Sciences Informatiques

Question 15

1 min de lecture

Algèbre

% base de données question 3
@let TRIPS = @relation [Date, Number_Plate, Driver, Destination, Departure_Time] {
  < 15/10/2001,   DDT 123,    John,   Antwerp Zoo,        09.00 >
  < 15/10/2001,   LPG 234,    Tim,    Ostende Beach,      08.00 >
  < 16/10/2001,   DDT 123,    Tim,    Dinant Citadel,     10.00 >
  < 17/10/2001,   LPG 234,    John,   Antwerp Zoo,        08.15 >
  < 17/10/2001,   DDT 123,    Tim,    Antwerp Zoo,        08.15 >
  < 18/10/2001,   DDT 123,    Tim,    Brussels Atomium,   09.20 >
}
 
@let BUSES = @relation [Number_Plate, Chassis, Make, Mileage]{
  < DDT 123,    XGUR6775,   Renault,    212 342 >
  < LPG 234,    ZXRY9823,   Mercedes,   321 734 >
  < RAM 221,    XXZZ7345,   Renault,     10 000 >
}
 
@let DESTINATIONS = @relation [Name]{
  < Antwerp Zoo       >
  < Ostende Beach     >
  < Dinant Citadel    >
  < Brussels Atomium  >
}
 
 
@let result = @project {Driver} (@select{Make='Renault'} BUSES @join @select{Destination='Antwerp Zoo'} TRIPS)
 
@print result

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