Database Reference
In-Depth Information
Table 4. Set of Export fuzzy relation from databases DB
1
& DB
2
[
DB
1
]:
Emp
1
[
DB
1
]:
Dept
1
Name
Age
Hall
μ
r
Dname
HoD
Fund
μ
r
Jaya
.5/old
MT
.50
Chem.
Jaya
.63/low
.63
Apu
.5/mid
JCB
.50
Eco
Maya
.63/mod
.63
[
DB
2
]:
Emp
2
[
DB
2
]:
Dept
2
Name
Age
μ
r
Dname
Staff
HoD
Fund
μ
r
Jaya
.5/mid
.50
Eco
10
Maya
.6/mod
.60
Maya
.5/mid
.50
Chem.
15
Jaya
.63/mod
.63
In some way the merge operation is similar to an outer-union except that an additional source at-
tribute is added before they are outer-unioned. An integrated global fuzzy relation thus obtained by the
use of merge operation is given the name FTS relations. A set of such FTS relations is called Fuzzy
Multidatabase.
FTS Relational Operations
m
( )
be two fuzzy tuples in FTS relations
R
and
S
respectively where
a
R
and
a
S
denote fuzzy attributes values,
m
(
)
and
a
Let
a
,
m
(
a
),
s
,
(
a
),
s
R
R
R
a
R
s
S
s
a
s
(
a
),
m
(
a
)
denote their membership grades to
R
and
S
R
R
S
s
, denote their source export fuzzy database identifiers (
DB
id
s
). Let
T
be the FTS
relation obtained as a result of applying an FTS relational operation over
R
and/or
S
. FTS relational
algebraic operators are mounted with a flag
fs
respectively, and
s
s
a
a
R
S
fs fs
fs
fs
fs
fs
(
viz.
σ π
DD
∪ ∩ −
and fuzzy relational algebraic op-
,
,
,
,
, )
fs fs
fs
fs
fs
fs
erators are mounted with a flag
f
viz.
σ π
DD
∪ ∩ −
to distinguish them from each other.
Now, we introduce the formal definition of FTS relational operators as follows:
(
,
,
,
,
, )
fs
fs
{
}
=
(
)
Definition: FTS
select
( )
σ
:
T
=
σ
( )
R
a
,
µ
(
a
),
s
|
p
(
a s
,
)
∧
µ
(
a
)
≥
β
p
,
α β
,
R
R
R
a
R
α
R
a
R
R
R
a
( , )
is a fuzzy predicate that uses fuzzy comparison operators. Value of α is used while
deciding α-resemblance of two fuzzy values in the predicate. The predicate may involve both fuzzy and
where,
p a s
R
a
R
Table 5. FTS Relations: Level-0 Integration of DB
1
& DB
2
Emp
=merge(
Emp
1
,
Emp
2
)
Dept
=merge(
Dept
1
,
Dept
2
)
Name
Age
Hall
μ
r
source
Dname
Staff
HoD
Fund
μ
r
source
Jaya
.5/old
MT
.50
DB
1
Chem.
Null
Jaya
.63/low
.63
DB
1
Apu
.5/mid
JCB
.50
DB
1
Eco
Null
Maya
.63/mod
.63
DB
1
Jaya
.5/old
Null
.50
DB
2
Eco
10
Maya
.6/mod
.60
DB
2
Maya
.5/mid
Null
.50
DB
2
Chem.
15
Jaya
.63/mod
.63
DB
2
