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with more than one attribute from another schema. We conclude with a discussion of
how to combine these three directions into a new, more powerful model of attribute
correspondences.
2
A Model for Attribute Correspondences
In this section, we present a simple model of attribute correspondences as a basis
for the proposed extensions. The model is based on
Marie and Gal
[
2008
]. We shall
accompany the description with a specific simplified case study that will assist us
in demonstrating the three extensions to the basic attribute correspondence model.
The case study is about the design of a hotel reservation portal. The portal merges
various hotel information databases, adding a mashup applications that assists in
positioning hotels on a geographical map.
We consider three relational databases, and we now provide a partial description
of the databases, as illustrated in Table
3.1
. Database
R
contains three relations,
CardInfo
,
HotelInfo
, and reservation information in the relation
Reservations
.
Database
S
stores data of a hotel chain
RoomsRUs
that separates information
of a store credit card from information of major credit cards. Therefore,
S
con-
tains the following two relations,
CardInformation
and
HotelCardInformation
.
It also contains reservation information in the relation
ReserveDetails
. Finally, a
database
T
contains urban information with two relations,
CityInfo
and
Subway
.
CityInfo
provides information about neighborhoods in cities and their approximate
GPS positioning whereas
Subway
provides similar information for subway stations.
In what follows, we use a path representation. An attribute A of a given relation R
in a given database D is referred to as D:R:A. For example,
R.CardInfo.cardNum
.
Tabl e 3. 1
Sample database schema description
Database
R
CardInfo
type
cardNum
lastName
firstName
securityCode
expiryMonth expiryYear
HotelInfo
hotelName
neighborhood city
Reservations
lastName
firstName
arrivalDate
numberOfDays
Database
S
CardInformation
type
cardNum
securityCode expiryMonth
expiryYear
HotelCardInformation clientNum
expiryMonth
expiryYear
ReserveDetails
clientNum
name
checkInDay
checkOutDay
Database
T
CityInfo
city
neighborhood GPSPosition
Subway
city
station
GPSPosition
