wrk of database

 wrk of database Article

1. Describe the associations that would be produced by the following relational algebra operations a) ПhotelNo(σprice> 100(Room))

It can produce a sole attribute (hotelNo) giving the amount of hotels place prices increased 100. b) σHotel. hotelNo=Room. hotelNo(Hotel By Room)

A join produce of resort and area containing each of the attributes of both equally. c) ПhotelName(Hotel Hotel. hotelNo=Room. hotelNo (σprice> 100(Room))) This can be a join of hotel and room together with the price more than 100. d) Guest(σdateTo> '1-June-12'(Booking)

It produces a join of guest and booking with an end date greater than Summer 12.

2 . Provide the equal tuple relational calculus expressions for each in the relational algebra queries given in question 1 a) ПhotelNo(σprice> 100(Room))

TRC: Room(R) /\ R.price > 100

b) σHotel. hotelNo=Room. hotelNo(Hotel Times Room)

TRC: Hotel(H) /\ (R) (Room(R) /\ (H.hotelNo = R.hotelNo)) c) ПhotelName(Hotel Resort. hotelNo=Room. hotelNo (σprice> 100(Room))) TRC: H.hotelName d) GuestσdateTo> '1-June-12'(Booking)

TRC: G.guestNo, G.guestName, G.guestAddress, B.hotelNo, B.dateFrom, B.dateTo, B.roomNo

three or more. Describe the relations that might be produced by the following tuple relational calculus expressions: a) H.hotelName

This will likely produce a regards containing what they are called of all hotels in London. b) H.hotelName This will produce a relationship containing the names of all accommodations that have a room price over 80. c) H.hotelName This will likely produce a relation containing what they are called of all hotels that have a booking to get a guest named Mike Brownish.

4. Generate the relational...

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