R
)
(
π
S
))
s
,
β
µ
( , . )
A t A
β
A
,
α β
,
A
,
α β
,
α β
,
α β
,
2
T
EQ
1
fs
Definition: FTS minus
( )
(
)
µ
( .
t A t A
,
. )
≥ ∧
α µ
( . ) max
t A
=
µ
( . ),
t A
µ
(
t A
. )
fs sameDB
EQ
R
T
T
R R
(
)
1
1
T
= ∩
R
S
=
t A
.
,
µ
( . ), .
t A t s
β
( .
t s
=
t
≠ ∗ ∧
)
µ
( .
t A t A
,
. )
< ∧
α µ
( . ) max
t A
=
α β
,
1
T
R
EQ
S
T
1
1
(
) < ∧
µ
( . ),
t A
µ
( . )
t A
β
(
t s
.
= ≠ ∗
t
)
T
S
S
S
1
fs anyDB
f
f
f
f
f
T
= ∩
R
S
=
( .
t A
,
µ
( . ),
t A smerge
(
π
(
σ
R t A
))) .
((
π
R
)
α β
(
π
S
))
s
,
β
µ
( , . )
A t A
α
A
,
α β
,
,
A
,
α β
,
α β
,
2
T
EQ
1
Remark: In definition of union, intersection, & minus , A is set of fuzzy attributes that are common
to R and S . Default value of α and β is 1.
FTS-SQL: AN EXTENSION OF SQL
Many users usually have their data in several databases and frequently need to jointly manipulate data
from different databases. For example: a traveler looking for cheapest route may need to fuzzy query
several airline, rail, and bus databases. The manager of a company may need to see the account balances
that the company has at different bank branches. Therefore, he would like to fuzzy query all the relevant
bank databases and his own databases.
Formulation of such a fuzzy query needs functions that do not exist in classical data manipulation
languages such as SQL, which is designed to manipulate data in a single database. Classical SQL deals
with single relation as an object of manipulation where as the current need is to allow sets of relations
as the objects. A system for the manipulation of data in autonomous databases is called a multidatabase
system (MDBS) and the corresponding language is called a multidatabase manipulation language (MML)
(Litwin W. et al, 1982). Databases may be manipulated together without global integration is called
interoperable (Litwin and Abdellatif, 1986). (Litwin, Abdellatif, Zeroual and Nicolas, 1989) present
the multidatabase extension of SQL called MSQL that contains new functions designed for nonproc-
edural manipulation of data in different and nonintegrated SQL databases. A theoretical foundation for
such languages has been proposed in (Grant, Litwin, Roussopoulos and Sellis, 1993) by presenting a
multirelational algebra and calculus based on relational algebra and calculus. In (Lee, Jeong-Oog, Baik
and Doo-Kwon, 1999) a semantic fuzzy query language, SemQL, has been provided to enable users
to issue queries to a large number of autonomous databases without prior knowledge of their schema.
(Juan Lavariega, Susan and Urban, 2002) presents an unique approach to fuzzy query decomposition in
a multidatabase environment which is based on performing transformations over an object algebra that
can be used as the basis for a global fuzzy query language.
 
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